Ex Parte Pan

Board of Patent Appeals and Interferences

Jul 27, 2012

10977874 (B.P.A.I. Jul. 27, 2012)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________________

Ex parte MENG-AN PAN
____________________

Appeal 2010-002188
Application 10/977,8741
Technology Center 2600
____________________

Before ST. JOHN COURTENAY III, CAROLYN D. THOMAS, and
JAMES R. HUGHES, Administrative Patent Judges.

HUGHES, Administrative Patent Judge.

DECISION ON APPEAL

1 Application filed October 29, 2004. The real party in interest is Broadcom
Corp. (App. Br. 2.)
Appeal 2010-002188
Application 10/977,874

2

STATEMENT OF THE CASE
Appellant appeals from the Examiner’s rejection of claims 1-26. We
have jurisdiction under 35 U.S.C. § 6(b).
We affirm-in-part.
Appellant’s Invention
The invention at issue on appeal concerns a method and system for
processing of Radio Frequency (RF) signals. More specifically, a method
and system for reducing DC offset for a mixer in a RF receiver. (Spec. ¶¶
[02], [07]; Abstract.)2
Representative Claims
Independent claims 1 and 19, reproduced below, with disputed
limitations italicized, further illustrate the invention:
1. A method for reducing DC offset in a receiver, the
method comprising:
averaging signals to determine an output common mode
DC offset level, said signals being generated from an output of
a mixer;
determining an average of said signals having said
common mode DC offset level;
comparing said determined average to a reference
voltage; and
correcting said common mode DC offset level at an input
of said mixer for signals which are subsequently generated
from an output of said mixer utilizing results from said
comparing.

2 We refer to Appellant’s Specification (“Spec.”); Appeal Brief (“App. Br.”)
filed March 9, 2009; and Reply Brief (“Reply Br.”) filed August 25, 2009.
We also refer to the Examiner’s Answer (“Ans.”) mailed June 25, 2009.
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19. A method for reducing DC offset in a receiver, the
method comprising compensating for output common mode DC
level at an input of a mixer rather than an output of said mixer.

Rejection on Appeal
The Examiner rejects claims 1-26 under 35 U.S.C. § 103(a) as being
unpatentable over U.S. Patent App. Pub. No. 2005/0037723 A1, published
Feb. 17, 2005 (filed Aug. 28, 2004) (“Khorram”) and U.S. Patent No.
7,164,329 B2, issued Jan. 16, 2007 (filed Apr. 10, 2002) (“Toncich”).

ISSUES
Based on our review of the administrative record, Appellant’s
contentions, and the Examiner’s findings and conclusions, the pivotal issues
before us are as follows:
1. Does the Examiner err in concluding that the combination of
Khorram and Toncich collectively would have taught or suggested
“correcting said common mode DC offset level at an input of said mixer for
signals which are subsequently generated from an output of said mixer
utilizing results from said comparing” within the meaning of claim 1 and
commensurate recitations of claims 10, 19, and 23?
2. Does the Examiner err in concluding that the combination of
Khorram and Toncich collectively would have taught or suggested “feeding
back said corrected common mode DC offset level to an input of said mixer”
within the meaning of claim 2 and commensurate recitations of claim 11?

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Application 10/977,874

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FINDINGS OF FACT
We adopt the Examiner’s findings in the Answer and the Final Office
Action as our own, except as to those findings that we expressly overturn or
set aside in the Analysis that follows.

ANALYSIS
Based on Appellant’s arguments (App. Br. 10-22) we select
independent claim 1 and dependent claim 2 as representative of Appellant’s
arguments and groupings with respect to claims 1-26. 37 C.F.R.
§ 41.37(c)(1)(vii).
Claim 1
Appellant contends that Khorram and Toncich do not teach
“correcting said common mode DC offset level at an input of said mixer for
signals which are subsequently generated from an output of said mixer”
(claim 1). (App. Br. 10-14; Reply Br.4-6.) Specifically, Appellant contends
that: “Khorram does not teach ‘correcting said common mode DC offset
level at an input of said mixer,’ as is recited in independent claim 1
(emphasis added)” (App. Br. 11); “Khorram provides no support for the
assertion that Khorram teaches providing an actual DC offset level
correction at an input of a mixer” (id. at 14); and “Toncich teaches input of a
time-varying signal to a mixer instead of input of the DC offset level to a
mixer as is recited in independent claim 1” (id. at 12).
The Examiner sets forth a detailed explanation of the obviousness
rejection in the Examiner’s Answer with respect to each of the claims and, in
particular, the rejection of claim 1. (Ans. 4-5, 7-8.) Specifically, the
Examiner submits that Khorram explicitly describes a feedback control
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signal based on a detected DC offset to the inputs of first and second mixing
stages of a mixer (Ans. 4, 7-8 (citing Khorram, ¶¶ [0011], [0036]-[0044],
[0048]-[0050], [0053]; Figs. 2, 4, 5, 6 & 9)) and Toncich describes an
alternative configuration of a DC offset detector and feedback network
which provides feedback to a mixer input based on a DC offset at the mixer
output (Ans. 4-5, 7-8 (see Toncich, col. 3, l. 31 to col. 4, l. 18; Fig. 2)).
Upon consideration of the evidence on this record and each of
Appellant’s contentions, we find that the preponderance of evidence on this
record supports the Examiner’s findings and ultimate legal conclusion that
Khorram and Toncich would have taught the disputed features of claim 1.
Accordingly, we sustain the Examiner’s rejection of claim 1 for the reasons
set forth in the Answer, which we incorporate herein by reference. (Ans. 3-
9.) Our additional analysis will be limited to the following points of
emphasis.
From Appellant’s contentions we understand Appellant to argue that
neither Khorram nor Toncich teaches or suggests providing some DC offset
to a mixer input. We find Appellant’s contentions unavailing of error in the
Examiner’s rejection because we disagree with Appellant’s overly narrow
interpretation of the disputed limitation and Appellant’s arguments are not
commensurate with the scope of the limitation as we construe it.
We give claim terminology the “broadest reasonable interpretation
consistent with the [S]pecification” in accordance with our mandate that
“claim language should be read in light of the [S]pecification as it would be
interpreted by one of ordinary skill in the art.” In re Am. Acad. of Sci. Tech
Ctr., 367 F.3d 1359, 1364 (Fed. Cir. 2004) (citations omitted). Therefore,
we construe “correcting said common mode DC offset level at an input of
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said mixer for signals which are subsequently generated from an output of
said mixer” (claim 1) to mean correcting for a direct current (DC) offset at
the input of a mixer based on the mixer output – i.e., providing feedback to
the mixer input to correct for a DC offset based on the mixer output.
Paragraph [07] of Appellant’s Specification and dependent claim 2, in
particular, inform our construction. Specifically, Appellant’s Specification
states, “The corrected common mode DC offset level may be fed back to an
input of the mixer.” (Spec. ¶ [07] (emphasis added)). The Specification
does not explain that the DC offset must be fed back to the mixer input.
More importantly, Appellant’s claim 2 (discussed infra) recites the
additional limitation of “feeding back said corrected common mode DC
offset level to an input of said mixer.” In other words, claim 2 requires
providing a corrected DC offset to the input of the mixer – this is the only
meaningful difference between independent claim 1 and dependent claim 2.
If claim 1 required this feature, then claim 2 would be superfluous.
Our reviewing court has provided clear guidance with respect to the
issue of claim differentiation. “[T]he presence of a dependent claim that
adds a particular limitation gives rise to a presumption that the limitation in
question is not present in the independent claim.” Phillips v. AWH Corp.,
415 F.3d 1303, 1315 (Fed. Cir. 2005) (reh’g en banc) (citing Liebel-
Flarsheim Co. v. Medrad, Inc., 358 F.3d 898, 910 (Fed. Cir. 2004). See
SunRace Roots Enterprise Co. v. SRAM Corp., 336 F.3d 1298, 1303 (Fed.
Cir. 2003) (“[The] presumption is especially strong when the limitation in
dispute is the only meaningful difference between an independent and
dependent claim, and one party is urging that the limitation in the dependent
claim should be read into the independent claim.” Id., (citation omitted)).
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Thus, we find Appellant’s contrary arguments unpersuasive of error in
the Examiner’s obviousness rejection of representative claim 1. Appellant
also does not persuade us of error in the Examiner’s obviousness rejection of
independent claims 10, 19, and 23, and dependent claims 3-9 (dependent on
claim 1), 12-18 (dependent on claim 10), 20-22 (dependent on claim 19),
and 24-26 (dependent on claim 23), which reiterate the arguments made with
respect to claim 1. (App. Br. 14-20.) Accordingly, we affirm the
Examiner’s obviousness rejection of claims 1, 3-10, and 12-26.
Claim 2
The Examiner rejects dependent claim 2 as being obvious over
Khorram and Toncich. Specifically, the Examiner asserts that “Khorram
teaches feeding back said corrected common mode DC offset level to an
input of said mixer (figure 5, paragraph 0041, processing module (64)
provides a feedback to the input of common mode mixers (130 and 132) of
the I or Q path of programmable mixers (100 or 102)).” (Ans. 5.) We
disagree.
As discussed with respect to claim 1 (supra), we construe claim 2,
which recites “feeding back said corrected common mode DC offset level to
an input of said mixer” (claim 2) to require providing a corrected DC offset
to the input of the mixer. As explained by Appellant, “Khorram does not
teach that the control signal 142 is itself a correction;” instead, “Khorram
discloses that the processing module 64 or 76 determines a DC offset of an
input signal to a mixing stage; the processing module 64 or 76 generates the
control signal 142, to which the compensation module 134 is ‘operably
coupled’; and the control signal enables ‘the compensation module to
compensate for the operational characteristic mismatches.’” (App. Br. 21.)
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Consequently, we are constrained by the record before us to conclude
that Khorram and Toncich do not teach or suggest the recited features of
Appellant’s claim 2, and the rejection of claim 2 fails to establish a prima
facie case of obviousness. Appellant’s dependent claim 11 includes a
limitation of commensurate scope. Accordingly, we reverse the Examiner’s
obviousness rejection of claims 2 and 11.

CONCLUSIONS OF LAW
Appellant has not shown that the Examiner erred in rejecting claims 1,
3-10, and 12-26 under 35 U.S.C. § 103(a).
Appellant has shown that the Examiner erred in rejecting claims 2 and
11 under 35 U.S.C. § 103(a).

DECISION
We affirm the Examiner’s rejection of claims 1, 3-10, and 12-26
under 35 U.S.C. § 103(a).
We reverse the Examiner’s rejection of claims 2 and 11 under 35
U.S.C. § 103(a).

No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).

AFFIRMED-IN-PART

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