PTAB

IPR2025-01452

SK Hynix Inc v. Advanced Memory Technologies LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Booster Circuit
  • Brief Description: The ’557 patent discloses a two-row booster circuit (charge pump) designed to suppress current consumption and minimize layout area. The circuit uses an analog comparison circuit to compare output potentials from each boosting cell row and apply an appropriate well bias potential to a deep N-well region of the switching elements to reduce the body effect.

3. Grounds for Unpatentability

Ground 1: Anticipation over 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 booster stages, with each stage containing boosting cells arranged in two rows. These cells include switching elements (NMOS transistors) fabricated within a first well region (deep N-well) and a second well region (P-well). Fukushima explicitly disclosed an analog comparison circuit (comprising PMOS transistors) that compares the output potentials of the two rows at each stage. Based on this comparison, it generates and applies a well bias potential to the deep N-well of the switching elements, thereby preventing forward biasing and minimizing substrate bias effects. Petitioner asserted that Fukushima's comparison circuit selects the higher of the two output potentials to use as the well bias, directly teaching the limitation of claim 3.
    • Key Aspects: The argument directly maps Fukushima’s structure, including the shared deep N-well for multiple switching elements (claims 10-12) and the connection between the P-well and the switching element’s source terminal (claim 5), to the corresponding claim limitations.

Ground 2: Anticipation over Meng - Claims 1-3, 9, 10, and 14 are anticipated by Meng under 35 U.S.C. §102.

  • Prior Art Relied Upon: Meng (Patent 6,501,325).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner contended that Meng, which the Examiner considered during prosecution, fully anticipates the claims. Meng discloses a high-efficiency, two-row, cross-coupled charge pump. Its boosting cells utilize transistors implemented as deep N-well NMOS transistors, which inherently include a first well region (deep N-well) on a substrate and a second well region (P-well) within the first. Meng’s circuit includes analog comparison circuits (comprising diodes) that compare the output potentials of the first and second boosting cell rows. Petitioner argued that the Examiner incorrectly concluded that Meng did not apply the resulting well bias potential to the deep N-well (first well region). The petition asserted that Meng explicitly states the output of the comparison circuit (node 204i) "may be the deep N-well region" of the switching transistors in both rows, thereby teaching the key limitation of claim 1[e]. The circuit's diode configuration was argued to output the higher of the two potentials, meeting claim 3.

Ground 3: Obviousness over Meng and Park - Claims 1-4, 6-12, and 14 are obvious over Meng in view of Park under 35 U.S.C. §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 argued that, to the extent Meng is found not to teach the application of the well bias potential to the first well region (the deep N-well), Park explicitly supplies this teaching. Meng provides the fundamental two-row booster circuit with an analog comparison circuit that generates a well bias potential. Park addresses the known problem of the body effect in charge pumps by teaching an auxiliary device that couples a boosted voltage to both the P-well and the deep N-well of the charge transfer transistor. Modifying Meng’s circuit to apply the bias potential from its comparison circuit to the deep N-well, as taught by Park, would have been obvious. This combination also allegedly renders claim 4 obvious, as Meng’s comparison circuit using cross-coupled NMOS transistors outputs the lower of the two potentials.
    • Motivation to Combine: A POSITA would combine Meng and Park to achieve the shared, stated goals of improving charge pump efficiency and reducing the body effect. Meng explicitly teaches that combining P-well and deep N-well biasing reduces body effect and threshold voltage. Park provides a specific, well-defined circuit solution for applying bias to the deep N-well to achieve this exact result. A POSITA would have been motivated to incorporate Park’s solution into Meng’s architecture to realize these known benefits.
    • Expectation of Success: A POSITA would have a reasonable expectation of success because both references operate in the same field, use conventional and well-understood circuit components, and address the same technical problems. Implementing Park’s straightforward biasing connection in Meng’s circuit would yield 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.