NXP B.V.

Patent Trials and Appeals Board

May 27, 2021

2020001514 (P.T.A.B. May. 27, 2021)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
15/412,659 01/23/2017 Clemens DE HAAS 81987721US02 2955
65913 7590 05/27/2021
Intellectual Property and Licensing
NXP B.V.
350 HOLGER WAY
SAN JOSE, CA 95134
EXAMINER
BORROMEO, JUANITO C
ART UNIT PAPER NUMBER
2184
NOTIFICATION DATE DELIVERY MODE
05/27/2021 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
ip.department.us@nxp.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte CLEMENS DE HAAS, MATTHIAS MUTH,
HARTMUT HABBEN, and ANTHONY ADAMSON

Appeal 2020-001514
Application 15/412,659
Technology Center 2100

Before CARL W. WHITEHEAD JR., DAVID M. KOHUT, and
IRVIN E. BRANCH, Administrative Patent Judges.

BRANCH, Administrative Patent Judge.

DECISION ON APPEAL
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision to reject claims 1–20. We have jurisdiction under
35 U.S.C. § 6(b).
We REVERSE.

1 We use “Appellant” to reference the applicant as defined in
37 C.F.R. § 1.42. Appellant identifies the real party in interest as
“NXP USA, Inc.” Appeal Br. 3.
Appeal 2020-001514
Application 15/412,659

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STATEMENT OF THE CASE
Appellant’s Invention
Appellant summarizes the invention’s focus and consequential “first
aspect” (Spec. 2, l. 5) as follows:
Current [Controller Area Network (CAN)] buses may [be] able
to support varying data rates, . . . [but] support of such data
rates is dependent on the network being correctly terminated[,
e.g.,] the termination resistance . . . .
[The background art consequently] . . . monitor[s] the signals
on the CAN bus [and, w]hen a state change on the bus is
detected, a switch is closed for a fixed period of time to provide
a lowering of impedance on the bus.
. . . [In the invention, l]owering the impedance of the bus may
comprise[] . . . driv[ing] the bus to a low impedance state. . . .
The transmitter may be configured to drive the bus in an
opposite polarity.
Spec. 1, ll. 13–15; 2, ll. 1–3, 11–12, 18 (paragraphing revised).
Claim 1, reproduced below, is illustrative of disputed subject matter.
1. A circuit comprising:
a first input coupled to a transmit data input of a bus
transceiver; and
a first output coupled to a bus;
wherein the circuit is configured to be coupled in parallel
with the bus transceiver and configured to, in response to a
dominant to recessive transition on the transmit data input,
lower an impedance of the bus by outputting a negative drive
current to the bus.
Appeal Br. 22 (emphasis added).
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Application 15/412,659

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Rejection
Claims 1–20 stand rejected under 35 U.S.C. § 102(a)(1) as anticipated
by Monroe (US 2014/0156893 A1; June 5, 2014). Final Act. 2–5.
OPINION
The same findings and arguments are presented on appeal for each of
claims 1–20. Ans. 3–4; Appeal Br. 20. We address, below, a dispositive
issue with reference to claim 1. For the following reasons, we are persuaded
of error in the rejection of claim 1 and therefore do not sustain the rejection
of claims 1–20.2
Appellant contends Monroe does not teach the claimed “lower an
impedance of the bus by outputting a negative drive current to the bus.”
Appeal Br. 13 (identifying the limitation), 13–20 (specific contentions).
The contentions are directed to Monroe’s Figures 6 and 10 (see, e.g.,
id. at 13, 16), which are reproduced below (Figure 10 and then Figure 6) and
respectively illustrate a “diagram of an apparatus for exercising [the cited
embodiment’s] CAN bus dominant-to-recessive transmit data bit timing
control” (Monroe ¶ 22) and a “diagram [of the embodiment’s] CAN bus
differential waveform” (Monroe ¶ 18).

2 Claims 2−14 are dependent upon claim 1. Claim 15 recites similar
limitations to claim 1. Claims 16−20 are dependent upon claim 15.
Appeal 2020-001514
Application 15/412,659

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Monroe’s Figure 10, reproduced above, illustrates “a schematic
diagram of an apparatus for exercising CAN bus
dominant-to-recessive transmit data bit timing control.” Monroe
¶ 22.

Monroe’s Figure 6, reproduced above, illustrates a “diagram [of]
a CAN bus differential waveform.” Monroe ¶ 18.
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Appellant contends the embodiment does not teach the claimed
“lower an impedance of the bus by outputting a negative drive current to the
bus” because:
[In t]he Monroe device of figure 10[, l]ogic circuit 1030 accepts
the FD and TXD inputs from the controller 1115[] and then
selectively enables or disables the fractional drivers 900A,
900B . . . to insert a nulling impedance across the CAN
bus. . . .
. . . .
. . . . Referring to FIG. 6 of Monroe, inserting the nulling
impedance on the bus causes the CANH and CANL signals to
return to a steady state bus voltage more quickly than
otherwise. . . .
. . . . [That is, t]he . . . nulling impedance . . . increases a
rate of decay of [the] CAN bus dominant-to-recessive
differential signal waveform 600 . . . . Claim 1, in contrast,
requires outputting a negative current on the bus . . . .
Appeal Br. 13, 16 (citing Monroe ¶ 46).
The Examiner responds that Appellant has failed to apply the
Specification’s description of a “negative drive current.” Ans. 3–4. The
Examiner quotes and emphasizes the description as follows:
The negative drive current is described in the applicant
specification . . . as follows:
. . . . The drive current 412 varies between the reference
value, for example zero, and a negative value -ICANBUS,
where the reference value corresponds to . . . not driving
the bus[]and -ICANBUS corresponds to . . . driving the bus
to an active- recessive state. It will be appreciated that
the positive drive current 411 value ICANBUS and the
negative drive current 412 value -ICANBUS in this example
may be equal in magnitude but of opposite polarity.
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The drive currents are described as varying between a
reference value and ICANBUS/-ICANBUS. The reference
value has been given as being equal to zero in some
examples. It [should] be appreciated that the reference
value may take on other values. For example, there may
be a current offset in the system in which case the current
will vary between zero +/- the offset, ICANBUS +/- offset
and -ICANBUS +/- the offset.
Id. (quoting Spec. 9, ll. 11–23; Examiner’s emphases; paragraphing and
emphases reformatted). The Examiner also states, in an Advisory Action,
that Monroe achieves a negative drive current by driving the CANH and
CANL lines respectively above and below a reference value. Advisory Act.,
Cont’n Sheet.
We are persuaded of Examiner error because the Examiner does not
show Monroe achieves the claimed negative current. Before explaining the
error, we construe “negative” current.
The Examiner seems to interpret “negative” current as a reversal of a
current’s direction. Ans. 3–4 (block-quoted at supra 5–6). We agree with
this uncontested interpretation. See Reply Br. 19 (“will never result in a
negative current . . . because . . . the diodes . . . would prevent current from
flowing in the opposite direction”). “Current” is a flow of positive charge
or, in other words, a flow of charge from a region of higher voltage to a
region of lower voltage. See, e.g., CURRENT. Dictionary.com, The
American Heritage® Science Dictionary, Houghton Mifflin Co. at http://
dictionary.reference.com/browse/current (last visited April 28, 2021)
(“A flow of positive electric charge . . . related to voltage differences in that
medium[.]”). Because current is a flow of positive charge, “negative”
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current can be reasonably construed as an opposite flow (i.e., reversed flow)
of positive charge.
Though the Examiner’s interpretation of “negative” current is
reasonable, the Examiner fails to support the finding that Monroe’s CANH
and CANL lines reverse a current direction (i.e., achieves a negative
current). Ans. 3–4. The Examiner does not explain why Monroe is found to
reverse a current direction by driving the CANH and CANL lines
respectively above and below a reference value. Advisory Act.,
Cont’n Sheet.
Moreover, the CANH and CANL lines are not configured to reverse a
current direction. Monroe’s CANH and CANL lines are biased at Vcc/2
(e.g., 2.5V) and only operate respectively above and below that reference
value. Monroe ¶ 10; Fig. 6. We explain, below, with reference to Monroe’s
background art and invention.
In Monroe’s background art, the bus’ dominant state (representing a
logic LOW level) is achieved when the bus’ drivers are activated to drive the
CANH and CANL lines respectively higher and lower than Vcc/2 (e.g.,
respectively at 3.5V and 1.5V). Id.; see also Monroe Fig. 3. The bus’
recessive state (representing a logic HIGH level) is achieved when the bus’
drivers are deactivated, the drivers consequently no longer drive the CANH
and CANL lines, and the bus accordingly returns to Vcc/2. Id. By this
mechanism, the CANH and CANL lines slowly return to Vcc/2. Id.; see
also Monroe Fig. 4. This slow return to Vcc/2 causes an undesirably long
dominant-to-recessive state transition. Id.
In Monroe’s invention, a shorter dominant-to-recessive state transition
is achieved by driving the CANH and CANL lines during the transition; the
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drivers are not deactivated as in the background art. Monroe ¶¶ 24, 32.
Specifically, the “CAN bus recessive nulling driver 900” receives a signal
“from recessive nulling logic” and responds by driving each of the CANH
and CANL lines to Vcc/2. Id. ¶¶ 39–40.
Therefore, in summary, Monroe biases the CANH and CANL lines at
Vcc/2, drives the CANH and CANL lines respectively higher and lower than
Vcc/2 to achieve the bus’ dominant state, and drives each of the CANH and
CANL lines to Vcc/2 (imparts the recessive nulling impedance) so as to
achieve a shorter dominant-to-recessive state transition to the bus’ recessive
state. Monroe ¶¶ 10, 24, 32, 39–40; Figs. 3–4; see also id. ¶¶ 6, 11 (driving
the CANH and CANL lines to Vcc/2 accelerates the decay of parasitic
capacitance (i.e., residual charge) remaining from the dominant state). The
dominant-to-recessive state transition does not reverse a current direction
because: the dominant state drives the CANH and CANL lines to voltages
respectively higher and lower than Vcc/2; the transition (to the recessive
state) drives the CANH line voltage down to only Vcc/2 and drives the
CANL line voltage up to only Vcc/2. In other words, the CANH line
voltage will always be greater than or equal to Vcc/2 and the CANL line
voltage will always be less than or equal to Vcc/2, such that current flows
from the CANH line to the CANL line or not at all (i.e., is never reversed so
as to flow from the CANL line to the CANH line).
OVERALL CONCLUSION
We reverse the Examiner’s decision to reject claims 1–20.
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DECISION SUMMARY
Claim(s)
Rejected 35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1–20 102(a)(1) Monroe 1–20

REVERSED