Unified Patents LLC v. Arigna Technology Ltd

1. Case Identification

• Case #: IPR2022-00285
• Patent #: 7,049,850
• Filed: December 9, 2021
• Petitioner(s): Unified Patents, LLC
• Patent Owner(s): Arigna Technology Limited
• Challenged Claims: 7

2. Patent Overview

• Title: Semiconductor Device
• Brief Description: The ’850 patent relates to a high voltage integrated circuit (HVIC) for driving power devices, such as integrated gate bipolar transistors (IGBTs), connected in series to form a half-bridge power device. The technology aims to prevent the "shoot-through" phenomenon, where high-side and low-side switching devices are turned on simultaneously, by monitoring a voltage considered substantially equal to the potential between the switching devices.

3. Grounds for Unpatentability

Ground 1: Obviousness of Claim 7 over Majumdar in view of Cowles

• Prior Art Relied Upon: Majumdar (Patent 6,452,365) and Cowles (Patent 6,545,510).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Majumdar, which was not considered during prosecution, discloses a power converter with an HVIC that teaches nearly all limitations of claim 7. Majumdar describes a semiconductor device with first and second power switching elements connected in series between high and low power potentials. It further discloses a "high potential part" including a control part (driving circuit 3a, switching elements 16, 23, buffer 22) and a "reverse level shift part" (switching element 27, etc.) that shifts a signal from the high potential part to a low side logic circuit. The central argument focused on the "voltage detecting device" limitation, which was the basis for allowance over the prior art of record (Okamoto). Petitioner contended that "buffer 15" in Majumdar's high potential part performs the function of the claimed voltage detecting device, as it is positioned to receive a potential from the output of the reverse level shift part and supply a logic value to the control part.
  • Motivation to Combine: While Majumdar describes a buffer 15, it does not explicitly state that the buffer detects a voltage. Cowles was cited to show that it was well-known in the art to configure a buffer as a voltage detector to determine if an input voltage is above or below a threshold and output a corresponding logic signal. Petitioner asserted a Person of Ordinary Skill in the Art (POSITA) would combine the teachings by modifying Majumdar’s buffer 15 to function as a voltage detector as taught by Cowles. This modification would be a simple application of a known technique to improve a similar device, yielding the predictable result of more accurately controlling the high-side switching element based on a detected voltage level. This would ensure the drive circuit receives the required signal to operate as intended, promoting operational accuracy.
  • Expectation of Success: A POSITA would have a reasonable expectation of success in this combination because Cowles provides clear teachings on how to configure a buffer to detect a voltage against a reference threshold. Applying this known technique to Majumdar's existing buffer circuit was presented as a straightforward modification that would predictably achieve the desired voltage detection and control function.

4. Key Claim Construction Positions

• Petitioner noted that in parallel district court litigation, the parties agreed to several constructions for terms in claim 7, which Petitioner applied in its analysis. Key agreed-upon constructions included:
  • "low side": construed as "outside of high potential part"
  • "to supply a logic value...for said control part": construed as "to supply a logic value...to said control part"
• Petitioner asserted that other terms should be construed according to their plain and ordinary meaning.

5. Arguments Regarding Discretionary Denial

• Arguments Against §325(d) Denial: Petitioner argued that discretionary denial would be inappropriate because the primary references, Majumdar and Cowles, were not cited or considered during the original prosecution of the ’850 patent. Furthermore, Petitioner contended the asserted combination is not cumulative to the art considered by the examiner (Okamoto). The examiner allowed claim 7 specifically because Okamoto allegedly lacked "a voltage detecting device provided in said high potential part," a feature Petitioner argued is expressly taught by the combination of Majumdar and Cowles.
• Arguments Against Discretionary Denial under Fintiv: Petitioner argued that the Fintiv factors weigh strongly in favor of institution. Key arguments included:
  • Petitioner is not a defendant, real party-in-interest, or in privity with any party in the parallel district court litigations involving the ’850 patent.
  • The parallel litigations were in an early stage with minimal investment, and any scheduled trial dates were speculative and subject to change.
  • There is no overlap in issues with the district court proceedings, as Petitioner is not a party and has no knowledge of the invalidity contentions in those cases.
  • The merits of the petition are exceptionally strong, as the asserted prior art addresses the specific limitation that was the basis for the patent's allowance.

6. Relief Requested

• Petitioner requests that the Board order an inter partes review trial for claim 7 and cancel claim 7 of the ’850 patent as unpatentable.