PTAB

IPR2017-01490

Unified Patents Inc v. Red Rock Analytics LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Calibration of I-Q Balance in Transceivers
  • Brief Description: The ’313 patent relates to a system for calibrating gain imbalance between the in-phase (I) and quadrature (Q) channels in a digital communications transceiver. The disclosed method uses a loopback signal path to inject a calibration signal from the transmit output to the receive input, enabling independent calibration of the entire transmit and receive chains by sequentially adjusting gains for each chain while holding the other constant.

3. Grounds for Unpatentability

The petition presents two primary grounds, anticipation under 35 U.S.C. §102 and obviousness under 35 U.S.C. §103, both based on the same single prior art reference.

Ground 1: Claims are anticipated by Warner

  • Prior Art Relied Upon: Warner (Patent 6,940,916).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Warner discloses every limitation of the challenged claims, particularly representative claim 1. Warner’s transceiver system, which includes an Analog Quadrature Modulator/Demodulator (AQMD) and digital pre-compensation processors (QMCSP/QDCSP), was asserted to meet the claimed system architecture. Petitioner mapped Warner’s coupler (106) to the claimed "signal path for injecting a calibration RF signal" from the transmit output to the receive input, which enables calibration of the entire signal path.
    • Petitioner further argued that Warner teaches "independently" calibrating the transmit and receive chains by disclosing the use of separate, independent time-domain equations (Equation 2 for the transmit chain, Equation 9 for the receive chain) to calculate impairment correction coefficients for each.
    • For the critical limitation requiring a two-step calibration cycle—determining transmitter I-Q gain settings while holding receive settings constant, and vice versa—Petitioner contended this is inherently disclosed. It argued that a person of ordinary skill in the art (POSITA), when implementing Warner's method for solving its Equation 15 (which has more unknown parameters than can be observed simultaneously), would be required to use an iterative approach, calibrating one set of parameters while holding the other constant, thereby anticipating the claimed cycle.

Ground 2: Claims are obvious over Warner

  • Prior Art Relied Upon: Warner (Patent 6,940,916).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground relied on the same mapping of Warner’s transceiver system, calibration path, and independent calibration methods as asserted for the anticipation ground.
    • Motivation to Combine/Modify: As an alternative to anticipation, Petitioner argued that even if Warner does not explicitly disclose the sequential, iterative calibration process, it would have been an obvious modification for a POSITA. The motivation for adopting this iterative approach (calibrating one chain while holding the other's gains constant) would be to simplify the calibration of the complex system described by Warner’s equations. This one-at-a-time method was presented as a common-sense, predictable design choice that offers advantages of quicker and more minimal processing compared to solving for all variables simultaneously.
    • Expectation of Success: Petitioner asserted a POSITA would have a high expectation of success in applying an iterative calibration technique to Warner's system. This is because such techniques were well-known and would predictably lead to the desired result of minimizing I-Q gain imbalance. Petitioner supported this by noting the ’313 patent’s own admission that the order of calibration is "immaterial," suggesting it was a simple and obvious design choice with a predictable outcome.

4. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1-7, 15, 16, 21, 22, 30, 32, 37-44, 52, 53, 58, 59, 67, 69, and 74 of the ’313 patent as unpatentable.