Frank Scherkenbach of Fish & Richardson/courtesy photo

Fifteen years ago, San Jose electronics company Power Integrations sued crosstown rival Fairchild Semiconductor, alleging infringement of technology used in chargers for mobile devices.

Numerous district court trials, Patent Trial and Appeal Board and International Trade Commission actions, and Federal Circuit appeals later, PI and Fairchild successor ON Semiconductor finally put down their swords earlier this month. ON will pay PI $175 million to settle all of the litigation, at least for the next several years.

"It's a little like sending your newborn off to college. It's almost been that long," said Fish & Richardson partner Frank Scherkenbach, who has litigated the cases for PI "arm-in-arm" with Fish partners Michael Headley and Howard Pollack from day one.

Across the table has been a long line of some of the world's top law firms: Orrick, Herrington & Sutcliff; Finnegan, Henderson, Farabow, Garrett & Dunner; McDermott Will & Emery; Morrison & Foerster, Paul Hastings; Baker Botts; and, most recently on the appeals, Quinn Emanuel Urquhart & Sullivan.

Initially, PI and Fish made some law they didn't want: The Federal Circuit ruled in 2013 that lost profits for overseas sales weren't recoverable, dropping PI's $34 million jury award in Delaware federal court to about $6 million. Then last year U.S. District Judge Leonard Stark ruled that the U.S. Supreme Court had implicitly overruled the Federal Circuit with its WesternGeco decision, and put worldwide damages back on the table.

"It was pending so long, we were right, then we were wrong, then we were right again," Scherkenbach quips.

The Federal Circuit had been scheduled to hear ON's appeal next month, one of several factors Scherkenbach said might have helped spur the settlement.

Another big factor, in his view, were two district court cases pending before U.S. District Judge Maxine Chesney in San Francisco. PI won verdicts of $105 million and $140 million in the first case, only to have the Federal Circuit order retrials each time as it refined the law of damages. Scherkenbach said he was confident the third trial was still going to yield a big number, perhaps $90 million. With liability already affirmed on appeal, "there really was no escape for them," he said. A separate, yet-to-be-tried case before Chesney had the potential for an even bigger award, Scherkenbach said.

It did look for awhile as if ON had one escape route. After announcing its planned acquisition of Fairchild in 2015, but before the deal closed, ON filed petitions at the Patent Trial and Appeal Board challenging PI's patents, ultimately invalidating quite a few claims, including some that supported the San Francisco jury awards. This time PI came away with the win at the Federal Circuit: The appellate court ruled in June last year that ON was in privity with Fairchild, and therefore was long past the one-year statutory deadline for bringing the challenges. "That caused pretty much their entire IPR strategy to crumble," Scherkenbach said.

ON Semiconductor declined to comment on the settlement.

According to a PI SEC filing, the settlement calls for each side to release the other from their current suits and countersuits, and not to file any additional actions until at least 2023. Neither party granted the other a license, which Scherkenbach acknowledged is unusual in patent settlements.

It reflects that PI lives and dies by innovation, he said. "They don't license their IP—never have, never will—because it's the lifeblood of their company."

Scherkenbach said the keys to success were perseverance and consistency. Their client never wavered from seeing the case through. And his team "always kept our eye on what the long-term goal was, and consistently focused on a strategy for winning the endgame."