Genuine Enabling Technology v. Nintendo Co., Ltd. ( 2022 )


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  • Case: 20-2167   Document: 40     Page: 1   Filed: 04/01/2022
    United States Court of Appeals
    for the Federal Circuit
    ______________________
    GENUINE ENABLING TECHNOLOGY LLC,
    Plaintiff-Appellant
    v.
    NINTENDO CO., LTD., NINTENDO OF AMERICA
    INC.,
    Defendants-Appellees
    ______________________
    2020-2167
    ______________________
    Appeal from the United States District Court for the
    Western District of Washington in No. 2:19-cv-00351-RSM,
    Judge Ricardo S. Martinez.
    ______________________
    Decided: April 1, 2022
    ______________________
    DEVAN V. PADMANABHAN, Padmanabhan & Dawson,
    PLLC, Minneapolis, MN, argued for plaintiff-appellant.
    Also represented by ERIN DUNGAN, PAUL J. ROBBENNOLT.
    JERRY A. RIEDINGER, Perkins Coie, LLP, Seattle, WA,
    argued for defendants-appellees. Also represented by
    KEVIN ANDREW ZECK; ANDREW DUFRESNE, DAVID R.
    PEKAREK KROHN, Madison, WI.
    ______________________
    Before NEWMAN, REYNA, and STOLL, Circuit Judges.
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    2       GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.
    REYNA, Circuit Judge.
    Genuine Enabling Technology LLC sued Nintendo Co.,
    Ltd. and Nintendo of America, Inc. accusing five products
    of infringing certain claims of 
    U.S. Patent No. 6,219,730
    .
    The U.S. District Court for the Western District of Wash-
    ington construed the term “input signal,” which appears in
    all the asserted claims, consistent with the defendants’ pro-
    posed construction, and on that basis granted summary
    judgment of non-infringement in favor of the defendants.
    Genuine appeals, arguing that the district court erred in
    construing the limitation by improperly relying on extrin-
    sic evidence and by improperly finding that the inventor,
    Mr. Nguyen, disclaimed certain claim scope during prose-
    cution. We conclude that the district court erred in its con-
    struction of “input signal” and construe the term to mean
    “a signal having an audio or higher frequency.” Accord-
    ingly, we reverse the district court’s grant of summary
    judgment and remand for further proceedings consistent
    with this opinion.
    BACKGROUND
    The ’730 Patent
    On June 20, 1998, inventor Nghi Nho Nguyen filed a
    patent application that issued on April 17, 2001, as 
    U.S. Patent No. 6,219,730
    . The ’730 patent is titled “Method
    and Apparatus for Producing a Combined Data Stream and
    Recovering Therefrom the Respective User Input Stream
    and at Least One Additional Input Signal.” The ’730 pa-
    tent discloses technology for combining data streams that
    Mr. Nguyen conceived when developing a “voice mouse”
    that conserved computer resources. Appellant’s Br. 7–8.
    According to the ’730 patent, in the prior art, comput-
    ers received user input via a “user input device” or “UID,”
    such as a mouse or keyboard. ’730 patent col. 1 ll. 14–18,
    col. 3 ll. 26–30. Computers also used “input/output” or
    “I/O” cards to process various types of signals. 
    Id.
     at col. 1
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    GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.          3
    ll. 18–22. As an example of an I/O card, a sound card would
    be used to receive speech input from a microphone and to
    transmit speech output to a speaker. 
    Id.
     at col. 3 ll. 26–30.
    The ’730 patent explains that devices and cards share com-
    puter resources and that their configuration can be cum-
    bersome:
    Devices and cards require and share common com-
    puter resources such as the direct memory access
    (DMA) channels and the interrupt request (IRQ)
    services. Computer resources for each device or
    each card equipped in a computer must be config-
    ured, or assigned, to pre-arranged memory loca-
    tions that are limited in number. Configuration
    setup for computer resources is cumbersome and
    sometimes causes conflict in running software.
    
    Id.
     at col. 1 ll. 21–28.
    To solve these problems, the ’730 patent “offers a new
    kind of UID utilizing the computer resources efficiently.”
    
    Id.
     at col. 1 ll. 41–42. The embodiment shown in Figure 1B
    “eliminates the [computer’s] sound card” so that the UID
    (i.e., mouse 18) “directly receives speech input from micro-
    phone 16 and transmits speech output to speaker 17.” 
    Id.
    at col. 3 ll. 30–36. This arrangement involves the use of a
    “framer” that (i) receives input from the UID and external
    device (e.g., speaker or microphone), and (ii) “synchro-
    nize[s] and merge[s]” those data streams into a “combined
    data stream.” 
    Id.
     at col. 4 ll. 28–31. Claim 1 is representa-
    tive and recites:
    1. A user input apparatus operatively coupled to a
    computer via a communication means additionally
    receiving at least one input signal, comprising:
    user input means for producing a user in-
    put stream;
    input means for producing the at least one
    input signal;
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    4        GENUINE ENABLING TECHNOLOGY     v. NINTENDO CO., LTD.
    converting means for receiving the at least
    one input signal and producing therefrom
    an input stream; and
    encoding means for synchronizing the user
    input stream with the input stream and en-
    coding the same into a combined data
    stream transferable by the communication
    means.
    
    Id.
     at col. 7 l. 61–col. 8 l. 4.
    During prosecution, the examiner rejected pending
    claims 1–27 as obvious. J.A. 1762, 1767–69. In particular,
    the examiner rejected pending claims 1, 16, and 23 as ob-
    vious in light of 
    U.S. Patent No. 5,990,866
     (“Yollin”).
    J.A. 1768–69.
    Yollin is titled “Pointing Device with Integrated Physi-
    ological Response Detection Facilities.” Yollin explains
    that prior art pointing devices (e.g., a mouse, joystick, or
    stylus) typically provided two-dimensional motion infor-
    mation for a cursor (i.e., positional change information) as
    well as signals for pushing a button (i.e., user selection in-
    formation). Yollin at col. 1 ll. 27–38. According to Yollin,
    a subset of prior art devices also processed input known as
    biofeedback from physiological sensors, but those systems
    generally “require a separate dedicated physiological re-
    sponse input device that consumes a valuable I/O port of
    the computer system, and . . . rel[y] on a specialized dedi-
    cated program.” 
    Id.
     at col. 1 ll. 53–62. Yollin thus disclosed
    “a pointing device with integrated physiological response
    detection facilities” that “does not consume excess I/O
    ports.” 
    Id.
     at col. 1 l. 66–col. 2 l. 6.
    Yollin further described the types of physiological re-
    sponse sensors that could be used. Yollin’s invention could
    use “any of a number of alternative devices which measure
    any of a number of physiological responses of a user who
    contacts the sensor(s).” 
    Id.
     at col. 3 l. 64–col. 4 l. 2.
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    GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.            5
    Exemplary sensors included “a [Galvanic Skin Response or
    GSR] sensor, an electromyograph (muscle tension), electro-
    cardiograph (heart activity), electroencephalograph (brain
    activity), thermometer (skin temperature), blood pressure
    sensor, and the like.” 
    Id.
     at col. 4 ll. 5–10. Yollin, however,
    did not specifically discuss the frequencies of the signals
    generated by the physiological sensors.
    With respect to the “input signal” limitation of pending
    claims 1, 16, and 23, the examiner cited Yollin’s teaching
    of “input information received from motion translation unit
    102, user selection unit 104 and physiological response sen-
    sor(s) 106” as grounds for rejection. J.A. 1768 (citing Yollin
    at col. 5 ll. 16–18).
    Mr. Nguyen responded to the office action on Septem-
    ber 28, 2000, arguing that Yollin failed to adequately teach
    the limitation. Mr. Nguyen distinguished the “slow vary-
    ing” physiological response signals discussed in Yollin from
    the “signals containing audio or higher frequencies” con-
    templated by his invention on the ground that the latter
    signals pose a signal “collision” problem solved by Mr. Ngu-
    yen’s inventions:
    Yollin’s invention . . . utilizes various implementa-
    tions and configurations for receiving input from
    motion translation unit 102, user selection unit 104
    and physiological response sensor(s) 106, and for
    processing their information prior to communica-
    tion to the host system via communication inter-
    face 108 and channel 112. These configurations are
    standard and well-known to the artisan. However,
    Yollin only uses the configuration to receive the
    slow varying signal coming from the physiological
    response sensor(s). Yollin is not motivated and
    does not anticipate their use for receiving signals
    containing audio or higher frequencies in place of
    the physiological response sensor(s). The high fre-
    quency input signal, which comes from a source
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    6       GENUINE ENABLING TECHNOLOGY        v. NINTENDO CO., LTD.
    different from those of motion and selection units,
    will run asynchronously relative to, and collide
    with, the other signals. Yollin’s invention does not
    teach or suggest any approach for receiving and re-
    covering that kind of input signal.
    J.A. 1784 (emphasis added). Mr. Nguyen then reiterated
    that distinction between Yollin and his inventions:
    [Yollin] utilizes . . . a controller to receive positional
    change information, user selection information and
    physiological change information to generate . . . a
    composite signal but does not anticipate its use with
    signals containing audio or higher frequencies. Us-
    ing a controller to generate the composite control
    signal out of the information changes, which are
    slow-varying, is standard and not worth [being]
    mentioned in Yollin’s description. Difficulties will
    arise when one signal runs asynchronously relative
    to another signal and fast. Yollin’s patent does not
    teach or suggest any method for the controller to
    receive and recover such signals. In contrast, this
    invention describes, in its representative embodi-
    ments, how to combine the data from a UID
    (mouse) and from a high-frequency signal, via a
    framer, which is unique and novel.
    J.A. 1785 (emphasis added). Mr. Nguyen made this essen-
    tial argument a third time:
    Yollin’s method of using the controller to generate
    a composite signal only works for slow varying sig-
    nals. In contrast, this invention teaches the arti-
    san the ways of synchronizing and encoding two
    sources of signals into a combined data, via a
    framer, before sending onto a communication link,
    and of recovering from the received combined data
    the original information of the respective signals.
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    GENUINE ENABLING TECHNOLOGY    v. NINTENDO CO., LTD.          7
    
    Id.
     (emphasis added). In late November 2000, the exam-
    iner entered an examiner’s amendment and allowed the
    claims. See J.A. 1796–810.
    The District Court Action
    On February 8, 2017, Genuine Enabling Technology
    LLC (“Genuine”) filed an action against Nintendo Co., Ltd.
    and Nintendo of America, Inc. (collectively, “Nintendo”) in
    the U.S. District Court for the District of Delaware.
    J.A. 63. Genuine alleged that five Nintendo products in-
    fringe the ’730 patent: (1) the Wii Remote and Wii Remote
    Plus; (2) the Nunchuk; (3) the WiiU Game Pad; (4) the
    Switch Joy-Con Controller; and (5) the Nintendo Switch
    Pro Controller. Genuine Enabling Tech. LLC v. Nintendo
    Co., No. C19-351RSM, 
    2020 WL 4366163
    , at *1 (W.D.
    Wash. July 30, 2020). Specifically, Genuine alleged that
    these products contain functionality that infringe claims
    10, 14–18, 21–23, and 25 of the ’730 patent. 
    Id.
     On March
    11, 2019, the case was transferred to the Western District
    of Washington. 
    Id. at *4
    ; J.A. 666.
    In early 2020, the parties submitted claim construction
    briefing in which they disputed the proper construction of
    the claim term “input signal” in all asserted claims. 1
    J.A. 1440–52, 1655–77. Genuine proposed the construc-
    tion, “a signal having an audio or higher frequency.”
    J.A. 1677. Nintendo proposed the following narrower con-
    struction:
    A signal containing audio or higher frequencies.
    Mr. Nguyen disclaimed signals that are 500 Hertz
    (Hz) or less. He also disclaimed signals that are
    generated from positional change information, user
    selection information, physiological response
    1   The district court held a Markman hearing on Feb-
    ruary 24, 2020. See J.A. 3263–321.
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    8       GENUINE ENABLING TECHNOLOGY     v. NINTENDO CO., LTD.
    information, and other slow-varying information.
    Alternatively, indefinite.
    J.A. 1448. In support, Nintendo submitted a declaration
    by Dr. Howard Chizeck, which discussed the features and
    operation of physiological sensors such as those disclosed
    in the Yollin reference. J.A. 1542–55. Dr. Chizeck included
    a chart titled “Range and Frequency of Select Physiological
    Phenomena” and indicated that the information in the
    chart came from a reference he called “Yuce, et al.”
    J.A. 1551. The chart provided frequency ranges for signals
    associated with various physiological phenomena, includ-
    ing a range of 10–500 Hz for EMG (electromyogram). 
    Id.
    Based on this chart, Dr. Chizeck opined that “the maxi-
    mum frequency of the signals from physiological sensors
    described by Yollin is at least 500 Hz.” J.A. 1553. Relying
    on Dr. Chizeck’s declaration, Nintendo argued that a per-
    son of ordinary skill in the art would have understood
    Yollin to teach physiological sensor signals having maxi-
    mum frequencies of at least 500 Hz, and that, therefore,
    Mr. Nguyen had disclaimed all such signals when he dis-
    tinguished Yollin from his inventions during prosecution.
    J.A. 1450–51. Nintendo accordingly opposed Genuine’s
    broader construction, which encompassed the range of fre-
    quencies that humans can hear (20 Hz to 20,000 Hz).
    J.A. 1451.
    On January 23, 2020, Nintendo moved for summary
    judgment of non-infringement, which was predicated on
    the district court’s acceptance of its claim construction of
    “input signal.” J.A. 2465–90. Nintendo argued that its ac-
    cused controllers produce the types of slow-varying signals
    that Mr. Nguyen disclaimed during prosecution when he
    distinguished his inventions from the Yollin reference. See
    J.A. 2482–84.
    On July 30, 2020, the district court issued an order
    granting Nintendo’s motion for summary judgment. Gen-
    uine, 
    2020 WL 4366163
    , at *1. The court construed the
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    GENUINE ENABLING TECHNOLOGY     v. NINTENDO CO., LTD.           9
    “input signal” limitation in all asserted claims to mean
    “signals above 500 Hz and excluding signals generated
    from positional change information, user selection infor-
    mation, physiological response information, and other
    slow-varying information,” consistent with Nintendo’s pro-
    posed construction. 
    Id. at *10
    . The court interpreted Mr.
    Nguyen’s arguments regarding Yollin during prosecution
    as “amount[ing] to disclaimer of the slow-varying signals
    addressed by Yollin.” 
    Id. at *8
    . In particular, the court
    found Mr. Nguyen’s assertions “to be a clear expression by
    Mr. Nguyen that if a sensor produces signals at the fre-
    quency of those contemplated by Yollin, those frequencies
    do not pose a collision problem when combined with slow-
    varying button data and are therefore distinct from ‘fast-
    varying’ signals addressed by the ’730 patent.” 
    Id.
     Based
    on this finding, the court determined that a person of ordi-
    nary skill in the art “would understand the upper bound of
    ‘slow-varying’ signals covered by Yollin to set the lower
    bound of ‘fast-varying’ signals covered by the ’730 patent.”
    
    Id.
     The court then credited Dr. Chizeck’s testimony iden-
    tifying “500 Hz as the upper limit of slow-varying signals
    covered by Yollin.” 
    Id.
     at *9–10.
    The district court rejected Genuine’s argument that
    Mr. Nguyen had only distinguished Yollin on the grounds
    that its signals were slow-varying rather than fast-varying,
    and that Mr. Nguyen accordingly should only be deemed to
    have disclaimed slow-varying signals below the audio fre-
    quency spectrum. 
    Id. at *9
    . The court cited Andersen Corp.
    v. Fiber Composites, LLC, 
    474 F.3d 1361
    , 1374 (Fed. Cir.
    2007), for the proposition that “an applicant’s argument
    that a prior art reference is distinguishable on a particular
    ground can serve as a disclaimer of claim scope even if the
    applicant distinguishes the reference on other grounds as
    well.” 
    Id.
     “Accordingly,” the district court explained, “even
    though Mr. Nguyen distinguished Yollin on the basis that
    the ’730 patent addressed ‘audio or higher frequencies,’ this
    distinction does not negate his additional statements
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    10     GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.
    expressly disavowing as ‘slow-varying’ the range of fre-
    quencies addressed by Yollin.” 
    Id.
     The court also stated
    that Genuine had not adequately rebutted Dr. Chizeck’s
    analysis and opinion regarding the 500 Hz threshold. 
    Id.
    Based on its claim construction of “input signal,” the dis-
    trict court granted summary judgment of non-infringement
    in favor of Nintendo. 
    Id.
     at *10–14.
    Genuine appealed.         We have jurisdiction under
    
    28 U.S.C. § 1295
    (a)(1).
    STANDARD OF REVIEW
    We review a district court’s grant of summary judg-
    ment under the standard applied in the regional circuit, in
    this case the Ninth Circuit. Neville v. Found. Constructors,
    Inc., 
    972 F.3d 1350
    , 1355 (Fed. Cir. 2020). The Ninth Cir-
    cuit reviews a grant of summary judgment de novo. 
    Id.
     (ci-
    tation omitted). Summary judgment is proper only when
    the court determines that “no reasonable jury could have
    found infringement on the undisputed facts or when all
    reasonable factual inferences are drawn in favor of the pa-
    tentee.” Netword, LLC v. Centraal Corp., 
    242 F.3d 1347
    ,
    1353 (Fed. Cir. 2001) (first citing Fed. R. Civ. P. 56(c); and
    then citing Anderson v. Liberty Lobby, Inc., 
    477 U.S. 242
    ,
    248 (1986)).
    We review a district court’s claim construction de novo
    and its underlying factual determinations for clear error.
    Teva Pharms. USA, Inc. v. Sandoz, Inc., 
    574 U.S. 318
    ,
    326–27 (2015). We review the application of prosecution
    disclaimer de novo. Shire Dev., LLC v. Watson Pharms.,
    Inc., 
    787 F.3d 1359
    , 1365 (Fed. Cir. 2015).
    DISCUSSION
    I
    A
    This court has long “emphasized the importance of the
    intrinsic evidence in claim construction” while also
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    GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.             11
    “authoriz[ing] district courts to rely on extrinsic evidence”
    in certain scenarios. Phillips v. AWH Corp., 
    415 F.3d 1303
    ,
    1317 (Fed. Cir. 2005) (en banc). Extrinsic evidence, we
    have observed, is generally “less reliable” for claim con-
    struction purposes than the intrinsic record for several rea-
    sons. 
    Id. at 1318
    . Extrinsic sources might not have been
    written for the purpose of illuminating the scope of the pa-
    tent at issue; they might have been written for an audience
    different from persons of ordinary skill in the art; they
    might suffer from litigation bias; and relatedly, they might
    have been selectively plucked from the unbounded uni-
    verse of potentially relevant material to advance a liti-
    gant’s position. 
    Id.
     We have therefore cautioned against
    “undue reliance” on extrinsic evidence because it “poses the
    risk that it will be used to change the meaning of claims in
    derogation of the indisputable public records consisting of
    the claims, the specification and the prosecution history,
    thereby undermining the public notice function of patents.”
    
    Id. at 1319
     (citation and quotation marks omitted). In
    other words, “[e]xtrinsic evidence is to be used for the
    court’s understanding of the patent, not for the purpose of
    varying or contradicting the terms of the claims.” Mark-
    man v. Westview Instruments, Inc., 
    52 F.3d 967
    , 981 (Fed.
    Cir. 1995), aff’d, 
    517 U.S. 370
     (1996).
    Expert testimony, one type of extrinsic evidence, may
    be useful in claim construction “to provide background on
    the technology at issue, to explain how an invention works,
    to ensure that the court’s understanding of the technical
    aspects of the patent is consistent with that of a person of
    skill in the art, or to establish that a particular term in the
    patent or the prior art has a particular meaning in the per-
    tinent field.” Phillips, 415 F.3d at 1318 (citations omitted).
    However, expert testimony may not be used to diverge sig-
    nificantly from the intrinsic record. See, e.g., id. (“[A] court
    should discount any expert testimony that is clearly at odds
    with the claim construction mandated by the claims them-
    selves, the written description, and the prosecution history,
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    12      GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.
    in other words, with the written record of the patent.” (ci-
    tation and quotation marks omitted)); see also Vitronics
    Corp. v. Conceptronic, Inc., 
    90 F.3d 1576
    , 1584 (Fed. Cir.
    1996) (“[E]xpert testimony . . . may not be used to vary or
    contradict the claim language. Nor may it contradict the
    import of other parts of the specification.” (citation omit-
    ted)); Aqua-Aerobic Sys., Inc. v. Aerators Inc., 
    211 F.3d 1241
    , 1245 (Fed. Cir. 2000) (stating that expert testimony
    “may not correct errors or erase limitations or otherwise
    diverge from the description of the invention as contained
    in the patent documents”); Omega Eng’g, Inc, v. Raytek
    Corp., 
    334 F.3d 1314
    , 1332 (Fed. Cir. 2003) (“Yet, Omega
    submits its expert declarations not to shed light on this
    field of art, but to rewrite the patent’s specification and ex-
    plicitly provide for the laser splitting device, lenses, and
    prisms to strike the center of the energy zone. That we
    cannot accept.”); U.S. Indus. Chems. v. Carbide & Carbon
    Chems. Corp., 
    315 U.S. 668
    , 678 (1942) (“It is inadmissible
    to enlarge the scope of the original patent by recourse to
    expert testimony to the effect that a process described and
    claimed in the reissue, different from that described and
    claimed in the original patent, is, because equally effica-
    cious, in substance that claimed originally.”).
    Accordingly, the intrinsic record “must be considered
    and where clear must be followed.” See Mantech Env’t
    Corp. v. Hudson Env’t Servs., Inc., 
    152 F.3d 1368
    , 1373
    (Fed. Cir. 1998); see also Vitronics, 
    90 F.3d at 1584
    (“[W]here the patent documents are unambiguous, expert
    testimony regarding the meaning of a claim is entitled to
    no weight.”). “Any other rule would be unfair to competi-
    tors who must be able to rely on the patent documents
    themselves, without consideration of expert opinion that
    then does not even exist, in ascertaining the scope of a pa-
    tentee’s right to exclude.” Vitronics, 
    90 F.3d at 1584
    . Reli-
    ance on expert testimony regarding the claim
    interpretation is thus permissible where the testimony is
    “consistent with [the interpretation] required by the
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    GENUINE ENABLING TECHNOLOGY       v. NINTENDO CO., LTD.         13
    intrinsic evidence.” Goldenberg v. Cytogen, Inc., 
    373 F.3d 1158
    , 1166 (Fed. Cir. 2004).
    B
    The doctrine of prosecution disclaimer “preclud[es] pa-
    tentees from recapturing through claim interpretation spe-
    cific meanings disclaimed during prosecution.” Omega,
    
    334 F.3d at 1323
    . “As a basic principle of claim interpreta-
    tion, prosecution disclaimer promotes the public notice
    function of the intrinsic evidence and protects the public’s
    reliance on definitive statements made during prosecu-
    tion.” 
    Id. at 1324
    . For a statement during prosecution to
    qualify as a disavowal of claim scope, it must be “so clear
    as to show reasonable clarity and deliberateness,” and “so
    unmistakable as to be unambiguous evidence of dis-
    claimer.” 
    Id. at 1325
     (citations omitted); see also Tech.
    Props. Ltd. LLC v. Huawei Techs. Co., 
    849 F.3d 1349
    , 1358
    (Fed. Cir. 2017) (“The patentee’s disclaimer may not have
    been necessary, but its statements made to overcome
    Magar were clear and unmistakable.”). If the challenged
    statements are ambiguous or amenable to multiple reason-
    able interpretations, prosecution disclaimer is not estab-
    lished. See Tech. Props., 849 F.3d at 1358 (citing Mass.
    Inst. of Tech. v. Shire Pharms., Inc., 
    839 F.3d 1111
    , 1119
    (Fed. Cir. 2016)). “The party seeking to invoke prosecution
    history disclaimer bears the burden of proving the exist-
    ence of a clear and unmistakable disclaimer that would
    have been evident to one skilled in the art.” Shire, 839 F.3d
    at 1119 (citation and quotation marks omitted).
    II
    The parties agree that Mr. Nguyen disavowed claim
    scope during prosecution of the ’730 patent in distinguish-
    ing his claimed inventions from the Yollin reference. Ap-
    pellant’s Br. 34; Appellee’s Br. 26. The parties dispute
    whether he disavowed claim scope beyond signals below
    the audio frequency spectrum.
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    14     GENUINE ENABLING TECHNOLOGY     v. NINTENDO CO., LTD.
    Genuine contends that the prosecution history clearly
    shows that Mr. Nguyen disclaimed “slow-varying” signals
    from the full scope of the term “input signal.” Appel-
    lant’s Br. 35. According to Genuine, Mr. Nguyen estab-
    lished a clear demarcation between Yollin’s low-frequency
    signals and the signals “of audio or higher frequency” used
    in his inventions. Id. Genuine further argues that the dis-
    trict court erred by finding disavowal of additional claim
    scope where the record shows no such disavowal. Id. at 38.
    According to Genuine, neither the intrinsic record nor
    Yollin ever discussed signal frequency in a manner that
    would allow a person of ordinary skill in the art to draw
    any bright line in claim scope based on frequency, let alone
    a bright line at 500 Hz. Id. Genuine also contends that the
    district court erroneously relied on testimony by Nin-
    tendo’s expert, Dr. Chizeck, that a person of ordinary skill
    in the art would have understood Mr. Nguyen’s assertions
    as a disavowal of all signals of frequencies up to 500 Hz.
    Id. at 44. Genuine points out that Dr. Chizeck’s testimony
    had no support in the intrinsic record, but rather was based
    solely on other extrinsic evidence purporting to describe
    various signals’ frequency ranges. Id. at 44–45. We agree
    with Genuine.
    We conclude that the only disavowal of claim scope that
    is clear and unmistakable in the record before us is Mr.
    Nguyen’s disavowal of signals below the audio frequency
    spectrum. Omega, 
    334 F.3d at
    1325–26 (prosecution his-
    tory disclaimer must be clear and unmistakable). Mr. Ngu-
    yen repeatedly distinguished his inventions from Yollin on
    the grounds that Yollin taught “slow-varying signals”
    whereas his inventions involved “audio or higher fre-
    quency” signals. See J.A. 1784–85. The examiner’s ac-
    ceptance of that distinction and resulting decision to allow
    the claims suggest that Mr. Nguyen and the examiner
    reached an understanding on that point. To the extent Mr.
    Nguyen’s statements may implicate other claim scope—
    such as signals of frequency up to 500 Hz—the record does
    Case: 20-2167     Document: 40      Page: 15    Filed: 04/01/2022
    GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.             15
    not rise to the level of establishing a “clear and unmistak-
    able” disavowal. Tech. Props., 849 F.3d at 1358 (disclaimer
    is not established where statements are ambiguous or ame-
    nable to multiple reasonable interpretations).
    Regarding the 500 Hz threshold, the district court
    erred by relying on expert testimony to limit the claim
    scope in a manner not contemplated by the intrinsic record.
    The district court credited Dr. Chizeck’s testimony that the
    signals disclosed in Yollin would have had frequencies up
    to 500 Hz. Genuine, 
    2020 WL 4366163
    , at *9 (“Based on
    Dr. Chizeck’s testimony, which identifies 500 Hz as the up-
    per limit of slow-varying signals covered by Yollin, Nin-
    tendo proposes that the Court construe ‘input signal’ as
    frequencies greater than 500 Hz.”). As Genuine points out,
    the 500 Hz frequency threshold has no basis anywhere in
    the intrinsic record; instead, Dr. Chizeck divines that
    threshold from another extrinsic reference he calls “Yuce
    et al.” The district court, however, did not assess the Yuce
    reference in its decision. Neither a full citation for that ref-
    erence nor the reference itself appears in the record before
    us. Nintendo does not make any mention of that reference,
    let alone attempt to defend its soundness as a basis for Dr.
    Chizeck’s testimony. We are left, therefore, with the con-
    clusion that the district court relied on extrinsic evidence
    upon extrinsic evidence to draw a bright line in claim scope
    not suggested anywhere in the intrinsic record. Such evi-
    dence cannot properly overcome the clarity with which Mr.
    Nguyen only disavowed signals below the audio frequency
    spectrum. Mantech, 
    152 F.3d at 1373
    ; Vitronics, 
    90 F.3d at 1584
    ; Goldenberg, 
    373 F.3d at 1166
    .
    In view of our conclusion above that Mr. Nguyen only
    disavowed signals below the audio spectrum, the district
    court also erred to the extent it found that Mr. Nguyen dis-
    avowed signals based on their content or nature—namely,
    “signals generated from positional change information,
    user selection information, physiological response infor-
    mation, and other slow-varying information.” Genuine,
    Case: 20-2167     Document: 40    Page: 16    Filed: 04/01/2022
    16     GENUINE ENABLING TECHNOLOGY      v. NINTENDO CO., LTD.
    
    2020 WL 4366163
    , at *10–11. Mr. Nguyen’s assertions dis-
    tinguishing his inventions from Yollin do not clearly and
    unmistakably demonstrate any such disclaimer. The ex-
    aminer cited Yollin’s teaching of “input information re-
    ceived from motion translation unit 102, user selection unit
    104 and physiological response sensor(s) 106” as disclosing
    the “input signal” limitation. J.A. 1768 (citing Yollin at
    col. 5 ll. 16–18). In response, Mr. Nguyen distinguished
    that teaching on the ground that those signals fell below
    the audio spectrum. See J.A. 1784–85. The record does not
    support finding a separate and distinct disclaimer of claim
    scope relating to the particular type or content of signal.
    Omega, 
    334 F.3d at
    1325–26; Tech. Props., 849 F.3d at
    1357–58.
    For the above reasons, we conclude that the district
    court erred in construing “input signal,” and we construe
    that term to mean “a signal having an audio or higher fre-
    quency.”
    CONCLUSION
    We hold that the district court erred in construing the
    term “input signal.” In particular, the district court erred
    in finding that Mr. Nguyen disclaimed subject matter other
    than signals below the audio frequency spectrum during
    prosecution, and it further erred in relying on extrinsic ev-
    idence to limit the claim scope to signals above 500 Hz. We
    therefore conclude that the proper construction of “input
    signal” is “a signal having an audio or higher frequency.”
    Accordingly, we reverse the district court’s grant of sum-
    mary judgment of non-infringement and remand for fur-
    ther proceedings consistent with this opinion.
    REVERSED AND REMANDED
    COSTS
    No costs.