PTAB

IPR2021-00002

Impinj Inc v. NXP USA Inc

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: High-Dynamic Range Low Ripple Voltage Multiplier
  • Brief Description: The ’951 patent relates to a multi-stage voltage multiplier, specifically a charge pump circuit, that utilizes a feedback loop. The system features an input level regulator that controls the voltage at the input of the first multiplier stage based on a feedback signal derived from the multiplier’s output, enabling regulation over a continuous range of voltage levels.

3. Grounds for Unpatentability

Ground 1: Claims 1-7, 9-13, and 15-19 are obvious over Kleveland in view of Zhang.

  • Prior Art Relied Upon: Kleveland (Patent 6,486,728) and Zhang (Patent 6,618,296).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kleveland discloses a multi-stage charge pump (voltage multiplier) with a feedback circuit that controls the output voltage by adjusting the frequency of a clock-generating oscillator. However, Kleveland applies a fixed supply voltage to its first stage. Petitioner asserted that Zhang discloses the missing element: a charge pump circuit featuring an input level regulator (a PMOS transistor) controlled by a feedback signal to regulate the voltage supplied to the pump. The petition contended that combining these teachings renders claim 1 obvious by using Kleveland's multi-stage pump and feedback circuit architecture, but modifying it to use that feedback signal to control Zhang's input level regulator. This combination would allegedly result in a system where the feedback signal regulates the output of the input level regulator over a continuous range, as claimed.
    • Prior Art Mapping (Dependent Claims): Petitioner argued that Kleveland’s teachings also render the dependent claims obvious. For instance, Kleveland's oscillator (30) meets the limitation of a "generator of a clock" (claims 2-3). Its feedback circuit, comprising a differential amplifier (32) and a resistor network (R1, R2), was argued to disclose the claimed operational amplifier (claims 5, 11) and switched-divider (claims 4, 10, 18), as Kleveland explicitly suggests implementing the resistors as switched capacitors. The identical structure of Kleveland's charge pump stages was argued to meet claims 7 and 13.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Zhang's input level regulator with Kleveland's multi-stage pump to gain an additional, independent mechanism for controlling the output voltage. Petitioner asserted this modification would provide more precise control, reduce output noise by stabilizing the input voltage, and prevent voltage surges, all of which were known design goals. The feedback structures in both references were argued to be virtually identical, making the integration straightforward.
    • Expectation of Success: Petitioner asserted a POSITA would have a reasonable expectation of success because the combination involved applying a known component (Zhang's input regulator) to a known system (Kleveland's multi-stage pump) to achieve the predictable result of improved voltage control.

Ground 2: Claims 1-7, 9-13, and 16-19 are obvious over Zhang in view of Li.

  • Prior Art Relied Upon: Zhang (Patent 6,618,296) and Li (Patent 6,891,764).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground presented an alternative combination to arrive at the claimed invention. Petitioner argued that Zhang teaches the core concept of an input level regulator controlled by a feedback loop but does not detail a multi-stage pump. Li, conversely, was said to disclose a sophisticated, four-stage charge pump with multiple regulated clocks but lacks an input level regulator. The core argument was that a POSITA would find it obvious to replace the generic charge pump in Zhang with the more advanced multi-stage pump disclosed in Li. In this combination, the output of Li's multi-stage pump would be fed into Zhang’s feedback circuit, and the resulting feedback signal from Zhang would control the input level regulator supplying voltage to Li's pump, thereby meeting the limitations of claim 1.
    • Prior Art Mapping (Dependent Claims): Petitioner asserted that Li’s disclosure satisfies the limitations of the dependent claims. Li’s clock generator (430) and oscillator (420) are coupled to the feedback circuit, affecting the clock magnitude as required by claims 2-3 and 17. Li’s disclosure of identical stages met claims 7 and 13. Furthermore, Petitioner argued it would have been obvious to implement Zhang’s static resistor divider as a switched divider to gain dynamic control, thus rendering claims 4, 10, and 18 obvious. Finally, the diode-connected transistors in Li's pump stages (e.g., transistor 808) were argued to meet the "diode" limitation of claim 19.
    • Motivation to Combine: The primary motivation was to improve the performance of Zhang's basic circuit. A POSITA would recognize that substituting Li's multi-stage pump would allow for a significantly greater voltage increase compared to Zhang's simple voltage doubler, a common requirement for such circuits. Incorporating Li’s design would also provide more granular control over the output voltage through its use of multiple, regulated clock phases.
    • Expectation of Success: Petitioner contended that success would be expected because the combination involved substituting one known functional block (a basic charge pump) with a more capable, well-understood alternative (a multi-stage charge pump) to predictably enhance the circuit's voltage multiplication capability.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-7, 9-13, and 15-19 of the ’951 patent as unpatentable.