Court Opinion

ID: 5132251
Source: CourtListenerOpinion
Date Created: 2021-12-07 00:02:18.298158+00
Date Added: 2024-06-11T08:23:29.098230
License: Public Domain

Case: 20-1874   Document: 52     Page: 1    Filed: 11/04/2021

        NOTE: This disposition is nonprecedential.

   United States Court of Appeals
       for the Federal Circuit
                 ______________________

         NORTH STAR INNOVATIONS, INC.,
                   Appellant

                            v.

   ANDREW HIRSHFELD, PERFORMING THE
    FUNCTIONS AND DUTIES OF THE UNDER
       SECRETARY OF COMMERCE FOR
 INTELLECTUAL PROPERTY AND DIRECTOR OF
 THE UNITED STATES PATENT AND TRADEMARK
                   OFFICE,
                   Intervenor
             ______________________

                       2020-1874
                 ______________________

     Appeal from the United States Patent and Trademark
 Office, Patent Trial and Appeal Board in No. IPR2019-
 00104.
                  ______________________

                Decided: November 4, 2021
                 ______________________

     EDWARD C. FLYNN, Eckert Seamans Cherin & Mellott,
 LLC, Pittsburgh, PA, argued for appellant. Also repre-
 sented by PHILIP LEVY, NATHANIEL COEN WILKS.

    WILLIAM LAMARCA, Office of the Solicitor, United
Case: 20-1874     Document: 52     Page: 2    Filed: 11/04/2021

 2                 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD

 States Patent and Trademark Office, Alexandria, VA, ar-
 gued for intervenor. Also represented by MAI-TRANG DUC
 DANG, THOMAS W. KRAUSE, FARHEENA YASMEEN RASHEED.
                  ______________________

     Before REYNA, SCHALL, and STOLL, Circuit Judges.
 REYNA, Circuit Judge.
      North Star Innovations, Inc. appeals the Patent Trial
 and Appeal Board’s final written decision in an inter partes
 review determining that all of the claims of the challenged
 patent are unpatentable as anticipated and obvious. North
 Star specifically challenges the Board’s constructions of the
 following claim terms: “a second phase signal that is oppo-
 site to the first phase signal,” “second terminal coupled for
 receiving [a/the] boost signal,” “inverting buffer,” and “non-
 inverting buffer.” Because the Board did not err in con-
 struing these terms, we affirm. 1
                         BACKGROUND
                               I
     North Star Innovations, Inc. owns U.S. Patent
 No. 6,127,875 (“’875 patent”). The ’875 patent issued on
 October 3, 2000, and relates to “voltage boosting converters
 and, more particularly[,] to a double pumping voltage
 boosting circuit for providing an output voltage greater
 than a supplied input voltage and which is suited to be
 manufactured in integrated circuit form.” ’875 patent col. 1

     1   North Star’s opening brief included a challenge to
 the appointment of the Administrative Patent Judges in-
 volved in the underlying IPR. Appellant’s Br. 67–70. Fol-
 lowing the Supreme Court’s decision in United States v.
 Arthrex, Inc., 141 S. Ct. 1970 (2021), however, North Star
 withdrew its request to vacate and remand to the Board on
 this basis. ECF No. 49.
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD                   3

 ll. 5–9. As shown in figure 3 below, the ’875 patent teaches
 a double pumping voltage boost converter circuit that in-
 cludes two sides—sides A and B—that “complement” each
 other during operation. See id. at col. 2 ll. 18–65. Put
 simply, sides A and B take turns supplying a boost signal.
 See id. at col. 2 ll. 38–65.

 Id. at fig. 3.
      Figure 3 shows a preferred embodiment in which a
 voltage VDD is supplied to the circuit. Id. at col. 2 ll. 15–28.
 During the first half cycle Θ1, side B boosts the voltage. See
 id. at col. 2 ll. 18–65. Switches 42A and 52B are closed and
 switches 42B and 52A are opened. Id. at col. 2 ll. 38–40.
 Capacitor 48B resides “between terminal 54 and the non-
 inverting buffer driver 56.” Id. at col. 2 ll. 31–33. Assum-
 ing capacitor 48B has already been charged to VDD, the
 boost signal “is in a high level state” and raises the voltage
 across the capacitor to “nearly 2VDD,” i.e., two times the
 supply voltage VDD, to drive load 58. Id. at col. 2 ll. 40–46.
 As current flows from capacitor 48B into load 58, the
 charge across capacitor 48B begins to decrease. Id. at col. 2
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 4                 NORTH STAR INNOVATIONS, INC.    v. HIRSHFELD

 ll. 46–48. But it does so “to a much less degree” than in
 prior art circuits represented by figure 1, id. at col. 2
 ll. 46–48, and therefore the embodiment in figure 3 reduces
 voltage distortion, see id. at col. 1 ll. 57–61. While the volt-
 age across capacitor 48B decreases, capacitor 48A is
 charged to voltage VDD. Id. at col. 2 ll. 54–56.
     Figure 2A shown below, together with figure 3, show
 that, at the end of the first half cycle Θ1, clock signals C1
 and C2 change phase so that side A boosts the voltage.

 Id. at fig. 2A. The ’875 patent describes C1 and C2 as a “pair
 of non-overlapping clock signals” that are “180 degrees out
 of phase with respect to one another.” Id. at col. 1 ll. 32–34.
 In the second half cycle Θ2, switches 42B and 52A are
 closed, whereas switches 42A and 52B are opened. Id. at
 col. 2 ll. 56–58. Capacitor 48A is positioned “between ter-
 minal 46 and inverting buffer driver 50.” Id. at col. 2
 ll. 28–30. The boost signal “changes states from a high
 level to a low level” and raises the voltage across capacitor
 48A to nearly 2VDD, which then drives load 58. Id. at col. 2
 ll. 56–63. Meanwhile, supply voltage VDD is applied
 across capacitor 48B. Id. at col. 2 ll. 59–63. According to
 the ’875 patent, the preferred embodiment shown in fig-
 ure 3 eliminates the need for an added load capacitance 28,
 as shown in figure 1 representing prior art, because “either
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD                  5

 capacitive device 48A or capacitive device 48B is driving
 load 58 at all times.” Id. at col. 3 ll. 3–7.
     The ’857 patent has three claims, all of which are at
 issue in this appeal. Claims 1 and 2, however, are repre-
 sentative of the issues in this appeal because they contain
 the disputed claim language, emphasized below:
     1. A boost circuit having an input terminal and an
     output terminal, comprising:
         a first switch coupled between the input
         terminal and the output terminal and oper-
         ated by a first phase signal;
         a second switch coupled between the input
         terminal and the output terminal and oper-
         ated by a second phase signal that is oppo-
         site to the first phase signal;
         a first capacitor having a first terminal cou-
         pled to the output terminal and a second
         terminal coupled for receiving a boost sig-
         nal; and
         a second capacitor having a first terminal
         coupled to the output terminal and a sec-
         ond terminal coupled for receiving the boost
         signal.
     2. The boost circuit of claim 1, further including:
         an inverting buffer having an input coupled
         for receiving the boost signal and an output
         coupled to the second terminal of the first
         capacitor; and
         a non-inverting buffer having an input cou-
         pled for receiving the boost signal and an
         output coupled to the second terminal of
         the second capacitor.
 Id. at col. 5 l. 9–col. 6 l. 10 (emphasis added).
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 6                NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD

                              II
      Kingston Technology Co. (“Kingston”) filed a petition
 for inter partes review on October 19, 2018. J.A. 69–148.
 Kingston argued that claims 1–3 of the ’875 patent were
 unpatentable as anticipated and/or obvious based on U.S.
 Patent No. 5,126,590 (“Chern”). J.A. 77. Chern is titled
 “High Efficiency Charge Pump” and relates to “charge
 pumps for biasing a semiconductor substrate, well, or the
 like, and more particularly, to a method and apparatus for
 efficiently, and therefore more quickly, biasing a substrate
 or well to a final desired voltage.” Chern col. 1 ll. 5–9.
     Chern’s figure 2 shows an exemplary charge pump.

 Id. at fig. 2. Chern explains that terminal 22 receives a
 supply voltage VCC, id. at col. 3 ll. 20–22, and terminal 24
 outputs a higher voltage VCCP, id. at col. 3 ll. 41–48.
 “[T]ransistors Q1–Q4 are coupled together,” id. at col. 3
 ll. 20–21, and transistors Q5 and Q6 “deliver current to the
 substrate or well,” id. at col. 3 ll. 41–44. Capacitors C1–C4
 each receive one of clock signals 1–4 respectively, and
 each of the four capacitors is coupled to a combination of
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 NORTH STAR INNOVATIONS, INC.    v. HIRSHFELD                    7

 transistors. 2 As shown in figures 6A and 6B, clock signals
 1–4 are driven by a ring oscillator 12 and a conditioning
 circuit 14 and are generated by a four-phase clock genera-
 tor 42. Id. at col. 7 ll. 1–32. Chern explains that “clock
 generator 42 creates clock signals 1–4 by providing de-
 lay paths” resulting in “an inverted and non-inverted half
 to create a total of four clock signals.” Id. at col. 7 ll. 33–38.

     2   Capacitor C1 is coupled to transistors Q1 and Q5
 at node P1; capacitor C2 is coupled to transistors Q2 and
 Q6 at node P2; capacitor C3 is coupled to transistors Q2,
 Q3, Q4, and Q5 at node P3; and capacitor C4 is coupled to
 transistors Q1, Q3, Q4, and Q6 at node P4. Id. at col. 3
 ll. 24–41.
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 8                 NORTH STAR INNOVATIONS, INC.    v. HIRSHFELD

 Id. at fig. 3.
      Chern’s figure 3 shows that each of the clock signals
 1–4 alternates between a “logic high state (H)” and a
 “logic low state (L),” such that the clock signals collectively
 undergo six intervals that Chern labels A through F. See
 id. at col. 3 ll. 61–68. As the interval sequence progresses,
 transistors Q5 and Q6 each take a turn delivering current
 to output terminal 24. Id. col. 5 ll. 9–12. 3 During the first
 half cycle, transistor Q5 delivers the current from capacitor
 C1, and meanwhile capacitor C2 charges. Id. at col. 5
 ll. 16–20. During the second half cycle, transistor Q6 de-
 livers the current from capacitor C2, and meanwhile capac-
 itor C1 charges. Id. at col. 5 ll. 20–23. Notably, however,
 Chern’s figure 3 shows brief periods at intervals B and E in
 which both clock signals 3 and 4 are at a logic low state.
 See id. at fig. 3.
                               III
     The Board issued its final written decision on April 1,
 2020, determining that challenged claims 1–3 of the ’875
 patent were anticipated by Chern and for that reason ren-
 dered the claims unpatentable under both §§ 102 and 103.
 Kingston Tech. Co., Inc. v. N. Star Innovations, Inc., No.
 IPR2019-00104, 2020 WL 1581575, at *22 (P.T.A.B. Apr. 1,
 2020) (citing In re McDaniel, 293 F.3d 1379, 1385 (Fed. Cir.
 2002) (“It is well settled that anticipation is the epitome of

     3    At interval A, transistor Q5 delivers current to out-
 put terminal 24. See Chern at col. 4 l. 15. In the transition
 from A to B, transistor Q5 turns off. Id. As B transitions
 to C, transistor Q6 turns on and thus begins delivering cur-
 rent to terminal 24. Id. at col. 4 ll. 25–27. Transistor Q6
 remains on until it turns off during the transition from D
 to E. Id. at col. 4 ll. 48–51. As E transitions to F, transistor
 Q5 turns on and remains on until the transition from A to
 B. Id. at col. 4 ll. 55–58.
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD                 9

 obviousness.” (quotation marks omitted))). The Board con-
 strued several claim phrases and then determined that
 Chern disclosed those phrases as construed. 4
     The Board first construed the phrase in claim 1, “a sec-
 ond phase signal that is opposite to the first phase signal,”
 as not limited to signals that are “inverted” versions of each
 other. Id. at *5. The Board rejected North Star’s narrow
 proposed construction requiring that the phase signals be
 “inverted” such that “the time during which the first phase
 signal is high is equal to the time during which the second
 phase signal is low and vice-versa.” Id. at *3. The Board
 reasoned that the claim language did not expressly require
 North Star’s proposed “inverted” limitation. Id. at *5. It
 further noted that the specification did not contain the
 word “opposite” and that it disclosed figure 3 as an exem-
 plary depiction of opposing clock signals. Id. The Board
 rejected North Star’s argument that extrinsic evidence
 proved that a person of ordinary skill in the art would have
 understood “opposite” clock signals necessarily as “in-
 verted” signals. Id. at *3, *6. The Board explained that
 one such reference, U.S. Patent No. 5,644,534 (“Soejima”),
 which the examiner relied on during prosecution, disclosed
 clock signals that were “opposite” in phase yet not inverted.
 Id. at *6. For these reasons, the Board concluded that the
 record did not adequately support limiting the claim
 phrase to cover only clock signals that are inverted ver-
 sions of each other. Id. at *5–6.

     4   Because the ’875 patent had expired on August 13,
 2018, the Board applied the Phillips claim construction
 standard applied by district courts. Id. at *2 (citing Sam-
 sung Elecs. Co. v. Elm 3DS Innovations, LLC, 925 F.3d
 1373, 1376 (Fed. Cir. 2019); and then citing Phillips v.
 AWH Corp., 415 F.3d 1303, 1312–13 (Fed. Cir. 2005) (en
 banc)).
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 10                NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD

     The Board then determined that Chern disclosed the
 phrase as construed. Kingston’s petition identified 4,
 shown in Chern’s figure 3, as corresponding to the first
 clock signal and 3 in the same figure as corresponding to
 the second clock signal. Id. at *13–14. Kingston also relied
 on a declaration by Dr. Jacob stating that Chern’s 3 and
 4 signals are “opposite” to each other because they “are
 the same signal, shifted 180 degrees (half a clock cycle) rel-
 ative to one another,” such that, “when clock 3 is high,
 clock 4 is low, and that when clock 3 is low, clock 4 is
 high.” Id. at *14 (citation omitted). The Board rejected
 North Star’s argument, predicated on its rejected claim
 construction, that Chern failed to disclose the “opposite”
 limitation because Chern’s 3 and 4 clock signals are not
 inverted versions of each other. Id. at *14–15.
     The Board also construed “boost signal” to mean “a sig-
 nal that is input into a voltage boosting circuit for provid-
 ing an output voltage greater than a supplied input
 voltage.” Id. at *8. The Board rejected North Star’s pro-
 posed construction limiting the term to require that “either
 a non-inverted or inverted version of [the boost] signal is
 received by the second terminal of a capacitor.” Id. at *6–8.
 The Board reasoned that the ’875 patent did not support
 limiting the claim scope as North Star proposed. Id.
     The Board then determined that Chern disclosed the
 “boost signal” limitation. Id. at *16–17. According to King-
 ston, Chern’s clock signals 1 and 2 constitute boost sig-
 nals because they increase the voltage at node P1 and P2
 respectively when the clock signals change from logic low
 state to logic high state. Id. at *17. These voltage increases
 in turn send current through transistors Q5 and Q6 respec-
 tively to drive the load through output terminal 24. Id.
 North Star’s disagreement with Kingston’s theory de-
 pended on its proposed claim construction requiring clock
 signals to be inverted versions of each other, which the
 Board rejected. Id. at *17–18.
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD                11

     The Board further construed “coupled for receiving” to
 mean “connected in order to receive.” Id. at *9. The Board
 rejected North Star’s argument that a person of ordinary
 skill in the art would understand the claim language to
 mean that the “terminal . . . is connected in a manner such
 that the signal received . . . is either always a non-inverted
 version of the boost signal or always an inverted version of
 the boost signal.” Id. at *8. The Board again determined
 that the ’875 patent did not support limiting the claim
 scope as proposed by North Star. Id. at *8–9.
     The Board then determined that Chern disclosed the
 limitation as construed. Id. at *18. Kingston contended
 that Chern’s capacitors C1 and C2 are coupled for receiving
 a boost signal (i.e., clock signals 1 and 2) because they
 are coupled by a circuitry path to clock generator 42, con-
 ditioning circuit 14 and ring oscillator 12, which collec-
 tively operated to create clock signals 1–4. See id. The
 Board rejected North Star’s argument, predicated on its
 proposed construction, that Chern was deficient because its
 clock signals underwent changes as they progressed
 through the circuitry leading to capacitors C1 and C2. Id.
 at *17–18. It was for that reason, North Star argued, that
 Chern’s clock signals 1 and 2 are not “always” either an
 inverted or non-inverted version of the signal generated by
 the conditioning circuit 14, as its proposed claim construc-
 tion required. See id. Because the Board rejected North
 Star’s claim construction argument, the Board likewise re-
 jected North Star’s position that Chern failed to meet the
 “coupled for receiving” limitation. Id. at *18.
      The Board also construed the phrase “inverting buffer”
 in claim 2 as not requiring either (1) a single input and sin-
 gle output, or (2) that the output is always an inverted ver-
 sion of the input. Id. at *9–10. North Star had proposed
 the following construction: “a circuit with a single input
 and a single output, where the output is always an inverted
 version of the input.” Id. For support, North Star pointed
 to the fact that the ’875 patent discloses an inverting buffer
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 12               NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD

 in the form of a NOT gate and argued that “a NOT gate,
 also known as an inverter, is a single input, single output
 circuit whose output is always 1 if the input is 0, and whose
 output is always 0 if the input is 1.” Id. at *9. The Board
 agreed with Kingston that, although figure 3 of the ’875
 patent discloses an embodiment where the inverting buffer
 has a single input and single output and the output is an
 inverted version of the input, nothing in the claim language
 or specification clearly supported limiting the claim scope
 to that embodiment. Id. at *9–10. For the same reason,
 the Board rejected North Star’s narrow proposed construc-
 tion of “non-inverting buffer” requiring “a circuit with a
 single input and a single output, where the output is al-
 ways a non-inverted version of the input.” Id. at *10.
     The Board determined that Chern disclosed the “in-
 verting buffer” and “non-inverting buffer” limitations.
 Kingston submitted annotated versions of Chern’s figure
 6B that identified the top half of clock generator 42 as an
 “inverting buffer” and the bottom half as a “non-inverting
 buffer.” Id. at *19. Kingston’s annotations, explained in
 Dr. Jacob’s declaration, illustrated the behavior of all the
 logic gates in clock generator 42 when the input buffer sig-
 nal is high or “1” and when it is low or “0.” Id. Kingston
 also pointed to Chern’s teaching that the clock generator
 42 provided delay paths to create the four clock signals
 1–4. Id. The Board rejected North Star’s arguments on
 the grounds that they were predicated on its proposed
 claim construction. Id. at *19–20.
     North Star appealed the Board’s final written decision
 that challenged claims 1–3 of the ’875 patent are unpatent-
 able under §§ 102 and 103 based on Chern. We have juris-
 diction under 28 U.S.C. § 1295(a)(4).
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD               13

                         DISCUSSION
                                I
     We review the Board’s “ultimate claim constructions de
 novo and its underlying factual determinations involving
 extrinsic evidence for substantial evidence.” In re Man
 Mach. Interface Techs. LLC, 822 F.3d 1282, 1285 (Fed. Cir.
 2016) (citations omitted). Obviousness under 35 U.S.C.
 § 103 is a question of law based on underlying facts. In re
 Ethicon, Inc., 844 F.3d 1344, 1349 (Fed. Cir. 2017); Mouttet,
 686 F.3d at 1330. We review the Board’s legal conclusions
 of obviousness de novo and its factual findings underlying
 those determinations for substantial evidence. In re
 Mouttet, 686 F.3d 1322, 1330–31 (Fed. Cir. 2012). Antici-
 pation under 35 U.S.C. § 102 is a question of fact, which we
 review for substantial evidence. In re Gleave, 560 F.3d
 1331, 1334–35 (Fed. Cir. 2009). Substantial evidence is ev-
 idence that “a reasonable mind might accept as adequate
 to support a conclusion.” In re Gartside, 203 F.3d 1305,
 1312 (Fed. Cir. 2000) (quoting Consol. Edison Co. v. NLRB,
 305 U.S. 197, 229–30 (1938)). Substantial evidence is
 “something less than the weight of the evidence but more
 than a mere scintilla of evidence.” In re Kotzab, 217 F.3d
 1365, 1369 (Fed. Cir. 2000). “[W]here two different, incon-
 sistent conclusions may reasonably be drawn from the evi-
 dence in record, an agency’s decision to favor one
 conclusion over the other is the epitome of a decision that
 must be sustained upon review for substantial evidence.”
 In re Jolley, 308 F.3d 1317, 1329 (Fed. Cir. 2002) (citing
 Grupo Indus. Camesa v. United States, 85 F.3d 1577, 1582
 (Fed. Cir. 1996)).
                              II
                              A
     North Star argues that the Board erroneously con-
 strued the phrase, “a second phase signal that is opposite
 to the first phase signal,” by declining to limit the phrase
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 14                NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD

 to require that the two signals are “inverted versions of
 each other, such that the time during which the first phase
 signal is high is equal to the time during which the second
 phase signal is low and vice-versa.” Appellant’s Br. 18. We
 disagree and affirm the Board’s construction.
     The person of ordinary skill in the art is deemed to read
 a claim in the context of all the patent’s claims, the specifi-
 cation, and the prosecution history. See Phillips v. AWH
 Corp., 415 F.3d 1303, 1314–17 (Fed. Cir. 2005). It is also
 permissible for courts, and the Board here, to rely on ex-
 trinsic evidence, such as dictionaries, treatises, and testi-
 mony of experts and inventors, with the understanding
 that such evidence “can shed useful light on the relevant
 art” but is generally “less significant than the intrinsic rec-
 ord.” Id. at 1317. We have further recognized a fine line
 between “using the specification to interpret the meaning
 of a claim and importing limitations from the specification
 into the claim,” and we have “repeatedly warned against”
 the latter. Id. at 1323; see also SuperGuide Corp. v. Di-
 recTV Enters., Inc., 358 F.3d 870, 875 (Fed. Cir. 2004) (“[A]
 particular embodiment appearing in the written descrip-
 tion may not be read into a claim when the claim language
 is broader than the embodiment.”); Verizon Servs. Corp. v.
 Vonage Holdings Corp., 503 F.3d 1295, 1302–03 (Fed. Cir.
 2007) (“The mere fact that the specification’s examples of
 translation may involve a change in protocol from a higher
 to a lower level protocol does not establish that such a lim-
 itation should be imported into the claims.”). We have re-
 jected the contention that, “if a patent describes only a
 single embodiment, the claims of the patent must be con-
 strued as being limited to that embodiment.” Phillips,
 415 F.3d at 1323. It is therefore improper to limit claims
 to a disclosed embodiment “absent a clear expression of in-
 tent to limit the claims’ scope.” Info-Hold, Inc. v. Applied
 Media Techs. Corp., 783 F.3d 1262, 1266 (Fed. Cir. 2015).
     North Star argues that the plain meaning of “opposite”
 is “inverted,” and therefore the Board’s interpretation
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD               15

 encompassing non-overlapping signals that are 180 de-
 grees out of phase with each other—yet are nevertheless
 not inverted versions of each other—contradicts the term’s
 plain meaning. Appellant’s Br. 18–19. North Star relies
 on the opinion of its expert, Dr. Khatri, regarding how a
 person of ordinary skill in the art would have understood
 the plain language of the claim limitation at the time of
 invention. Id. at 20 (citing J.A. 1726 ¶ 102). However, we
 read the cited portions of Dr. Khatri’s opinion as the type
 of conclusory testimony our court has described as “not use-
 ful.” Phillips, 415 F.3d at 1318. Dr. Khatri cites no support
 for his opinion on this point. See J.A. 1726. North Star
 also attempts to support its position by pointing to the as-
 sertion in Kingston’s petition and Dr. Jacob’s supporting
 declaration that Chern’s clock signals 3 and 4 are “op-
 posite” to each other because when “clock []3 is high, clock
 []4 is low, and that when clock []3 is low, clock []4 is
 high.” Id. at 20 (citing J.A. 115, 615 ¶ 152). But we are not
 persuaded that this assertion amounts to an admission
 that “opposite” signals include only inverted signals.
      North Star next argues that the specification supports
 its interpretation of “opposite” as “inverted.” North Star
 does not dispute that the ’875 patent does not use the term
 “opposite.” North Star nevertheless points to figure 2A as
 showing clock signals C1 and C2 that are inverted versions
 of each other, as well as the patent’s description of figure
 2A as showing “the clocking signals useful for explaining
 the operation of the present invention.” Id. at 21–22 (citing
 ’875 patent col. 2 ll. 1–2). North Star also relies on the
 specification’s assertion that “either capacitive device 48A
 or capacitive device 48B is driving load 58 at all times,”
 and for that reason North Star argues that “all four
 switches are never open at the same time.” Id. at 23 (quot-
 ing ’875 patent col. 3 ll. 3–7). We are not persuaded that
 these disclosures clearly establish that the claim scope
 should be limited to only “inverted” signals. Figure 2A is
 described in the background section of the ’875 patent in
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 16                NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD

 the context of discussing not an embodiment but a “basic
 voltage boosting circuit” in the prior art. ’875 patent col. 1
 ll. 23–24. The background section also describes the clock
 signals C1 and C2 shown in figure 2A, not as “inverted”
 versions of each other, but rather as “non-overlapping” and
 “180 degrees out of phase with respect to one another.” ’875
 patent col. 1 ll. 32–34. The detailed description section be-
 gins by discussing figure 3, which is described as “one em-
 bodiment of the present invention.” Id. at col. 2 ll. 3–4. The
 ’875 patent’s teachings taken together lead to the conclu-
 sion that using “inverted” clock signals is an embodiment
 of the claimed inventions. This alone is not enough to limit
 the claim term “opposite” to only the narrow scope afforded
 by the distinct term “inverted.” Phillips, 415 F.3d at 1323;
 Superguide, 358 F.3d at 875; Verizon, 503 F.3d at 1302–03.
      North Star also argues that extrinsic evidence proves
 that a person of ordinary skill would understand the term
 “opposite” to mean only “inverted.” However, certain ref-
 erences suggest that inverted signals are merely a subset
 of opposite signals. For example, Soejima teaches clock
 pulses having opposite phases and yet are not inverted.
 Soejima col. 5 ll. 38–40 & fig. 4B. U.S. Patent No. 5,701,096
 (“Higashiho”), referenced by North Star on appeal, Appel-
 lant’s Br. 28, teaches that its “second signal . . . may be an
 inverted signal of the clock signal.” Higashiho col. 3 ll. 3–6.
 Further, Higashiho’s claims expressly recite “inverted”
 clock signals, suggesting that the inventors of the ’875 pa-
 tent could have limited the claims to inverted signals if
 they had chosen to do so. See, e.g., id. at col. 14 ll. 4–8,
 col. 15, ll. 28–32.
      We conclude that the Board did not commit reversible
 error in rejecting North Star’s argument that a person of
 ordinary skill in the art would have understood “opposite”
 as “inverted.” Because North Star’s arguments that Chern
 fails to disclose this limitation depend on its claim inter-
 pretation, we also affirm the Board’s finding that Chern
 discloses this limitation.
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD                17

                               B
     North Star next argues that the Board erroneously con-
 strued “second terminal coupled for receiving [a/the] boost
 signal.” Appellant’s Br. 35. North Star contends that that
 language should be construed to mean that each of the first
 and second capacitors “is connected in a manner such that
 the signal received by that second terminal is either always
 a non-inverted version of the boost signal or always an in-
 verted version of the boost signal.” Id. at 36. We disagree
 and affirm the Board’s construction that does not include
 the limitations North Star asks to be imported from the
 ’875 patent’s specification.
      North Star contends that the plain language, “coupled
 for receiving,” conveys “something more” than the second
 terminals of the capacitors being “coupled” to the boost sig-
 nal or “coupled to a connection that is capable of receiving
 [the] boost signal.” Id. at 38. Instead, North Star argues,
 the language “explicitly identifies which terminals, or con-
 nections, actually receive the boost signal.” Id. Therefore,
 according to North Star, Chern’s teachings that allegedly
 involve “intervening circuitry generat[ing] a new signal
 that is different from the boost signal” is not enough to sat-
 isfy the plain language. Id. at 39–40. For further support,
 North Star points out that the ’875 patent “only describes
 one particular embodiment,” and in that embodiment “the
 second terminals of the first and second capacitors actually
 receive either an inverted or non-inverted version of the
 boost signal.” Id. at 40–41. We are not persuaded by North
 Star’s narrow reading of the claim language that is tailored
 to certain details of the ’875 patent’s embodiment but not
 recited in the claims. Even where a patent only describes
 one embodiment, that is not enough to justify limiting
 broader claim language to unrecited details of that embod-
 iment. Phillips, 415 F.3d at 1323. Because North Star’s
 arguments that Chern fails to disclose this disputed claim
 language rests on its proposed construction, see Appellant’s
 Br. 43–48, we also reject those arguments.
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 18                 NORTH STAR INNOVATIONS, INC.     v. HIRSHFELD

                                 C
     North Star finally contends that the Board erroneously
 construed “inverting buffer” and “non-inverting buffer” by
 rejecting its proposed constructions requiring “a single in-
 put and a single output” and that the output is “always” an
 inverted or non-inverted version, respectively, of the input.
 Appellant’s Br. 48–49. We disagree and affirm the Board’s
 constructions.
      North Star contends that the Board improperly focused
 its construction on the term, “buffer,” and failed to recog-
 nize that the complete terms, “inverting buffer” and “non-
 inverting buffer,” refer to a “a particular kind of circuit, i.e.,
 one that has a single input and single output, where the
 output of the ‘inverting buffer’ is always inverted from its
 input, and the output of the ‘non-inverting buffer’ is always
 non-inverted from its input.” Appellant’s Br. 51. North
 Star does not persuasively explain or provide support for
 why the plain language conveys that meaning. North Star
 contends that the ’875 patent’s specification supports its
 construction by disclosing inverting buffer 50 as a NOT
 gate in figure 3. Id. at 53–54. North Star further points to
 a dictionary that defines a “NOT circuit” as a “binary cir-
 cuit with a single output that is always the opposite of the
 single input” and that states that such a circuit is “[a]lso
 called [an] inverter circuit.” Id. at 54 (quoting J.A. 1882–
 83). North Star also cites another extrinsic source showing
 an “inverter” as having “a single binary input variable and
 a single output binary variable.” Id. (citing J.A. 1893–94).
 In support for its construction of “non-inverting buffer,”
 North Star argues that the ’875 patent uses the common
 electrical symbol of a “buffer gate” in its figures, arguing
 that “[i]t is well known that a buffer gate has the opposite
 functionality of a NOT gate.” Id. at 54–55.
     North Star thus points to examples, in the specification
 and certain extrinsic references, of inverting and non-in-
 verting buffers that are consistent with its proposed
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 NORTH STAR INNOVATIONS, INC.   v. HIRSHFELD               19

 construction. We conclude that the Board’s determination
 that the claim scope is not limited to those examples is not
 erroneous. The specification’s use of certain electrical sym-
 bols in its figures does not necessarily mean that the claims
 are limited in the manner North Star argues. Info-Hold,
 783 F.3d at 1266 (“[W]e have rejected the contention that
 it is proper to limit the claims to the single disclosed em-
 bodiment absent a clear expression of intent to limit the
 claims’ scope.”). Kingston’s expert, Dr. Jacobs, opined that
 a buffer can have more than one input and need not always
 invert or not invert its input. See J.A. 1400–06 (discussing
 examples including tri-state buffers). We therefore reject
 North Star’s arguments and affirm the Board’s construc-
 tions of “inverting buffer” and “non-inverting buffer.” And
 because North Star’s arguments for patentability depend
 on its proposed constructions of those terms, we likewise
 reject those arguments.
                        CONCLUSION
     We have considered North Star’s remaining arguments
 but find them unpersuasive. For the reasons explained
 above, we conclude that North Star has not identified any
 reversible error in the Board’s determination that Chern
 renders challenged claims 1–3 of the ’875 patent unpatent-
 able. We therefore affirm.
                        AFFIRMED
                            COSTS
 No costs.