On Semiconductor Corp v. Power Integrations Inc

1. Case Identification

• Case #: Unassigned
• Patent #: 6,414,471
• Filed: November 7, 2017
• Petitioner(s): Semiconductor Components Industries, LLC d/b/a ON Semiconductor
• Patent Owner(s): Power Integrations, Inc.
• Challenged Claims: 1-3, 5-6, 19-21, 23-24

2. Patent Overview

• Title: Switching Power Converter with Digital Feedback
• Brief Description: The ’471 patent discloses a switching power converter that regulates its output voltage using a "digital" feedback scheme. The technology purports to overcome the disadvantages of traditional pulse-width modulation (PWM) by enabling or disabling the power switch based on whether the output voltage is above or below a set threshold, which allows for a faster response and simpler design.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over Barbehenn and Grebene - Claims 19, 20, 23-24

• Prior Art Relied Upon: Barbehenn (Patent 5,914,865) and Grebene (a 1984 textbook titled "Bipolar and MOS Analog Integrated Circuit Design").
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that claim 19, a method claim, is anticipated by Barbehenn under 35 U.S.C. §102. Barbehenn allegedly discloses an AC-DC switching converter with a "bang-bang" architecture that performs all steps of claim 19: receiving a feedback signal with two states (representing output voltage above or below a threshold), providing a duty cycle signal from a 555 timer oscillator, and enabling or disabling energy flow in response to changes between the feedback states. For dependent claims 20, 23, and 24, Petitioner argued obviousness under 35 U.S.C. §103. Barbehenn's "bang-bang" architecture is described as "inherently very fast," meeting the "substantially instantaneously" limitation of claim 20. Grebene, a standard textbook, was introduced to show the internal digital logic of the industry-standard 555 timer used in Barbehenn, confirming the absence of filtering that would prevent instantaneous operation. The halting and restarting of the duty cycle signal (claims 23-24) was allegedly taught by Barbehenn’s description of inhibiting and resuming the 555 timer's oscillation.
  • Motivation to Combine (for §103 grounds): A person of ordinary skill in the art (POSITA) would be motivated to consult Grebene's standard textbook to understand the internal circuitry and confirm the operational characteristics of the "industry standard" 555 timer explicitly disclosed in Barbehenn.
  • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success, as the combination merely involved referencing a standard textbook to confirm the known properties of a standard component used in the primary reference.

Ground 2: Obviousness over Barbehenn (Alternative Embodiment) - Claims 1-3 and 19-21

• Prior Art Relied Upon: Barbehenn (Patent 5,914,865).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground was based on an alternative embodiment explicitly suggested in the text of Barbehenn. Petitioner argued it would have been obvious to implement a circuit where, "instead of using an oscillator's inhibit control line to control oscillation, a logic gate connected to the optoisolator and the oscillator could effectively create the desired bursts of waveform from a continuously running oscillator." In this configuration, the 555 timer runs continuously, and its output (the duty cycle signal) is fed to one input of a logic gate (e.g., an AND gate). The feedback signal from the optocoupler is fed to the other input, and the gate’s output controls the power switch. This arrangement was argued to meet all limitations of the challenged claims, including enabling/disabling energy flow "at any point in a cycle of the duty cycle signal" (claim 21).
  • Motivation to Combine (for §103 grounds): The motivation stemmed directly from Barbehenn's own text, which explicitly suggested this alternative implementation as a way to achieve the same result.
  • Expectation of Success (for §103 grounds): A POSITA would have had a high expectation of success in implementing a circuit design using a standard logic gate that was expressly described in the prior art reference itself.

Ground 3: Obviousness over Krupka - Claims 1-3 and 19-21

• Prior Art Relied Upon: Krupka (Patent 4,413,224).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner asserted that Krupka, on its own, renders the challenged claims obvious. Krupka discloses a complete DC-DC power conversion system that uses a control method analogous to the ’471 patent. It describes a pulse generator (oscillator) that provides a duty cycle signal and a separate voltage comparator that provides a digital feedback signal (logic one or zero) based on whether the output voltage is above or below a reference. An AND gate logically combines the duty cycle signal and the feedback signal, and the output of the gate controls a switching device to enable or disable the flow of energy. Petitioner argued this structure and method directly map to the limitations of the challenged circuit and method claims.
  • Motivation to Combine (for §103 grounds): As a single-reference ground, the motivation was inherent in Krupka's purpose: to provide a complete, efficient system for creating a stabilized voltage output using the very techniques claimed.
  • Expectation of Success (for §103 grounds): Krupka describes a complete and functional circuit, providing a POSITA with a clear blueprint and a high expectation of success in achieving the claimed invention.

• Additional Grounds: Petitioner asserted an additional obviousness challenge (Ground 2 in the petition) for claims 1-2 and 5-6 based on Barbehenn in view of Grebene, relying on a different mapping of the "duty cycle signal" and "control signal" terms based on the internal circuitry of the 555 timer shown in Grebene.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that institution would be appropriate and not barred by discretionary denial under §325(d). The argument centered on the assertion that the prior art presented in the petition was not cumulative of the art considered during the original examination. Petitioner contended that the examiner reviewed prior art with "analog" feedback mechanisms, which the Patent Owner distinguished. In contrast, the petition's primary references (Barbehenn and Krupka) disclose "digital" or "bang-bang" feedback schemes that are substantially similar to the control method of the ’471 patent and were never before the examiner.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-3, 5-6, 19-21, and 23-24 as unpatentable.