INTEL IP CORPORATION

Patent Trials and Appeals Board

Sep 9, 2020

15290300 - (D) (P.T.A.B. Sep. 9, 2020)

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.
15/290,300 10/11/2016 Christian Mayer 42536-1053 8100
116341 7590 09/09/2020
Schiff Hardin LLP (Intel)
c/o Laura C. Brutman
Schiff Hardin LLP
1185 Avenue of the Americas, Suite 3000
New York, NY 10036
EXAMINER
CADEAU, WEDNEL
ART UNIT PAPER NUMBER
2632
NOTIFICATION DATE DELIVERY MODE
09/09/2020 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):
Patents-NY@schiffhardin.com
inteldocs_docketing@cpaglobal.com
lbrutman@schiffhardin.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte CHRISTIAN MAYER and JOVAN MARKOVIC
____________

Appeal 2019-003670
Application 15/290,300
Technology Center 2600
____________

Before JOHNNY A. KUMAR, JAMES W. DEJMEK, and
STEPHEN E. BELISLE, Administrative Patent Judges.

BELISLE, Administrative Patent Judge.

DECISION ON APPEAL
Appellant1 appeals under 35 U.S.C. § 134(a) from a Final Rejection of
claims 1–25. Appeal Br. 3–4. We have jurisdiction under 35 U.S.C. § 6(b).
We reverse.

1 Throughout this Decision, we use the word “Appellant” to refer to
“applicant” as defined in 37 C.F.R. § 1.42 (2018). Appellant identifies the
real party in interest as INTEL IP Corporation. Appeal Br. 2.
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STATEMENT OF THE CASE
The Claimed Invention
Appellant’s invention relates generally to reducing or eliminating
“signed local oscillator (LO) leakage of a signed radio frequency digital-to-
analog converter (RFDAC).” Spec. ¶ 13. According to the Specification,
“LO leakage [has] two components, an unsigned LO leakage that originates
from the original LO generation, which leaks directly to the RFDAC output,
and a signed LO leakage which originates after mixing the sign signal(s) of a
sign signal branch with the LO signal(s) (in-phase carrier signal and
quadrature carrier signal), and leaks after this mixing into the RFDAC
output.” Spec. ¶ 17. The Specification summarizes an exemplary
embodiment of Appellant’s invention as follows:
A communication system receives an input signal along a signal
processing path and generates a converted output signal via a
digital-to-analog converter (DAC). The signal processing path
branches into two different branches, a magnitude branch and a
sign branch for different components of the baseband signal.
A local oscillator (LO) provides a carrier signal to the signal
processing path at the DAC and further generates an LO leakage
signal comprising a signed LO leakage and an unsigned LO
leakage during the up-conversion of signals of the sign branch
with a carrier. An unsigned LO suppression component is
configured to reduce or eliminate the unsigned LO leakage and a
signed LO suppression component is configured to reduce or
eliminate the signed LO leakage form a baseband signal of the
signal processing path.
Spec., Abstract.
Claim 1, reproduced below, is illustrative of the subject matter on
appeal:
1. An apparatus of a mobile communication device
comprising:
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an radio frequency (RF) frontend;
a radio frequency digital-to-analog converter (RFDAC)
configured to up-convert a digital baseband signal to a radio
frequency, and convert the digital baseband signal from a signal
processing chain to an analog signal, wherein the RFDAC is
coupled to a local oscillator configured to provide an oscillator
signal to the digital baseband signal of the signal processing
chain, and generate a local oscillator (LO) leakage comprising a
signed LO leakage and an unsigned LO leakage at an output of
the RFDAC;
an unsigned local oscillator LO leakage suppression
component configured to suppress the unsigned LO leakage from
the digital baseband signal; and
a signed LO leakage suppression component configured to
suppress the signed LO leakage.
Appeal Br. 12 (Claims App.).
The Applied References
The Examiner relies on the following references as evidence of
unpatentability of the claims on appeal:
Sahlman US 2002/0048326 A1 Apr. 25, 2002
van Waasen US 2009/0225903 A1 Sept. 10, 2009
The Examiner’s Rejections
The Examiner made the following rejections of the claims on appeal:
Claims 1, 2, and 11 stand rejected under 35 U.S.C. § 103 as being
unpatentable over Sahlman. Final Act. 10–12.
Claim 3–10 and 12–25 stand rejected under 35 U.S.C. § 103 as being
unpatentable over the combination of Sahlman and van Waasen. Final
Act. 12–21.
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ANALYSIS2
Appellant disputes the Examiner’s findings that the various
combinations of Sahlman and van Waasen render obvious claims 1–25.
Appeal Br. 4–10; Reply Br. 2–7.
Appellant argues, inter alia, that independent claims 1, 11, and 19
involve (i) an unsigned local oscillator (LO) leakage suppression component
configured to suppress unsigned LO leakage from a digital baseband signal;
and (ii) a signed LO leakage suppression component configured to suppress
signed LO leakage, and that there is no basis in the record, but for
impermissible hindsight, for modifying Sahlman (or other cited art) to
satisfy these claim limitations. See Appeal Br. 4–7; Reply Br. 2–7. On the
present record, we find Appellant’s argument persuasive as discussed below.
We turn first to the teachings of Sahlman.
Sahlman relates generally to “power amplifier linearization and up-
conversion of digital signals to radio-frequency signals.” Sahlman ¶ 1. An
exemplary embodiment of Sahlman’s digital compensation technique for an
analog I/Q3 up-converter is shown in Figure 7A, reproduced below.
Sahlman ¶ 23, Fig. 7A.

2 Throughout this Decision, we have considered Appellant’s Appeal Brief
filed October 24, 2018 (“Appeal Br.”); Appellant’s Reply Brief filed April 4,
2018 (“Reply Br.”); the Examiner’s Answer mailed February 4, 2018
(“Ans.”); the Final Office Action mailed May 25, 2018 (“Final Act.”); and
Appellant’s Specification filed October 11, 2016 (“Spec.”).
3 A digital input signal may include in-phase (I) and quadrature-phase (Q)
components. Sahlman ¶ 36.
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Figure 7A illustrates the correction structure
required for minimizing analog modulator up-
converter errors to acceptable levels.
Sahlman ¶¶ 23, 48, Fig. 7A. Salhman discloses “IF-LO [Intermediate
Frequency-Local Oscillator] leakage is corrected by adjusting the DC-
offsets to add or subtract a DC-correction value to each I- and Q-signal in
respective summers 718, 719,” and “corrected I-and Q-signals are each
supplied to a respective DAC 721, 722 and analog low-pass filter 724, 725
before being provided to the analog I/Q-modulator 730.” Id. ¶ 48.
The Examiner finds, and Appellant likewise agrees and emphasizes,
“Sahlman fails to explicitly teach an unsigned local oscillator LO leakage
suppression component configured to suppress the unsigned LO leakage
from the digital baseband signal; and a signed LO leakage suppression
component configured to suppress the signed LO leakage.” Final Act. 11;
Appeal Br. 4–5. Nevertheless, the Examiner also finds (i) “Sahlman
discloses performing pre-distortion using a pre-distortion unit and I/Q
compensation using an I/Q compensation unit and DC adjusting units for
compensating for DC offsets cause[d] by oscillator leakage and perform[ing]
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signal compensation or correction at several place[s] in the received signal
chain using several components,” and (ii) “Sahlman further teaches using
normal signal processing filtering and autocorrelation techniques can be
used for distinguishing the different DC-leakages.” Final Act. 11 (citations
omitted); see Ans. 5–6. In view of these various findings concerning
distortion and compensation, the Examiner determines that it would have
been obvious to the skilled artisan to incorporate the claim limitations at
issue into Sahlman, because it would have been obvious to the skilled artisan
“to determine the various DC-leakages and correct for each of them
separately using different components.” Final Act. 11.
Appellant responds, unlike as required by the limitations of
independent claim 1, “Sahlman do[es] not provide an oscillator signal to the
digital baseband signal of the signal processing chain, but rather, the IF-
LO 1315 and RF-LO1 1316 provide analog signals to a pre-distortion Up-
Converter 1308 coupled after the digital-to-analog converter in Sahlman,”
and argues that, “[a]s such, the local oscillator (e.g., 424, IF-LO at
modulator 730, 825, 1040, 1315) of Sahlman does not generate an oscillator
signal to the digital baseband signal of the signal processing chain.” Reply
Br. 2–3 (emphases altered). Appellant argues that this configuration of
Sahlman does not teach or suggest “a local oscillator (LO) leakage with a
signed LO leakage and an unsigned LO leakage along the signal processing
chain as claimed, or from the digital baseband signal, as claimed, or at an
output of a radio frequency digital-to-analog converter (RFDAC).” Reply
Br. 3. Appellant further argues “there is no indication of LO leakage at
the output of the DAC of Sahlman, nor of an oscillator signal being
provided to the digital baseband signal, and thus, no motivation to suppress
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unsigned LO leakage from the digital baseband signal, and with a
different structural component (a signed LO leakage suppression
component) to further suppress signed LO leakage.” Reply Br. 3.
Appellant submits: “Why would Sahlman change from placing IF-LO 1315
or otherwise before the DAC and change this to remove both unsigned and
signed local oscillator leakage, other than the Appellant’s claims giving hint
of this different configuration? There is no reason, except for improper
hindsight.” Reply Br. 3; see Sahlman, Fig. 13 (item 1315).
As noted above, although the Examiner agrees that “Sahlman fails to
explicitly teach an unsigned local oscillator LO leakage suppression
component configured to suppress the unsigned LO leakage from the digital
baseband signal; and a signed LO leakage suppression component
configured to suppress the signed LO leakage,” the Examiner nevertheless
finds that the skilled artisan, in view of Sahlman alone, would have been
motivated to introduce these features into Sahlman, merely because Sahlman
teaches certain other (not claimed) compensation or suppression techniques.
Final Act. 11; Appeal Br. 3–7. We find that the Examiner has not provided
sufficient evidence or technical reasoning to explain clearly why the skilled
artisan, absent hindsight, would have (1) recognized Sahlman’s system as
presenting both signed and unsigned LO leakage issues as claimed to be
remedied, particularly where Sahlman introduces a LO signal after the
digital-to-analog converter rather than to the digital baseband signal of the
signal processing chain as recited in claim 1; and then (2) leaped to
reconfiguring Sahlman’s system, including altering LO utilization, to
include both (i) an unsigned LO leakage suppression component configured
to suppress unsigned LO leakage from a digital baseband signal, and
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(ii) a signed LO leakage suppression component configured to suppress
signed LO leakage. See Sensonics, Inc. v. Aerosonic Corp., 81 F.3d 1566,
1570 (Fed. Cir. 1996) (“To draw on hindsight knowledge of the patented
invention, when the prior art does not contain or suggest that knowledge, is
to use the invention as a template for its own reconstruction—an illogical
and inappropriate process by which to determine patentability.” (citing W.L.
Gore & Assoc. v. Garlock, Inc., 721 F.2d 1540, 1553 (Fed. Cir. 1983))).
The Examiner’s determination of obviousness over Sahlman appears
to be based, at least in part, on a finding that the skilled artisan could modify
Sahlman to arrive at the invention of claim 1: “Sahlman teaches the system
is capable of distinguishing between different DC leakages and is directed to
correct or mitigate various DC offsets.” Ans. 3. However, we are mindful
that although one of ordinary skill in the art may understand that a reference
could be modified as reasoned by the Examiner, this does not imply a
motivation to modify the reference. See Personal Web Techs., LLC v. Apple,
Inc., 848 F.3d 987 993–94 (Fed. Cir. 2017); see also Belden Inc. v. Berk–Tek
LLC, 805 F.3d 1064, 1073 (Fed. Cir. 2015) (“[O]bviousness concerns
whether a skilled artisan not only could have made but would have been
motivated to make the combinations or modifications of prior art to arrive at
the claimed invention.”); InTouch Techs., Inc. v. VGO Communications,
Inc., 751 F.3d 1327, 1352 (Fed. Cir. 2014).
The Examiner also has not persuasively shown how the other cited art,
namely van Waasen, remedies the foregoing deficiencies. First, the
Examiner rejected independent claims 1 and 11 as obvious over Sahlman
alone (not over any combination of art). Ans. 3. Second, although the
Examiner states, “[v]an Waasen further solidifies the interpretation given
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and teaches how one of ordinary skill in the [art] can calculate different
errors such as signed and unsigned errors such as error cause[d] by any
component in the system and channel” (Ans. 6–7 (emphasis added)), we find
the Examiner’s combination of Sahlman and van Waasen suffers from the
same deficiencies noted above as to Sahlman. See Reply Br. 5–6 (“[T]he
local oscillator 306 of [v]an Waasen does not take into account different
types of leakage, or any component addressing LO leakage, either singly or
with different structural components corresponding to different aspects of
the LO leakage (unsigned LO leakage AND signed LO leakage). [v]an
Waasen simply addresses the I and Q paths by providing an offset or
predefined bias before or after Analog to Digital conversion at paragraph
[0034]. There is no suggestion of addressing leakage from the local
oscillator 306 of [v]an Waasen.”).
Accordingly, constrained by the present record, we do not sustain the
Examiner’s rejection under 35 U.S.C. § 103 of independent claims 1, 11,
and 19. Additionally, we do not sustain the Examiner’s rejection under
35 U.S.C. § 103 of claims 2–10, 12–18, and 20–25, which depend therefrom.
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DECISION SUMMARY
In summary:
Claims
Rejected 35 U.S.C. §
Reference(s)/
Basis Affirmed Reversed
1, 2, 11 103 Sahlman 1, 2, 11
3–10, 12–25 103 Sahlman,
van Waasen
3–10, 12–25
Overall
Outcome
1–25

REVERSED