Sony Group Corporation v. Greenthread, LLC

Case Overview and Background

This inter partes review (IPR) was part of a coordinated, multi-front defense by major technology companies against a widespread patent assertion campaign by Greenthread, LLC, a Texas-based patent assertion entity (PAE). Greenthread, which was formed in 2004 and is backed by litigation funding, holds a portfolio of semiconductor patents invented by its founder, G.R. Mohan Rao. It has launched litigation against numerous industry heavyweights, including Intel, Dell, Samsung, and ON Semiconductor. This specific IPR was filed by Sony Group Corporation in response to being named a defendant, alongside Intel and Dell, in a patent infringement suit in the U.S. District Court for the Western District of Texas (Case 6:22-cv-00105), a venue known for a high volume of patent litigation.

The dispute centers on foundational semiconductor manufacturing technology. The patent at issue, U.S. Patent No. 11,316,014, is titled "Semiconductor device with graded dopant regions and method of manufacture thereof" and generally claims methods for creating a semiconductor device with a precisely controlled, gradually varying concentration of impurities (dopants) near the boundary of a transistor's channel region to enhance performance. Greenthread alleged that a vast array of Sony products, likely including those containing image sensors, system-on-chip (SoC) components, and other processors used in its consumer electronics like the PlayStation, infringed this and other related patents. The IPR was a strategic move by Sony to challenge the validity of the '014 patent at the Patent Trial and Appeal Board (PTAB), a common tactic for defendants to pause expensive district court litigation and potentially invalidate the asserted patents.

The case is notable for demonstrating the strategic interplay between district court litigation and PTAB proceedings in the context of a large-scale PAE campaign targeting the core products of the semiconductor industry. Multiple defendants in Greenthread's campaign, including Cirrus Logic, ON Semiconductor, and Monolithic Power Systems, filed their own IPRs, creating a unified front against the asserted patent portfolio. This IPR, however, had a short lifespan. Filed on December 12, 2022, it was terminated just over five months later on May 18, 2023, before the PTAB issued an institution decision. While the official docket does not specify the reason, such an early termination is most commonly the result of a settlement between the parties, which would have simultaneously resolved the parallel district court litigation between Sony and Greenthread. The termination of this IPR before a decision on the merits highlights the significant pressure such validity challenges can place on patent owners, often leading to out-of-court resolutions.

Here are the key legal developments and the outcome of the patent dispute between Sony Group Corporation and Greenthread, LLC, concerning U.S. Patent No. 11,316,014.

Executive Summary

The dispute between Sony Group Corporation ("Sony") and Greenthread, LLC ("Greenthread") originated from a broader patent assertion campaign by Greenthread targeting multiple technology companies. Sony was implicated in a district court lawsuit in the Western District of Texas. In response, Sony filed an Inter Partes Review (IPR) petition, IPR2023-00325, challenging the validity of Greenthread's U.S. Patent No. 11,316,014. The conflict was short-lived; the parties reached a settlement approximately five months after the IPR was filed. This led to a joint request to terminate the IPR, which the Patent Trial and Appeal Board (PTAB) granted on May 18, 2023, officially ending the proceeding before an institution decision was made. Subsequently, Sony was dismissed from the district court case.

Chronological Developments

Parallel District Court Litigation

• 2022-04-29: Filing of Amended Complaint Implicating Sony
  Greenthread, LLC, a Texas-based patent assertion entity, was engaged in multi-front litigation over a family of semiconductor patents. In the case of Greenthread, LLC v. Dell Inc., et al., filed in the U.S. District Court for the Western District of Texas (Case No. 6:22-cv-00105), Greenthread's First Amended Complaint accused Dell's products of infringement. The complaint specified that some of these products, referred to as "Dell-Sony Accused Products," contained components supplied by various Sony entities. While Sony was not initially a named defendant, this pleading laid the groundwork for its involvement.

• Late 2022 / Early 2023: Sony Entities Formally Added
  Sony Group Corporation and several of its subsidiaries were formally brought into the Western District of Texas lawsuit as defendants. This action directly exposed Sony to infringement claims involving the '014 patent, alongside other patents from the same family.

Inter Partes Review (IPR) Proceeding

• 2022-12-12: Sony Files IPR Petition
  In response to the district court litigation, Sony Group Corporation filed petition IPR2023-00325 with the PTAB, challenging the validity of U.S. Patent No. 11,316,014. This was part of a broader defensive strategy by Sony, which also filed other IPRs against different Greenthread patents on the same day and shortly after (including IPR2023-00324, IPR2023-00375, and IPR2023-00376). These petitions argued that the claims of the Greenthread patents were invalid based on prior art.

Settlement and Termination

• c. May 2023: Sony and Greenthread Reach a Settlement
  Prior to the PTAB's deadline for deciding whether to institute a trial, Sony and Greenthread entered into a confidential settlement agreement. This agreement resolved the disputes between them, encompassing both the district court litigation and the pending IPRs.

• 2023-05-18: IPR Terminated Due to Settlement
  Following the settlement, the parties filed a joint motion to terminate the IPR proceedings. The PTAB granted this motion on May 18, 2023, officially terminating IPR2023-00325. The termination order applied to a batch of related IPRs Sony had filed against Greenthread. The termination occurred before the Board made a decision on the merits of Sony's invalidity contentions.

• Post-Settlement: Dismissal from District Court
  As a term of the settlement, Greenthread moved to dismiss its claims against the Sony defendants from the Western District of Texas lawsuit. The termination of the IPR was directly linked to the resolution of the underlying district court case.

Final Outcome

The patent dispute between Sony and Greenthread was resolved through a settlement in May 2023. This settlement led to the pre-institution termination of IPR2023-00325 and the dismissal of Sony from the parallel district court litigation in the Western District of Texas. The terms of the settlement were confidential. Consequently, there were no substantive rulings on claim construction, infringement, or the validity of U.S. Patent No. 11,316,014 in either the PTAB or the district court with respect to Sony.

Based on available filings, counsel for the petitioner, Sony Group Corporation, were attorneys from the law firm Perkins Coie LLP. While the petition for IPR2023-00325 is not directly available, a Certificate of Service filed in a related proceeding against the same patent owner lists the following attorneys as counsel for the petitioner in that matter. This team is understood to have represented Sony in IPR2023-00325.

Here are the identified counsel of record for the plaintiff:

Lead Counsel

• Name: Bing Ai, Ph.D.

  • Firm: Perkins Coie LLP (San Diego)
  • Note: A partner with over 25 years of experience, Dr. Ai has been lead or backup counsel in over 140 PTAB proceedings and specializes in technologies including semiconductors and electronics.

• Name: John P. Schnurer

  • Firm: Formerly Perkins Coie LLP (San Diego); moved to Foley & Lardner LLP in April 2025.
  • Note: An experienced trial lawyer with a background in electrical engineering, he has litigated over 40 Section 337 investigations before the ITC and has extensive experience in inter partes reviews.

• Name: Miguel Bombach

  • Firm: Formerly Perkins Coie LLP (San Diego); moved to Foley & Lardner LLP in April 2025.
  • Note: A trial lawyer with experience in federal courts and before the PTAB, he focuses on technologies such as semiconductor devices, wireless systems, and computer science.

Of Counsel

• Name: John D. Esterhay
  • Firm: Perkins Coie LLP (San Diego)
  • Note: A partner whose practice focuses on patent, trade secret, and other complex commercial litigation involving advanced technical issues.

Other Attorneys

The following attorneys were also listed on the certificate of service, likely serving in associate or supporting roles. Specific roles and extensive litigation histories are not as publicly available.

• Name: Brianna Kadjo

  • Firm: Perkins Coie LLP (San Diego)
  • Note: Her specific role and experience are not detailed in the available public records.

• Name: Runkun Jiang

  • Firm: Perkins Coie LLP (San Diego)
  • Note: His specific role and experience are not detailed in the available public records.

While no notice of appearance is publicly available for the terminated Sony Group Corporation v. Greenthread, LLC (IPR2023-00325) proceeding, filings in a contemporaneously filed IPR against a related patent, Monolithic Power Systems, Inc. v. Greenthread, LLC (IPR2024-00550), identify the counsel representing patent owner Greenthread, LLC. A filing in that case explicitly lists the petition from IPR2023-00325 as an exhibit, confirming the same legal team was involved.

The legal team from the law firm McKool Smith, P.C. has represented Greenthread in numerous PTAB proceedings and related district court litigations.

Counsel for Defendant Greenthread, LLC

Alan Whitehurst

• Role: Lead Counsel
• Firm: McKool Smith, P.C., Washington, D.C. office.
• Note: A principal and veteran patent trial lawyer, Whitehurst has deep experience in telecom and semiconductor litigation and has successfully argued numerous inter partes reviews (IPRs) at the PTAB.

Nicholas T. Matich

• Role: Of Counsel
• Firm: McKool Smith, P.C., Washington, D.C. office.
• Note: Matich is a former Acting General Counsel of the U.S. Patent and Trademark Office (USPTO), where he supervised all IP litigation on behalf of the agency, including matters before the PTAB.

Arvind Jairam

• Role: Of Counsel
• Firm: McKool Smith, P.C., Washington, D.C. office.
• Note: Jairam is a senior counsel with over fifteen years of experience in all areas of patent law and is a highly active IPR practitioner on McKool Smith's top-ranked PTAB team.

Stuart McCommas

• Role: Of Counsel
• Firm: McKool Smith, P.C., Washington, D.C. office.
• Note: McCommas is a former Deputy White House Counsel and associate at McKool Smith with experience in government and private practice.

Archis "Neil" Ozarkar

• Role: Of Counsel
• Firm: McKool Smith, P.C., Houston office.
• Note: Ozarkar is Senior Counsel representing clients in complex IP disputes in federal courts, the ITC, and in post-grant proceedings before the PTAB.