Intel Corp v. R2 Semiconductor Inc

1. Case Identification

• Case #: IPR2017-00706
• Patent #: 8,233,250
• Filed: January 20, 2017
• Petitioner(s): Intel Corporation
• Patent Owner(s): R2 Semiconductor, Inc.
• Challenged Claims: 10-12, 23-26, 28, and 31

2. Patent Overview

• Title: Voltage Spike Protection Circuitry and Method
• Brief Description: The ’250 patent discloses voltage spike protection circuits, commonly known as "snubber circuits," for use in switching voltage regulators. The technology involves using a "dissipative element" (resistor) and a "charge-storage circuit" (capacitor) to suppress voltage spikes caused by parasitic inductances during high-speed switching operations.

3. Grounds for Unpatentability

Ground 1: Obviousness over Hibino and McMurray - Claims 10-12 and 23-26 are obvious over Hibino in view of McMurray.

• Prior Art Relied Upon: Hibino (WO 2009/113298) and McMurray (a 1972 article titled “Optimum Snubbers for Power Semiconductors”).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Hibino taught all structural elements of the claimed voltage regulator, including a snubber circuit with a resistor and capacitor, segmented switching elements, and the physical arrangement of these components. However, Hibino did not explicitly disclose the specific method for calculating the resistor’s value. Petitioner asserted that McMurray, a classic reference on snubber circuit design that was not before the examiner during prosecution, remedied this deficiency. McMurray taught the precise formula for determining the optimal resistance value based on the circuit’s characteristic impedance (calculated from the square root of the circuit’s lumped-element inductance and capacitance). This formula was the very feature added by the applicant during prosecution to overcome a prior art rejection and secure the patent.
  • Motivation to Combine: A person of ordinary skill in the art (POSITA), when implementing the snubber circuit disclosed in Hibino, would have been motivated to consult a well-known, foundational reference like McMurray to determine the optimal component values. Hibino’s stated goal was to reduce surge voltage, and McMurray provided the standard, time-tested engineering method for selecting a resistor value to achieve that exact goal by minimizing peak voltage and damping ringing.
  • Expectation of Success: McMurray’s teachings were presented as generally applicable design principles for any snubber circuit. A POSITA would have had a high expectation of success in applying McMurray’s standard mathematical formulas to the conventional snubber circuit in Hibino to predictably and reliably suppress voltage spikes.

Ground 2: Obviousness over Hibino - Claims 28 and 31 are obvious over Hibino.

• Prior Art Relied Upon: Hibino (WO 2009/113298).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground asserted that Hibino alone rendered the claims directed to the physical layout of segmented circuits obvious. Petitioner argued Hibino disclosed a voltage regulator with multiple switching block segments (series circuits 170) and corresponding charge-storage circuit segments (capacitors 301 in snubber circuits 300). The key limitation was that each charge-storage segment is "physically closer to the switching block segment it protects than any other switching block segment." Hibino explicitly taught arranging the snubber circuit "as close as possible" to the switching device it protects to minimize the parasitic inductance of the connecting wires, which in turn reduces surge voltage.
  • Motivation to Combine: The motivation was inherent in Hibino's own disclosure. A POSITA would follow Hibino’s direct instruction to place snubbers close to their corresponding switches to achieve the stated objective of reducing surge voltage. Furthermore, Hibino discussed thermal management, noting that heat-generating power devices should not be placed too close together. This provided a second, independent reason for a POSITA to place each snubber next to its designated switching segment rather than clustering the switching segments together.
  • Expectation of Success: Following Hibino's explicit teachings on component placement to minimize inductance and manage heat would predictably result in the claimed physical arrangement and its associated functional benefits.

4. Key Claim Construction Positions

• "dissipative element": Petitioner dedicated significant argument to this term, contending it was central to the invention.
  • Petitioner's primary position was that "dissipative element" should be construed as a means-plus-function term under 35 U.S.C. §112(f). The claimed function was "dissipates energy," and the only corresponding structure disclosed in the ’250 patent specification was a "resistor."
  • In the alternative, if the term was not found to be means-plus-function, Petitioner argued it should still be construed as a "resistor" under the broadest reasonable interpretation standard. This construction was based on the specification consistently and exclusively using the resistor symbol (Rsp) and zig-zag line diagram to depict the "dissipative element."

5. Relief Requested

• Petitioner requested the institution of an inter partes review and cancellation of claims 10-12, 23-26, 28, and 31 of Patent 8,233,250 as unpatentable.