Aptiv Services US LLC v. Microchip Technology Inc

1. Case Identification

• Case #: IPR2024-00646
• Patent #: Patent 9,471,074
• Filed: March 8, 2024
• Petitioner(s): Aptiv Services US, LLC
• Patent Owner(s): Microchip Technology, Inc.
• Challenged Claims: 1-18

2. Patent Overview

• Title: Low-Dropout Voltage Regulator
• Brief Description: The ’074 patent describes a low-dropout (LDO) voltage regulator that uses a current feedback mechanism to improve stability. The circuit is designed to sense changes in the output load current and boost the transconductance (gm) of a buffer driver, which purportedly allows the LDO to remain stable across a wider range of external capacitor values.

3. Grounds for Unpatentability

Ground 1: Claims 1-18 are obvious over Al-Shyoukh in view of Ivanov and/or Stanescu

• Prior Art Relied Upon: Al-Shyoukh (a 2007 IEEE journal article), Ivanov (Patent 6,400,207), and Stanescu (Patent 6,710,583).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Al-Shyoukh, which was before the examiner during prosecution, discloses every limitation of the challenged claims except for an “enable/disable function” for the biasing circuit. Al-Shyoukh teaches an LDO with an “impedance-attenuated buffer” and a current feedback mechanism that boosts the buffer driver’s transconductance to achieve a stable, pseudo-one-pole system, mirroring the functionality described in the ’074 patent. Petitioner noted that the enable/disable function was the sole feature added to the claims to secure allowance over Al-Shyoukh. Ivanov was asserted to disclose this exact feature: a disable/enable bias control circuit designed to reduce standby power in applications such as voltage regulators. For claim 11, Stanescu was argued to teach using an operational transconductance amplifier (OTA) as a buffer driver in an LDO.
  • Motivation to Combine: A POSITA would combine Ivanov with Al-Shyoukh to improve power efficiency, a primary concern for both references which are directed to LDOs for battery-powered devices. Ivanov provided a known solution to a known problem (power consumption during standby) that was directly applicable to Al-Shyoukh's circuit. Similarly, a POSITA would have been motivated to use the OTA buffer from Stanescu in Al-Shyoukh's LDO to achieve benefits like lower output impedance and better transient response.
  • Expectation of Success: Petitioner asserted a high expectation of success because Ivanov provided a “ready-to-use circuit” that required only conventional modifications to integrate into Al-Shyoukh's LDO.

Ground 2: Claims 1-18 are obvious over the Rincon-Mora references in view of Ivanov and/or Stanescu

• Prior Art Relied Upon: Rincon-Mora (Patent 6,046,577 and a 1998 IEEE journal paper), Ivanov (Patent 6,400,207), Al-Shyoukh, and Stanescu.
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Rincon-Mora, published years before Al-Shyoukh, discloses a similar LDO architecture featuring a “transient response boost circuit.” This circuit functions as a feedback mechanism to boost the buffer driver’s gm in response to load changes, thereby pushing a parasitic pole to a higher frequency and improving stability over a broad range of capacitors, achieving the same result as the ’074 patent. As with Al-Shyoukh, Rincon-Mora allegedly teaches all claim elements except for the specific “enable/disable function” for reducing standby current. Ivanov supplies this missing element.
  • Motivation to Combine: The motivation to combine Rincon-Mora with Ivanov is identical to that for Ground 1. Both references focused on power-efficient LDOs for portable applications, and adding Ivanov’s power-saving enable/disable feature would have been a logical and obvious improvement to Rincon-Mora's design. The petition also argued for combining Rincon-Mora with Al-Shyoukh’s folded-cascode amplifier architecture or Stanescu’s OTA buffer for predictable performance enhancements.
  • Expectation of Success: Petitioner argued success was expected, as Rincon-Mora’s disclosure of a “start-up circuit” with an “external enabling input” would make integration with Ivanov’s shutdown control circuit straightforward for a POSITA.

4. Key Claim Construction Positions

• Petitioner presented arguments under the Patent Owner’s anticipated claim constructions from a parallel district court proceeding.
• “enable/disable function”: Petitioner argued that even if this term is not treated as a means-plus-function limitation and is construed to cover the corresponding structure of a signal input line (e.g., at node M of Figure 3 of the patent), the combination of Al-Shyoukh or Rincon-Mora with Ivanov still renders the claims obvious. Ivanov’s shutdown control circuit was argued to provide an identical signal for the same purpose.
• “biasing ratio”: Petitioner argued that under either its own interpretation or the Patent Owner’s alternative construction, both Al-Shyoukh and Rincon-Mora disclose a biasing circuit that sets a ratio for the gm-boost of the buffer driver.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §325(d) is inappropriate for Ground 1, even though Al-Shyoukh was previously considered by the PTO.
• The argument relied on the Board’s two-part test from Advanced Bionics. Petitioner contended that (1) the art and arguments are not substantially the same because the combination includes Ivanov, which was never before the examiner, and (2) the examiner materially erred because Ivanov discloses the very limitation that the Patent Owner added to the claims to overcome the rejection based on Al-Shyoukh alone.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-18 of Patent 9,471,074 as unpatentable.