PTAB

IPR2015-00593

MaxLinear Inc v. Cresta Technology Corp

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1. Case Identification

2. Patent Overview

  • Title: Television Receiver for Digital and Analog Television Signals
  • Brief Description: The ’792 patent discloses a television receiver capable of processing both digital and analog television signals. The receiver architecture includes a frequency conversion circuit to generate an intermediate frequency (IF) signal, an analog-to-digital converter (ADC), a digital signal processor (DSP) that applies selectable filters based on the signal format, and a signal output circuit to provide various output formats.

3. Grounds for Unpatentability

Ground 1: Obviousness over Thomson in view of Harris - Claims 1, 2, 4, 10, 11, and 26 are obvious over Thomson in view of Harris.

  • Prior Art Relied Upon: Thomson (European Patent Application No. EP 0696854) and Harris (DSP Applications Magazine, Sep. 1992).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Thomson disclosed a multi-standard television tuner capable of receiving analog and digital signals, including a frequency conversion circuit, an ADC, and an adaptive bandpass filter that selects a filter function based on the television standard (analog or digital). Petitioner contended that while Thomson’s adaptive filter performs signal processing, a POSITA would look to Harris to implement this function using a more modern digital signal processor. Harris taught replacing analog second IF processor functions with a high-performance DSP chain, including a reconfigurable finite impulse response (FIR) filter that could be programmed to implement a bank of different filters. The combination of Thomson's overall receiver architecture with Harris's DSP-based adaptive FIR filter allegedly rendered the limitations of claim 1 obvious.
    • Motivation to Combine: A POSITA would combine Thomson and Harris because they addressed similar problems of tuning an adaptive filter based on the system's operational mode. Petitioner asserted a POSITA would be motivated to incorporate the reconfigurable FIR filters of Harris into Thomson's adaptive filter to save cost and board space by using a single reconfigurable filter instead of a bank of filters. Harris further motivated this combination by teaching that declining technology costs made DSPs a desirable alternative for a wide range of communication problems, including digital television.
    • Expectation of Success: The combination involved implementing a known type of digital filter (Harris's FIR filter) within a known receiver architecture (Thomson's) to perform a predictable function (adaptive filtering), giving a POSITA a reasonable expectation of success.

Ground 2: Obviousness over Thomson and Harris in further view of Gunter - Claim 3 is obvious over Thomson, Harris, and Gunter.

  • Prior Art Relied Upon: Thomson, Harris, and Gunter (Patent 4,782,385).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claim 3, which requires the television receiver to be formed as a monolithic integrated circuit. Petitioner argued that Gunter explicitly disclosed that circuits for frequency conversion of television signals could be implemented using "monolithic integrated circuit techniques."
    • Motivation to Combine: A POSITA would have been motivated to implement the receiver of Thomson and Harris on a single monolithic IC as taught by Gunter for well-known reasons, including reducing size, saving printed circuit board space, lowering manufacturing costs, and reducing parasitic effects. Petitioner asserted that the desire for integration was a powerful and well-established trend in electronics design, echoing Moore's Law.

Ground 3: Obviousness over Thomson and Harris in further view of Cirrus Logic - Claims 5 and 6 are obvious over Thomson, Harris, and Cirrus Logic.

  • Prior Art Relied Upon: Thomson, Harris, and Cirrus Logic (various product bulletins and data sheets).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground targeted claims 5 and 6, which add limitations for first and second decoder circuits for processing video and audio baseband signals according to analog television formats (e.g., PAL/SECAM/NTSC). Petitioner pointed to Cirrus Logic, which described audio/video encoder/decoder (CODEC) chips, including a specific NTSC/PAL video decoder that outputs baseband video signals and an audio CODEC that outputs baseband audio.
    • Motivation to Combine: Petitioner argued that a POSITA building the receiver of Thomson and Harris would have needed to decode the processed signals into standard baseband formats for use by display and audio devices. It would have been a simple and obvious design choice to incorporate known, commercially available decoder circuits like those from Cirrus Logic to perform this standard function. Cirrus Logic's compatibility with both analog and digital signals made it a suitable choice for the multi-standard receiver.

  • Additional Grounds: Petitioner asserted additional obviousness challenges, including combinations of Thomson and Harris with:

    • Kerth to teach differential output signals (Ground 4, claims 7 and 12).
    • Oku and Kerth to teach specific configurations of digital-to-analog converters and driver circuits (Ground 5, claims 13-17).
    • Kerth and Cirrus Logic to teach MPEG decoding for digital signals (Ground 6, claims 8 and 9).
    • Balaban to teach an automatic format/standard selection circuit (Ground 7, claims 26 and 27).

4. Key Claim Construction Positions

  • Petitioner argued for a construction of the term "signal processor" as a "digital module that processes signals in the digital domain," such as a programmable digital signal processor (DSP). This construction was critical to its primary ground, as it supported the argument that Thomson's adaptive filter was not itself a "signal processor" under this construction, thereby necessitating the combination with Harris's explicit DSP teachings to meet the claim limitation.

5. Arguments Regarding Discretionary Denial

  • Petitioner acknowledged a parallel IPR proceeding (IPR2014-00809) filed by another party against the same patent, in which the Board had already instituted review. Petitioner requested institution of the present petition, arguing that the prior proceeding could be terminated due to settlement at any time. To avoid a scenario where the patentability of the claims was not fully adjudicated, Petitioner requested that its petition be instituted but potentially held in abeyance pending the outcome of the earlier IPR.

6. Relief Requested

  • Petitioner requests institution of inter partes review and cancellation of claims 1-17, 26, and 27 of the ’792 patent as unpatentable.