Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Nengda Microelectronics (Shenzhen) Co., Ltd., Nengda Semiconductor Technology (Shenzhen) Co., Ltd.

CourtDistrict Court, D. Delaware
DecidedApril 13, 2026
Docket1:23-cv-01155
StatusUnknown

This text of Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Nengda Microelectronics (Shenzhen) Co., Ltd., Nengda Semiconductor Technology (Shenzhen) Co., Ltd. (Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Nengda Microelectronics (Shenzhen) Co., Ltd., Nengda Semiconductor Technology (Shenzhen) Co., Ltd.) is published on Counsel Stack Legal Research, covering District Court, D. Delaware primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Nengda Microelectronics (Shenzhen) Co., Ltd., Nengda Semiconductor Technology (Shenzhen) Co., Ltd., (D. Del. 2026).

Opinion

IN THE UNITED STATES DISTRICT COURT FOR THE DISTRICT OF DELAWARE

MONOLITHIC POWER SYSTEMS, : CIVIL ACTION INC. : : v. : NO. 23-1155 : REED SEMICONDUCTOR CORP. :

MONOLITHIC POWER SYSTEMS, INC. : CIVIL ACTION : v. : NO. 24-165 : REED SEMICONDUCTOR CORP. :

MONOLITHIC POWER SYSTEMS, INC. : CIVIL ACTION : v. : NO. 24-166 : NENGDA MICROELECTRICS : (SHENZHEN) CO., LTD., NENGDA : SEMICONDUCTOR TECHNOLOGY : (SHENZHEN) CO., LTD. :

MEMORANDUM

MURPHY, J. April 13, 2026

This is a patent infringement case about power management circuitry. Having progressed through discovery and claim construction, defendants filed summary judgment and Daubert motions, and plaintiff filed a Daubert motion of its own. For one patent, defendants argue a technical basis for noninfringement that we suspect might be hiding another claim-construction dispute; that one is denied. For the other patent, defendants say the plaintiff fatally disavowed claim scope during an IPR; we disagree. Defendants also argue that plaintiff is barred from pre- suit damages because of a failure to mark, but as far as we can tell from the record, nobody ever said that there were products that had to be marked. Finally, the Nengda defendants correctly call out plaintiff for adducing no evidence that they committed any acts of infringement, so they are out of the case. Reed remains. In the Daubert motions, the parties attack each other’s damages experts under the robust Federal Circuit law applying Rule 702(d) to reasonable royalty opinion testimony. In the spirit of the Federal Circuit’s “measure twice cut once” approach in this area, we took a hard look at the arguments presented by the parties, but in the end conclude that the experts are ready to face the jury. This case is going to trial.

I. Background

In these related actions, Monolithic accuses defendants (Reed collectively, except for issues involving the Nenga defendants specifically) of infringing two U.S. patents, no. 9,041,377 and no. 9,590,608. We construed terms of the 608 patent on January 10, 2025. DI 180.1 Trial is set to begin on November 2, 2026. The motions on the table are as follows. Reed filed a combined motion for summary judgment and to exclude the testimony of Monolithic’s damages expert, Justin Blok. DI 334, 335. Monolithic opposes, DI 348, and Reed filed a reply brief, DI 357. Monolithic, for its part, filed a motion to preclude the testimony of Reed’s damages expert, W. Todd Schoettelkotte. DI 338, 339. Reed opposes, DI 349, and Monolithic filed a reply brief, DI 358. We held oral argument on March 11, 2026. DI 376. The various arguments and relevant facts will be addressed on an issue-by-issue basis below. II. Standard of review for summary judgment and Daubert

We “grant summary judgment if the movant shows that there is no genuine dispute as to any material fact and the movant is entitled to judgment as a matter of law.” Fed. R. Civ. P.

1 Throughout this memorandum, reference will be made to the docket in the oldest case, no. 23-1155; using the docket numbers of the under-seal versions; and using the page numbers on the documents if available, or the ECF page numbering if not. 2 56(a). A factual dispute is genuine and material if a reasonable jury could find for the nonmoving party. Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 248 (1986). On a non-infringement motion — or other motion addressed to the patent owner’s case in chief — the defendant “bears the initial responsibility of informing the district court of the basis for its motion, and identifying those portions of the pleadings, depositions, answers to interrogatories, and admissions on file, together with the affidavits, if any, which it believes

demonstrate the absence of a genuine issue of material fact.” Celotex Corp. v. Catrett, 477 U.S. 317, 323 (1986) (citation modified). Alternatively, defendant may show that there is no genuine issue of material fact by pointing out “an absence of evidence to support the nonmoving party’s case.” Id. at 325. After that, the patent owner must “come forward with specific facts showing that there is a genuine issue for trial.” Matsushita Elec. Indus. Co. v. Zenith Radio Corp., 475 U.S. 574, 587 (1986) (citation modified). Turning to Daubert, Rule 702 requires the proponent of the expert to “demonstrate[] to the court that it is more likely than not that: . . . (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.”

Fed. R. Evid 702; see also Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 (1993). Where the challenged expert “testimony’s factual basis, data, principles, methods, or their application are called sufficiently into question . . . the trial judge must determine whether the testimony has ‘a reliable basis in the knowledge and experience of [the relevant] discipline.’” Kumho Tire Co. v. Carmichael, 526 U.S. 137, 149 (1999) (alteration in original) (citation modified) (quoting Daubert, 509 U.S. at 592). Courts must carefully distinguish between Rule 702’s threshold gatekeeping analysis and disputes over factual weight that go to a jury. EcoFactor, Inc. v. 3 Google LLC, 137 F.4th 1333, 1338-40 (Fed. Cir. 2025) (en banc). “The distinction is particularly important in the context of patent damages because estimating a reasonable royalty ‘necessarily involves an element of approximation and uncertainty.’” Willis Electric Co., Ltd. v. Polygroup Ltd., 166 F.4th 1363, 1374 (Fed. Cir. 2026) (quoting EcoFactor, 137 F.4th at 1340). III. Analysis

a. Reed’s noninfringement motion for the 608 patent is denied

Reed advances two noninfringement arguments for the 608 patent, both of which are factbound. First, as Reed puts it, the claims “require a specific sequential order of operations,” namely, “that recharging the bootstrap capacitor be initiated by decreasing the output voltage of the voltage converter.” DI 335 at 17. Reed’s focus is, e.g., the final clause of claim 1: when the first comparing signal has the first logic state, the bootstrap refresh module is configured to decrease the output voltage of the voltage converter; and wherein when the feedback signal is smaller than the reference voltage signal, the bootstrap refresh control circuit is configured to control the high side switch and the low side switch to switch on and off based on the difference signal so as to charge the bootstrap capacitor for refreshing the bootstrap voltage signal. 608 patent, claim 1. Reed argues that in the accused products, “recharging the bootstrap capacitor is not initiated by any decrease of the output voltage of the voltage converter.” DI 336 at 12 (statement of fact 18); DI 335 at 2-3 (discussing the same). Monolithic disputes statement of fact 18, citing its expert Mr. Fan, who testified that in the accused products, “recharging the bootstrap capacitor will initially ‘slightly pull down Vout a little bit.’” DI 336 at 8 (citing Appx. 736-39; 746). That sounds like enough to forestall summary judgment, but Reed adds another twist to its argument. According to Reed, the drop in Vout is irrelevant because it comes “after the recharge of the bootstrap capacitor.” DI 335 at 10.

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Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Reed Semiconductor Corp.; Monolithic Power Systems, Inc. v. Nengda Microelectronics (Shenzhen) Co., Ltd., Nengda Semiconductor Technology (Shenzhen) Co., Ltd., Counsel Stack Legal Research, https://law.counselstack.com/opinion/monolithic-power-systems-inc-v-reed-semiconductor-corp-monolithic-ded-2026.