PTAB challenges

Proceedings overview

One Inter Partes Review (IPR) proceeding has been filed against US Patent 10,140,028. This IPR was denied institution, meaning no claims were ever reviewed on the merits by the Patent Trial and Appeal Board (PTAB). This outcome strengthens the patent's defensive posture, as it has survived an IPR challenge at the institution stage.

IPR2025-01456 — Infineon Technologies Americas Corp. et al. v. Mosaid Technologies Inc.

• Type: Inter Partes Review
• Filed: 2025-08-29
• Status: Discretionary Denial – The PTAB declined to institute the inter partes review.
• Judge panel: Not publicly available due to discretionary denial.
• Petition grounds: Specific claims, prior art, and statutory bases (§ 102 / § 103) are not detailed in the public record for a discretionary denial where no institution decision on the merits was issued.
• Institution decision: Denied. The PTAB issued a "Discretionary Denial" on 2026-04-17. The specific reasoning for the discretionary denial is not immediately available in public snippets but typically involves factors such as parallel district court litigation, advanced stage of litigation, or inefficient use of Board resources.
• Final Written Decision (if issued): Not applicable. A Final Written Decision is only issued if the IPR is instituted.
• Settlement / termination: Not applicable. The proceeding terminated at the institution stage by discretionary denial.
• Appeal: No appeal to the Federal Circuit regarding a Final Written Decision, as none was issued.
• Defensive value: This proceeding indicates that Infineon Technologies Americas Corp. et al. attempted to challenge the patent at the PTAB but were unsuccessful at the institution stage. For a defendant facing assertion of this patent, this means that the patent has not been weakened by a PTAB ruling, and any IPR-based defense using the same grounds as Infineon would need to overcome the PTAB's reasoning for discretionary denial.

Strategic summary

No claims of US10140028 have been canceled or sustained by the PTAB. The patent has been subjected to one Inter Partes Review, IPR2025-01456, which resulted in a discretionary denial of institution. This means that the PTAB did not proceed to a full review of the patentability of the challenged claims. Consequently, all claims of US10140028 remain untested by a PTAB Final Written Decision on the merits.

Regarding the estoppel landscape, since IPR2025-01456 was denied institution, the statutory estoppel provisions of 35 U.S.C. § 315(e)(2), which apply to grounds raised and claims found unpatentable in a Final Written Decision, do not come into play. However, the petitioner (Infineon Technologies Americas Corp. et al.) and their privies may face a common law or analogous preclusion from asserting the same specific invalidity grounds in district court that were presented in the IPR petition and denied institution. For other potential defendants, all prior art grounds remain available for challenge, subject to the usual statutory and regulatory requirements for filing an IPR petition. There are no clear pattern signals from a single, non-instituted IPR to suggest aggressive PTAB appeals by the patent owner or multiple filings by the same petitioner.

Recommended next steps

• Since IPR2025-01456 resulted in a discretionary denial, there is no Final Written Decision to link to for claim invalidation. The PTAB's decision to deny institution can be found in the USPTO's PTAB E2E system. For IPR2025-01456, the status is "Not Instituted - Procedural". A defendant should review the specific order for discretionary denial to understand the Board's reasoning, as this could inform future invalidity strategies.
• Currently, there are no active PTAB proceedings on file for US10140028 that are proceeding to trial.