Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
`
`
`DOCKET NO.: 0107131-00564US4
`Filed on behalf of Intel Corporation
`By: David L. Cavanaugh, Reg. No. 36,476
`Richard Goldenberg, Reg. No. 38,895
`Wilmer Cutler Pickering Hale and Dorr LLP
`60 State Street
`Boston, Massachusetts 02109
`Email: david.cavanaugh@wilmerhale.com
`
` richard.goldenberg@wilmerhale.com
`
`
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________________________________________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________________________________________
`
`
`Intel Corporation
`Petitioner
`
`v.
`
`Qualcomm Incorporated
`Patent Owner
`
`Case IPR2018-01240
`
`
`PETITION FOR INTER PARTES REVIEW OF
`U.S. PATENT NO. 8,698,558
`CHALLENGING CLAIMS 10 AND 11
`
`
`
`
`
`
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`

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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`V. 
`
`TABLE OF CONTENTS
`I. 
`INTRODUCTION ........................................................................................... 1 
`II.  MANDATORY NOTICES ............................................................................. 2 
`A. 
`Real Party-in-Interest ............................................................................ 2 
`B. 
`Related Matters ...................................................................................... 2 
`C. 
`Counsel .................................................................................................. 3 
`D. 
`Service Information ............................................................................... 3 
`III.  CERTIFICATION OF GROUNDS FOR STANDING .................................. 4 
`IV.  OVERVIEW OF CHALLENGE AND RELIEF REQUESTED .................... 4 
`A. 
`Prior Art Patents and Printed Publications ............................................ 4 
`B. 
`Grounds for Challenge .......................................................................... 6 
`BRIEF DESCRIPTION OF TECHNOLOGY ................................................ 6 
`A. 
`Radio Frequency (RF) Power Amplifiers ............................................. 6 
`B. 
`Power Supplies for Power Amplifiers ................................................... 7 
`Envelope Amplifiers ................................................................... 8 
` 
`Switchers ................................................................................... 10 
` 
`Hybrid Supply Generators ........................................................ 11 
` 
`Boost Converters ....................................................................... 16 
` 
`C.  Multiplexers ......................................................................................... 19 
`VI.  OVERVIEW OF THE ’558 PATENT .......................................................... 21 
`A. 
`The Alleged Problem in the Art .......................................................... 21 
`B. 
`The Alleged Invention of the ’558 Patent ........................................... 22 
`C. 
`Relevant Prosecution History .............................................................. 29 
`November 23, 2012 Office Action ........................................... 29 
` 
`February 19, 2013 Amendment ................................................ 30 
` 
`  May 10, 2013 Office Action ..................................................... 30 
`April 15, 2015 Patent Issuance ................................................. 31 
` 
`June 27, 2017 Certificate of Correction .................................... 31 
` 
`VII.  OVERVIEW OF THE PRIOR ART REFERENCES ................................... 31 
`A. 
`Chu ...................................................................................................... 31 
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`C. 
`
`D. 
`
`B. 
`Choi 2010 ............................................................................................ 36 
`VIII.  CLAIM CONSTRUCTION .......................................................................... 38 
`A. 
`“envelope signal” (claim 11) ............................................................... 39 
`B. 
`“means for generating a boosted supply voltage based on a first
`supply voltage” (claim 10) .................................................................. 40 
`“means for generating a second supply voltage based on the
`envelope signal and the boosted supply voltage” (claim 10) .............. 43 
`“means for generating the second supply voltage based on an
`envelope signal and either the boosted supply voltage or the
`first supply voltage” (claim 11) ........................................................... 46 
`IX.  LEVEL OF ORDINARY SKILL IN THE ART ........................................... 49 
`X. 
`SPECIFIC GROUNDS FOR PETITION ...................................................... 50 
`A.  Ground I: Claim 10 is obvious in view of Chu combined with
`Choi 2010 and Hanington ................................................................... 51 
`Claim 10 .................................................................................... 51 
` 
`Ground II: Claim 11 is obvious over Chu combined with Choi
`2010, Hanington, and Myers ............................................................... 72 
`Claim 11 .................................................................................... 72 
` 
`XI.  CONCLUSION .............................................................................................. 82 
`
`
`B. 
`
`ii
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`
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`Petitioner Intel Corporation (“Intel”) respectfully requests Inter Partes
`
`Review of claims 10 and 11 of U.S. Patent No. 8,698,558 (the “’558 patent”) (Ex.
`
`1301) pursuant to 35 U.S.C. §§ 311-19 and 37 C.F.R. § 42.1 et seq.
`
`I.
`
`INTRODUCTION
`The ’558 patent claims various structures for “efficiently generating a power
`
`supply for a power amplifier.” Ex. 1301, 1:30-31. Power supply generators for
`
`power amplifiers, however, were well-known at the time of the claimed invention,
`
`and the challenged claims either are not novel or are obvious variations of known
`
`power supply generators. The aspects of the ’558 patent that are identified by the
`
`patent as inventive and that the Patent Owner itself has identified as inventive in
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`parallel litigation (i.e., the addition of a boost converter to an envelope amplifier
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`and the use of an “offset” current to generate a larger supply current) were known
`
`in the prior art at the time of the claimed invention, and they provide only known
`
`and predictable results that cannot justify a patent.
`
`
`
`Moreover, the primary prior art reference, Chu and Kwak, relied upon in this
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`and related petitions—neither of which was before the Patent Office during
`
`prosecution—disclose the key elements that the Examiner found to be allegedly
`
`missing from the prior art during prosecution. For example, the Examiner allowed
`
`claims 10 and 11 because he found that the prior art of record did not disclose the
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`required operational amplifier, driver, and PMOS and NMOS transistors. The Chu
`
`reference cited in this Petition discloses those limitations.
`
`
`
`Accordingly, the prior art cited in this Petition renders obvious claims 10
`
`and 11 of the ’558 patent.
`
`II. MANDATORY NOTICES
`A. Real Party-in-Interest
`Intel Corporation (“Petitioner”) is a real party-in-interest and submits this
`
`inter partes review Petition for review of certain claims of U.S. Patent No.
`
`8,698,558 (the “’558 patent”). Petitioner also identifies Apple Inc. (“Apple”) as a
`
`real party-in-interest.
`
`B. Related Matters
`Qualcomm Incorporated (“Qualcomm” or “Patent Owner”) has asserted
`
`the ’558 patent against Apple in Certain Mobile Electronic Devices and Radio
`
`Frequency and Processing Components Thereof, Investigation No. 337-ITC-1065,
`
`currently pending before the International Trade Commission. Qualcomm also has
`
`asserted the ’558 patent against Apple in Qualcomm Inc. v. Apple Inc., No. 3:17-
`
`cv-1375 (S.D. Cal.).
`
`Concurrently with this inter partes review Petition, Petitioner is also filing
`
`inter partes review petitions for claims 12-14 of the ’558 patent (IPR2018-01152),
`
`claims 1-9 of the ʼ558 patent (IPR2018- 01153), and claims 15-20 of the ʼ558
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`patent (IPR2018- 01154). Petitioner requests that these petitions be assigned to the
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`same panel.
`
`C. Counsel
`Lead Counsel: David L. Cavanaugh (Registration No. 36,476)
`
`Backup Counsel: Richard Goldenberg (Registration No. 38,895), Nina
`
`Tallon (pro hac vice to be requested), Joseph Mueller (pro hac vice to be
`
`requested), Todd Zubler (pro hac vice to be requested), and Kathryn Zalewski (pro
`
`hac vice to be requested), Theodoros Konstantakopoulos (Registration No. 74,155)
`
`D.
`Service Information
`E-mail:
`
`
`david.cavanaugh@wilmerhale.com
`
`richard.goldenberg@wilmerhale.com
`
`nina.tallon@wilmerhale.com
`
`joseph.mueller@wilmerhale.com
`
`todd.zubler@wilmerhale.com
`
`kathryn.zalewski@wilmerhale.com
`
`theodoros.konstantakopoulos@wilmerhale.com
`
`Post and hand delivery: Wilmer Cutler Pickering Hale and Dorr LLP
`
`
`
`
`
`
`
`
`
`60 State Street
`
`Boston, Massachusetts 02109
`
`Telephone: (617) 526-6000
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`
`
`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`Fax: (617) 526-5000
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`Petitioner consents to email delivery on lead and backup counsel.
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`III. CERTIFICATION OF GROUNDS FOR STANDING
`Petitioner certifies pursuant to Rule 42.104(a) that the patent for which
`
`review is sought is available for inter partes review and that Petitioner is not
`
`barred or estopped from requesting an inter partes review challenging the patent
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`claims on the grounds identified in this Petition.
`
`IV. OVERVIEW OF CHALLENGE AND RELIEF REQUESTED
`Pursuant to Rules 42.22(a)(1) and 42.104(b)(1)-(2), Petitioner challenges
`
`claims 10 and 11 of the ’558 patent.
`
`A.
`Prior Art Patents and Printed Publications
`The ’558 patent was filed June 23, 2011 and does not claim priority to any
`
`prior applications.
`
`The following references are pertinent to the grounds of unpatentability
`
`explained below:
`
`1.
`
`Chu, W.Y. et al., “A 10 MHz Bandwidth, 2 mV Ripple PA Regulator
`
`for CDMA Transmitters,” IEEE Journal of Solid-State Circuits 2809-
`
`2819 (2008) (“Chu”) (Ex. 1304). Chu was published in 2008 and is
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`prior art under at least 35 U.S.C. § 102(b). Ex. 1305 at ¶14.
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`2.
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`Choi, J. et al., “Envelope Tracking Power Amplifier Robust to Battery
`
`Depletion,” Microwave Symposium Digest (MTT), 2010 IEEE MTT-
`
`S International 1332-36 (2010) (“Choi 2010”) (Ex. 1306). Choi 2010
`
`has been available from the IEEE Xplore website at
`
`http://ieeexplore.ieee.org/abstract/document/5517825/ since July 23,
`
`2010 and is therefore prior art under at least 35 U.S.C. § 102(a). Ex.
`
`1307 at ¶11. Choi 2010 is also prior art under 35 U.S.C. § 102(b).
`
`Choi 2010 was presented in May 2010 at a leading technical
`
`conference of skilled artisans, the IEEE International Microwave
`
`Symposium (“IMS”) 2010 conference, in Anaheim, California. Ex.
`
`1308; Ex. 1306 at cover; Ex. 1309 at ¶¶4-5; Ex. 1307 at ¶11. Choi
`
`2010 was distributed to hundreds of conference attendees via USB
`
`drives in May 2010. Ex. 1308 at ¶17; Ex. 1309 at ¶¶6-9.
`
`3.
`
`Hanington, Gary et al., “High-Efficiency Power Amplifier Using
`
`Dynamic Power-Supply Voltage for CDMA Applications,” IEEE
`
`Transactions on Microwave Theory and Techniques 47:8 (1999)
`
`(“Hanington”) (Ex. 1324). Hanington was published in 1999 and is
`
`prior art under at least 35 U.SC. § 102(b). See Ex. 1304 at 1077 (Choi
`
`2010 citing Hanington).
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`4.
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`U.S. Patent No. 5,929,702, “Method and Apparatus for High
`
`Efficiency High Dynamic Range Power Amplification,” to Myers et
`
`al. (“Myers”) (Ex. 1312). Myers was filed on November 28, 1997 and
`
`issued on July 27, 1999, making it prior art under at least 35 U.S.C.
`
`§ 102(a), (b), and (e).
`
`B. Grounds for Challenge
`Petitioner requests cancellation of claims 10 and 11 of the ’558 patent as
`
`unpatentable under 35 U.S.C. § 103. This Petition, supported by the declaration of
`
`Dr. Alyssa Apsel (Ex. 1303) filed herewith, demonstrates that there is a reasonable
`
`likelihood that Petitioner will prevail with respect to cancellation of at least one
`
`challenged claim. See 35 U.S.C. § 314(a).
`
`V. BRIEF DESCRIPTION OF TECHNOLOGY
`The challenged claims of the ’558 patent are directed to an apparatus for
`
`generating a power supply signal for a power amplifier. The apparatus includes
`
`several components that were well known in the art—envelope amplifiers, boost
`
`converters, and power amplifiers—as explained below.
`
`A. Radio Frequency (RF) Power Amplifiers
`In wireless communications, mobile devices exchange information (such as
`
`phone calls, text messages, or other data to and from the Internet) with a base
`
`station that connects the mobile devices to other devices and a wider network.
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
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`This information is transmitted using radio frequency (“RF”) signals. To reach a
`
`base station or a mobile device, RF signals require a certain amount of power.
`
`Mobile devices and base stations therefore commonly contain a component known
`
`as a “power amplifier” (or “PA”) that increases the power of RF signals to a level
`
`sufficient to reach the receiving base station or mobile device. Typically, the
`
`further the device moves from a base station, the more power amplification is
`
`needed to ensure successful transmission of the RF signal. Ex. 1303 at ¶¶36-37.
`
`In operation, a PA accepts an input signal (such as the signal that carries
`
`voice data for a cell phone call) and produces an output signal that, ideally,
`
`replicates the input signal but with proportionally greater power. Ex. 1303 at ¶38.
`
`B.
`Power Supplies for Power Amplifiers
`A PA needs to receive power sufficient to amplify the input signal. A PA
`
`typically receives its power in the form of a supply voltage from a power supply
`
`generator/modulator. For example, in the prior-art structure shown below, the PA
`
`receives a supply voltage (“Modulated Supply”) from a power supply
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`generator/modulator:
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
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`Kim – Figure 1(b)
`
`Ex. 1313 [Kim, D. et al., “High Efficiency and Wideband Envelope Tracking
`
`Power Amplifier with Sweet Spot Tracking,” Radio Frequency Integrated Circuits
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`Symposium (RFIC): 255-258 (2010) (“Kim”)] at 255. In this case, the supply
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`voltage provides the PA with sufficient power to transmit an output signal
`
`(“RF_OUT”) based on the input signal (“RF_IN”) that the PA receives, without
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`degrading the quality of the signal or wasting power through resistive losses. The
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`amount of power required at the RF PA depends on the RF signal that must be
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`transmitted. Ex. 1303 at ¶¶39-40.
`
`
`Envelope Amplifiers
`An envelope amplifier—also sometimes referred to as a “linear amplifier”—
`
`is one type of power supply generator for a PA. As shown in the diagram above,
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`the envelope amplifier (the “Supply Modulator”) receives an “envelope” signal,
`
`which is a signal that tracks the RF signal to be transmitted. As shown in the
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`diagram below, the envelope signal (shown in blue) tracks the outermost points of
`
`the oscillating RF signal (shown in black):
`
`
`
`
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`Ex. 1303 at ¶41-42. The envelope amplifier receives the envelope signal and uses
`
`it to provide a supply voltage to the PA that increases and decreases as the
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`amplitude of the envelope signal increases and decreases. Ideally, the power
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`provided to the PA will match the envelope signal as closely as possible—thereby
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`providing the power that the PA needs to transmit the RF signal, but without
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`providing more power than necessary. Ex. 1303 at ¶42.
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`Envelope amplifiers have many advantages: they have a simple circuit
`
`configuration; they can generate output signals that are accurate copies of the input
`
`signals, even when the input changes rapidly (i.e., when the RF signal has a high
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
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`bandwidth); and they do not generate significant noise that could affect other
`
`circuits. Ex. 1303 at ¶43.
`
`Envelope amplifiers, however, are also energy inefficient and generate
`
`considerable heat. To generate a voltage for the PA, an envelope amplifier
`
`requires its own input supply voltage. An envelope amplifier is a type of “linear
`
`regulator,” which is a device that takes an input voltage and reduces (or “steps-
`
`down”) that voltage as necessary to generate the output supply voltage for the PA.
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`This step-down in voltage is necessarily inefficient because it involves dissipating
`
`the power difference between the input and output voltages in the form of heat.
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`Using an envelope amplifier alone to supply power to a PA therefore consumes
`
`more power than desired. Ex. 1303 at ¶43.
`
`
`Switchers
`Another prior art device for supplying power to a PA is a “switcher,” also
`
`sometimes referred to as a “switching regulator” or “switching amplifier.” A
`
`switcher takes small chunks of energy from an input voltage source and stores
`
`them in energy-storing elements (such as an inductor) that will transform the
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`energy into an output. A switcher accomplishes this task by alternately connecting
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`and disconnecting the input supply voltage (e.g., the battery of the mobile device)
`
`to the energy-storage element. When the switcher connects the input supply
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`voltage to the energy storage element, energy is added to the storage element. The
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`storage element can then release this energy in the form of a steady current to the
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`PA. By controlling the timing of these alternating connections / disconnections to
`
`increase the energy in the storage element, a switcher can supply energy to a PA
`
`without dissipating voltage as heat, like an envelope amplifier does. The energy
`
`losses involved in moving chunks of energy around in this way are thus relatively
`
`small. Ex. 1303 at ¶¶44-45.
`
`As a result, switchers generally achieve higher efficiency than envelope
`
`amplifiers. But there are limits on the frequency at which switchers can operate.
`
`Because of this, switchers were generally known to have higher efficiency, but
`
`lower operating bandwidth, than envelope amplifiers. Ex. 1303 at ¶45.
`
` Hybrid Supply Generators
`Hybrid supply generators combine envelope amplifiers and switchers to gain
`
`the benefits of both. A hybrid supply generator can use the envelope amplifier
`
`and/or the switcher, as appropriate, to supply the power to a power amplifier,
`
`thereby obtaining both (a) the high frequency response of an envelope amplifier,
`
`and (b) the high efficiency of a switcher. Ex. 1303 at ¶46.
`
`Hybrid supply generators were well known in the art at the time of the
`
`purported invention of the ’558 patent. For example, another patent filed eleven
`
`years earlier by the lead inventor of the ’558 patent discloses combining a linear
`
`amplifier with a type of switcher known as a synchronous buck DC/DC converter.
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
`IPR2018-01240
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`Ex. 1314 [U.S. Patent No. 6,300,826, “Apparatus and Method for Efficiently
`
`Amplifying Wideband Envelope Signals” (filed May 5, 2000) (“Mathe ’826”)]. As
`
`shown below, circuit 110 in Mathe ’826 is a buffer amplifier circuit that includes
`
`(1) an envelope amplifier (“an AB-type RF amplifier 122” highlighted in purple),
`
`which is described as “a moderately power efficient device having high bandwidth
`
`capabilities”, and (2) a switcher (“synchronous buck DC/DC converter 124”
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`highlighted in yellow), which is described as “a highly efficient device having low
`
`bandwidth capabilities.” Id. at 5:17-22; Ex. 1303 at ¶47.
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`
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`Mathe ’826 – Figure 6
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`A paper by Ertl from 1997 also discloses a hybrid supply generator. Ex.
`
`1316 [Ertl, H. et al., “Basic Considerations and Topologies of Switched-Mode
`
`Assisted Linear Power Amplifiers,” IEEE Transactions on Industrial Electronics
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`44.1 (1997): 116-123 (“Ertl”)]. Ertl presents “a combined power amplifier system”
`
`consisting of an envelope amplifier (“linear amplifier unit”) and a switcher (“a
`
`switched-mode (class D) current dumping stage”), as shown in Figure 2 below:
`
`Ertl – Figure 2
`
`
`
`Ex. 1316 at 117. Ertl touts this combination as providing the best of both worlds:
`
`(a) “the fundamental drawback of conventional linear power amplifiers—the high
`
`loss—is avoided;” and (b) “[c]ompared to a pure class D (switching) amplifier, the
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`presented system needs no output filter to reduce the switching frequency
`
`harmonics.” Id.; Ex. 1303 at ¶48.
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`Blanken also proposes a hybrid supply modulator for a PA, combining “a
`
`high-bandwidth class-AB linear regulator [envelope amplifier] with an efficient
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`Petition for Inter Partes Review of U.S. Patent No. 8,698,558
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`DC/DC converter [switcher] in a master-slave configuration.” Ex. 1310 [Blanken,
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`P.G. et al., “A 50MHz bandwidth multi-mode PA supply modulator for GSM,
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`EDGE and UMTS application,” 2008 Radio Frequency Integrated Circuits
`
`Symposium (IEEE) 401-04 (2008) (“Blanken”)] at 401. Blanken explains that:
`
`[h]igh-efficiency voltage conversion can be obtained with a switched-
`mode inductive DC/DC buck converter, but its bandwidth is limited
`due to practical limits to the switching frequency. Alternatively,
`linear regulators enable higher bandwidth at the cost of efficiency. As
`a good compromise between efficiency and bandwidth, hybrid supply
`modulators have been proposed combining a switched-mode DC/DC
`converter in parallel to a linear regulator.
`Id.; see also id. (“The supply-modulator topology is shown in Fig. 1. It contains a
`
`linear regulator and a DC/DC converter in master-slave configuration. The linear
`
`regulator is formed by a Miller-compensated two-stage amplifier built with class-A
`
`input transconductor gin and class-AB output transconductor go. … [T]he DC/DC
`
`converter supplies the DC and low-frequency part of the load current, and the
`
`linear regulator supplies the high-frequency part.”). Ex. 1303 at ¶49.
`
`Finally, a 2010 paper by Kang describes “a highly efficient supply
`
`modulator” that combines an envelope amplifier with a switcher. Ex. 1317 [Kang,
`
`D. et al., “A Multimode/Multiband Power Amplifier With a Boosted Supply
`
`Modulator,” IEEE Transactions on Microwave Theory and Techniques 58.10
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`(2010): 2598-2608 (“Kang”)]. Kang acknowledges the disadvantages of both
`
`linear amplifiers (i.e., envelope amplifiers) and switching amplifiers (i.e.,
`
`switchers): “the limited BW [bandwidth] of switching amplifiers and the low
`
`efficiency of wideband linear amplifiers.” Ex. 1317 at 2599. Kang explains that
`
`researchers therefore have utilized both envelope amplifiers and switchers in
`
`hybrid systems that are “suitable for the envelope signal of modern wireless
`
`communication systems, which has the most power in the low-frequency region.”
`
`Id. at 2599. Kang specifically proposes “a hybrid switching amplifier (HSA) for
`
`multistandard applications.” Id. As shown in Figure 4 below, Kang’s hybrid
`
`supply generator includes not only an envelope amplifier (“linear stage”) and a
`
`switcher (“switching stage”), but also a boost converter (highlighted in light blue
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`and discussed further in the next section):
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`Kang – Figure 4
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`
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`Id. at 2602; Ex. 1303 at ¶50.
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`Boost Converters
`If the supply voltage from a device’s battery is too low, the output signal
`
`from the PA can be distorted. A boost converter (also known as a “step-up”
`
`converter) can prevent this by boosting the battery voltage to a higher voltage,
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`which the envelope amplifier can then use to provide power to the PA. This
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`boosting capability is achieved by storing energy in a storage element, and then
`
`releasing the energy in the form of a higher voltage. Ex. 1303 at ¶51.
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`Boost converters have been standard components in power electronics since
`
`well before the earliest alleged priority date of the ʼ558 patent. For example, a
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`patent from the 1990s discloses a boost (“step-up”) converter that provides
`
`increased voltage to a power amplifier to prevent distortion. Ex. 1318 [U.S. Patent
`
`No. 5,834,977, “Amplifying Circuit with Power Supply Switching Circuit” (filed
`
`October 30, 1996 and issued November 10, 1998) (“Maehara”)] at Abstract (“An
`
`amplifying circuit according to the present invention has an amplifying unit for
`
`amplifying an input signal to produce an amplified signal, a battery for generating
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`a constant voltage (a first voltage), a step-up converter for always generating an
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`increased voltage (or a second voltage) by increasing the constant voltage ….
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`[B]ecause the increased voltage is always generated by the step-up converter …
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`any distortion of the amplified signal can be prevented.”). Ex. 1303 at ¶52.
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`Boost converters typically include a transistor, a diode, an inductor, and a
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`capacitor. For example, the book Fundamentals of Power Electronics, published
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`in 2001, describes a boost converter with these components:
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`Ex. 1324 [Erickson et al., Fundamentals of Power Electronics, Second Edition
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`(Kluwer Academic Publisher) (2001) (“Erickson”)] at Fig. 2.13(b), 22-24. The
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`boost converter in Erickson includes a switch implemented with a MOSFET
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`(outlined in green) and a diode (outlined in red) that connects the inductor
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`(outlined in purple) either to ground or to a capacitor (outlined in fuchsia) and the
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`output (resistor R). The operation of this circuit allows the transfer of energy to
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`the capacitor through the diode so that the output voltage is higher than the input
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`voltage. Id. at 24. Ex. 1303 ¶53.
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`It is well known that boost converters can be used in a hybrid supply
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`generator. As noted in the preceding section, the Kang paper from 2010 discloses
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`a hybrid supply generator that includes a boost converter connected to the envelope
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`amplifier. Ex. 1317 at 2602 (“An HSA [hybrid switching amplifier] consists of a
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`boost converter, linear stage, hysteretic comparator, and switching stage, as shown
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`in Fig. 4. The boost converter is connected to the linear stage to boost the output
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`voltage swing.”). Ex. 1303 at ¶54.
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`Finally, during prosecution, the Examiner found that Kim disclosed a hybrid
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`supply generator with a boost converter, as required by the ’558 patent. See Ex.
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`1313. The Examiner initially rejected patent claims 6-8 and 10-11 (prosecution
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`claims 10-12, 14-15) because Kim disclosed, among other things, the required
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`boost converter. Ex. 1302 at 61-62. The applicant did not dispute the Examiner’s
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`rejection on this ground but instead made a narrowing amendment. Id. at 81-82,
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`86-87; Ex. 1303 at ¶55.
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`C. Multiplexers
`A multiplexer is a circuit with several input signals and a single selectable
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`output signal. As U.S. Patent No. 5,870,340 to Ohsawa explains, “a signal line is
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`selected from the plurality of signal lines, and the selected signal line is electrically
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`connected to the single signal line.” Ex. 1319 [U.S. Patent No. 5,870,340,
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`“Multiplexer” (filed July 8, 1997 and issued February 9, 1999) (“Ohsawa”)] at
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`1:17-20. At the time of the alleged invention, it was well known that multiplexers
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`could be used for data selection in many electronic devices. Ex. 1303 at ¶56.
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`For example, Ohsawa discloses a multiplexer circuit using PMOS
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`transistors. Each input signal is connected to the gate of a PMOS transistor, and
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`the drain of each transistor is connected to a common node. Ex. 1319 at 4:50-5:5,
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`Fig. 4. When an input signal is to be selected, the PMOS transistor associated with
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`that signal turns on, which sends the signal to the common node. Id.; Ex. 1303 at
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`¶57.
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`Such multiplexers have been used to select between multiple power supplies.
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`A two-input multiplexer for selecting between power supplies V1 and V2 is shown
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`in Figure 1 of U.S. Patent No. 6,566,935 to Renous:
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`Renous – Figure 1
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`
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`Ex. 1320 [U.S. Patent No. 6,566,935, “Power Supply Circuit With a Voltage
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`Selector” (filed August 28, 2000 and issued May 20, 2003) (“Renous”)] at Fig. 1.
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`Renous explains that Figure 1 “shows a conventional power supply circuit
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`receiving two supply voltages V1 and V2 on two respective supply lines L1 and
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`L2, and providing a voltage Vdd on an output node S.” Ex. 1320 at 1:14-17; Ex.
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`1303 at ¶58.
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`The multiplexer uses two PMOS transistors (T1 and T2) to implement the
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`selection between the two supply voltages (V1 and V2). A comparator A1
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`determines which voltage supply should be used. The comparator A1 sends one
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`control signal to the gate of transistor T1 and a second control signal (which is an
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`inverted version of the first control signal) to the gate of transistor T2. This will
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`activate one or the other of the transistors and thereby send one of the supply
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`voltages (V1 or V2) to the output node S. Id. at 1:17-25 (“[T]he output of
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`comparator A1 is at a low level when voltage V1 is greater than voltage V2 and at
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`a high level otherwise. The output of comparator A1 is directly connected to the
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`gate of transistor T1, and is connected to the gate of transistor T2 via an inverter
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`I1.”). Ex. 1303 at ¶59.
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`VI. OVERVIEW OF THE ’558 PATENT
`A. The Alleged Problem in the Art
`The ’558 patent describes “techniques for efficiently generating a power
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`supply for a power amplifier and/or other circuits.” Ex. 1301 at 1:30-31. The ’558
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`patent explains that although it is advantageous to operate a wireless device using a
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`low battery voltage to reduce power consumption and extend battery life, a power
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`amplifier sometimes “may need to operate with a PA supply voltage (e.g., 3.2V)
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`that is higher than the battery voltage.” Id. at 3:51-52. The ’558 patent also
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`acknowledges that it was known to use boost converters to generate the necessary
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`higher PA supply voltage. Id. at 3:52-54. But the ’558 patent says using a boost
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`converter to “directly supply the PA supply voltage” may “increase cost and power
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`consumption.” Id. at 3:54-56; Ex. 1303 at ¶60. These alleged problems, however,
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`had already been identified and solved in the prior art before the filing of the ’558
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`patent, as discussed below.
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`B.
`The Alleged Invention of the ’558 Patent
`The challenged claims of the ’558 patent comprise combinations of well-
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`known components in the field: specifically, PAs, envelope amplifiers, switchers,
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`hybrid supply generators (envelope amplifier + switcher), and boost converters.
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`The ’558 patent does not claim to have invented any of these components, all of
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`which were known in the prior art years before the filing date of the ’558 patent, as
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`explained above. Ex. 1303 at ¶61.
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`The ’558 patent purports to provide two alleged improvements to hybrid
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`supply generators: (1) connecting a boost converter to the envelope amplifier; and
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`(2) adding an “offset” current to the switcher’s input current to increase the amount
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`of current generated by the switcher.1 Ex. 1303 at ¶61. As explained in this
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`Petition, eac