Ex Parte Paulson et al

Board of Patent Appeals and Interferences

May 11, 2012

11147855 (B.P.A.I. May. 11, 2012)

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.
11/147,855 06/07/2005 Christopher D. Paulson LSI.110US01 (04-0488) 7670
84654 7590 05/11/2012
COCHRAN FREUND & YOUNG LLC
LSI CORPORATION
2026 CARIBOU DRIVE
SUITE 201
FORT COLLINS, CO 80525
EXAMINER
TSENG, CHENG YUAN
ART UNIT PAPER NUMBER
3992
MAIL DATE DELIVERY MODE
05/11/2012 PAPER
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.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________________

Ex parte CHRISTOPHER D. PAULSON,
TIMOTHY D. THOMPSON,
and KEVIN T. CAMPBELL
____________________

Appeal 2010-003305
Application 11/147,855
Technology Center 2100
____________________

Before DEBRA K. STEPHENS, KALYAN K. DESHPANDE, and
MICHAEL J. STRAUSS, Administrative Patent Judges.

STRAUSS, Administrative Patent Judge.

DECISION ON APPEAL
Appeal 2010-003305
Application 11/147,855

2
Appellants appeal under 35 U.S.C. § 134(a) (2002) from a final
rejection of claims 2-5 and 7-13. We have jurisdiction under 35 U.S.C.
§ 6(b).
We REVERSE.
Introduction
According to Appellants, the invention relates to a device and method
for synchronizing data between two clock domains having the same
frequency but which may be out of phase. A First In First Out (FIFO)
queue, i.e., a buffer, is used as an intermediary through which data is
transmitted between the two domains. The system is particularly applicable
to initiating transfer of data immediately after a system reset when the queue
is initially empty. Thus, the system delays a first write to the FIFO queue by
up to one cycle of the write clock of the transmitting domain. A first read of
the FIFO queue is additionally delayed by at least one cycle of the read
clock of the domain receiving the data to achieve a meta-stable data storage
condition and then a second time, again by at least one read clock cycle, to
achieve a stable data storage condition. According to Appellants, delaying
the first write has the effect of reducing the latency between (i) the first write
and the corresponding subsequent read, the reduced latency continuing
between (i) subsequent writes and (ii) the corresponding reads. The
reduction in latency between writes and reads reduces the required size of
the FIFO queue.

Appeal 2010-003305
Application 11/147,855

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STATEMENT OF THE CASE
Exemplary Claim
Claim 2 is an exemplary claim and is reproduced below:
2. A method for synchronizing data between two clock domains
comprising:
delaying a first data write to a FIFO queue from a first (write)
clock domain by up to one write clock cycle thereby reducing latency
between subsequent data writes to said FIFO queue and data reads
from said FIFO queue into a second (read) clock domain by said up to
one write clock cycle, said first (write) clock domain and said second
(read) clock domain having equivalent frequencies, said first (write)
clock domain and said second (read) clock domain having any phase
relationship with respect to each other;
delaying a first data read of said FIFO queue by up to a first
read clock cycle occurring after said up to one write clock cycle to
achieve a meta-stable data storage condition;
writing a first data element into a first position of said FIFO
queue;
delaying said first data read of said FIFO queue by up to a
second read clock cycle to achieve a stable data storage condition;
reading said first data element from said first position of said
FIFO queue;
writing data to each position in said FIFO queue by writing data
to a position in said FIFO queue on a write clock cycle and writing to
a next position of said FIFO queue on a next write clock cycle, said
next position of said FIFO queue being said first position of said FIFO
queue when a last position of said FIFO queue was written on said
write clock cycle; and
reading each written data position in said FIFO queue less than
two read clock cycles after said written data position of said FIFO
queue receives data from said first (write) clock domain.
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Application 11/147,855

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References
Liao 2003/0169644 A1 Sep. 11, 2003
Mike Stein et al., Crossing the Abyss: Asynchronous Signals in a
Synchronous World, EDN, Jul. 24, 2003, at 59 (“Stein”)

Rejection
Claims 2-5 and 7-13 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Liao and Stein.
We have only considered those arguments that Appellants actually
raised in the Briefs. Arguments Appellants could have made but chose not
to make in the Briefs have not been considered and are deemed to be
waived. See 37 C.F.R. § 41.37(c)(1)(vii)(2009).

ISSUE
35 U.S.C. § 103(a): claims 2-5 and 7-13
Appellants assert their invention is not obvious over Liao and Stein
because the combination of Liao and Stein is improper and because it fails to
disclose a system that (i) delays a first data write to a FIFO queue from a
first clock domain by up to one write clock cycle or (ii) delays a first read of
the FIFO queue by at least one read clock cycle and then again by a second
at least one read clock cycle. (App. Br. 11-14). Specifically, Appellants
contend neither Liao nor Stein teaches the steps of:
“delaying a first data write to a FIFO queue from a first (write) clock
domain by up to one write clock cycle thereby reducing latency between
subsequent data writes to said FIFO queue and data reads from said FIFO
Appeal 2010-003305
Application 11/147,855

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queue into a second (read) clock domain by said up to one write clock cycle,
said first (write) clock domain and said second (read) clock domain having
equivalent frequencies, said first (write) clock domain and said second (read)
clock domain having any phase relationship with respect to each other”; or
“delaying a first data read of said FIFO queue by up to a first read
clock cycle occurring after said up to one write clock cycle to achieve a
meta-stable data storage condition” and “delaying said first data read of said
FIFO queue by up to a second read clock cycle to achieve a stable data
storage condition.”
Issue: Has the Examiner erred in rejecting the subject claims under
35 U.S.C. § 103(a) based on the combination of Liao and Stein?

ANALYSIS
The Examiner asserts that the suggestion and/or motivation for
combining Liao with Stein would be to address a metastable state problem.
We disagree. While both disclosures mention the metastable state problem,
there is no disclosure suggesting that the technique of Stein relied upon by
the Examiner would address any metastable problem of Liao. We find that
modifying Liao according to Stein is more than a mere substitution of one
element for another known in the field. To the contrary, Appellants have put
forth compelling arguments that, even if made, the combination would be
inoperative for its intended purpose. For these reasons, we are unconvinced
that an artisan would have combined the Liao and Stein references in the
manner proffered by the Examiner without having the benefit of Appellants’
claimed subject matter. Therefore, we find the Examiner erred by
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Application 11/147,855

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improperly combining the Liao and Stein references under 35 U.S.C.
§ 103(a).
Since Appellants have shown at least one error in the Examiner’s
rejection, we need not address Appellants’ other arguments. Accordingly,
the Examiner has not shown the combination of Liao and Stein teaches or
suggests the invention of claim 2 and claims 7 and 11, not separately argued.
Dependent claims 3-5, 8-10 and 12-13 stand with their respective
independent claims. Accordingly, the Examiner erred in rejecting claims 2-5
and 7-13 under 35 U.S.C. § 103(a) as being obvious over Liao and Stein.

CONCLUSION
Appellants have shown the Examiner erred in rejecting claims 2-5 and
7-13 under 35 U.S.C. § 103(a) as being obvious over Liao and Stein.

DECISION
The Examiner’s rejection of claims 2-5 and 7-13 under 35 U.S.C.
§ 103(a) as being obvious over Liao and Stein is reversed.

REVERSED

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