Intel Corporation v. Qualcomm Incorporated ( 2021 )


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  • Case: 20-1664   Document: 103    Page: 1     Filed: 12/28/2021
    United States Court of Appeals
    for the Federal Circuit
    ______________________
    INTEL CORPORATION,
    Appellant
    v.
    QUALCOMM INCORPORATED,
    Appellee
    ______________________
    2020-1664
    ______________________
    Appeal from the United States Patent and Trademark
    Office, Patent Trial and Appeal Board in No. IPR2018-
    01429.
    ______________________
    Decided: December 28, 2021
    ______________________
    GREGORY H. LANTIER, Wilmer Cutler Pickering Hale
    and Dorr LLP, Washington, DC, argued for appellant. Also
    represented by DAVID LANGDON CAVANAUGH, THOMAS
    SAUNDERS; BENJAMIN S. FERNANDEZ, Denver, CO; JASON
    KIPNIS, Palo Alto, CA; CRISTINA SALCEDO, Los Angeles, CA.
    JONATHAN S. FRANKLIN, Norton Rose Fulbright US
    LLP, Washington, DC, argued for appellee. Also repre-
    sented by PETER B. SIEGAL; STEPHANIE DEBROW, EAGLE
    HOWARD ROBINSON, Austin, TX; DANIEL LEVENTHAL,
    RICHARD STEPHEN ZEMBEK, Houston, TX.
    ______________________
    Case: 20-1664     Document: 103      Page: 2   Filed: 12/28/2021
    2              INTEL CORPORATION   v. QUALCOMM INCORPORATED
    Before PROST, TARANTO, and HUGHES, Circuit Judges.
    PROST, Circuit Judge.
    Intel Corporation (“Intel”) petitioned the Patent Trial
    and Appeal Board (“Board”) for inter partes review (“IPR”)
    of various claims of 
    U.S. Patent No. 8,229,043
     (“the
    ’043 patent”), owned by Qualcomm Incorporated (“Qual-
    comm”). Intel proved unpatentable some (but not all) of
    these claims and some (but not all) of Qualcomm’s proposed
    substitute claims. Now, Intel appeals the Board’s determi-
    nations regarding the surviving claims. We affirm as to the
    originally challenged claims, but we vacate as to the sub-
    stitute claims. We remand for further proceedings.
    BACKGROUND
    I
    This appeal relates to radio frequency communication
    systems. On the sending end of such systems, a sending
    device converts a data signal (e.g., voice data) to a higher
    “carrier” frequency for transmission over the air. On the
    receiving end, a receiving device down-converts (or demod-
    ulates) that signal to its original “baseband” frequency.
    The receiver can also amplify the signal via an amplifier.
    A “low-noise amplifier” (“LNA”), for example, does so while
    minimizing noise, which distorts the signal. “Gain” quan-
    tifies the amplification a system provides, and the need for
    it varies with the incoming signal’s strength.
    Qualcomm’s patent is about the receiving end. Enti-
    tled Stepped Gain Mixer, it discloses a “mixer” (i.e., the
    component that performs demodulation) in a “receiver
    front end” that provides “stepped gain control” (i.e., gain
    adjustment in a stepwise manner). ’043 patent col. 1
    ll. 6–8. It explains that receivers with “many fine gain
    steps,” as opposed to “just a few large gain steps,” can
    “achieve a consistently high and smooth signal-to-noise ra-
    tio over a large gain range”—which helps them keep pace
    with the “higher data rates” of newer systems on the
    Case: 20-1664    Document: 103     Page: 3   Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED              3
    sending end. 
    Id.
     at col. 1 ll. 21–27, 54–57. Pursuing that
    benefit, therefore, the patent uses “multiple gain states.”
    
    Id.
     at col. 2 ll. 9–12.
    Take the example pictured below (Qualcomm’s annota-
    tion of ’043 patent Fig. 2). Antenna 16 receives radio fre-
    quency input signal 32, which is amplified by one of three
    LNAs 17–19 and then (annotated in red) proceeds to tran-
    sistors 39 and 40 of stepped gain mixer 38. The mixer de-
    modulates this carrier signal by processing it with local
    oscillator signal 36. The signal ultimately emerges as base-
    band signal 84. Notably, switches 41 and 42 can alter the
    gain. Closing switch 41 (forming a connection) and opening
    switch 42 (breaking a connection) increases gain, as the
    transistor outputs (green and blue) add to make a higher-
    amplitude baseband signal (yellow):
    J.A. 3697. Things change if the switches’ states are
    swapped. Then, green goes to ground while blue becomes
    the baseband:
    Case: 20-1664     Document: 103      Page: 4   Filed: 12/28/2021
    4              INTEL CORPORATION   v. QUALCOMM INCORPORATED
    J.A. 3698. Thus, toggling “two mixer gain modes for each
    of three amplifier gain modes” translates to “six gain
    states.” 
    Id.
     at col. 7 ll. 24–26.
    II
    Intel petitioned for IPR identifying itself and its cus-
    tomer Apple, Inc. (“Apple”) as real parties-in-interest. Intel
    Corp. v. Qualcomm Inc., No. IPR2018-01429, 
    2020 WL 573274
    , at *1 (P.T.A.B. Jan. 30, 2020) (“Final Written De-
    cision”). It advanced three unpatentability grounds: that
    claims 1, 17, 19, and 21 were anticipated by Der 1; that
    claims 2, 3, and 7 were obvious in view of Der and Razavi 2;
    and that claims 1–3, 6, 7, 17–19, and 21 were obvious in
    view of Der and Valla. 3 
    Id. at *3
    . Intel prevailed on
    claims 1–3 and 7 but not claims 6, 17–19, and 21. 
    Id. at *30
    . Granting in part Qualcomm’s motion to amend, the
    Board replaced claims 2, 3, and 7 with substitute claims 27,
    1   Lawrence Der & Behzad Razavi, A 2-GHz CMOS
    Image-Reject Receiver with LMS Calibration, 38(2) IEEE J.
    Solid-State Circuits 167 (2003).
    2   Behzad Razavi, Rf Microelectronics (1998).
    3   Valla et al., A 72-mW CMOS 802.11a Direct Con-
    version Front-End With 3.5-dB NF and 200-KhZ 1/f Noise
    Corner, 40(4) IEEE J. Solid-State Circuits 970 (2005).
    Case: 20-1664     Document: 103       Page: 5    Filed: 12/28/2021
    INTEL CORPORATION    v. QUALCOMM INCORPORATED                  5
    28, and 31 after disagreeing that these claims were obvious
    in view of Der, Razavi, and Burgener. 4 
    Id. at *28, *30
    .
    After Intel appealed, Qualcomm moved to dismiss for
    lack of standing. We denied that motion and directed the
    parties to address standing in their briefs. 5 We have juris-
    diction over final Board decisions under 
    28 U.S.C. § 1295
    (a)(4)(A). As discussed below, Intel has standing to
    invoke that jurisdiction.
    DISCUSSION
    I
    Before proceeding to the merits, we address the thresh-
    old question of our jurisdiction. We are limited to deciding
    “cases” and “controversies.” U.S. CONST. art. III, § 2. This
    “fundamental limitation” is reflected in the Article III
    standing requirement. Summers v. Earth Island Inst.,
    
    555 U.S. 488
    , 493 (2009). Although “not necessarily a re-
    quirement to appear before an administrative agency,” it
    “kicks in when a party seeks review in a federal court.” Ap-
    ple Inc. v. Qualcomm Inc., 
    17 F.4th 1131
    , 1135–36
    (Fed. Cir. 2021) (cleaned up). That party must demon-
    strate: (1) an “injury in fact” (2) “fairly traceable” to the de-
    fendant’s challenged conduct and (3) “likely to be redressed
    by a favorable judicial decision.” Spokeo, Inc. v. Robins,
    
    578 U.S. 330
    , 338 (2016).
    Relevant here, an injury in fact must be “concrete and
    particularized and actual or imminent, not conjectural or
    hypothetical.” 
    Id. at 339
     (cleaned up). That’s generally so
    when an IPR petitioner “has engaged in, is engaging in, or
    will likely engage in activity that would give rise to a pos-
    sible infringement suit.” Grit Energy Sols., LLC v. Oren
    4   
    U.S. Patent No. 6,804,502
    .
    5   We also denied Apple’s motions to intervene and to
    participate as amicus curiae.
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    6              INTEL CORPORATION   v. QUALCOMM INCORPORATED
    Techs., LLC, 
    957 F.3d 1309
    , 1319 (Fed. Cir. 2020) (cleaned
    up). The appellant in Grit, for instance, engaged in acts
    that not only could have but “did give rise to an infringe-
    ment suit”—a suit dismissed without prejudice, leaving the
    patentee “free to reassert those infringement claims.” 
    Id. at 1320
    . Intel’s predicament here is similar. Although
    Qualcomm didn’t sue Intel for infringement, Qualcomm
    has not disputed that it mapped the ’043 patent claims to
    an Intel product (and only an Intel product) in a prior suit
    against Apple. See Appellant’s Br. 46; J.A. 4713–65;
    J.A. 4794–96; Intel’s Response to Qualcomm’s Motion to
    Dismiss, ECF No. 40 at 5 (and cited exhibits)). Like in Grit,
    therefore, Intel’s acts “did give rise to an infringement
    suit.” 957 F.3d at 1320. In Intel’s words, Qualcomm “al-
    ready has engaged in litigation involving that technology
    and this patent.” Reply Br. 29.
    It is of no moment that the suit wasn’t against Intel, as
    Intel “need not face a specific threat of infringement.” Grit,
    957 F.3d at 1319 (cleaned up). Nor does it matter that the
    suit settled in 2019. See J.A. 4594–95. True, such settle-
    ments can deprive parties of standing. E.g., Apple,
    17 F.4th at 1134; Apple Inc. v. Qualcomm Inc., 
    992 F.3d 1378
    , 1385 (Fed. Cir. 2021). But Intel isn’t a party to this
    one. In contrast, Intel was informed that “Qualcomm is not
    offering a covenant not to sue.” J.A. 4713. Although that
    refusal isn’t on its own “sufficient to create an actual con-
    troversy,” Prasco, LLC v. Medicis Pharm. Corp., 
    537 F.3d 1329
    , 1341 (Fed. Cir. 2008), it reinforces the analogy to
    Grit, where the patentee declined to stipulate that it would
    not reassert its previous infringement allegations,
    957 F.3d at 1320 n.3.
    Moreover, Intel represents that it continues to sell the
    relevant products to Apple and at least one other customer,
    and that in doing so it must “address[] the ’043 patent and
    the risk of an infringement suit by Qualcomm.”
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    INTEL CORPORATION   v. QUALCOMM INCORPORATED                 7
    J.A. 4794–96; see J.A. 4785. 6 Because Intel’s risks trans-
    cend mere conjecture or hypothesis, see Spokeo, 578 U.S.
    at 339, we conclude that Intel has standing. See also Intel
    Corp. v. Qualcomm Inc., No. 20-1828, slip op. at 9–10
    (Fed. Cir. Dec. 28, 2021).
    II
    On to the merits. We start with the parties’ dispute
    over the proper construction of the phrase “radio frequency
    input signal” in ’043 patent claims 17, 19, and 21. Before
    the Board, Intel said this phrase “should take its ordinary
    meaning of an input signal having a radio frequency.” Fi-
    nal Written Decision, at *7. Qualcomm disagreed, arguing
    that a skilled artisan reading the patent would have un-
    derstood the phrase to reference the radio frequency signal
    that is received before down-conversion: “a signal centered
    at a carrier frequency at which the signal was transmit-
    ted/received.” Id. at *6.
    The upshot is that Intel’s proposal (and not Qual-
    comm’s) covers a signal called the intermediate frequency
    (“IF”) signal in the two-stage “super heterodyne” architec-
    ture of prior-art reference Der. Unlike the one-stage “ho-
    modyne” architecture disclosed in the ’043 patent, receivers
    in super heterodyne architectures like Der demodulate a
    carrier signal in two stages: first to that IF signal, and then
    to baseband. Adopting Qualcomm’s proposal, the Board de-
    termined that Der didn’t anticipate claims 17, 19, and 21.
    Id. at *15.
    “We review claim construction based on intrinsic evi-
    dence de novo and review any findings of fact regarding ex-
    trinsic evidence for clear error.” SpeedTrack, Inc. v.
    6   Given Intel’s past and ongoing acts, Apple’s 2019
    acquisition of “the majority of Intel’s smartphone modem
    business” also doesn’t negate Intel’s standing.       See
    J.A. 4597–607.
    Case: 20-1664     Document: 103      Page: 8   Filed: 12/28/2021
    8              INTEL CORPORATION   v. QUALCOMM INCORPORATED
    Amazon.com, Inc., 
    998 F.3d 1373
    , 1378 (Fed. Cir. 2021) (cit-
    ing Teva Pharms. USA, Inc. v. Sandoz, Inc., 
    574 U.S. 318
    ,
    331–32 (2015)). Applying the “broadest reasonable inter-
    pretation” standard, 7 we affirm the Board’s construction.
    Claim terms are generally accorded their ordinary
    meaning—that is, their meaning to a skilled artisan at the
    time of the invention. Phillips v. AWH Corp., 
    415 F.3d 1303
    , 1312–13 (Fed. Cir. 2005) (en banc). This approach
    “provides an objective baseline” for our inquiry. 
    Id. at 1313
    . To that end, we consult the sources available to
    such artisans, including “the words of the claims them-
    selves, the remainder of the specification, the prosecution
    history, and extrinsic evidence concerning relevant scien-
    tific principles, the meaning of technical terms, and the
    state of the art.” 
    Id. at 1314
     (quoting Innova/Pure Water,
    Inc. v. Safari Water Filtration Sys., Inc., 
    381 F.3d 1111
    ,
    1116 (Fed. Cir. 2004)). “Importantly,” skilled artisans are
    “deemed to read the claim term . . . in the context of the
    entire patent.” Id. at 1313. Even when seeking the “broad-
    est reasonable construction in light of the specification,”
    
    37 C.F.R. § 42.100
    (b) (2017), we still give words “their plain
    meaning” unless “inconsistent with the specification and
    prosecution history.” Arista Networks, Inc. v. Cisco Sys.,
    Inc., 
    908 F.3d 792
    , 796–98 (Fed. Cir. 2018) (rejecting con-
    struction as “overly broad, even under the broadest reason-
    able interpretation standard”). “Above all, the broadest
    reasonable interpretation must be reasonable in light of the
    claims and specification.” PPC Broadband, Inc. v. Corning
    Optical Commc’ns RF, LLC, 
    815 F.3d 747
    , 755 (Fed. Cir.
    2016).
    Considering the disputed phrase “radio frequency in-
    put signal” in a vacuum, both proposals have some appeal.
    7   Although that standard applies in this case, it has
    been superseded by the standard “used to construe the
    claim[s] in a civil action.” 
    37 C.F.R. § 42.100
    (b) (2018).
    Case: 20-1664    Document: 103      Page: 9    Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED                9
    From that vantage, it’s plausible that the disputed phrase
    equals the sum of its parts as Intel contends—a “signal”
    that is “within the range defined as the radio frequency
    spectrum” and is an “input to a circuit or component re-
    ceiver part.” E.g., Appellant’s Br. 25. But the phrase could
    just as easily mean something more specific, referring to a
    particular signal in the receiving process, as Qualcomm
    contends. Even without considering the surrounding claim
    language or the rest of the patent document, we note that
    it is not always appropriate to break down a phrase and
    give it an interpretation that is merely the sum of its parts.
    See FCC v. AT&T Inc., 
    562 U.S. 397
    , 406 (2011) (rejecting
    interpretation of “personal privacy” as “simply the sum of
    its two words”). In any event, and decisively, our inquiry
    is not limited to an analysis of the phrase in isolation. See,
    e.g., Hockerson-Halberstadt, Inc. v. Converse Inc., 
    183 F.3d 1369
    , 1374 (Fed. Cir. 1999) (“Proper claim construction . . .
    demands interpretation of the entire claim in context, not
    a single element in isolation.”). “[A] term can be defined
    only in a way that comports with the instrument as a
    whole.” Markman v. Westview Instruments, Inc., 
    517 U.S. 370
    , 389 (1996).
    We therefore continue by examining the surrounding
    claim language. Phillips, 415 F.3d at 1314. Claim 17 below
    (emphasis added) has a tripartite structure: it describes
    (a) the signal received, (b) the signal output, and (c) the
    switching functionality:
    17. A method comprising:
    (a) receiving a radio frequency input signal onto a
    source lead of a first transistor and onto a source
    lead of a second transistor;
    (b) outputting a baseband signal from a drain lead
    of the first transistor, wherein the baseband signal
    has a current with a magnitude; and
    Case: 20-1664     Document: 103      Page: 10     Filed: 12/28/2021
    10            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    (c) increasing the magnitude of the current of the
    baseband signal by coupling the drain lead of the
    first transistor to a drain lead of the second tran-
    sistor, wherein the drain lead of the first transistor
    is coupled to the drain lead of the second transistor
    by closing a switch that is coupled to both the drain
    lead of the first transistor and the drain lead of the
    second transistor.
    This language points in favor of Qualcomm’s reading
    adopted by the Board. First, if the “radio frequency input
    signal” refers to just any radio frequency signal that is an
    input, then the word “input” makes no contribution to the
    claim. Omitting it would change nothing, given the mixer’s
    “receiving” of the signal “onto a source lead.” See Antonin
    Scalia & Bryan A. Garner, Reading Law 176 (2012) (“Be-
    cause legal drafters should not include words that have no
    effect, courts avoid a reading that renders some words al-
    together redundant.”); see also Intel, No. 20-1828, slip op.
    at 13 (collecting cases). Second, part (a) of the claim doesn’t
    strictly parallel part (b), raising the question why part (a)
    doesn’t instead say “inputting a radio frequency signal” if
    indeed “a radio frequency input signal” is just a radio fre-
    quency signal that is input. These linguistic clues suggest
    that “radio frequency input signal,” to the relevant audi-
    ence, refers to the signal entering the device as a whole, not
    (as Intel proposes) to any radio frequency signal entering
    any component.
    The specification provides further support for the
    Board’s reading. It consistently and repeatedly uses “radio
    frequency input signal” to reference the carrier frequency
    signal received at the antenna, amplified by the low-noise
    amplifiers, and received at the mixer’s transistors for direct
    down-conversion to baseband. For example, Figure 2 (see
    annotated versions above) shows a signal 32 that’s received
    at antenna 16 and that, Qualcomm has not disputed, is the
    carrier frequency signal sent over the air. Indeed, the pa-
    tent in the context of Figure 1 expressly calls signal 32 “the
    Case: 20-1664     Document: 103       Page: 11     Filed: 12/28/2021
    INTEL CORPORATION    v. QUALCOMM INCORPORATED                 11
    carrier signal” that is “downconvert[ed]” to “baseband.” Id.
    at col. 5 ll. 43–58. 8 And then in its subsequent discussion
    of Figure 2, the patent explains that “[r]adio frequency in-
    put signal 32 is amplified by LNAs 17–19 and then received
    onto the source leads of transistors 39–40,” after which
    point “a baseband signal current 84 is output from the
    drain lead [of the] first transistor 39.” Id. at col. 10
    l. 64–col. 11 l. 8 (emphasis added); see also id. at col. 3
    ll. 52–58 (similar); id. at col. 3 ll. 18–30 (similar). That dis-
    cussion also references and parallels the flowchart of Fig-
    ure 11, which as its first step recites “receive a radio
    frequency input signal onto a source lead of a first transis-
    tor and onto a source lead of a second transistor” followed
    by direct down-conversion of that signal to baseband. Id.
    at Fig. 11 (capitalization normalized). We find this con-
    sistency compelling.
    Intel objects that the Board’s construction limits the or-
    dinary meaning of the claims to the patent’s embodiments,
    an approach we’ve “expressly rejected.” Info-Hold, Inc. v.
    Applied Media Techs. Corp., 
    783 F.3d 1262
    , 1267 (Fed. Cir.
    2015). Just because the patent doesn’t “specifically use the
    term ‘RF input signal’ to describe the input into a second-
    stage mixing circuit,” Intel says, that doesn’t limit the pa-
    tent “to homodyne receiver architectures” and exclude “su-
    per heterodyne” ones. Appellant’s Br. 26–27. But this
    presupposes the point it purports to prove. It takes for
    granted that Intel has the ordinary meaning right. In this
    case, however, the question is what the contextually correct
    meaning is, not whether anything affirmatively limits an
    undisputed ordinary meaning.
    8   Elsewhere, the patent also suggests that the inven-
    tion could be used in reverse to “modulate baseband data”
    up to a radio frequency signal “transmitted from the wire-
    less device” (i.e., a carrier signal). ’043 patent col. 11
    ll. 56–61 (emphasis added).
    Case: 20-1664     Document: 103      Page: 12   Filed: 12/28/2021
    12            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    And although the patent doesn’t disclose any super het-
    erodyne embodiments, it does (once) mention intermediate
    frequencies in a way that favors the Board’s construction.
    As background, it states: “Receivers for wireless communi-
    cation systems typically require low noise amplifiers
    (LNAs) followed by double-balanced mixers to pre-amplify
    incoming signals and to down-convert those signals to an
    appropriate intermediate frequency (IF) or baseband fre-
    quency.” ’043 patent col. 1 ll. 11–15. This statement
    doesn’t describe an intermediate frequency as a species of
    “radio frequency input signal.” Rather, it uses a distinct
    label, “intermediate frequency (IF).” Generally speaking,
    “[a] word or phrase is presumed to bear the same meaning
    throughout a text; a material variation in terms suggests a
    variation in meaning.” Scalia & Garner, supra, at 170; see
    PPC, 815 F.3d at 752 (noting this canon is “employed in
    both statutory interpretation and claim construction”).
    Here we discern such a material variation, suggesting that
    “intermediate frequency (IF)” means something different
    from “radio frequency input signal.”
    Further, beyond indicating a material variation in
    terms, the structure of the patent’s “IF” passage also hints
    that an intermediate frequency isn’t covered by the claimed
    “radio frequency input signal.” By describing both the “in-
    termediate frequency (IF)”and the “baseband frequency” as
    results of down-converting “incoming” signals, the passage
    parallels the claim’s structure—which reflects “receiving”
    an incoming “radio frequency input signal” and outputting
    the result of down-conversion: a “baseband signal.” Id.
    at claim17. As Intel’s counsel observed, the claim structure
    “juxtapos[es]” the “radio frequency input signal” with the
    “baseband.” Oral Arg. at 2:30–50, No. 20-1664. 9 There-
    fore, although the passage may not explicitly distinguish
    9  https://oralarguments.cafc.uscourts.gov/de-
    fault.aspx?fl=20-1664_10072021.mp3.
    Case: 20-1664    Document: 103       Page: 13   Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED              13
    IF from RF, see Oral Arg. at 30:15–32:37; Final Written De-
    cision, at *7, it treats intermediate frequencies as akin to
    baseband signals—which map to the “outputting” phrase
    of part (b) rather than the “radio frequency input signal” of
    part (a).
    Indeed, this framing illuminates how, rather than be-
    ing limited to homodyne architectures as Intel suggests,
    the Board’s construction can indeed cover super hetero-
    dyne architectures. The first stage would “receiv[e]” a “ra-
    dio frequency input signal” that, per the Board’s
    construction, is centered at a carrier frequency, and the
    second stage would “output[]” a baseband signal. Id. at
    claim 17. In between would be the work of down-conver-
    sion, first to an intermediate frequency and then to the
    “output[]” baseband signal of the claim. Id. The effect of
    the Board’s construction is not, therefore, that all super
    heterodyne architectures are excluded, but more modestly
    that the intermediate signal of such an architecture simply
    isn’t the “radio frequency input signal” of the claims.
    In sum, while Intel’s interpretation may have superfi-
    cial appeal, Qualcomm’s better reflects the usage of “radio
    frequency input signal” in the intrinsic record. It prevents
    the word “input” from being redundant in the claim and
    comports with the claim’s tripartite structure. And it re-
    flects the specification’s repeated use of the disputed
    phrase to reference incoming carrier signals before down-
    conversion. See Arista, 908 F.3d at 798 (construing “broad-
    cast” to mean “a transmission to one or more devices using
    a multicast address” based on “the specification’s con-
    sistent focus on broadcasting via a multicast address”). Be-
    cause the Board’s construction gives effect to the
    contextually appropriate meaning of “radio frequency in-
    put signal,” we affirm it.
    III
    Next we turn to obviousness, addressing first the orig-
    inally challenged claims and second the substitute claims.
    Case: 20-1664     Document: 103      Page: 14    Filed: 12/28/2021
    14            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    The ultimate judgment of obviousness under 
    35 U.S.C. § 103
     is a legal determination based on underlying factual
    inquiries. “[T]he scope and content of the prior art are to
    be determined; differences between the prior art and the
    claims at issue are to be ascertained; and the level of ordi-
    nary skill in the pertinent art resolved.” Graham v. John
    Deere Co. of Kan. City, 
    383 U.S. 1
    , 17 (1966). Also, “[s]uch
    secondary considerations as commercial success, long felt
    but unsolved needs, failure of others, etc., might be utilized
    to give light to the circumstances surrounding the origin of
    the subject matter sought to be patented.” 
    Id.
     at 17–18.
    In cases where “the question is whether a patent claim-
    ing the combination of elements of prior art is obvious,” “it
    can be important to identify a reason that would have
    prompted a person of ordinary skill in the relevant field to
    combine the elements in the way the claimed new inven-
    tion does.” KSR Int’l Co. v. Teleflex Inc., 
    550 U.S. 398
    ,
    417–18 (2007). That, too, is a factual inquiry. ZUP, LLC
    v. Nash Mfg., Inc., 
    896 F.3d 1365
    , 1371 (Fed. Cir. 2018).
    We review the Board’s factual findings for substantial evi-
    dence and its legal conclusions de novo. Donner Tech., LLC
    v. Pro Stage Gear, LLC, 
    979 F.3d 1353
    , 1358 (Fed. Cir.
    2020).
    Both obviousness issues on appeal involve “whether
    there was an apparent reason to combine” the prior-art el-
    ements. KSR, 
    550 U.S. at 418
    . In KSR (decided over 10
    years ago now), the Supreme Court rejected the “teaching,
    suggestion, or motivation” (“TSM”) test that we inherited
    from our predecessor court. 
    Id. at 407, 418
    . Under that
    test, “a patent claim [was] only proved obvious if some mo-
    tivation or suggestion to combine the prior art teachings
    [could] be found in the prior art, the nature of the problem,
    or the knowledge of a person having ordinary skill in the
    art.” 
    Id. at 407
     (cleaned up). The Court acknowledged that
    the TSM test “captured a helpful insight” by addressing the
    intuition that “a patent composed of several elements is not
    proved obvious merely by demonstrating that each of its
    Case: 20-1664    Document: 103      Page: 15     Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED               15
    elements was, independently, known in the prior art.” 
    Id. at 418
    . “Helpful insights, however, need not become rigid
    and mandatory formulas.” 
    Id. at 419
    . Therefore, the Court
    instead adopted an “expansive and flexible approach.” 
    Id. at 415
    . No longer would “[t]he obviousness analysis . . . be
    confined by a formalistic conception of the words teaching,
    suggestion, and motivation, or by overemphasis on the im-
    portance of published articles and the explicit content of
    issued patents.” 
    Id. at 419
    .
    We assess Intel’s challenges to the Board’s obviousness
    determinations under the principles in KSR. We reject the
    first, (A) that the Board didn’t satisfactorily explain why a
    skilled artisan would not have combined Der with Valla.
    We accept the second, (B) that a skilled artisan would have
    had reason to combine Burgener with Der, because the
    Board’s decision rejecting that rationale is not supported
    by substantial evidence.
    A
    We begin with the Board’s determination that Intel
    didn’t prove claims 6, 17–19, and 21 were obvious in light
    of Der and Valla (nor, for the same reason, substitute
    claims 27, 28, and 31 in light of Der, Valla, and Burgener).
    Before the Board, Intel argued that a skilled artisan
    would have “modified Valla to include two parallel passive
    mixers having outputs coupled by a gain control block con-
    sisting of switches . . . to achieve the advantages of Der and
    Valla.” Final Written Decision, at *19. Qualcomm disa-
    greed, reasoning that “the transistors from Der would im-
    pair the low impedance that Valla seeks for its amplifier.”
    Id. at *20. The Board agreed with Qualcomm. As the
    Board explained, “Valla discusses the importance of a pas-
    sive mixer with a ‘low impedance’ load” for obtaining the
    system’s benefits, calling this a “key feature.” Id. at *21.
    Along the way, it rejected Intel’s riposte: that in “triode
    mode” Der’s transistors “would have very low impedance
    Case: 20-1664     Document: 103      Page: 16    Filed: 12/28/2021
    16            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    and would have no adverse impact” on Valla’s circuit. Id.
    at *20 (quoting J.A. 1834 ¶ 61).
    On appeal, Intel doesn’t argue that the Board’s deter-
    mination lacks substantial-evidence support. 10 Rather, it
    says the Board didn’t “apply the proper mode of legal anal-
    ysis [of] weigh[ing] the putative disadvantage . . . against
    the combination’s undisputed benefits.” Reply Br. 18. As
    an initial matter, we agree that “simultaneous advantages
    and disadvantages . . . do[] not necessarily obviate motiva-
    tion to combine.” Medichem, S.A. v. Rolabo, S.L., 
    437 F.3d 1157
    , 1165 (Fed. Cir. 2006). In KSR itself, for example, ev-
    idence indicating that a prior-art product was “bulky, com-
    plex, and expensive” wasn’t on its own enough to dismiss it
    as “too flawed to upgrade.” 
    550 U.S. at
    425–26. But here
    we conclude the Board’s analysis is adequate, applying the
    proper standard.
    Specifically, the Board noted that Intel’s expert didn’t
    disagree with Qualcomm’s expert as to what would happen
    in the non-triode modes. Final Written Decision, at *21–22.
    The thrust of both experts’ testimony, the Board explained,
    is that “although there are some conditions . . . that result
    in Der’s transistor M9 operating in the triode mode . . . over
    most of the operating conditions the transistor is in a dif-
    ferent mode.” Id. at *22. Therefore, the Board concluded,
    a skilled artisan would have lacked motivation to combine
    Valla with Der because that “would impair Valla’s need for
    low impedance during the majority of operation.” Id. (em-
    phasis added). On this record, we’re satisfied that the
    Board weighed the competing evidence regarding the
    10  Oral Arg. at 14:06–32 (Q: “So you’re not making a
    substantial-evidence challenge?” A: “No your Honor, we’re
    not.”); Oral Arg. at 15:34–49 (Q: “So, just to be clear, if we
    don’t find that the Board applied the incorrect legal test for
    obviousness, you’re not saying their conclusion lacks sub-
    stantial evidence?” A: “That is correct, your Honor.”).
    Case: 20-1664    Document: 103      Page: 17    Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED                17
    relevant tradeoffs and concluded, based on the stated im-
    portance of low impedance as “key” to Valla, that negating
    this benefit during “the majority of the operation” would
    have outweighed any reason to combine. 11
    B
    Last, we conclude that substantial evidence does not
    support the Board’s determination that a skilled artisan
    would have lacked reason to combine Der with Burgener
    (in the Der-Burgener-Razavi combination) to achieve sub-
    stitute claims 27, 28, and 31. Those claims depend on sub-
    stitute claim 26, which adds a single limitation to claim 1
    (additions italicized; deletions bracketed):
    26. (Proposed Substitute for Claim 1) A device com-
    prising:
    (a) an amplifier having an output lead;
    (b) a first transistor having a source lead, a drain
    lead and a gate lead;
    (c) a second transistor having a source lead, a drain
    lead and a gate lead, wherein the output lead of the
    amplifier is coupled to the source lead of the first
    11  The Board also said Intel relied “at least in part[]
    on impermissible hindsight” because it “provide[d] no sup-
    port—whether from Valla, Der, or some other source” for a
    benefit also identified in the patent. Final Written Deci-
    sion, at *22. We’re skeptical that this necessarily trans-
    lates to hindsight. There’s another possibility: that
    without “seek[ing] out precise teachings,” Intel merely took
    “account of the inferences and creative steps” a skilled ar-
    tisan would employ. KSR, 
    550 U.S. at 418
    . At any rate,
    Intel doesn’t press a substantial-evidence challenge (see
    above), so we affirm the Board’s Der-Valla determination.
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    18            INTEL CORPORATION    v. QUALCOMM INCORPORATED
    transistor and to the source lead of the second tran-
    sistor; [[and]]
    (d) a first switch, wherein the drain lead of the first
    transistor is coupled to the drain lead of the second
    transistor through the first switch when the first
    switch is closed, and wherein an oscillating signal
    is present on the gate lead of the first transistor
    and on the gate lead of the second transistor; and
    (e) a second switch, wherein the drain lead of the
    second transistor is coupled to ground through the
    second switch when the second switch is closed.
    J.A. 3763 (alterations in original).
    Intel relied on Burgener to disclose this added limita-
    tion. Burgener describes as background a “prior art
    switch” that includes “a switching transistor” and “a shunt-
    ing transistor.” J.A. 1873. Via that switch, Burgener
    states, “RF signals are either routed from an RF input
    node” to “an RF output node,” or else are “shunted to
    ground through the shunting transistor M2 7.” J.A. 1873.
    From there, Intel argued that a skilled artisan would have
    had reason to combine Burgener’s switch with Der’s re-
    ceiver architecture (and the teachings of Razavi)—render-
    ing these substitute claims unpatentable. Intel’s asserted
    rationale proceeds in two steps. First, a skilled artisan
    would have sought to improve energy efficiency by turning
    off a portion of Der’s circuit when not in use. Second, doing
    so would have triggered a known problem to which Bur-
    gener’s switch was a predictable solution.
    The Board disagreed for three reasons: (1) that Intel’s
    energy-efficiency theory was too generic, (2) that Burgener
    described the switch as prior art with shortcomings, and
    (3) that the combination would render Der unsuitable for
    its intended purpose. Under applicable legal principles,
    none of the Board’s reasons are supported by substantial
    evidence.
    Case: 20-1664    Document: 103      Page: 19    Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED              19
    1
    First, we evaluate whether substantial evidence sup-
    ports the Board’s conclusion that Intel’s energy-efficiency
    rationale was deficient because, in the Board’s view, it was
    “nothing more than a generic reason to make something
    better” and “[i]ncreasing energy efficiency is no more than
    a generic concern that exists in many, if not all, electronic
    devices.” Final Written Decision, at *27 (emphasis added).
    For support, the Board looked to ActiveVideo Networks,
    Inc. v. Verizon Communications, Inc., in which we rejected
    a rationale premised on the following testimony:
    The motivation to combine would be because you
    wanted to build something better. You wanted a
    system that was more efficient, cheaper, or you
    wanted a system that had more features, makes it
    more attractive to your customers, because by com-
    bining these two things you could do something
    new that [you] hadn’t been able to do before.
    
    694 F.3d 1312
    , 1328 (Fed. Cir. 2012). That decision, how-
    ever, didn’t denounce energy efficiency as per se insuffi-
    cient as the Board’s decision suggests. Such a rationale is
    not inherently suspect merely because it’s generic in the
    sense of having broad applicability or appeal. Quite the
    opposite. Even before KSR, we held that because such im-
    provements are “technology-independent,” “universal,” and
    “even common-sensical,” “there exists in these situations a
    motivation to combine prior art references even absent any
    hint of suggestion in the references themselves.” DyStar
    Textilfarben GmbH v. C.H. Patrick Co., 
    464 F.3d 1356
    ,
    1368 (Fed. Cir. 2006) (emphasis added) (referencing an
    “implicit motivation to combine” to make a device “more de-
    sirable, for example because it is stronger, cheaper,
    cleaner, faster, lighter, smaller, more durable, or more ef-
    ficient”); see KSR, 
    550 U.S. at 421
     (quoting DyStar,
    
    464 F.3d at 1367
    ).
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    20            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    Of course, “generic” might also have a different sense:
    conclusory. Certainly, “[c]onclusory expert testimony does
    not qualify as substantial evidence,” TQ Delta, LLC v.
    Cisco Sys., Inc., 
    942 F.3d 1352
    , 1358–59 (Fed. Cir. 2019),
    as demonstrated in ActiveVideo. But unlike ActiveVideo,
    this isn’t a case “where the motivation of increased effi-
    ciency is asserted so generically as to be legally insuffi-
    cient.” Huawei Techs. Co. v. Iancu, 813 F. App’x 505, 510
    (Fed. Cir. 2020) (describing ActiveVideo). The testimony in
    ActiveVideo bore “no relation to any specific combination of
    prior art elements . . . from specific references” and didn’t
    explain why a skilled artisan would have combined them
    “in the way the claimed invention does,” 694 F.3d at 1328,
    but here Intel’s expert indicated precisely how and why a
    skilled artisan would have combined the references.
    Recall that Der has a super heterodyne architecture.
    Der’s second stage “employs two parallel mixers . . . a main
    mixer and a variable-gain mixer,” along with “a gain con-
    trol circuit at the output of the variable-gain mixer.” Ap-
    pellee’s Br. 42 (cleaned up). According to Intel’s expert, a
    skilled artisan “would have recognized that, in cases where
    gain control is not required (e.g. when the gain of the ‘main
    mixer’ alone is sufficient), it would have been advantageous
    to disable the variable-gain mixer to save power.”
    J.A. 1840 ¶ 70 (capitalization normalized). Specifically,
    such an artisan “would have combined the mixer circuit of
    Der Figure 9(b) with the shunt transistor M2 7 of
    Case: 20-1664    Document: 103      Page: 21    Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED              21
    Burgener,” as shown in Intel’s annotated Figure 9(b) below
    (which incorporates Burgener’s switches into Der’s circuit):
    J.A. 3802. As Intel’s expert explained, “one way to disable
    the variable-gain mixer in Der would be to turn off transis-
    tor switches M7-M10 to shut off the input signal into the
    gain control circuit, by setting Der’s VG+ and VG- to a low
    voltage (e.g. 0V).” Id. (capitalization normalized and em-
    phasis omitted). This explanation for the how isn’t re-
    motely conclusory. J.A. 1840 ¶ 70.
    Nor is Intel’s explanation for the why. For one thing,
    Intel’s expert pointed out that Der expressly highlights
    power consumption as a consideration. J.A. 1840 ¶ 70 (cit-
    ing J.A. 1178 (quantifying power consumption)). For an-
    other, Intel’s expert explained that the idea of “disabl[ing]
    the variable-gain mixer to save power” flows directly from
    the observation that the variable-gain mixer isn’t always
    needed. J.A. 1840 ¶ 70 (capitalization normalized). That,
    in turn, follows from Der’s statement that the “gain-control
    circuit . . . can add, subtract, or null signal currents from
    the variable-gain mixer.” J.A. 1840 ¶ 70 (quoting J.A. 1182
    (emphasis added)). In Intel’s words, “the gain-control cir-
    cuit will block all, some, or none of the output signal cur-
    rent from the variable-gain mixer, whichever is
    appropriate to achieve the desired level of gain.” Appel-
    lant’s Br. 10. Consistent with that observation, Qual-
    comm’s expert acknowledged at least one scenario in which
    Case: 20-1664     Document: 103      Page: 22   Filed: 12/28/2021
    22            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    “the output of the variable gain mixer would not contribute
    anything to the output.” J.A. 1909–10. And if that weren’t
    enough, Der expressly contemplates the idea of turning off
    unused circuits. As Intel noted to the Board, “although Der
    does not expressly describe turning off the variable gain
    mixer, it does describe turning off the calibration circuit.”
    Final Written Decision, at *26.
    The facts of KSR are instructive here. The patent in
    KSR claimed a design for an adjustable pedal with an elec-
    tronic sensor mounted on its fixed pivot point. 
    550 U.S. at 425
    . This, the Court concluded, was an obvious improve-
    ment to a prior-art adjustable pedal (disclosed in the Asano
    reference) with a sensor (like those disclosed in other ref-
    erences). 
    Id.
     at 425–26. Just as KSR examined whether a
    skilled artisan “would have seen a benefit to upgrading As-
    ano with a sensor,” Intel argued that a skilled artisan
    would have “seen a benefit” to upgrading Der with Bur-
    gener’s switch. 
    Id. at 424
    . Intel explained that doing so
    would improve energy efficiency for situations in which the
    variable-gain mixer is not in use. Far from being conclu-
    sory, Intel “fit the teachings of multiple patents together
    like pieces of a puzzle.” 
    Id. at 420
    . The Board’s critique of
    this rationale as impermissibly “generic” is not supported
    by substantial evidence.
    2
    The Board’s second complaint about Intel’s rationale is
    that it relied on the prior-art switch described as back-
    ground in Burgener, which Burgener criticizes and pur-
    ports to improve. Under the applicable legal standard,
    substantial evidence does not support rejecting Intel’s ra-
    tionale on this ground.
    Before the Board, Intel argued that a skilled artisan
    would have used Burgener’s prior-art switch to solve a
    known problem—the “feedthrough problem”—that was an
    expected negative consequence of disabling Der’s variable-
    gain mixer. As Intel’s expert explained, “due to the finite
    Case: 20-1664    Document: 103      Page: 23     Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED               23
    isolation of the transistor switches M7-M10, even when
    those transistors are off, some of the local oscillator (‘LO’)
    signal (applied to the gates of transistors M3A-M6A) would
    still feed through and appear at the output of the variable-
    gain mixer, degrading the signal quality.” J.A. 1840 ¶ 70
    (capitalization normalized). Using the prior-art switch of
    Burgener, with its “shunting transistor,” Intel’s expert ex-
    plained, would “allow for improved signal quality . . . by
    shunting any LO feedthrough current to ground.”
    J.A. 1840 ¶ 71. Intel’s expert opined, accordingly, that this
    combination “would have involved nothing more than use
    of a known technique (adding a shunt switch to an RF
    switch) to improve a similar device (e.g., the overall mixer
    of Der) in the same way (providing a shunt path to ground
    to improve isolation).” J.A. 1840 ¶ 72.
    Here again, KSR is our guide. In KSR, a key question
    was “where to attach the sensor” to Asano’s pedal—specif-
    ically, whether a skilled artisan “starting with Asano
    would have found it obvious to put the sensor on a fixed
    pivot point.” 
    550 U.S. at
    424–25. One prior-art reference
    taught “putting the sensor on the pedal device.” 
    Id. at 425
    .
    Another (Smith) taught putting it “not on the pedal’s foot-
    pad but instead on its support structure,” and a third
    (Rixon) noted that a “wire-chafing” problem arises when
    placing a sensor on a moving part of a pedal. 
    Id.
     From this
    constellation of references, a skilled artisan “would know
    to place the sensor on a nonmoving part of the pedal struc-
    ture” and that “[t]he most obvious nonmoving point on the
    structure from which a sensor can easily detect the pedal’s
    position is a pivot point” like the one in Asano—arriving at
    the claimed invention. 
    Id.
    Just as the known wire-chafing problem in KSR had an
    obvious solution (placing the sensor on a nonmoving point),
    so too here undisputed evidence shows that incorporating
    Burgener’s switch was an “obvious solution” to the “known
    [feedthrough] problem.” 
    Id. at 420
    ; see generally J.A. 1873
    (Burgener discussing feedthrough problem and shunting
    Case: 20-1664     Document: 103      Page: 24    Filed: 12/28/2021
    24            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    solution). There is therefore little difference between this
    circumstance and the one in KSR, where “the prior art was
    replete with patents indicating that a fixed pivot point was
    an ideal mount for a sensor.” 
    550 U.S. at 420
    . Intel’s ex-
    pert explained that combining Der with Burgener “results
    in the LO feedthrough being reduced,” and “predictable re-
    sults and benefits are obtained as described in Burgener.”
    J.A. 1840 ¶ 72 (emphasis omitted). To use KSR’s words,
    this is “the predictable use of prior art elements according
    to their established functions.” 
    550 U.S. at 417
    .
    The Board saw things differently. Noting that “Bur-
    gener discusses problems associated with [the] prior art de-
    signs” (namely “insertion loss, switch isolation, and switch
    compression”), and that for that reason Burgener “provides
    improvements,” the Board reasoned that although a skilled
    artisan “could have selected the less effective prior art RF
    switches over the improved switches that are the subject of
    Burgener, [Intel] has not sufficiently demonstrated” why
    such an artisan “would have selected using elements from
    the less effective prior art designs.” Final Written Decision,
    at *27. “Without such an explanation,” the Board said, “the
    only reasonable inference is that [Intel] focused on Bur-
    gener’s description of prior art switches using impermissi-
    ble hindsight.” 
    Id.
     Not so. Our caselaw is clear. It’s not
    necessary to show that a combination is “the best option,
    only that it be a suitable option.” PAR Pharm., Inc. v. TWI
    Pharms., Inc., 
    773 F.3d 1186
    , 1197–98 (Fed. Cir. 2014).
    And “if a technique has been used to improve one device,
    and a person of ordinary skill in the art would recognize
    that it would improve similar devices in the same way, us-
    ing the technique is obvious unless its actual application is
    beyond his or her skill.” KSR, 
    550 U.S. at 417
    . That’s what
    we have here. Given the facts and reasoning of KSR, it is
    readily apparent that the Board’s hindsight inference lacks
    substantial evidence.
    Qualcomm describes Intel’s theory as fixing a “problem
    of their own making.” Appellee’s Br. 52. But the same can
    Case: 20-1664    Document: 103      Page: 25    Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED              25
    be said of the known wire-chafing problem in KSR, which
    arose by virtue of combining an adjustable pedal with an
    electronic sensor. 
    550 U.S. at 425
    . As the KSR Court
    noted, “[i]n automotive design, as in many other fields, the
    interaction of multiple components means that changing
    one component often requires the others to be modified as
    well.” 
    Id. at 424
    . So too here. Like modifying Asano in a
    way that avoided the wire-chafing problem in KSR, modi-
    fying Der with Burgener in a way that avoids the feed-
    through problem doesn’t neutralize Intel’s rationale.
    3
    Last, the Board rejected Intel’s asserted rationale be-
    cause “powering off the variable gain mixer would have re-
    sulted in the circuit not being suitable for its intended
    purpose.” Final Written Decision, at *27. In so concluding,
    the Board explained that “Der describes two modes: a cali-
    bration mode and an operating mode” and then reasoned
    that “it does not logically flow that because the calibration
    mode is only used for calibration, other parts of the circuit
    that are intended to be used during normal operation
    would be turned off during normal operation.” 
    Id.
     That,
    apparently, is because “nothing in Der suggests turning off
    any part of the functional circuit elements, let alone the
    ‘important’ variable gain mixer.” 
    Id.
    Once again, the Board’s decision lacks substantial evi-
    dence under the standards articulated in KSR. Intel’s ob-
    viousness rationale isn’t defective merely because “nothing
    in Der suggests” it. 
    Id.
     But even if that were the correct
    test, which it is not, portions of Der do suggest this ra-
    tionale—suggesting that power consumption was a consid-
    eration, that circuits may be turned off when not in use,
    and that the variable-gain mixer is not always in use, as
    detailed above. See generally J.A. 1840 ¶ 70.
    Further, the intended purpose of Der does not control.
    “Common sense teaches . . . that familiar items may have
    obvious uses beyond their primary purposes.” KSR,
    Case: 20-1664     Document: 103      Page: 26   Filed: 12/28/2021
    26            INTEL CORPORATION   v. QUALCOMM INCORPORATED
    
    550 U.S. at 420
    . Indeed, one of the points on which the
    Court in KSR disagreed with our decision below in that
    case was our reliance on the primary purposes of prior-art
    references. We had pointed out that Asano “was designed
    to solve the constant ratio problem,” that Rixon “suffered
    from the problem of wire chafing but was not designed to
    solve it,” and that Smith “did not relate to adjustable ped-
    als and did not necessarily go to the issue of motivation to
    attach the electronic control on the support bracket of the
    pedal assembly.” 
    Id. at 414
     (internal quotation marks
    omitted). That was misguided. “Regardless of Asano’s pri-
    mary purpose, the design provided an obvious example of
    an adjustable pedal with a fixed pivot point” such that
    “[t]he idea that a designer hoping to make an adjustable
    electronic pedal would ignore Asano because Asano was de-
    signed to solve the constant ratio problem makes little
    sense.” 
    Id.
     at 420–21. Finally, the Board didn’t explain
    how disabling Der’s variable-gain mixer would hinder its
    purpose in use cases where “achieving the ‘desired output’
    requires that the output of the variable-gain mixer be
    ‘null[ed]’—a possibility that Der itself contemplates.” Ap-
    pellant’s Br. 45–46 (quoting J.A. 1182) (alteration in origi-
    nal).
    Accordingly, the Board’s analysis lacks substantial ev-
    idence under KSR. We vacate the Board’s decision as to
    substitute claims 27, 28, and 31 and remand with instruc-
    tions that Intel demonstrated sufficient reason for combin-
    ing Der with Burgener. The Board should resolve any
    remaining disputes regarding that combination on re-
    mand. E.g., Appellee’s Br. 52 n.11.
    CONCLUSION
    We have considered the parties’ remaining arguments
    but find them unpersuasive. We affirm the Board’s claim
    construction and decision as to claims 6, 17–19, and 21. We
    vacate the Board’s determination as to substitute
    claims 27, 28, and 31 and remand for further proceedings.
    Case: 20-1664    Document: 103      Page: 27   Filed: 12/28/2021
    INTEL CORPORATION   v. QUALCOMM INCORPORATED            27
    AFFIRMED-IN-PART, VACATED-IN-PART, AND
    REMANDED
    COSTS
    The parties shall bear their own costs.