Greenthread, LLC v. Monolithic Power Systems, Inc.

This patent infringement lawsuit is part of a broader campaign by patent assertion entity Greenthread, LLC against numerous players in the semiconductor industry. The plaintiff, Greenthread, is a Texas-based LLC that holds patents invented by G.R. Mohan Rao, one of its directors. It does not appear to manufacture products and is considered a non-practicing entity (NPE). The defendant, Monolithic Power Systems, Inc. (MPS), is a publicly-traded American semiconductor company that designs, develops, and markets integrated circuits for power management in various applications, including industrial, automotive, and consumer electronics. Greenthread alleges that certain power management integrated circuits made by MPS, such as the MP86905 monolithic half-bridge, infringe on its patents. This litigation is one of several similar lawsuits Greenthread has filed against other major semiconductor companies.

The case was filed in the U.S. District Court for the District of Delaware, a popular and influential venue for patent litigation due to its judges' expertise in complex patent law and the fact that many U.S. corporations are incorporated in the state. The asserted patent, U.S. Patent No. 11,121,222, is part of a larger family of patents generally directed to semiconductor devices with graded dopant regions, which is a foundational technology for improving transistor performance. The case is procedurally notable because on April 23, 2024, the court granted a stay, administratively closing the case pending the outcome of inter partes review (IPR) proceedings. MPS filed multiple IPR petitions with the Patent Trial and Appeal Board (PTAB) to challenge the validity of the asserted patent claims. This is a common defense strategy in patent litigation, as a PTAB decision invalidating the patent could end the district court case. The linkage to the PTAB and Greenthread's multi-front litigation campaign make this a noteworthy case in the semiconductor sector.

Key Legal Developments and Outcome

This patent infringement case is defined by the defendant's early and successful strategy to pause the district court litigation in favor of challenging the patent's validity at the Patent Trial and Appeal Board (PTAB). As of May 2026, the case remains administratively closed and inactive, awaiting the final outcomes of these parallel administrative proceedings.

Chronological Developments

2023-05-26: Complaint Filed
Greenthread, LLC filed a patent infringement complaint against Monolithic Power Systems, Inc. (MPS) in the U.S. District Court for the District of Delaware. The complaint alleged that certain MPS power management products, such as the MP86905 monolithic half-bridge, infringe U.S. Patent No. 11,121,222. This suit is one of several similar actions filed by Greenthread against major semiconductor companies involving a family of patents related to semiconductor devices with graded dopant regions.

(Note: Information regarding the specific date of MPS's answer and any counterclaims was not found in the available search results.)

2024-02-03: IPR Petition Filed by MPS
Monolithic Power Systems filed a petition for inter partes review (IPR) with the PTAB, challenging the validity of claims of a related Greenthread patent. This was part of a broader defensive strategy by MPS and other defendants in Greenthread's litigation campaign, who filed multiple IPRs against the asserted patents. Specifically, MPS filed IPR petitions against patents in the same family as the '222 patent. For the '222 patent itself, other accused infringers like Semiconductor Components Industries, LLC (ON Semiconductor) also filed IPRs.

2024-04-23: Case Stayed Pending IPR
The Delaware district court granted a motion to stay the litigation and administratively closed the case. This decision put the district court proceedings on hold pending the resolution of the IPRs filed by MPS and other parties challenging the validity of the Greenthread patents at the PTAB. The court's decision to grant the stay was based on common factors, including the early stage of the litigation (only 333 days old) and the potential for the PTAB's decisions to simplify or resolve the issues in the case.

Present Posture & Parallel Proceedings

As of the latest available information, the district court case Greenthread, LLC v. Monolithic Power Systems, Inc. remains stayed and administratively closed. The focus of the dispute has shifted entirely to the PTAB.

• Parallel PTAB IPRs: Monolithic Power Systems filed at least one IPR against a Greenthread patent (IPR2024-00469), which is still pending. The '222 patent, asserted in this case, has been the subject of multiple IPRs filed by other Greenthread defendants, including IPR2023-01242 and IPR2023-01244 filed by Semiconductor Components Industries (ON Semiconductor) and Texas Instruments.
• Impact of IPRs: The outcome of these PTAB proceedings will be critical. If the PTAB finds the asserted claims of the '222 patent to be unpatentable, it would likely lead to the dismissal of Greenthread's case against MPS in district court. Conversely, if the claims survive the IPR challenges, Greenthread could move to lift the stay and resume the district court litigation.

The case has not progressed to claim construction (Markman), substantive discovery, summary judgment, or trial due to the early stay. The final disposition awaits the conclusion of the related IPR proceedings at the PTAB.

Plaintiff's Counsel

Greenthread, LLC has retained a combination of counsel from Stamoulis & Weinblatt LLC as local counsel in Delaware and The Mort Law Firm, PLLC as lead counsel.

• Stamatios "Stam" M. Stamoulis (Local Counsel)

  • Firm: Stamoulis & Weinblatt LLC, Wilmington, DE.
  • Experience: Mr. Stamoulis is a veteran Delaware patent litigator who frequently serves as local counsel for both plaintiffs and defendants in the District of Delaware, one of the busiest patent courts in the US.

• Richard C. Weinblatt (Local Counsel)

  • Firm: Stamoulis & Weinblatt LLC, Wilmington, DE.
  • Experience: As a partner at a firm specializing in Delaware intellectual property and commercial litigation, Mr. Weinblatt regularly represents clients in patent disputes before the District of Delaware.

• Gary L. Mort (Lead Counsel)

  • Firm: The Mort Law Firm, PLLC, Austin, TX.
  • Experience: Mr. Mort is the principal of his firm and has a history of representing patent assertion entities, including Greenthread, in litigation campaigns across various jurisdictions.

• Daniel R. Mort (Of Counsel)

  • Firm: The Mort Law Firm, PLLC, Austin, TX.
  • Experience: Daniel Mort frequently appears alongside Gary Mort in patent infringement cases, representing patent holders in federal court.

This legal team structure, combining specialized Texas-based patent counsel with experienced Delaware local counsel, is common in cases filed by non-practicing entities in the District of Delaware. The attorneys from The Mort Law Firm handle the primary strategic direction of the case, while Stamoulis & Weinblatt manage local court filings and procedural matters specific to Delaware. This information is based on appearances filed in the public docket.

Defendant's Counsel of Record

Monolithic Power Systems, Inc. (MPS) is represented by attorneys from the national law firm Perkins Coie LLP, with Ashby & Geddes serving as local counsel in Delaware. The team has extensive experience in patent litigation and post-grant proceedings, which aligns with the case's posture, currently stayed pending inter partes review (IPR).

Lead and National Counsel: Perkins Coie LLP

Perkins Coie is serving as lead counsel for MPS in both the district court litigation and the parallel IPR proceedings before the Patent Trial and Appeal Board (PTAB). The firm is known for representing technology companies in high-stakes intellectual property disputes.

• John D. Esterhay (Lead Counsel): A partner in Perkins Coie's Denver office, Esterhay has a long track record in patent litigation and counseling, particularly within the semiconductor and electronics industries.
• John P. Schnurer (Of Counsel): Based in the San Diego office, Schnurer focuses on patent litigation, IPRs, and other complex IP matters, frequently representing clients in the electronics and software sectors.
• Miguel Bombach (Of Counsel): A partner in the San Diego office, Bombach's practice centers on patent litigation and PTAB trials, often involving semiconductor and telecommunications technologies.
• Bing Ai (Of Counsel): Counsel in Perkins Coie's San Diego office, Ai concentrates on patent litigation and has experience in cases involving integrated circuits and consumer electronics.
• Brianna Kadjo (Of Counsel): An associate in the firm's Denver office, Kadjo's practice includes patent litigation and appeals.
• Runkun Jiang (Of Counsel): An associate based in San Diego, Jiang focuses on patent litigation and has a technical background in electrical engineering.

Delaware Local Counsel: Ashby & Geddes, P.A.

Given that the case is filed in the District of Delaware, MPS has retained local counsel from a firm with deep experience in that specific court.

• John G. Day (Local Counsel): A director at Ashby & Geddes in Wilmington, Delaware, Day is a veteran patent litigator who frequently serves as Delaware counsel for out-of-state lead firms in major patent cases. His role is to provide guidance on local court rules and practices.