Impinj, Inc.

Patent Trials and Appeals Board

Aug 27, 2021

IPR2020-00556 (P.T.A.B. Aug. 27, 2021)

Trials@uspto.gov Paper No. 52
571.272.7822 Date: August 27, 2021

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

NXP USA, INC.,
Petitioner,

v.

IMPINJ, INC.,
Patent Owner.
____________

IPR2020-00556
Patent 9,031,504 B1
____________

Before BRIAN J. McNAMARA, ROBERT J. WEINSCHENK, and
KEVIN C. TROCK, Administrative Patent Judges.

TROCK, Administrative Patent Judge.

JUDGMENT
Final Written Decision
Granting-in-Part and Denying-in-Part
Patent Owner’s Motion to Amend
35 U.S.C. § 318(a)

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INTRODUCTION
We have authority to hear this inter partes review under 35 U.S.C.
§ 6. This Final Written Decision issues pursuant to 35 U.S.C. § 318(a) and
37 C.F.R. § 42.73. For the reasons discussed herein, Patent Owner’s Non-
Contingent Motion to Amend is granted-in-part as to the cancellation of
claims 1, 2, 4, 7–10, 13–15, 17–19, and 21 (the “challenged claims”) of U.S.
Patent No. 9,031,504 B1 (Ex. 1002, “the ’504 patent”), and denied-in-part as
to proposed substitute claims 22–35 (the “substitute claims”).
A. Procedural History
NXP USA, Inc. (“Petitioner”) filed a Petition for inter partes review
of claims 1, 2, 4, 7–10, 13–15, 17–19, and 21. Paper 1 (“Pet.” or “Petition”).
Impinj, Inc. (“Patent Owner”) filed a Preliminary Response, Paper 10
(“Prelim. Resp.”). We instituted inter partes review of all challenged claims
on the grounds presented in the Petition. Paper 15 (“Institution Decision” or
“Dec.”).
After institution, Patent Owner filed a Non-Contingent Motion to
Amend, cancelling all the challenged claims and proposing substitute claims
22–35. Paper 25 (“Mot. to Amend.”). Petitioner thereafter filed an
Opposition to the Motion to Amend. Paper 30 (“Pet. Opp.”). We then
issued Preliminary Guidance to Patent Owner’s Non-Contingent Motion to
Amend. Paper 31 (“Prelim. Guid.”). Patent Owner filed a Reply in support
of the Non-Contingent Motion to Amend. Paper 32 (“PO Reply”). With our
authorization, Petitioner filed a Supplemental Opposition to Patent Owner’s
Non-Contingent Motion to Amend. Paper 38 (“Pet. Supp. Opp.”). Patent
Owner filed a Response to Petitioner’s Supplemental Opposition. Paper 41
(“PO Resp. to Supp. Opp.”). Petitioner filed a Sur-Reply to Patent Owner’s
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Reply in support of the Non-Contingent Motion to Amend. Paper 42 (“Pet.
Sur-Reply”).
An oral hearing was held on May 18, 2021. A transcript of the
hearing is included in the record. Paper 51 (“Tr.”).
Subsequent to the hearing, Patent Owner filed, with our authorization,
a Revised Non-Contingent Motion to Amend. Paper 49 (“Rev. Mot. to
Amend.”). Petitioner filed a response to Patent Owner’s Revised Non-
Contingent Motion to Amend. Paper 50 (“Pet. Resp. to Rev. Mot. to
Amend.”).
B. Related Proceedings
According to the parties, the ’504 patent is the subject of the
following action: Impinj, Inc. v. NXP USA, Inc., No. 4:19-cv-03161-YGR
(N.D. Cal.) filed June 6, 2019. Pet. 60; Paper 4, 2–3. The parties
acknowledge that Petitioner has filed another petition (IPR2020-00554)
challenging the ’504 patent. Paper 4, 3; see Pet. 61. The parties also
identify IPR petitions Petitioner has filed against other family members of
the ’504 patent. Paper 4, 3–4; Pet. 61. The following table identifies these
inter partes review case numbers and their respective patent numbers:
Case No. U.S. Patent No.
IPR2020-00514 9,471,816 (“the ’816 patent”)
IPR2020-00516 9,633,302 (“the ’302 patent”)
IPR2020-00519 8,115,597 (“the ’597 patent”)
IPR2020-00543 9,495,631 (“the ’631 patent”)
IPR2020-00544 8,344,857 (“the ’857 patent”)
IPR2020-00552 8,600,298 (“the ’298 patent”)
IPR2020-00553 the ’298 patent
IPR2020-00554 9,031,504 (“the ’504 patent”)
IPR2020-00589 10,002,266 (“the ’266 patent”)
See Paper 4, 3–4.
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C. The ’504 Patent (Ex. 1002)
The ’504 patent relates to Radio Frequency Identification (“RFID”)
systems that use a RFID reader to interrogate a RFID tag attached to an
object. Ex. 1002, 1:19–22, 1:30–31. In a RFID system, a RFID reader may
transmit an interrogating RF wave. Id. at 1:31–32, 4:40–41, Fig. 1. A RFID
tag in the vicinity may sense the RF wave and respond by transmitting back
another RF wave that the RFID reader may then sense and interpret. Id. at
1:32–34, 4:41–44, Fig. 1. The ’504 patent recognizes, however, that an
interrogating RF wave may experience distortion due to interference caused
by, for example, other RF signals sent from nearby mobile devices. Id. at
1:55–61. As a result, when the RFID tag circuit converts the received RF
wave into a received signal, that signal may also be distorted. Id. at 1:62–
64. “The distorted signal may cause false bits to be detected by the RFID
tag, which in turn can result in the RFID tag not being able to detect the
interrogating RF wave reliably, or parse its commands.” Id. at 1:64–67. For
example, the RFID tag circuit may include a demodulator that receives the
distorted RF input signal and converts it to a digital output signal that also
includes distortion. Id. at 8:18–23, Fig. 7 (item 742). Due to the distortion,
the digital output signal may include an artifact feature that is received and
interpreted by a processor such that the processor may not respond exactly
as intended. Id. at 8:28–33, Fig. 7 (item 744).
To address this problem, the ’504 patent describes an interference
rejection filtering circuit (“IRF”) for filtering a received RF signal to remove
any artifact features from the signal and generating a filtered output that
does not include artifact features. Id. at 1:14–16, 10:14, 10:16–19. Figure 9
of the ’504 patent is reproduced below.
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Figure 9, above, depicts a partial block diagram of a RFID tag circuit
including a first circuit (e.g., demodulator) 942, an IRF 968 with a filter
portion 969, and a processor 944 for generating filtered output 972 from
unfiltered input 971. Id. at 9:54–58. Filter portion 969 may identify features
of unfiltered input 971 and apply them to a first criterion related to time
duration to determine whether the feature is an artifact arising from a
distortion due to interference. Id. at 10:43–47, 11:6–10. Features that meet
the first criterion may be detected as artifact features and may be removed
from filtered output 972, whereas features that do not meet the first criterion
may be deemed legitimate and included in filtered output 972. Id. at 10:45–
51.
Responsive to received periodic samples such as a clock signal CLK,
a counter may count an artifact number for the time duration of an identified
feature while the identified feature is taking place. Id. at 11:22–26, Fig. 10.
The first criterion may be met if the artifact number is less than a low
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number, which corresponds to a low threshold time. Id. at 11:21–29, see
also id. at 13:11–14.
Figure 12A of the ’504 patent is reproduced below.

Figure 12A, above, depicts how an unfiltered digital signal input 1210 can
be rendered over time. Id. at 12:24–25. Signal 1210 is digital—meaning
that it has two extreme values (high and low) as well as transitions between
them. Id. at 12:26–27. In signal 1210, low going pulses 1212, 1214, and
1216 can be identified by their respective transitions from high-to-low and
then low-to-high. Id. at 12:40–41. According to the figure, pulses 1212 and
1216 meet a low time duration threshold and, thus, are retained, whereas
pulse 1214 does not meet the threshold and, thus, is detected as an artifact
and rejected. Id. at 12:41–44.
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Figure 12B of the ’504 patent is reproduced below.

Figure 12B, above, depicts a filtered output generated as a reconstructed
signal 1260 from the unfiltered input of Figure 12A. Id. at 12:48–49. As
noted by comment 1264, there is no pulse corresponding to pulse 1214 of
signal 1260 because the artifact feature associated with that pulse has been
rejected. Id. at 12:55–58.
IRF 968 of the ’504 patent’s RFID tag circuit can also reject features
of duration longer than a high threshold time. Id. at 14:23–30, 14:42–52.
Figure 14B of the ’504 patent is reproduced below.

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Figure 14B, above, “is a diagram showing another possible characteristic
1440 of IRF 968.” Id. at 14:42–43.
The filter with characteristic 1440 is configured to accept
features within a preset range between a low threshold time
1446, which occurs at a time TMIN4, and a high threshold time
1448, which occurs at a time TMAX4 . . . . Any features with
duration less than TMIN4 or more than TMAX4 are rejected as
artifact features. As such, characteristic 1440 enables rejection
of both short features as well as features that are too long.
Id. at 14:43–52.
Also according to the ’504 patent, the time duration threshold may be
adjusted based on information associated with a RF input signal, such as a
preamble, a received packet, a filtered output signal, a data rate, or an
expected next packet. See, e.g., id. at 10:53–55, 14:60–61, 15:15–27, 16:60–
61, 17:13–18, 17:37–39, 18:1–14, 18:42–44, Figs. 15, 20, 22, 23B.
D. Cancelled Claims 1, 2, 4, 7–10, 13–15, 17–19, and 21
Our rules provide for cancellation of challenged claims. See 37
C.F.R. § 42.121(a)(3) (2019) (“A motion to amend may cancel a challenged
claim”). Patent Owner’s Non-Contingent Motion to Amend requests
cancellation of all the challenged claims: 1, 2, 4, 7–10, 13–15, 17–19, and
21.1 Paper 25, 5; Paper 49, 5. Patent Owner’s counsel also confirmed at the
oral hearing that it intended to cancel all of the challenged claims. Paper 51,
5:19–6:9. Petitioner does not oppose Patent Owner’s request. Therefore, we

1 In a non-contingent motion to amend, “the Board provides a final decision
on the patentability of substitute claims in place of determining the
patentability of corresponding original claims.” Notice Regarding a New
Pilot Program Concerning Motion To Amend Practice and Procedures in
Trial Proceedings Under the America Invents Act Before the Patent Trial
and Appeal Board, 84 Fed. Reg. 9497, 9505 (Mar. 15, 2019).
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grant Patent Owner’s non-contingent request to cancel claims 1, 2, 4, 7–10,
13–15, 17–19, and 21 of the ’504 patent.
E. Proposed Substitute Claims 22–35
Proposed substitute claims 22, 30, and 33 are independent, with
proposed substitute claims 23–26 depending from claim 22, proposed
substitute claims 27–28 depending from claim 26, proposed substitute claim
29 depending from claim 27, proposed substitute claims 31–32 depending
from claim 30, and proposed substitute claims 34–35 depending from claim
33. Proposed substitute claims 22 and 30 recite a method for a Radio
Frequency Identification (RFID) tag circuit, and proposed substitute claim
33 recites a Radio Frequency Identification (RFID) tag circuit. Claim 22 is
proposed as a substitute for cancelled claim 1 and is set out below, showing
added language underlined and deleted language struck out.
[22-pre] A method for a Radio Frequency Identification (RFID)
tag circuit comprising:
[22-a] receiving a modulated wireless RF input signal; deriving
a first digital output signal responsive to the modulated wireless
RF input signal, wherein the first digital output signal
comprises a sequence of digital pulses;
[22-b1] filtering the first digital output signal with an
interference rejection circuit of the tag circuit to derive a second
digital output signal by: receiving the first digital output signal;
[22-b2] generating artifact numbers by counting time durations
of the digital pulses;
[22-b3] setting a filter pass range to detect a delimiter, detecting
the delimiter
[22-b4] detecting an expected next packet after the delimiter
[22-b5, b6] adjusting the filter pass range based on an aspect of
the expected next packet, wherein deriving a the second digital
output signal comprises responsive to the first digital output
signal at an interference rejection circuit of a RFID tag circuit
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by substantially removing retaining digital pulses with artifact
numbers less than a first low number within the pass range
while substantially retaining and removing digital pulses with
artifact numbers greater less than the first low number pass
range, wherein the first low number corresponds to a first time
duration threshold.
Paper 25, App. A (bracketed designations added).
F. Evidence
Petitioner relies upon the following evidence to challenge the
patentability of the proposed substitute claims:
(1) U.S. Patent Application Publication No. US 2006/0244598 A1,
published November 2, 2006 (“Hyde ’598”) (Ex. 1005);
(2) U.S. Patent Application Publication No. US 2002/0152044 A1,
published October 17, 2002 (“Shanks”) (Ex. 1006);
(3) U.S. Patent No. 3,997,798, issued December 14, 1976
(“Breimesser”) (Ex. 1007);
(4) U.S. Patent No. 4,779,077, issued October 18, 1988 (“Lichtblau”)
(Ex. 1008);
(5) EPC™ Radio-Frequency Identity Protocols Class-1 Generation-2
UHF RFID Protocol for Communications at 860 Mhz – 960 Mhz Version
1.0.9, EPCglobal, Inc. (January 2005) (“Gen2”) (Ex. 1015);
(6) First Declaration of Dr. Travis Blalock, dated February 10, 2020
(Ex. 1003); and
(7) Second Declaration of Dr. Travis Blalock, dated February 2, 2021
(Ex. 1020).
Patent Owner relies upon the following evidence in support of the
patentability of the proposed substitute claims:
(1) First Declaration of Dr. James Kenney, dated May 20, 2020
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(Ex. 2001); and
(2) Second Declaration of Dr. James Kenney, dated March 16,
2021 (Ex. 2009).
G. Asserted Grounds of Unpatentability
Petitioner challenges the patentability of the proposed substitute
claims on the following grounds:
Claims Challenged 35 U.S.C. § References
22–35 103(a) Shanks, Breimesser, Lichtblau,
Gen2
22–35 102(b) Hyde ’598 2

ANALYSIS
A. Principles of Law
In an inter partes review, amended claims are not added to a patent as
of right, but rather must be proposed as a part of a motion to amend.
35 U.S.C. § 316(d). The Board must assess the patentability of proposed
substitute claims “without placing the burden of persuasion on the patent
owner.” Aqua Prods., Inc. v. Matal, 872 F.3d 1290, 1328 (Fed. Cir. 2017)
(en banc); see also Lectrosonics, Inc. v. Zaxcom, Inc., IPR2018-001129,

2 In its Supplemental Opposition to Patent Owner’s Non-Contingent Motion
to Amend, Petitioner alleges Hyde ’598 anticipates substitute claims 22–35
because “Patent Owner relies on the ’177 Application, which published as
Hyde ’598, for its disclosure of the subject matter it seeks to claim” and
Hyde ’598 “is prior art to the . . . ’504 Patent.” Paper 38, 4; see also id. at
1–4. Hyde ’598 was part of the subject matter of a certificate of correction
sought by Patent Owner for the ’504 patent. See Paper 41, 1–2. Patent
Owner asks us to use our “discretion in not considering the new Hyde ’598
ground in the instant trial.” Id. at 1. As explained below, we need not reach
the asserted ground based on Hyde ’598.
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Paper 15 at 3–4 (PTAB Feb. 25, 2019) (precedential). Subsequent to the
issuance of Aqua Products, the Federal Circuit issued a decision in Bosch
Automotive Service Solutions, LLC v. Matal, 878 F.3d 1027 (Fed. Cir. 2017)
(“Bosch”), as well as a follow-up Order amending that decision on
rehearing. See Bosch Auto. Serv. Sols., LLC v. Iancu, No. 2015-1928 (Fed.
Cir. Mar. 15, 2018) (Order on Petition for Panel Rehearing).
In accordance with Aqua Products, Bosch, and Lectrosonics, a patent
owner does not bear the burden of persuasion to demonstrate the
patentability of the substitute claims presented in the motion to amend.
Rather, ordinarily, “the petitioner bears the burden of proving that the
proposed amended claims are unpatentable by a preponderance of the
evidence.” Bosch, 878 F.3d at 1040 (as amended on rehearing); see
Lectrosonics, Paper 15 at 3–4. In determining whether a petitioner has
proven unpatentability of the substitute claims, the Board focuses on
“arguments and theories raised by the petitioner in its petition or opposition
to the motion to amend.” Nike, Inc. v. Adidas AG, 955 F.3d 45, 51 (Fed. Cir.
2020).
Patent Owner’s proposed substitute claims, however, must meet the
statutory requirements of 35 U.S.C. § 316(d) and the procedural
requirements of 37 C.F.R. § 42.121. Lectrosonics, Paper 15 at 4–8.
Accordingly, Patent Owner must demonstrate: (1) the amendment proposes
a reasonable number of substitute claims; (2) the proposed claims are
supported in the original disclosure (and any earlier filed disclosure for
which the benefit of filing date is sought); (3) the amendment responds to a
ground of unpatentability involved in the trial; and (4) the amendment does
not seek to enlarge the scope of the claims of the patent or introduce new
subject matter. See 35 U.S.C. § 316(d); 37 C.F.R. § 42.121.
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A proposed substitute claim, however, is unpatentable under
35 U.S.C. § 102 if the claimed invention is anticipated by a disclosure that is
available as prior art. “A claim is anticipated when ‘the four corners of a
single, prior art document describe every element of the claimed invention,
either expressly or inherently, such that a person of ordinary skill in the art
could practice the invention without undue experimentation.’” Spansion,
Inc. v. Int’l Trade Comm’n, 629 F.3d 1331, 1356 (Fed. Cir. 2010) (quoting
Advanced Display Sys., Inc. v. Kent State Univ., 212 F.3d 1272, 1282 (Fed.
Cir. 2000)). The elements must be arranged as required by the claim, but
this is not an ipsissimis verbis test, i.e., identity of terminology is not
required. In re Bond, 910 F.2d 831 (Fed. Cir. 1990).
A proposed substitute claim may also be unpatentable under
35 U.S.C. § 103 if “the differences between the subject matter sought to be
patented and the prior art are such that the subject matter as a whole would
have been obvious at the time the invention was made to a person having
ordinary skill in the art to which said subject matter pertains.” KSR Int’l Co.
v. Teleflex Inc., 550 U.S. 398, 406 (2007). The question of obviousness is
resolved on the basis of underlying factual determinations, including:
(1) the scope and content of the prior art; (2) any differences between the
claimed subject matter and the prior art; (3) the level of skill in the art; and,
where presented, (4) objective evidence of nonobviousness, i.e., secondary
considerations. See Graham v. John Deere Co. of Kansas City, 383 U.S. 1,
17–18 (1966).
The Supreme Court has made clear that we apply “an expansive and
flexible approach” to the question of obviousness. KSR, 550 U.S. at 415.
Whether a patent claiming the combination of prior art elements would have
been obvious is determined by whether the improvement is more than the
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predictable use of prior art elements according to their established functions.
Id. at 417. Reaching this conclusion, however, requires more than a mere
showing that the prior art includes separate references covering each
separate limitation in a claim under examination. Unigene Labs., Inc. v.
Apotex, Inc., 655 F.3d 1352, 1360 (Fed. Cir. 2011). Rather, obviousness
requires the additional showing that a person of ordinary skill at the time of
the invention would have selected and combined those prior art elements in
the normal course of research and development to yield the claimed
invention. Id.
B. Level of Ordinary Skill
We review the grounds of unpatentability in view of the
understanding of a person of ordinary skill in the art at the time of the
invention. Graham, 383 U.S. at 17. In the Institution Decision, we
generally adopted Petitioner’s assessment of a person of ordinary skill in the
art, as a person having a bachelor’s degree in electrical engineering or
computer engineering and two years of experience in the field of integrated
circuit design or an equivalent combination of education, work, and/or
experience. Paper 15, 9–10 (citing Pet. 11). In its Motion to Amend, Patent
Owner accepts this assessment of a person of ordinary skill in the art for
purposes of this proceeding. Paper 25, 17. We continue to apply that
assessment here.
C. Claim Construction
In this proceeding, a claim shall be construed using the same claim
construction standard that would be used to construe the claim in a civil
action under 35 U.S.C. § 282(b), including construing the claim in
accordance with the ordinary and customary meaning of such claim as
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understood by one of ordinary skill in the art and the prosecution history
pertaining to the patent. 37 C.F.R. § 42.100 (2019). We therefore apply the
claim construction standard as set forth in Phillips v. AWH Corp., 415 F.3d
1303 (Fed. Cir. 2005) (en banc).
Under Phillips, claim terms are generally given their ordinary and
customary meaning as would have been understood by one with ordinary
skill in the art in the context of the specification, the prosecution history,
other claims, and even extrinsic evidence including expert and inventor
testimony, dictionaries, and learned treatises, although extrinsic evidence is
less significant than the intrinsic record. Phillips, 415 F.3d at 1312–17.
Usually, the specification is dispositive, and it is the single best guide to the
meaning of a disputed term. Id. at 1315.
Only terms that are in controversy need to be construed, and then only
to the extent necessary to resolve the controversy. Nidec Motor Corp. v.
Zhongshan Broad Ocean Motor Co. Matal, 868 F.3d 1013, 1017 (Fed. Cir.
2017) (in the context of an inter partes review, applying Vivid Techs., Inc. v.
Am. Sci. & Eng’g, Inc., 200 F.3d 795, 803 (Fed. Cir. 1999)).
In the Institution Decision, we determined that no claim term required
express construction at that stage of the proceeding. Paper 15, 10–18. In its
Motion to Amend, Patent Owner stated that it “does not believe that any of
the limitations added to the substitute claims require construction and should
instead be construed in accordance with their ordinary meaning.” Paper 25,
17. In its Opposition to the Motion to Amend, Petitioner does not propose
any express claim construction. To the extent that the determination of the
meaning of any claim term is necessary, we use its ordinary and customary
meaning.
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D. Statutory and Regulatory Requirements
As noted above, Patent Owner’s proposed substitute claims must meet
the statutory requirements of 35 U.S.C. § 316(d) and the procedural
requirements of 37 C.F.R. § 42.121.
1. Reasonable Number of Substitute Claims
A motion to amend must “propose a reasonable number of substitute
claims.” 35 U.S.C. § 316(d)(1)(B); see 37 C.F.R. § 42.121(a)(3) (“A motion
to amend may cancel a challenged claim or propose a reasonable number of
substitute claims.”). Patent Owner proposes the same number of substitute
claims as the original challenged claims that are cancelled, i.e., a one-to-one
substitution for a total of fifteen substitute claims. Paper 25, 6–7. “There is
a rebuttable presumption that a reasonable number of substitute claims per
challenged claim is one (1) substitute claim.” Lectrosonics, Paper 15 at 4;
see 37 C.F.R. § 42.121(a)(3). Petitioner does not argue otherwise. See
generally Paper 30. Therefore, we determine that Patent Owner proposes a
reasonable number of substitute claims.
2. Support in the Original Disclosure
A motion to amend may not present substitute claims that introduce
new subject matter. 35 U.S.C. § 316(d); 37 C.F.R. § 41.121(a)(2)(ii). New
matter is any addition to the claims without support in the original
disclosure. See TurboCare Div. of Demag Delaval Turbomach. v. Gen.
Elec. Co., 264 F.3d 1111, 1118 (Fed. Cir. 2001) (“When [an] applicant adds
a claim . . . the new claim[] . . . must find support in the original
specification.”); see also Lectrosonics, Paper 15 at 7 (“the Board requires
that a motion to amend set forth written description support in the originally
filed disclosure of the subject patent for each proposed substitute claim”).
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As noted, supra, subsequent to the hearing, Patent Owner filed, with
our authorization, a Revised Non-Contingent Motion to Amend. Paper 49.
The purpose of this filing was to allow Patent Owner the opportunity to
revise its Motion to Amend to provide citation support to the originally filed
disclosure for the ’504 patent, which Patent Owner asserts was left out of the
original motion because of its good-faith reliance on an inadvertently issued
certificate of correction. See Paper 48, 3–5; Paper 49, 7–18. In its Response
to Patent Owner’s Revised Motion, Petitioner states that it “does not oppose
Patent Owner’s revised Motion to Amend to provide citations to Application
No. 13/666,285 for its argument that the proposed substitute claims are
supported by the written description.” Paper 50, 1 (citing Paper 49 at 7, n.3).
Patent Owner has identified written description support in the
originally filed disclosure of the ’504 patent for the new limitations added
for the proposed substitute claims. See Paper 49, 7–18. We have reviewed
Patent Owner’s assertions of support in the original disclosure for the
proposed substitute claims and determine that sufficient support exists.
3. Respond to a Ground of Unpatentability
“A motion to amend may be denied where . . . [t]he amendment does
not respond to a ground of unpatentability involved in the trial.” 37 C.F.R.
§ 42.121(a)(2)(i). Patent Owner asserts that the proposed substitute claims
are patentable over the combination of references that forms the basis of the
obviousness ground on which we instituted trial. Paper 25, 14–15. In
particular, Patent Owner asserts that “the amended claims recite filtering a
digital signal in a manner not disclosed or taught by the prior art of record.”
Id. at 14. Petitioner does not dispute that Patent Owner’s amendment
responds to a ground of unpatentability in this trial. See generally Paper 30.
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We determine that the amended language in the proposed substitute claims is
responsive to a ground of unpatentability involved in this trial.
4. Scope of the Claims
Patent Owner asserts that the substitute claims are each narrower than
the corresponding original claim. Paper 25, 15–17. “For example,” Patent
Owner argues, “substitute claim 22 recites a method for an RFID tag circuit
that is narrower than that of the corresponding original claim 1, because it
recites a method where the digital pulses are filtered in a more specific way
than claim 1.” Id. at 15. “Specifically,” Patent Owner argues, “original
claim 1 recites, in part, ‘generating artifact numbers’ and ‘deriving’ a digital
output signal using the artifact numbers.” Id. “Claim 22 includes those
limitations, but adds filtering by also ‘setting a filter pass range to detect a
delimiter,’ ‘detecting the delimiter,’ ‘detecting an expected next packet after
the delimiter,’ ‘adjusting the filter pass range based on an aspect of the
expected next packet,’ and retaining and removing digital pulses based on
the ‘pass range.’” Id.
Patent Owner argues “[n]one of these added limitations appear in or
are otherwise required by original claim 1.” Id. “Thus,” Patent Owner
argues, “substitute claim 22 recites a narrower, more specific way of
filtering than original claim 1.” Id.
Patent Owner makes similar arguments with respect to the other
proposed substitute claims. See id. at 15–17.
Petitioner does not argue otherwise. See generally Paper 30.
We, therefore, determine that the amendment does not seek to enlarge
the scope of the claims of the patent.
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E. Relevant Prior Art
1. Shanks (Ex. 1006)
Shanks is a U.S. Patent Application Publication that published on
October 17, 2002, more than one year before the earliest priority date of the
’504 patent. Ex. 1002, code (63); Ex. 1006, code (43). Petitioner asserts
that Shanks is prior art under pre-AIA 35 U.S.C. § 102(a), (b), and (e).
Pet. 13.
Shanks relates to an RFID architecture including readers for
interrogating and powering tags at data rates, distances, and reliability levels
greater than existing readers. Ex. 1006 ¶ 9.
Figure 10 of Shanks is reproduced below.

Figure 10, shown above, depicts a block diagram of an RFID tag
according to an embodiment of Shanks. Id. ¶¶ 25, 124. Tag 1002, which is
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printed on substrate 1001, includes integrated circuit 1002, data
programming unit 1020, state machine 1024, timing subsystem 1023, and
RF interface portion 1021. Id. ¶ 142. RF interface portion 1021 “includes
components that . . . demodulate RF signals into digital information
symbols.” Id. ¶ 144.
Figure 30 of Shanks is reproduced below.

Figure 30, shown above, depicts analog front-end 3000 of an
exemplary RF tag. Id. ¶ 526. Analog front-end 3000 includes data recovery
circuit 3010, which demodulates RF signal 3003 and generates a digital
output signal labeled “DMOD” at output terminal 3012. Id. ¶ 527.
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Figure 42 of Shanks is reproduced below.

Figure 42, shown above, depicts an exemplary data recovery circuit
4200 that is an embodiment of data recovery circuit 3010 of Figure 30. Id.
¶ 562. Data recovery circuit 4200 may include fast charge pump 4202 to
demodulate RF signal 3003 and comparator 4216 to further process the
demodulated output signal 4203 to generate digital output signal 4220. Id.
¶¶ 562–63.
In one embodiment of Shanks, the tag may receive, from a reader
network, a modulated wireless RF input signal that conveys information in
the form of one or more symbols for a particular duration of time. Id. ¶¶ 73,
74, 95, 96, 150.
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Figures 3, 4, and 5 of Shanks are reproduced below.

Figure 3, above, shows that, when transmitting a symbol that
represents a logical “0”, the reader network maintains its carrier signal
amplitude at Slow for a duration of TA = 3 microseconds. Id. ¶¶ 96, 99.

Figure 4, above, shows that, when transmitting a symbol that
represents a logical “1”, the reader network maintains its carrier signal
amplitude at Slow for a duration of TA = 6 microseconds. Id.
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Figure 5, above, shows that, when transmitting a symbol that
represents a logical “NULL” symbol, the reader network maintains its
carrier signal amplitude at Slow for a duration of TA = 9.5 microseconds. Id.
As shown in Figures 3 through 5, the reader network may transmit one
symbol every 12.5 microseconds, which represents a “symbol exchange
period.” Id. ¶ 97.
The duration of timing intervals that define these symbols may be set
during a calibration routine in which the reader network transmits a series of
pulse waveforms received by a tag. Id. ¶¶ 475, 477–78. The tag may use
the received pulse waveforms to set boundaries for the timing intervals that
define the symbols. Id. ¶ 475. The duration of a received calibration
waveform may be measured as the duration of time passing between the
falling edge and rising edge of its pulse. Id. ¶ 478.
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Figure 26A is reproduced below.

Figure 26A, above, shows calibration waveforms for three time
periods: 2602 (the time between TCS and TTO, e.g., 4.5 milliseconds), 2604
(the time between TCS and TT1, e.g., 7.75 milliseconds), and 2606 (the time
between TCS and TT2, e.g., 11.5 milliseconds). Id. ¶¶ 478–80. Figure 26B is
reproduced below.

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Figure 26B, above, shows that if the trailing rising edge of a data
symbol pulse occurs between time TCS and TT0, the data symbol will be
interpreted as a logical “0” value; if the trailing rising edge occurs between
time TT0 and TT1, the data symbol will be interpreted as a logical “1”; and if
the trailing rising edge occurs between time TT1 and TT2, the data symbol
will be interpreted as a logical “NULL” value. Id. ¶¶ 479–480. TT2 may be
set to a longer time period to allow the reader network to decrease
transmitted data rates such that noise immunity may be improved.
2. Breimesser (Ex. 1007)
Breimesser is a U.S. Patent that issued on December 14, 1976, more
than one year before the earliest priority date of the ’504 patent. Ex. 1002,
code (63); Ex. 1007, code (45). Petitioner asserts that Breimesser is prior art
under pre-AIA 35 U.S.C. § 102(a), (b), and (e). Pet. 13.
Breimesser relates to a circuit arrangement for gating out pulses and
pulse gaps whose duration is shorter than a given test period. Ex. 1007, 1:9–
12.
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Figure 1 of Breimesser is reproduced below.

Figure 1, above, shows a circuit arrangement for gating out pulses
according to an embodiment of Breimesser. Id. at 4:52–53. “If pulse gaps
are to be gated out it is also possible to use this circuit arrangement if the
input signal is inverted” by “preced[ing] the gate 1 by an inverter whose
output is connected to the first input 5.” Id. at 4:53–57; see also id. at 5:62–
6:16, Fig. 3. According to Figure 1, output 7 of gate 1 is connected to
counter input 8 of counter 2. Id. at 3:3–4. From counter 2, parallel outputs
12 and 14 are connected to inputs 15 and 17 of decoder 3. Id. at 3:4–6.
Output 18 of decoder 3 is connected to first input 19 of binary storage circuit
4. Id. at 3:6–8. First input 5 of gate 1 is connected to setting input 21 of
counter 2 and to second input 20 of the binary storage circuit 4. Id. at 3:8–
10.
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Figure 2 of Breimesser is reproduced below.

Figure 2 of Breimesser, above, shows a mode of operation of the
circuit arrangement shown above in Figure 1 of Breimesser.
“The digital pulse sequence I is fed to the first input 5 of the gate 1,”
which may be an AND gate or a NAND gate. Id. at 3:15–16, 3:26–28. “A
counter pulse sequence II is connected to the second input 6 of the gate,”
with a pulse train length of counter pulses assumed to be tt. Id. at 3:21–23.
Output Q inverse of the binary storage element 4 is connected to the third
input 22 of gate 1. Id. at 4:67–5:1.
“The gate 1 in the circuit . . . is only open for the counter pulses when
and for as long as an input pulse is present at the input 5.” Id. at 3:23–27.
“If then an input pulse appears at the input 5 of the gate, . . . the pulse
sequence III composed of individual groups of counter pulses appears at the
output 7 of the gate.” Id. at 3:28–31. “These counter pulses pass to the
counter input 8 and the counter 2,” which counts the counter pulses “from a
given initial value m with the first pulse of each pulse group, and continues
to count for the maximum until the pulse at the input 5 is at an end.” Id. at
3:35–41. “The decoder 3 establishe[s] the individual states of the counter
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and when a predetermined value n is reached in the counter, it emits a pulse
at the output 18. Id. at 3:46–49. “The pulses E and F of the pulse sequence
IV represent the pulses from the output of the decoder.” Id. at 3:51–53.
“[P]ulses only appear at the output 18 of the decoder if the input pulse is
longer than the test period tp.” Id. at 3:55–58.
The pulse from the output 18 of the decoder sets the
output Q of the binary storage element via the input 19 to l.
This state continues until the storage element is reset via the
input 20. . . . [T]he output pulse sequence V with the pulses G
and H arises at the output Q of the storage element. As will be
seen from this sequence, pulses occur only if the input pulse is
longer than the test period tp. The front edges of the pulses G
and H are displaced by the time tp + td and shortened in
comparison to the input pulses A and D in the sequence I.
Id. at 3:63–4:7.
“The values m and n, and the pulse train length tt of the counter pulses
determine the test period tp in accordance with tp = (m – n) ∙ tt.” Id. at 3:49–
51. “The test period may be freely programmed and can be varied within
wide limits.” Id. at 2:40–41. “In FIG. 2, tp = 4 ∙ tt was selected by way of
example.” Id. at 3:53–54.
“The above described circuit arrangements can be used for gating out
interference signals of shorter duration than the useful signal.” Id. at 7:47–
49.
3. Lichtblau (Ex. 1008)
Lichtblau is a U.S. Patent that issued on October 18, 1988, more than
one year before the earliest priority date of the ’298 patent. Ex. 1002, code
(63); Ex. 1008, code (45). Petitioner asserts that Lichtblau is prior art under
pre-AIA 35 U.S.C. § 102(a), (b), and (e). Pet. 13.

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Lichtblau “is directed to the field of noise rejection circuitry, and
more particularly, to a continuously armed, highly reliable, pulse train
processor especially for magnetic strip and resonant tag signal detection.”
Ex. 1008, 1:6–10. Figure 1 of Lichtblau is reproduced below.

Figure 1, above, shows a continuously armed, high reliability pulse
train processor in an exemplary magnetic and resonant interrogation system
receiver application according to one embodiment. Id. at 2:34–38.
Lichtblau describes a circuit whose antenna 15 receives a “radio frequency
signal” that is “demodulated by the receiver 16, filtered in a band-pass filter
20 to remove noise, and amplified in amplifier 22. Thereafter the signal is
fed in parallel into the pulse train processor 24.” Id. at 2:56–3:4. The pulse
train processer may include three pulse processing modules, each of which
includes a “minimum and maximum pulse width detector pair[] . . . selected
to conform to the expected duration time . . . of the corresponding . . . pulses
of the expected pulse train.” Id. at 4:34–36, 4:65–5:6, Fig. 2. “Only the
correct polarity sequence of pulses above a preselected threshold that exist
within carefully defined time durational windows are passed through by the
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pulse train processor, while all other pulse signals kinds and types are
rejected thereby as undesirable noise.” Id. at 5:6–11. Thus, Lichtblau
describes “a pulse train processor that is responsive to both the minimum
duration and to the maximum duration of each of the several pulses.” Id. at
2:3–9.
4. Gen2 (Ex. 1015)3
The article, EPC™ Radio-Frequency Identity Protocols Class-1
Generation-2 UHF RFID Protocol for Communications at 860 MHz – 960
MHz Version 1.0.9, published by EPC Global, Inc., is a specification for
RFID air interface. The specification defines the base class (Class-1) of four
RFID Tag classes. Ex. 1015, App. A, 8. The Gen2 system comprises
“Interrogators, also known as Readers, and Tags.” Id. at 1, 9. “An
Interrogator transmits information to a Tag by modulating an RF signal.” Id.
at 9. The information is pulse-interval encoded (PIE), whereby pulses of
energy are transmitted for different intervals of time (i.e., symbols) to
communicate information that is interpreted by the tag as either a binary 0 or
a binary 1. Ex. 1020 ¶ 351.
In Gen2, the duration (pulse-interval) of the encoded symbols is
specified by a “Tari” reference time interval where 1 Tari is equivalent to the
duration of a data-0 symbol. Ex. 1015 § 6.3.1.2.3, Fig. 6.1; see Ex. 1020
¶ 355. Data-1 symbols are transmitted using pulses between 1.5 to 2.0 Tari.

3 Exhibit 1015 includes an Affidavit of Elizabeth Rosenberg, averring to
certain facts Petitioner uses to establish the public availability of the Gen2
reference as prior art to the ’504 patent. See Ex. 1015, 1–2; Paper 30, 2–3.
Patent Owner does not challenge the public availability of Gen2, or its status
as prior art to the ’504 patent. See Paper 51, 31:1–11. Based on the
evidence of record, we determine that Petitioner has established the public
availability of the Gen2 reference as prior art to the ’504 patent.
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Ex. 1015 § 6.3.1.2.3, Fig. 6.1. Tari values of 6.25μs, 12.5μs, or 25μs are
preferred for reader to tag (“R=>T”) communications. Id. at Tables 6.5, 6.6.
Gen 2 specifies an “inventory” process that is used for identifying
tags. Ex. 1015 § 6.3.2.6; Ex. 1020 ¶ 356. To initiate the R=>T signaling for
“an inventory round,” readers transmit a “preamble or a framesync.”
Ex. 1015 § 6.3.1.2.8, Fig. 6.4. Both the preamble and the frame-sync
include a fixed-length start delimiter, a data-0 symbol, and an R=>T
calibration (RTcal) symbol. Id. The data-0 symbol that follows the
delimiter is used to specify the length of a data-0 symbol for the R=>T
communications. Id. The RTcal symbol specifies the combined length of a
data-0 symbol and a data-1 symbol. Id. A tag interprets subsequent symbols
that are shorter than duration of RTcal / 2 as data-0 symbols, and symbols
longer than RTcal / 2 as data-1 symbols, except that symbols longer than
four times RTcal are “bad data.” Id.; Ex. 1020 ¶ 356.
F. Obviousness Based on Shanks, Breimesser, Lichtblau, and Gen2
Petitioner asserts proposed substitute claims 22–35 are unpatentable
as obvious under 35 U.S.C. § 103 over the combined teachings of Shanks,
Breimesser, Lichtblau, and Gen2. See Paper 30, 5–25. The parties
principally rely on their arguments directed to independent claim 22. See
Paper 30, 22–23; Paper 32, 1. We address any arguments specifically
directed to independent claims 30 and 33 separately.
1. Proposed Substitute Independent Claim 22
[22-pre] A method for a Radio Frequency Identification
(RFID) tag circuit comprising [not amended]
Proposed substitute claim 22 recites the same preamble as claim 1.
See Paper 25, App. A; Ex. 1002, 21:37–38. Petitioner asserts that “Shanks
discloses an RFID tag circuit.” Paper 30, 5–6 (citing Pet. § VI.A.1(a) (claim
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[1-preamble]); Ex. 1020 ¶ 400). The cited section of the Petition states that
“[a]s shown in FIG. 10, integrated circuit 1002 includes a data programming
unit 1020, a state machine 1024, a timing subsystem 1023, and an RF
interface portion 1021.” Pet. 24 (citing Ex. 1006 ¶ 142).
Figure 10 of Shanks is shown below.

Shanks Figure 10, shown above, is a block diagram of a RFID tag
showing integrated circuit 1002. Ex. 1006 ¶ 124, Fig. 10.
Petitioner also asserts that “Gen2 discloses ‘operating procedures’ for
an RFID tag circuit, and ‘the signaling layer of the communication link’
between a reader and the tag circuit.” Paper 30, 6 (citing Ex. 1015, 10).
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Patent Owner does not contest Petitioner’s evidence that Shanks
teaches a RFID tag circuit and Gen2 teaches operating procedures for a
RFID tag circuit. See Paper 32, 1–12. Petitioner’s arguments are supported
by the cited evidence. Based on the evidence of record, we are persuaded
that Petitioner has demonstrated that the combined teachings of Shanks and
Gen2 amount to a “method for a Radio Frequency Identification (RFID) tag
circuit” as recited in the preamble of proposed substitute claim 22.
[22-a] receiving a modulated wireless RF input signal;
deriving a first digital output signal responsive to the
modulated wireless RF input signal, wherein the first
digital output signal comprises a sequence of digital
pulses [not amended]
Petitioner asserts that Shanks teaches this limitation because “Shanks
discloses demodulating an RF input signal that is received from an RF
reader, and deriving a first digital output signal comprising a sequence of
digital pulses.” Paper 30, 6 (citing Pet. § VI.A.1(b) (claim [1-a]); Ex. 1020
¶ 401). Petitioner also argues that “[t]his limitation is also disclosed by
Figure 7 of the ’177 Application, which the applicant admitted was prior
art.” Paper 30, 6 (citing Ex. 1010, 11).
Petitioner further argues that “Gen2 also discloses tags that ‘receive a
modulated wireless RF input signal from an RFID reader.’” Paper 30, 6
(citing Ex. 1015 §§ 6.3.1.1, 6.3.1.2). Petitioner explains that “Gen2 tags
demodulate the received wireless RF input signal, which uses a pulse-
interval encoding (PIE) format, to derive a first digital output signal that
comprises a sequence of digital pulses.” Paper 30, 6 (citing Ex. 1015
§§ 6.3.1.2.2, 6.3.1.2.3, Fig. 6.1 (illustrating digital pulses); Ex. 1020 ¶ 402).
Patent Owner does not contest Petitioner’s evidence that Shanks and
Gen2 teach the recited demodulator. See Paper 32, 1–12.
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Petitioner’s arguments are supported by the cited evidence.
Petitioner’s declarant, Dr. Blalock, provides credible testimonial evidence
that Shanks’ RF interface portion 1021, as shown in Shanks’ Figure 10,
amounts to a demodulator configured for receiving a modulated wireless RF
input signal from an RFID reader and derives an output signal comprising a
sequence of digital pulses, aspects of which are illustrated in Shanks’
Figures 30 and 42. See Ex. 1003 ¶¶ 282–285. Dr. Blalock also provides
credible evidence that the Gen2 tags demodulate a received wireless RF
signal using a pulse-interval encoding format (PIE). See Ex. 1020 ¶¶ 401–
402.
Based on the evidence of record, we are persuaded that Petitioner has
demonstrated that Shanks and Gen 2 teach the recited limitation.
[22-b1] filtering the first digital output signal with an
interference rejection circuit of the tag circuit to derive a
second digital output signal by: receiving the first digital
output signal
Petitioner asserts that the combination of Shanks, Breimesser, and
Lichtblau teaches this limitation. Paper 30, 6–7. Petitioner first asserts that
“the combination of Shanks in view of Breimesser discloses an interference
rejection circuit configured to receive the first digital output signal.” Id.
(citing Pet. § VI.A.1(d) (claim [1-c(i)]); Ex. 1020 ¶ 403). Petitioner argues
that “Breimesser’s circuit would have been configured by setting a test
period tp, a filter pass range, that ‘can be arbitrarily varied’ to filter the first
digital output signal in order to derive a second digital output signal.”
Paper 30, 7 (citing Pet. § VI.A.1(d) (claim [1-c(i)]); Ex. 1007, 1:48–53;
Ex. 1020 ¶ 403). Petitioner argues that a person of ordinary skill in the art
“would have been motivated to form this combination to address a specific
need in Shanks to filter digital pulses in order to improve the performance of
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the digital circuitry by preventing noise pulses from being interpreted as
valid data. Paper 30, 7 (citing Pet. § VI.A.1(d) (claim [1-c(i)]).
Petitioner next asserts that a person of ordinary skill in the art “would
have been motivated to modify Breimesser’s circuit in view of Lichtblau to
include both a first and second test period (e.g., tp-min and tp-max) to filter
(remove) pulses shorter than the first test period (“a low threshold time”)
and also to filter (remove) pulses longer than the second test period (“a high
threshold time”). Paper 30, 7 (citing Pet. § VI.B; Ex. 1020 ¶ 404).
Patent Owner asserts that Petitioner’s proposed modification to
Breimesser’s circuit sets the wrong pass range. See Paper 32, 4–6. Patent
Owner argues that:
“modify[ing] Breimesser’s circuit to include both a first and
second test period (e.g., tp-min and tp-max),” as NXP alleges
(Paper 30, 7), would not have produced a pass range “to filter
(remove) pulses longer than the second test period.” Id. In fact,
implementing a second test period, tp-max, using Breimesser’s
circuit would have resulted in retaining pulses that were longer
than tp-max. This is shown in the illustrative diagram below,
where setting NXP’s second test period, tp-max would result in
pulses larger than tp-max (~1.7 tp-max and ~ 2.0 tp-max in the
examples shown) to pass through, as opposed to passing those
pulses that were in the range between tp-min and tp-max. Ex.
2009, ¶¶ 27-31.
Paper 32, 5–6 (alteration in original). Patent Owner’s illustration of
Petitioner’s proposed pass range is shown below.

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Paper 32, 6. According to Patent Owner, the illustration above shows output
pulses from Petitioner’s proposed modification to Breimesser’s circuit
allowing pulses longer than tp-max to pass through. Id.
Petitioner points out, however, and we agree, that Patent Owner’s
argument fails to consider Lichtblau’s contribution to Petitioner’s proposed
combination. See Paper 42, 6–8.4 Petitioner argues that Lichtblau teaches
filtering pulses shorter than tp-min and longer than tp-max. Id. at 6 (citing
Paper 30, 7). Petitioner explains, and we agree, that Lichtblau teaches “a
pulse train processor 24 that includes ‘minimum and maximum pulse width
detector(s),’ corresponding to a low threshold (e.g., tp-min) and a high
threshold (e.g., tp-max), that ‘are selected to conform to the expected
duration time’ of the expected pulses.” Paper 42, 6–7 (citing Pet. 53;
Ex 1008, 5:1–6; Ex. 1003 ¶ 325). Petitioner argues that a person of ordinary
skill in the art “would have been motivated to modify Breimesser’s
interference rejection circuit based on the teachings of Lichtblau to include a
first and second test period (e.g., tp-min and tp-max), thus providing a filter
pass range to filter pulses shorter than the first test period and pulses longer
than the second test period.” Paper 42, 7 (citing Paper 30, 7; Pet. § VI.B);
Ex. 1003 ¶¶ 320–323; Ex. 1020 ¶¶ 383–385, 404). Patent Owner’s failure to
consider the contribution of Lichtblau to Petitioner’s proposed combination
undermines Patent Owner’s argument on this point.
Petitioner’s arguments are supported by the cited evidence.
Petitioner’s declarant, Dr. Blalock, provides credible testimonial evidence
that Breimesser’s circuit arrangement, in combination with Shanks and

4 Petitioner also asserts that Patent Owner’s argument is only relevant to
proposed substitute dependent claims 26, 30, and 33, because “only these
claims recite filtering pulses longer than the pass range.” Paper 42, 6.
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Lichtblau, can be used for gating out digital pulses or digital pulse gaps and
amounts to the recited interference rejection circuit. See Ex. 1003 ¶ 289;
Ex. 1020 ¶¶ 403–404.
Based on the evidence of record, we are persuaded that Petitioner has
demonstrated that the proposed combination of prior art teaches the recited
claim limitation. We consider the evidence and arguments with respect to
the rationale to combine the prior art, infra.
[22-b2] generating artifact numbers by counting time
durations of the digital pulses [not amended]
Petitioner asserts that the combination of Shanks and Breimesser
teaches this limitation because “Breimesser[’s] counter 2 would have been
configured for generating a count (artifact numbers) by counting counter
pulses that reflect time durations of the digital pulses.” Paper 30, 7 (citing
Pet. § VI.A.1(c) (claim [1-b]); Ex. 1020 ¶ 405). Patent Owner does not
contest Petitioner’s evidence that the combination of Shanks and Breimesser
teaches this limitation. See Paper 32, 1–12.
Dr. Blalock points out that “Shanks discloses a tag that ‘uses oscillator
1026 to serve as a system time reference for internal digital functions’” and
that “[c]ounter 1028 ‘counts the number of cycles of master clock signal
1062 that occur during a cycle of input signal 2100.’” Ex. 1003 ¶ 286
(citing Ex. 1006 ¶¶ 358, 377; Fig. 10). Dr. Blalock also points out that
Breimesser similarly “discloses counter 2 for counting a pulse sequence.”
Ex. 1003 ¶ 287 (citing Ex. 1007, 3:35–41).
Dr. Blalock testifies persuasively that a person of ordinary skill in the
art:
would have understood that Breimesser’s counter 2 would count,
similar to the operation of Shanks counter 1028, the time
durations of the digital pulses using a clock signal derived from
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Shanks’ oscillator 1026. In combination, a POSITA would have
configured, for example, input 5 of the circuit of Breimesser to
receive the first digital output signal disclosed by Shanks. . . .
Thus, in combination, Breimesser counter 2 would have been
configured for generating a count (artifact numbers), for
example at parallel outputs 12 to 14, by counting counter pulses
that reflect time durations of the digital pulses.
Ex. 1003 ¶ 288.
Petitioner provides an annotated illustration depicting the combination
of Breimesser’s interference rejection circuit with Shanks’ RFID tag circuit,
shown below. Ex. 1003, 136.

The illustration shown above is a block diagram depicting Petitioner’s
combination of Breimesser’s interference rejection circuit, shown on the
right as Figure 1, with Shanks’ RFID tag circuit, shown on the left as Figure
10.
Based on the evidence of record, we are persuaded that Petitioner has
demonstrated that the proposed combination of prior art teaches the recited
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claim limitation. We consider the evidence and arguments with respect to
the rationale to combine the prior art, infra.
[22-b3] setting a filter pass range to detect a delimiter,
detecting the delimiter
Petitioner asserts that the combination of Shanks, Breimesser,
Lichblau, and Gen2 teaches this limitation. Paper 30, 7–8. Petitioner argues
that “Shanks discloses that a signal of a specified length serves as a master
reset event to cause a tag to enter a mode to calibrate the duration of each
data symbol, which establishes the communication data rate for transmitting
information to the tag.” Id. at 8 (citing Ex. 1006 ¶¶ 166, 172, 483–486,
Fig. 27; Ex. 1020 ¶ 406). Petitioner argues that “to establish the R=>T data
rate in a Gen2 system, at ‘the start of an inventory round’ tags receive a
preamble or a frame-sync that includes a fixed-length start delimiter, a data-
0 symbol, and an R=>T calibration (RTcal) symbol.” Id. (citing Ex. 1015
§ 6.3.1.2.8, Fig. 6.4; Ex. 1020 ¶ 406). Petitioner also argues that “[t]he pulse
duration of a Gen2 fixed-length start delimiter is ‘12.5μs +/- 5%.’” Id.
(citing Ex. 2015, § 6.3.1.2.8, Fig. 6.4). Petitioner further argues that it
would have been obvious for a person of ordinary skill in the art in view of
Gen2
to configure Breimesser’s circuit in combination with Lichtblau
to filter the first digital output signal to detect a Gen2 delimiter
by setting the first and second test period to, for example,
11.875μs and 13.125μs, a filter pass range, to detect a delimiter
having a “12.5μs +/- 5%” pulse duration,[] and then detecting
the delimiter.
Paper 30, 8 (citing Ex. 1015 § 6.3.1.2.8, Fig. 6.4; Ex. 1020 ¶ 406).
Patent Owner asserts that Petitioner’s proposed initial pass range
would have failed to detect the majority of Gen2 Tari values and associated
pulses. Paper 32, 8–10. Patent Owner argues that “[s]uch a modification
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would have detected the delimiter, but would have rendered a large range of
Gen2 Tari values undetectable.” Id. at 9. Patent Owner concedes, however,
that Petitioner’s proposed modification “would have detected the delimiter.”
Id.
Petitioner’s arguments are supported by the cited evidence. Dr.
Blalock explains how a person of ordinary skill in the art would have
configured Breimesser’s circuit in combination with Lichtblau to filter the
first digital output signal to detect a Gen2 delimiter. See Ex. 1020 ¶ 406.
Petitioner provides an annotated illustration of Gen2’s Figure 6.4 below.

Petitioner’s annotated illustration of Gen2’s Figure 6.4, shown above,
depicts a R=>T preamble and frame-sync, indicating the portions of the
signal relating to the recited limitation. Id. at 33.
Based on the evidence of record, we are persuaded that Petitioner has
demonstrated that the proposed combination of prior art teaches the recited
claim limitation. We consider the evidence and arguments with respect to
the rationale to combine the prior art, infra.
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[22-b4] detecting an expected next packet after the
delimiter
For this limitation, Petitioner argues that:
[a]fter receiving the delimiter, Gen2 tags must detect a data-0
symbol, an expected next packet. Ex. 1015, § 6.3.1.2.8, Fig. 6.4;
Ex. 1020 ¶ 407. That data-0 symbol is then followed by an RTcal
symbol that is “equal to the length of a data-0 symbol plus the
length of a data-1 symbol.” Id. These waveforms calibrate the tag
to interpret subsequent symbols as either data-0 (i.e., shorter than
RTcal / 2) or data-1 (i.e., longer than RTcal / 2). Ex. 1015,
§ 6.3.1.2.8, Fig. 6.4; Ex. 1020 ¶ 407. Gen2’s data-0 and RTcal
waveforms that are received after the delimiter are analogous to
Shanks’ data calibration waveforms that are received after a
master reset event. Ex. 1006 ¶¶ 477–78, Fig. 26A; Ex. 1020
¶ 407; Pet. § V.A.
Paper 30, 9.
Patent Owner argues that “[s]uch a proposed modification, however,
while would have detected the delimiter, it would have rendered a large
range of Gen2 Tari values undetectable.” Paper 32, 9. Patent Owner argues
that “[t]he initial pass range of 12.5μs (± 5%), at best, would have allowed
only a small percentage of Tari values to be detected, but would not have
detected the great majority of possible Tari values that are specified in
Gen2.” Id. (citing Ex. 2009 ¶¶ 38–46). Patent Owner also argues that
Petitioner’s proposed combination “would also fail to detect any of Gen2’s
Tari values in practical implementations of the system.” Paper 32, 9–10
(citing Ex. 2009 ¶¶ 43–46).
Petitioner asserts that Patent Owner’s argument is misplaced,
“because [the] claim elements . . . do not recite ‘setting a filter pass range to
detect a delimiter’ and then maintaining that same pass range for ‘detecting
an expected next packet after the delimiter.’” Paper 42, 8–9 (emphasis
added). Petitioner points out that “claim 22 is silent as to whether a different
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filter pass range may be set in the purported sequence of operations after
‘detecting the delimiter’ and before ‘detecting an expected next packet.’” Id.
at 9. “Indeed,” Petitioner notes, “none of the proposed claims recite
maintaining the same pass range to detect both a delimiter and an expected
next packet.” Id. Petitioner argues that Patent Owner “did not bother to
analyze the operation of the prior art combination after the filter pass range
had been readjusted in this manner, and did not dispute that altering the filter
pass range would change the range of pulse widths (Tari values) detected.”
Id. (citing Ex. 1021, 62:24–63:18, 59:5–24).5
We agree with Petitioner. Claim 22 does not require that the pass
range used to detect a delimiter must also be the same pass range used to
detect an expected next packet after the delimiter. Nothing in claim 22
precludes adjustment of the pass range. Patent Owner’s argument assumes
incorrectly that the pass range used to detect a delimiter must necessarily be
the same pass range used to detect an expected next packet. Claim 22 has no
such restriction and a person of ordinary skill in the art would understand
that there are valid reasons to adjust the pass range. Indeed, as Dr. Blalock
explains:
it would have been obvious that the first and second test periods,
the filter pass range, must be readjusted to detect a command,
such as a Query command, that included valid data-0 symbols
based on pulses as short as 6.25μs or as long as 25μs. Ex. 1015,
§ 6.3.2.10.2.1 (identifying Query command with a four bit code
“1000”). Accordingly, based on the Tari value of the data-0
symbol that was received after the delimiter, an aspect of the
expected next packet, it would have been obvious to adjust the

5 Petitioner also points out that claim 27 “recites the very operational
sequence that [Patent Owner] complains is required for claim 22: ‘after
detecting the delimiter, adjust the filter pass range for detecting the expected
next packet.’” Paper 42, 9.
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first and second test periods, the filter pass range, for detecting
a Gen2 Query command.
Ex. 1020 ¶ 411.
We are persuaded that Petitioner has demonstrated that the proposed
combination of prior art teaches the recited claim limitation. We consider
the evidence and arguments with respect to the rationale to combine the
prior art, infra.
[22-b5, b6] adjusting the filter pass range based on an
aspect of the expected next packet, wherein deriving a the
second digital output signal comprises responsive to the
first digital output signal at an interference rejection
circuit of a RFID tag circuit by substantially removing
retaining digital pulses with artifact numbers less than a
first low number within the pass range while
substantially retaining and removing digital pulses with
artifact numbers greater less than the first low number
pass range, wherein the first low number corresponds to
a first time duration threshold.
Petitioner asserts that the combination of Shanks and Breimesser
teaches this limitation. Paper 30, 9–12. Petitioner argues that the
combination would “filter interference pulses shorter than the calibrated
value for the shortest valid signal (e.g., bit ‘0’) to prevent the
misidentification of a noise pulse as a valid data bit.” Id. at 9 (citing
Pet. § VI.A.1(d) (claim [1-c(i)]); Ex. 1020 ¶ 408). Specifically, Petitioner
argues, a person of ordinary skill in the art “would have adjusted
Breimesser’s test period tp, the filter pass range, based on the duration of
data symbols used with a particular data rate.” Id. at 9–10 (citing
Pet. § VI.A.1(d, e) (claim [1-c(i, ii)]); Ex. 1020 ¶ 408). As a result,
Petitioner argues interference pulses shorter than the test period would not
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be interpreted as a logical “0.” Id. at 10 (citing Pet. § VI.A.1(d, e) (claim [1-
b(i, ii)]); Ex. 1020 ¶ 408).
Petitioner provides an annotated version of Breimesser’s Figure 2,
shown below.

Breimesser’s Figure 2, annotated by Petitioner and shown above,
depicts a series of digital pulse sequences, I–V, over time t. Paper 30, 10.
According to Breimesser, Figure 2 shows the mode of operation of
Breimesser’s circuit arrangement depicted in Breimesser Figure 1.6
Ex. 1007, 3:11–31; Fig. 1. Petitioner’s annotations of Breimesser’s Figure 2
relate the digital pulse sequences to the recited claim limitations.
Petitioner also argues that for tags implemented in compliance with
the Gen2 specification, it would have been similarly obvious to filter such

6 In Figure 2, according to Breimesser, sequence I shows a series of digital
input pulses, A–D, fed to a first input of gate 1. Ex. 1007, 3:11–31; Fig. 1.
Sequence II shows a series of counter pulses fed to a second input of the
gate. Id. Sequence III shows individual groups of output counter pulses that
pass through the gate when an input pulse, A–D, is present. Id. Sequence
IV shows decoder output pulses E, F and sequence V shows storage element
output pulses G, H. Id. at 3:51–53, 4:1–3.
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interference pulses. Paper 30, 10 (citing Ex. 1020 ¶ 409). According to
Petitioner, Gen2 specifies that the duration of a data-0 symbol is 1 Tari
value. Paper 30, 10 (citing Ex. 1015 §§ 6.3.1.2.3, 6.3.1.2.8, Figs. 6.1, 6.4;
Ex. 1020 ¶ 409). “The duration of a RTcal symbol,” Petitioner explains,
“which is ‘equal to the length of a data-0 symbol plus the length of a data-1
symbol,’ is between 2.5 and 3.0 Tari.” Paper 30, 10 (citing Ex. 1015
§§ 6.3.1.2.3, 6.3.1.2.8, Figs. 6.1, 6.4; Ex. 1020 ¶ 409). Petitioner also
explains that Gen2 provides for R=>T communications at a data rate based
on Tari values between 6.25μs and 25μs. Paper 30, 10–11 (citing Ex. 1015
§ 6.3.1.2.4, Table 6.5. Ex. 1020 ¶ 409).
“To inventory a tag population,” Petitioner argues, “the Gen2
command set includes a ‘Query’ command that ‘initiates an inventory round
and decides which Tags participate in the round (where “inventory round” is
defined as the period between successive Query commands).’” Paper 30, 11
(citing Ex. 1015 §§ 6.3.2.8, 6.3.2.10.2.1; Ex. 1020 ¶ 410). Petitioner points
out that “Gen2 commands, such as the Query command, ‘begin with either a
preamble or a frame-sync.’” Paper 30, 11 (citing Ex. 1015 § 6.3.2.10;
Ex. 1020 ¶ 410).
Petitioner argues that:
[a]fter detecting the Gen2 delimiter where the first and second
test period of Breimesser’s circuit had been set to, for example,
11.875μs and 13.125μs as explained above, it would have been
obvious that the first and second test periods, the filter pass
range, must be readjusted to detect a command, such as a Query
command, that included valid data-0 symbols based on pulses as
short as 6.25μs or as long as 25μs. Ex. 1015, § 6.3.2.10.2.1
(identifying Query command with a four bit code “1000”); Ex.
1020 ¶ 411. Furthermore, Breimesser teaches filtering both high
and low portions of pulses, such as pulse-encoded data-0
symbols. Ex. 1007 2:13-15, 6:63-66, Figs. 3-4; Ex. 1020 ¶ 412.
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Accordingly, based on the Tari value of the data-0 symbol that
was received after the delimiter, an aspect of the expected next
packet, it would have been obvious to adjust the first and second
test periods, the filter pass range, for detecting a Gen2 Query
command in order for Breimesser’s circuit to retain digital
pulses within the pass range and remove digital pulses shorter
than the pass range.
Paper 30, 11–12 (citing Ex. 1020 ¶ 411).
Patent Owner argues that Breimesser’s circuit does not retain digital
pulses within the pass range because it shortens, lengthens and shifts the
digital pulses. Paper 32, 1–4. Patent Owner argues that:
[a] closer analysis of Breimesser reveals that neither Fig.
2, nor Fig. 4, describes retaining digital pulses within the pass
range. Fig. 2, at best, produces a shortened output pulse if the
input pulse exceeds the test period, tp. Fig. 4 also shows pulses
that are shortened even if an intervening gap is removed, and
notably both figures illustrate output pulses (bottom rows V, XII
in annotated Figs. 2 and 4) that are always shifted in time
compared to the input signal.
Id. at 2.
Patent Owner provides annotated versions of Breimesser’s Figures 2
and 4, set out below.

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Breimesser’s Figures 2 and 4, annotated by Patent Owner as shown
above, depict Breimesser’s digital pulse sequences I–V (Fig. 2) and digital
pulse sequences VI–XII (Fig. 4).
Patent Owner argues that:
[u]nlike claim 1, the amended claims simply recite “to
[sic] retaining digital pulses within the pass range” - without
qualifications regarding substantially removing or retaining the
pulses. Accordingly, the plain language of the claim (as
corroborated by the detailed description (e.g., ‘504 Patent; Figs.
12A-D; Ex. 2001, ¶¶ 50-52) requires digital pulses within the
pass range to be retained. Ex. 2009, ¶¶ 9-15. Breimesser does not
retain digital pulses within the pass range, but rather produces
shortened and shifted-in-time pulses.
Paper 32, 3. Patent Owner also argues that Petitioner “has failed to address
Breimesser’s express statement that despite any such modifications, the
pulse ‘exhibits an inaccuracy of a maximum of one pulse train length tt.’”
Id. at 4.
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In reply, Petitioner argues that Patent Owner improperly equates the
recited claim language “retaining digital pulses” with “retaining the exact
length of any digital pulse.” Paper 42, 2. Petitioner argues that “[u]nder
[Patent Owner’s] reasoning, a circuit that ‘shortens, lengthens and shifts the
digital pulses’ does not ‘retain digital pulses,’” and “there can be no
‘inaccuracy’ in the length of the retained digital pulse—not even less than a
clock cycle.” Id. (citing Paper 32, 1, 3–4). Petitioner further argues that
Patent Owner “does not identify sufficient evidence to import an absolute
‘no inaccuracy’ limitation into the claims,” because Figures 12 A–D cited by
Patent Owner are only “‘example[s],’ in which pulse transitions are aligned
with ‘clock cycles.’” Id. at 2–3 (citing Ex. 1002, 12:22–23, 12:27–30,
12:65–67 (alteration in original).
Petitioner argues that the “specification refers to ‘substantially
retaining digital pulses’ (Ex. 1002, 20:48–49, 20:56, 21:12, 21:15–16), but
there is no mention of retaining digital pulses, let alone retaining pulses that
transition during a clock cycle.” Paper 42, 3. Petitioner further argues that
“under PO’s interpretation of ‘retains,’ the proposed claims are indefinite
because they ‘fail to inform, with reasonable certainty, those skilled in the
art about the scope of the invention.’” Id. at 4 (citing Nautilus, Inc. v. Biosig
Instruments, Inc., 572 U.S. 898, 901 (2014)). “If ‘retains the exact length of
any digital pulse’ were the intended scope,” Petitioner argues, Patent Owner
“simply could have proposed claims explicitly reciting that meaning rather
than asking the Board to read limitations into the claims.” Id. at 3.
Petitioner also asserts that Patent Owner’s argument “that retained
pulses cannot be shifted-in-time is not supported by the ’504 patent
specification.” Paper 42, 4. Petitioner argues that “Figures 12A-B illustrate
retained pulses that are shifted ‘along a time axis’ ‘with intercepts [of signal
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1260] occurring later in time than corresponding intercepts of signal 1210.’”
Id. (citing Ex. 1002, 12:50–52). Petitioner asserts that Patent Owner’s
expert “agrees ‘the patent teaches that the output signal occurs later in time
than the input signal.’” Paper 42, 4 (citing Ex. 1021, 38:8–11).
Petitioner also argues that “even if ‘retain digital pulses’ means that
output pulses cannot be shortened, Breimesser expressly teaches
embodiments that avoid shortened pulses.” Paper 42, 4. Petitioner asserts
that “Breimesser recognized ‘the pulses of the output signal are shortened’
by the circuit in Figure 1 and explained that ‘[t]his shortening can easily be
cancelled by addition or subtraction.’” Id. at 4–5 (citing Ex. 1007, 5:56–60;
see also id. at 4:5–21 (“The displacement and shortening … may be
avoided.”); Paper 30, 6–7 (citing Pet. §VI.A.1(d)). “In other words,”
Petitioner argues, “Breimesser provides a circuit modification to precisely
maintain pulse widths.” Paper 42, 5 (citing Ex. 1003 ¶ 182).
Petitioner further argues that Patent Owner:
fails to acknowledge the teachings of Breimesser’s Figure 3
circuit, which produces an output pulse that is not necessarily
shortened and, even if it were, is accurate within two clock
cycles. Ex. 1007, 7:1-20, Fig. 4 (illustrating output pulse Z and
corresponding input pulse group N to O); Ex. 1021, 51:14-22
(Breimesser “doesn’t say that the embodiment of Figure 3 always
shortens the output.”). [Patent Owner] deceptively represents
that pulse Z is “shorter” (Reply, 2), but [Patent Owner’s] expert
admitted on cross-examination that he simply “assumed” output
pulse Z was shorter, even “though there’s no real indication in
Figure 4 if it is, in fact, shorter or longer.” Ex. 1021, 52:3-12; id.
at 49:6-50:14 (PO’s expert conceded that he did not, and could
not, “count the CLK pulses from N to O and compare that to the
CLK pulses for pulse Z.”)
Paper 42, 5.
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Petitioner also points out that:
Breimesser explains that pulse length inaccuracy arises
“due to the position of the front edge of the input pulse in relation
to the triggering edge of the first counter pulse,” and can be
reduced by increasing the clock frequency (i.e., selecting a
smaller tt). Ex. 1007, 4:12-19; see also Ex 1021, 33:13-24
(describing inaccuracy where pulse “transitions occurred in the
middle of a CLK cycle”). Thus Breimesser teaches that the
magnitude of any inaccuracy can be reduced to the extent
necessary as a matter of design.
Paper 42, 5.
We disagree with Patent Owner’s arguments that we summarized
above. Implicit in Patent Owner’s arguments is that the proposed claim
language, “retaining digital pulses,” must mean that any such digital pulses
cannot be altered in any way, such as by shortening, time-shifting, or
creating any type of inaccuracy. Such an interpretation is not warranted and
would require us to improperly read into the proposed claim language a
limitation that is not expressly set out in the claim, or clearly supported by
the specification. “Though understanding the claim language may be aided
by the explanations contained in the written description, it is important not to
import into a claim limitations that are not a part of the claim.” SuperGuide
Corp. v. DirecTV Enters., Inc., 358 F.3d 870, 875 (Fed. Cir. 2004).
The proposed claim language reads “adjusting the filter pass range
based on an aspect of the expected next packet, wherein deriving the second
digital output signal comprises retaining digital pulses with artifact numbers
within the pass range and removing digital pulses with artifact numbers less
than the pass range.” The proposed claim language does not require
“retaining unaltered digital pulses” or “retaining the exact length of any
digital pulses.” Neither does the proposed claim language expressly prohibit
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retaining digital pulses that have been shortened, lengthened, time-shifted, or
having an inaccuracy.
The ’504 Specification does not define “retaining digital pulses” to
mean excluding digital pulses that have been shortened, lengthened, time-
shifted, or having an inaccuracy. Rather, the ’504 Specification describes an
interference rejection circuit that “substantially remov[es] digital pulses
shorter than a first time duration threshold while substantially retaining
digital pulses longer than the first time duration threshold.” Ex. 1002,
20:47–49; see id. at 21:10–17. Indeed, even Figures 12A–D cited by Patent
Owner to support its argument are just examples in which pulse transitions
are aligned with clock cycles. See id. at 12:22–23, 12:27–30, 12:65–67.
As Petitioner points out, Patent Owner could have, but did not,
propose substitute claim language that recited “retaining the exact length of
any digital pulses,” or perhaps “retaining unaltered digital pulses” or even
“retaining digital pulses that have not been shortened, lengthened, time-
shifted, or having an inaccuracy.”
To the extent that Breimesser’s circuit shortens output pulses,
Breimesser also teaches embodiments that avoid shortened pulses. As
Petitioner points out, “Breimesser recognized ‘the pulses of the output signal
are shortened’ by the circuit in Figure 1 and explained that ‘[t]his shortening
can easily be cancelled by addition or subtraction.’” See Ex. 1007, 5:56–60;
see also id. at 4:5–21. In other words, Breimesser provides a circuit
modification to maintain pulse widths. Ex. 1003 ¶ 297.
As for any inaccuracy in Breimesser’s circuit, Breimesser explains
that pulse length inaccuracy arises “due to the position of the front edge of
the input pulse in relation to the triggering edge of the first counter pulse,”
and can be reduced by increasing the clock frequency. See Ex. 1007, 4:12–
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19. Petitioner points out, and we agree, “in cases where the input pulse and
the counter pulse are aligned, such as in Figure 12A of the patent, this
clocking inaccuracy would not result.” See Paper 42, 5.
We are persuaded that Petitioner has demonstrated that the proposed
combination of prior art teaches the recited claim limitation. We consider
the evidence and arguments with respect to the rationale to combine the
prior art, infra.
2. Rationale to Combine the Prior Art
Petitioner asserts that a person of ordinary skill in the art would have
been motivated to combine the teachings of Shanks, Breimesser, Lichtblau,
and Gen 2, such that the proposed substitute claims would have been
obvious at the time of the claimed invention. See Paper 30, 12–16.
Petitioner argues that Shanks and Gen2 teach similar RFID systems such
that it would have been obvious to a person of ordinary skill in the art to
modify Shanks’ pulse-interval encoded signaling system for use in Gen2
systems. See id. at 12–14 (citing Ex. 1020 ¶ 419).
Petitioner acknowledges that Gen2 describes a protocol for
communication, “but does not define any particular circuitry or structure for
implementing a Gen-2 compliant tag.” Paper 30, 13 (citing Ex. 1020 ¶ 419).
Petitioner points out that Shanks provides circuitry to demodulate a wireless
RF input signal from an RFID reader, as well as clocking and counter
circuitry, that could be readily adapted for use in constructing a Gen-2
compliant tag. Id. (citing Ex. 1020 ¶¶ 419–420).
Petitioner also argues that a person of ordinary skill in the art “would
have known that interference causing spurious digital output pulses could be
filtered in order to remove pulses that did not conform to certain minimum
or maximum expected pulse durations.” Paper 30, 13–14 (citing Ex. 1003
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¶ 169); see Ex. 1003 ¶ 290. Petitioner argues that such filtering was known
for decades prior to the alleged invention. Paper 30, 14 (citing Ex. 1003
¶¶ 62–63). Petitioner points to Breimesser, which “teaches a circuit that
‘can be used for gating out interference signals of shorter duration than the
useful signal.’” Paper 30, 14 (citing Ex. 1007, 7:47–49, 7:63–8:15); see also
Ex. 1013, 1:6–11 (“The present invention relates to filters for removing short
noise pulses from digital signals. . . . Noise in a digital transmission may
introduce extra pulses . . . .”).
Petitioner also argues that a person of ordinary skill in the art would
have looked to existing solutions that could be combined with Shanks, such
as Breimesser, to filter pulses arising from interference in a Gen-2 system
and to overcome the known limitations in Shanks’ data recovery circuit.
Paper 30, 14 (citing Ex. 1020 ¶¶ 421–422). Petitioner points out that
Breimesser teaches a circuit for filtering pulses that do not conform to a
minimum expected pulse duration. Paper 30, 14. Petitioner also argues that
a person of ordinary skill in the art “would be motivated to combine
Breimesser’s interference rejection circuit with Shanks,” such that
“interference pulses shorter than the calibrated value for the Gen2 data-0
symbol (e.g., bit ‘0’) would be filtered so that they would not be processed
as invalid data.” Id.
Petitioner argues that “combining the circuits disclosed in Shanks and
Breimesser is a straightforward modification.” Id. (citing Ex. 1003 ¶ 171).
Petitioner points out that Shanks, Breimesser, and Gen2 all “disclose the use
of timing pulse widths for calibration.” Paper 30, 14 (citing Ex. 1020
¶ 423). Petitioner argues a person of ordinary skill in the art “would have
understood that this concept could be expanded to use timing to distinguish
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valid pulses from interference pulses.” Paper 30, 14–15 (citing Ex. 1020
¶ 423).
Petitioner also argues that “whereas Breimesser’s circuit is configured
to reject only pulses that do not conform to a minimum duration (i.e, test
period tp), Lichtblau’s ‘pulse train processor . . . is responsive to both the
minimum duration and to the maximum duration of each of the several
pulses.’” Paper 30, 15 (citing Ex. 1008, 2:3–9; Ex. 1003 ¶ 223); see
Ex. 1003 ¶ 320. “And Gen2,” Petitioner argues, “provides an explicit
motivation for this combination by specifying, for example, that symbols
longer than 4 times RTcal are not data-1 symbols, but instead are invalid
data.” Paper 30, 15 (citing Ex. 1015 § 6.3.1.2.8; Ex. 1020 ¶ 424). “To filter
longer pulses arising from interference that exceed a maximum duration in a
Gen2 system,” Petitioner argues, a person of ordinary skill in the art “would
have looked to the teaching of Lichtblau for use in the combination with
Shanks and Breimesser.” Paper 30, 15 (citing Ex. 1020 ¶ 424).
“In particular,” Petitioner argues, a person of ordinary skill in the art
“would have been motivated to modify Breimesser’s interference rejection
circuit to include both a first and second test period (e.g., tp-min and tp-max)
to filter pulses shorter than the first test period [] and also to filter pulses
longer than the second test period.” Paper 30, 15 (citing Ex. 1003 ¶¶ 225,
425); Ex. 1020 ¶ 385. “To the extent modifications would have been needed
to the combination of Shanks and Breimesser to accommodate a second test
period to filter pulses that exceed a maximum duration,” Petitioner argues,
“such modifications would have been within the level of ordinary skill in the
art at the time of the alleged invention.” Paper 30, 15; Ex. 1020 ¶ 425.
Petitioner argues that the “combination of these aspects of Shanks,
Breimesser, Lichtblau, and Gen2 represents the use of known techniques
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(i.e., filtering digital pulses that do not conform to a minimum expected
pulse duration as Breimesser teaches and to a maximum expected pulse
duration as Lichtblau teaches) to address a specific need in Shanks to filter
digital pulses in order to improve the performance of the digital circuitry by
preventing noise pulses from being interpreted as valid data in a Gen2
system.” Paper 30, 16 (citing Ex. 1020 ¶ 426).
Petitioner also argues that the “proposed combination also amounts to
combining prior art elements according to conventional methods (adding
circuitry to further filter digital pulses) to yield obvious, predictable and
beneficial results from processing a received wireless communication signal,
such as a Gen2 R=>T signal, to eliminate noise pulses that do not conform
to a specified minimum and maximum pulse duration.” Paper 30, 16 (citing
Ex. 1020 ¶ 427).
Petitioner further argues a person of ordinary skill in the art “would
have looked to combine Shanks and Gen2 with Breimesser’s circuit
arrangement, including modifications to include a maximum expected pulse
duration as Lichtblau teaches, with a reasonable expectation of success.”
Paper 30, 16 (citing Ex. 1020 ¶ 428). A person of ordinary skill in the art,
Petitioner argues, “would have recognized that combining the teachings of
these references would yield improved performance in cases where the Gen2
tag circuit is subjected to noise pulses not filtered by Shanks’ data recovery
circuit.” Paper 30, 16 (citing Ex. 1020 ¶ 428).
Patent Owner argues that a person of ordinary skill in the art “at the
time of the invention in mid-2000’s, reading Breimesser’s disclosure from
the mid-1970s, would not have been motivated to use Breimesser’s circuit
with inferior pulse-shortening and pulse shifting characteristics to tackle the
noisy, power-starved and dynamic RFID environment, and yet undertake
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unspecified modifications to Breimesser’s circuit.” Paper 32, 4 (citing
Ex. 2009 ¶¶ 32–37).
Patent Owner also argues that a person of ordinary skill in the art
“would not have been motivated, and would not have found it obvious, to
combine Gen2 with three other references with a reasonable expectation of
success because such a system could not have been used to verify
interrogator compliance as required by Gen2.” Paper 32, 11 (citing Ex. 2009
¶¶ 47–49).
Patent Owner further argues that a person of ordinary skill in the art
“would have had no reason to change the pass range” as Petitioner proposes,
because:
the initial pass range was already successfully used to detect the
“expected next packet” (and the associated pulse width (PW)).
This detection would have provided the needed information (data
rate and other characteristics) regarding all subsequent Data-0
symbols in the subsequent command. Ex. 2009, ¶¶ 50-52.
Therefore, there would NOT have been a need to change the pass
range to detect subsequent Data-0 symbols associated with the
following command, and [Petitioner’s] assertion that the pass
range must be readjusted is an attempt to fill a gap in the
proposed combination with an arbitrary operation that lacks
logical sense.
Paper 32, 10–11.
We disagree with Patent Owner. With respect to Patent Owner’s
argument concerning the use of Breimesser’s circuit in an RFID
environment, Dr. Blalock first explains that “Shanks’ analog front-end
includes a data recovery circuit to demodulate a wireless RF input signal
from an RFID reader.” Ex. 1003 ¶ 165; see id. ¶ 290. “Since the Shanks
demodulator is designed to demodulate signals from a range of frequencies
of interest for its particular application(s),” Dr. Blalock explains, “any
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interfering signals within the same range of frequencies will also be
processed by the demodulator.” Id. ¶ 167. Dr. Blalock testifies that a person
of ordinary skill in the art “would have understood that such a circuit would
allow RF interference to pass through the detector and comparator.” Id.
¶ 168. Dr. Blalock also testifies that “[a]t the time of the alleged invention, a
[person of ordinary skill in the art] would have known that interference that
resulted in spurious digital output pulses could be further filtered in order to
remove pulses that did not conform to certain minimum or maximum
expected pulse durations.” Id. ¶ 169.
Dr. Blalock further testifies that in order to “filter pulses arising from
interference and also to overcome the known limitations in Shanks data
recovery circuit (susceptibility to interference), a [person of ordinary skill in
the art] would have looked to [] existing solutions that could be combined
with Shanks, such as Breimesser, which discloses a circuit for filtering
pulses that do not conform to an expected pulse duration. Id. ¶ 170. “The
combination of these two circuits,” Dr. Blalock testifies, “represent the use
of known techniques (Breimesser’s pulse filtering circuit) to address a
specific need in Shanks to further filter digital pulses to improve the
performance of the digital circuitry.” Id.
We find Dr. Blalock’s testimony persuasive, explaining why a person
of ordinary skill in the art at the time of the invention would have looked to
Breimesser’s known filtering circuit to improve Shanks’ RFID data recovery
circuit in order to filter out undesirable RF interference.
Patent Owner’s argument with respect to Gen2 compliance is
misplaced. The question is not whether “such a system could not have been
used to verify interrogator compliance as required by Gen2,” but rather,
“whether there is something in the prior art as a whole to suggest the
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desirability, and thus the obviousness, of making the combination.” In re
Fulton, 391 F.3d 1195, 1200 (Fed. Cir. 2004). Moreover, “[t]here is no
requirement that one of ordinary skill have a reasonable expectation of
success in developing” a system that could be used to verify interrogator
compliance as required by Gen2, as Patent Owner argues.7 Allergan, Inc. v.
Sandoz Inc., 726 F.3d 1286, 1292 (Fed. Cir. 2013). “Rather, the person of
ordinary skill need only have a reasonable expectation of success of
developing the claimed invention.” Id.
Here, Dr. Blalock explains that a person of ordinary skill in the art
“would have referred to Gen2 in developing RFID tags, because Gen2 was
an industry standard that had been ‘designed to work globally and be
approved as an international standard by the International Organization for
Standardization (ISO).’” Ex. 1020 ¶ 415; see Ex. 1016, 1. Dr. Blalock
explains that “[l]ike Shanks, Gen2 discloses an RFID system where reader to
tag information is pulse-interval encoded.” Ex. 1020 ¶ 416. Also like
Shanks, Dr. Blalock explains, “Gen2 discloses an RFID system, in which
passive tags backscatter modulate information to a reader,” and “discloses
tags that store information in memory, such as an identification number, that
can be retrieved by a reader.” Id. ¶ 418.
“Given these similarities,” Dr. Blalock testifies persuasively that:
it would have been obvious to [a person of ordinary skill in the
art] to modify Shanks pulse-interval encoded signaling system
for use in Gen2 systems. Gen2 describes a protocol for
communication, but does not define any particular circuitry or
structure for implementing a Gen-2 compliant tag. Shanks

7 Petitioner also points out that Gen2 “section 6.3.1.2.4 describes
requirements for an RFID interrogator, which is not within the scope of the
claims. Instead, the claims recite an RFID tag circuit.” Paper 42, 11 (citing
Ex. 1015, 23).
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provides circuitry to demodulate a wireless RF input signal from
an RFID reader, as well as for example, clocking and counter
circuitry, that could be readily adapted for use in constructing a
Gen2 compliant tag.
Id. ¶ 419.
Dr. Blalock further testifies that:
[u]tilizing both Shanks and Gen2 is simply an example of
how design work is typically done. Gen2 is essentially a design
specification stating the functional requirements of a Reader-Tag
wireless communication protocol. Given the Gen2 specification
that has timing requirements, it is suggestive of hardware for
timing and pulse validation. Rather than start from scratch, it is
typical to look for existing similar designs that could be adapted
to meet the needs of a specification. Shanks describes circuitry
to implement a similar wireless protocol so combining Shanks
with Gen2 is a natural design approach for [a person of ordinary
skill in the art].
Id. ¶ 420.
As for Patent Owner’s argument that a person of ordinary skill in the
art “would have had no reason to change the pass range,” Petitioner
persuasively argues that it would have been obvious to readjust the filter
pass range after receiving the expected next packet because “Gen2 specifies
that the preamble and frame-sync may include a data-0 symbol as short as
6.25μsec or as long as 25μsec. The duration of this data-0 symbol (Tari)
calibrates the tag to interpret subsequent symbols as either data-0 or data-1,”
making it “obvious to adjust the filter pass range based on this calibrated
duration.” Paper 42, 10 (citing Paper 30, 9–12, 19; Ex. 1020 ¶¶ 407–411,
434).
We find that Petitioner has shown by a preponderance of the evidence
that one of ordinary skill in the art at the time of the invention would have
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had reason to combine the teachings of the prior art in the manner described
by Petitioner.
3. Conclusion as to Proposed Substitute Independent Claim 22
Based upon consideration of the entire record, we are persuaded by
Petitioner’s arguments and evidence and determine that Petitioner has
demonstrated by a preponderance of the evidence that proposed substitute
independent claim 22 is unpatentable under 35 U.S.C. § 103(a) as obvious
over the combined teachings of the prior art.
4. Proposed Substitute Independent Claims 30 and 33
As noted, supra, the parties, in general, do not argue proposed
substitute independent claims 30 and 33 separately, relying instead on their
arguments directed to independent claim 22. See Paper 30, 22–23; Ex. 1020
¶ 439; Paper 32, 1. Petitioner, however, does argue the adjusting the filter
pass range based on an aspect of the expected next packet limitation of
claim 30 and claim 33 separately. See Paper 30, 23–25.
The proposed limitation in claim 30 reads:
[30-b5, b6]: adjusting the filter pass range based on an aspect of
the expected next packet, wherein deriving a the second digital
output signal responsive to the first digital output signal at an
interference rejection circuit of a RFID tag circuit by comprises
substantially removing retaining digital pulses with artifact
numbers greater than a first high number within the pass range
while substantially retaining and removing digital pulses with
artifact numbers lower greater than the first high number,
wherein the first high number corresponds to a first time
duration threshold pass range.
Paper 25, App. A. The proposed limitations in claim 33 (33-c4, c5) recite
substantially the same limitations. Id. Accordingly, Petitioner asserts claim
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33 would have been obvious for the same reasons claim 30 would have been
obvious. Paper 30, 25 (citing Ex. 1020 ¶ 445).
For this limitation, Petitioner largely reiterates its arguments for the
equivalent limitation in claim 22 (22-b5, b6). Paper 30, 23–25 (citing
Ex. 1020 ¶¶ 440–445); see § II.F.1 (claim 22-b5, b6), supra. For example,
Petitioner argues a person of ordinary skill in the art “would have been
motivated to combine Shanks and Breimesser to filter interference pulses
shorter than the calibrated value for the shortest valid signal (e.g., bit ‘0’) to
prevent the misidentification of a noise pulse as a valid data bit.” Paper 30,
23 (citing Pet. § VI.A.1(d) (claim [1-c(i)]); Ex. 1020 ¶ 440). Petitioner
argues a person of ordinary skill in the art “would have adjusted
Breimesser’s test period tp, the filter pass range, based on the duration of
data symbols used with a particular data rate.” Id. (citing Pet. § VI.A.1(d, e)
(claim [1-c(i, ii)]); Ex. 1020 ¶ 440). “As a result,” Petitioner concludes,
“interference pulses shorter than the test period, that is pulses with artifact
numbers less than the pass range, would not be interpreted as a logical ‘0.’”
Id. (citing Pet. § VI.A.1(d, e) (claim [1-c(i, ii)]); Ex. 1020 ¶ 440).
Patent Owner does not specifically address Petitioner’s argument with
respect to this limitation. See generally Paper 32.
Petitioner’s argument is supported by the cited evidence. We are
persuaded that Petitioner has demonstrated that the proposed combination of
prior art teaches the recited claim limitation.
Based upon consideration of the entire record, and for the reasons
discussed, supra, with respect to proposed substitute independent claim 22,
we are persuaded by Petitioner’s arguments and evidence and determine that
Petitioner has demonstrated by a preponderance of the evidence that
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proposed substitute independent claims 30 and 33 are unpatentable under
35 U.S.C. § 103(a) as obvious over the combined teachings of the prior art.
5. Proposed Substitute Dependent Claims 23–29, 31–32, 34–35
As noted above, Petitioner asserts that proposed substitute dependent
claims 23–29, 31–32, and 34–35 (see Paper 25, App. A) are unpatentable as
obvious over the combined teachings of Shanks, Breimesser, Lichtblau, and
Gen2. Paper 30, 17–25.
Petitioner provides evidence and argument showing that the
combination of Shanks, Breimesser, Lichtblau, and Gen2 teaches the
limitations of these proposed substitute dependent claims. Id. Petitioner
also provides evidence and argument that one of ordinary skill in the art
would have combined the teachings of the prior art in the manner described.
Id.
Patent Owner does not specifically address Petitioner’s arguments
with respect to the dependent claims. Paper 32, 12.
We have considered the evidence and arguments with respect to
proposed substitute dependent claims 23–29, 31–32, and 34–35. We are
persuaded that Petitioner has demonstrated that the combined teachings of
the prior art meet the recited limitations of these claims and that one of
ordinary skill in the art would have been motivated to combine the prior art
in the manner described.
Based upon consideration of the entire record, we are persuaded that
Petitioner has demonstrated by a preponderance of the evidence that
proposed substitute dependent claims 23–29, 31–32, and 34–35 are
unpatentable under 35 U.S.C. § 103(a) as obvious over the combined
teachings of the prior art.
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G. Anticipation Based on Hyde ’598
Petitioner asserts proposed substitute claims 22–35 are unpatentable
as anticipated under 35 U.S.C. § 102(b) by Hyde ’598. Because Petitioner
has already shown that all of the proposed substitute claims are unpatentable
as discussed supra, we do not reach this additional asserted ground. See
Beloit Corp. v. Valmet Oy, 742 F.2d 1421, 1423 (Fed. Cir. 1984) (“The
Commission . . . is at perfect liberty to reach a ‘no violation’ determination
on a single dispositive issue.”); Boston Sci. Scimed, Inc. v. Cook Grp. Inc.,
809 F. App’x 984, 990 (Fed. Cir. 2020) (recognizing that “[t]he Board has
the discretion to decline to decide additional instituted grounds once the
petitioner has prevailed on all its challenged claims”).
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CONCLUSION
For the foregoing reasons, we cancel claims 1, 2, 4, 7–10, 13–15, 17–
19, and 21 of the ’504 patent, and we deny Patent Owner’s motion to amend
the ’504 patent to add proposed substitute claims 22–35. In summary:

Claims 35
U.S.C. §
Reference(s)/Basis Claims
Shown
Unpatentable
Claims Not
Shown
Unpatenable
1–2, 4, 7,
13
103(a) Shanks,
Breimesser8

8–10,
14–15,
17–19,
21
103(a) Shanks,
Breimesser,
Lichtblau9

Overall
Outcome

Motion to Amend Outcome Claims
Original Claims Cancelled by Amendment 1, 2, 4, 7–10, 13–15, 17–
19, 21
Substitute Claims Proposed in the Amendment 22–35
Substitute Claims: Motion to Amend Granted
Substitute Claims: Motion to Amend Denied 22–35
Substitute Claims: Not Reached

8 We do not reach this asserted ground. See Section I.D.
9 We do not reach this asserted ground. See Section I.D.
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ORDER
Accordingly, it is
ORDERED that Patent Owner’s Motion to Amend is granted-in-part
as to its non-contingent request to cancel claims 1, 2, 4, 7–10, 13–15, 17–19,
and 21; and
FURTHER ORDERED that Patent Owner’s Motion to Amend is
denied-in-part as to substitute claims 22–35.
This is a final decision. Parties to the proceeding seeking judicial
review of the decision must comply with the notice and service requirements
of 37 C.F.R. § 90.2.

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PETITIONER:

David L. Witcoff
Matthew W. Johnson
David Cochran
Thomas Ritchie
Joshua Nightingale
Yury Kalish
JONES DAY
dlwitcoff@jonesday.com
mwjohnson@jonesday.com
dcochran@jonesday.com
twritchie@jonesday.com
jrnightingale@jonesday.com
ykalish@jonesday.com

PATENT OWNER:

Christina J. McCullough
Amy Simpson
Babak Tehranchi
Daniel Keese
PERKINS COIE LLP
mccullough-ptab@perkinscoie.com
Simpson-ptab@perkinscoie.com
tehranchi-ptab@perkinscoie.com
keese-ptab@perkinscoie.com