TEXAS INSTRUMENTS INCORPORATED

Patent Trials and Appeals Board

Sep 18, 2020

2019006383 (P.T.A.B. Sep. 18, 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.
15/094,866 04/08/2016 ANANDHA RUBAN TT TI-75976 4499
23494 7590 09/18/2020
TEXAS INSTRUMENTS INCORPORATED
P O BOX 655474, MS 3999
DALLAS, TX 75265
EXAMINER
SPRENGER, KEVIN H
ART UNIT PAPER NUMBER
2838
NOTIFICATION DATE DELIVERY MODE
09/18/2020 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):
uspto@ti.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte ANANDHA RUBAN TT,
PREETAM CHARAN ANAND TADEPARTHY,
VIKRAM GAKHAR, and MUTHUSUBRAMANIAN NV

Appeal 2019-006383
Application 15/094,866
Technology Center 2800
____________

Before JEFFREY T. SMITH, KAREN M. HASTINGS, and
MICHAEL G. McMANUS, Administrative Patent Judges.

McMANUS, Administrative Patent Judge.

DECISION ON APPEAL

Pursuant to 35 U.S.C. § 134(a), Appellant1 seeks review of the
Examiner’s decision to reject claims 1–11, 13, 14, and 16–20. We have
jurisdiction under 35 U.S.C. § 6(b).
We reverse.

1 We use the word “Appellant” to refer to “applicant” as defined in 37
C.F.R. § 1.42. Appellant identifies the real party in interest as Texas
Instruments, Incorporated. Appeal Brief dated March 4, 2019 (“Appeal
Br.”) 2.
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Application 15/094,866

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CLAIMED SUBJECT MATTER

The present application generally relates to DC-DC converters used to
regulate a voltage source to a fixed output voltage. Specification filed April
8, 2016 (“Spec.”) ¶ 3. The Specification teaches that, where a converter has
multiple DC-DC converter units, it is known as a multi-phase DC-DC
converter. Id. A multi-phase DC-DC converter consists of several single-
phase DC-DC converter units connected in parallel. Id. Multi-phase DC-
DC converters are used to supply current for higher loads. Id.
The Specification further teaches that, with multiphase DC-DC
converters, it is efficient to use a greater number of phases at high load
currents. Id. ¶ 5. Conversely, it is efficient to use fewer phases in low load
conditions. Id. “The threshold currents to change the phases, is chosen such
that the DC-DC converter operates with maximum efficiency.” Id. The
Specification teaches that the processing unit “stores a threshold current
limit corresponding to each phase of the N phases based on the input voltage
and a switching frequency.” Id. ¶ 6. Figure 6, reproduced below, is
exemplary.
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Figure 6 is a graph that illustrates power loss for various load currents in a
multi-phase converter. Id. ¶ 57. As the load current increases, power loss is
mitigated by increasing the number of phases. “The threshold current limit
corresponding to a first phase is represented as 602, and the threshold
current limit corresponding to a second phase is represented as 604, and the
threshold current limit corresponding to a third phase is represented as 606.”
Id.
Claim 1 is illustrative of the subject matter on appeal and is
reproduced below with certain limitations italicized for emphasis:
1. A multi-phase converter comprising:
N switches coupled to an input voltage terminal and an
output terminal, wherein N is a positive integer greater than 1;
a processing unit configured to store a threshold current
limit corresponding to an input voltage and a switching
frequency of one or more of the N switches; and
a controller coupled to the processing unit and the N
switches, the controller configured to activate a number of the
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Application 15/094,866

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N switches based on a comparison of a measured load current
against the threshold current limit.
Appeal Br. 9 (Claims App.) (emphasis added).
DISCUSSION
The Examiner rejects claims 1–11, 13, 14, and 16–20 under 35 U.S.C
§ 102(a)(1) as anticipated by Mathew et al. (US 2016/0116549 A1, filed Oct.
24, 2014; hereinafter “Mathew”). Final Office Action dated Feb. 8, 2018
(“Final Act.”).
In support of the rejection, the Examiner finds that Mathew teaches “a
processing unit (Figure 1: 118) configured to store a threshold current limit
(Paragraph [0043]) corresponding to an input voltage and a switching
frequency of one or more of the N switches; and a controller” where the
controller is “configured to activate a number of the N switches based on a
comparison of a measured load current against the threshold current limit.”
Final Act. 4.
The Examiner additionally quotes the following portion of Mathew:
[A] voltage regulator may operate in an autonomous phase
shedding mode in which the number of phases in operation may
vary as a load current of the voltage regulator varies. In light
loading conditions, a voltage regulator may operate in a
discontinuous conduction mode (DCM) with only one phase at
lower currents and a continuous conduction mode (CCM) with
one or more multiple phases 114 at higher currents, and the
efficiency or power loss of each mode versus current may be
approximated by a different polynomial.

Id. at 2–3 (citing Mathew ¶ 43) (Examiner’s emphases omitted). The
Examiner determines that the foregoing “is analogous to storing a threshold
current limit corresponding to an input voltage and a switching frequency . .
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. and controlling a number of the N switches based on a comparison of a
measured load current against the threshold current limit” as required by
claim 1. Id. at 3. The Examiner further states that the “profile” and “curve
fit” of Mathew teach the threshold current limit because the output is
compared to these metrics. Id.
Appellant argues that the rejection should be reversed. Appeal Br. 4–
8. Appellant directs us to Mathew’s teaching “to calculate an input current
to the voltage regulator based on a fitted curve indicative of power
efficiency of the voltage regulator.” Id. at 5 (quoting Mathew ¶ 41).
Mathew further teaches that “curve-fit information 118 may store
information indicative of the power loss (e.g., input power minus output
power) of a voltage regulator versus measured output current.” Id.
Appellant argues that Mathew does not teach that curve-fit information 118
includes any “threshold current limit corresponding to an input voltage and a
switching frequency.” Id. Appellant asserts that the Examiner did not
explain how a “threshold current limit corresponding to an input voltage and
a switching frequency” is expressly or inherently taught by Mathew. Id. at
6.
Appellant further directs us to the Examiner’s determination that the
teachings of Mathew’s Paragraph 43 are “analogous” to storing a threshold
current limit corresponding to an input voltage and a switching frequency.
Id. (citing Final Act. 3). Appellant argues that a finding that a feature of a
prior art reference is analogous to a claim element is insufficient to support a
prima facie case of anticipation. Id.

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In the Answer, the Examiner summarizes the steps of Mathew.
Answer 4. Such summary, however, does not address switching frequency.
Id.
In another portion of the Answer, the Examiner contends that Mathew
teaches a processing unit configured to store a threshold current limit
corresponding to an input voltage and a switching frequency of one or more
of the N switches. Id. at 5. In support of the finding regarding “switching
frequency,” the Examiner directs us to switches 108 and 109 of Figure 1 and
Paragraphs 39–41, 43 of Mathew. Id. None of the cited portions of
Mathew, however, teach a switching frequency or a threshold current limit
corresponding to a switching frequency.
In view of the foregoing, we are persuaded that the rejection fails to
show an express teaching of a threshold current limit corresponding to a
switching frequency.2 Nor does the rejection include an explanation as to
whether and how such limitation may be inherently disclosed. In view of
the foregoing, we determine that Appellant has shown error in the rejection
of claim 1 and claims depending therefrom. As independent claims 16 and
19 (the only other independent claims pending) include similar limitations,
we likewise determine that Appellant has shown error in the rejection of
these claims and their dependent claims.

2 Our decision is limited to the determination under review. The Board relies
on the involved parties to focus the issues and decides those issues based on
facts and arguments presented by the involved parties. Ex Parte Frye, 94
USPQ2d 1072 (BPAI 2010 (precedential)). The Examiner has not based any
pending rejection on a theory that a threshold current limit corresponding to
an input voltage and a switching frequency as claimed would have been
obvious to a person having ordinary skill in the art at the time of Appellant’s
invention. Accordingly, we take no position on this issue.
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CONCLUSION

The Examiner’s rejection is reversed.
In summary:
Claims
Rejected
35 U.S.C.
§
Reference(s)/Basis Affirmed Reversed
1–11, 13,
14, 16–20
102(a)(1) Mathew 1–11, 13,
14, 16–20

REVERSED