PTAB

IPR2025-01452

SK hynix Inc. v. Advanced Memory Technologies, LLC

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1. Case Identification

2. Patent Overview

  • Title: Booster Circuit
  • Brief Description: The ’557 patent discloses a two-row booster circuit, also known as a charge pump, designed to generate a voltage higher than the supply voltage. The circuit uses an analog comparison circuit to compare the output potentials of the two boosting rows and apply a resulting well bias potential to a deep N-well of the circuit's switching elements to improve efficiency and reduce the body effect.

3. Grounds for Unpatentability

Ground 1: Anticipation by Fukushima - Claims 1, 3, 5, 10-12, and 14 are anticipated by Fukushima under 35 U.S.C. §102.

  • Prior Art Relied Upon: Fukushima (Patent 6,107,864).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Fukushima teaches a two-row charge pump circuit that meets every limitation of the challenged claims. Fukushima’s circuit comprises multiple boosting cell stages, with each stage containing a first boosting cell row (top charge pumps) and a second boosting cell row (bottom charge pumps). These cells are built with a first well region (an N-well) on a substrate and a second well region (a P-well) inside the first. Critically, Petitioner asserted that Fukushima’s PMOS transistors (PT1n, PT2n) in each stage function as an analog comparison circuit that compares the output potentials of the two rows. This circuit generates a well bias potential and applies it directly to the N-well (the claimed "first well region") of the switching elements to minimize the substrate bias effect. For claim 3, Petitioner contended that Fukushima's comparison circuit outputs the higher of the two potentials as the well bias. For claims 10-12, Petitioner argued Fukushima discloses switching elements and comparison circuits that share a common N-well, as recited.

Ground 2: Anticipation by Meng - Claims 1-3, 9, 10, and 14 are anticipated by Meng under §102.

  • Prior Art Relied Upon: Meng (Patent 6,501,325).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Meng discloses a two-row, cross-coupled high-voltage charge pump that anticipates the challenged claims. Meng’s circuit includes boosting cells arranged in two rows, with transistors fabricated in a P-well (second well region) within a deep N-well (first well region). Petitioner identified Meng's diodes (208i, 210i) or cross-coupled transistors as the claimed "analog comparison circuit." This circuit compares the output potentials of the two boosting rows at each stage and outputs a well bias potential. Petitioner emphasized that Meng explicitly teaches this bias potential is applied to node 204i, which "may be the deep N-well region" of the switching transistors. This directly maps to the core limitation of applying the bias potential to the first well region. Petitioner further argued that Meng’s comparison circuit outputs the higher potential (claim 3) and that its switching elements share a common deep N-well (claim 10).

Ground 3: Obviousness over Meng and Park - Claims 1-4, 6-12, and 14 are obvious over Meng in view of Park under §103.

  • Prior Art Relied Upon: Meng (Patent 6,501,325) and Park (Patent 6,914,791).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted this ground as an alternative, arguing that if Meng is found not to explicitly teach applying the bias potential from the comparison circuit to the first well region (deep N-well), Park supplies this teaching. Meng discloses the complete two-row booster circuit with an analog comparison circuit. Park teaches a multi-stage charge pump that uses an auxiliary device to couple a boosted potential to both the P-well and the deep N-well of the charge transfer device, expressly for the purpose of reducing the body effect. The combination, therefore, arrives at the claimed invention.
    • Motivation to Combine: A POSITA would combine Meng with Park to improve the performance of Meng’s circuit. Meng describes the objective of reducing the body effect and minimizing threshold voltage through well biasing. Park provides a specific, effective solution for achieving this same objective by applying a bias potential to the deep N-well. Petitioner argued a POSITA would have been motivated to incorporate Park’s explicit body-effect-reduction technique into Meng’s established two-row architecture to achieve the improved efficiency and reduced die area sought by both references.
    • Expectation of Success: Petitioner contended that a POSITA would have a reasonable expectation of success because both Meng and Park operate in the same field of charge pump design and use conventional, well-understood circuit components. Combining Park's biasing scheme with Meng's circuit would be a straightforward implementation yielding the predictable result of reduced body effect.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-12 and 14 of the ’557 patent as unpatentable.