By absolving Infineon, the judge removed the German chip maker itself from any liability, but that left the Rambus SDRAM and DDR patents standing.

By continuing the trial on the issue of Rambus' alleged secrecy at the industry JEDEC standards committee, Judge Payne left the door open for the synchronous patents to be declared unenforceable on the grounds of antitrust violations.

Judge Payne dismissed infringement claims against Infineon on the grounds that the German firm's SDRAM and DDR chips didn't use a multiplexed memory bus.

In March, the judge had ruled Rambus' synchronous patents only covered memory chips connected to a multiplexed bus. That set a precedent likely to be cited in other pending Rambus patent litigation trials in the U.S. and in Europe.

Micron Technology, which is suing Rambus in Wilmington, Del., federal court, has already asked the judge in that case to adopt the same narrow multiplexed bus coverage that decided the Infineon case.

Infineon itself is expected to raise the same defense when another Rambus infringement trial begins May 18 in Mannheim, Germany.

Beyond that, the continuing trial in Richmond will draw even greater interest as the jury will decide whether Rambus engaged in alleged restraint of trade and fraud by keeping its synchronous patent applications hidden while a member of the industry JEDEC panel drafting an open SDRAM standard.

Infineon this week started calling witnesses to testify on Rambus conduct at JEDEC. Attorneys for the German firm have also disclosed handwritten notes by Rambus patent attorneys describing what was alleged to be urgent pleas from Rambus officials to amend the applications in 1998 and 1999 to cover JEDEC features.

Rambus has denied any such actions, and said JEDEC's patent policy was ambiguous and not adhered to by other industry members of the panel.

Rambus on Friday said that it plans to appeal today's ruling by Judge Payne.

"We are disappointed with the Court's decision and plan to appeal the ruling," said Geoff Tate, CEO of Rambus, in a released statement. "If today's decision is allowed to stand, all companies that innovate risk having their intellectual property rights unjustly expropriated.

"Though Rambus is a relatively small company, we will not be cowed by the aggressive tactics of some industry giants who would take our innovations without any compensation," he added.

Judge Payne's ruling leaves Infineon free to escape the 3.5% royalty payments on DDR chips that eight other DRAM makers have agreed to pay Rambus.

Early in the week, Judge Payne dismissed dozens of patent infringement claims made by Rambus against Infineon, leaving just the three claims, which Judge Payne has now also dismissed.

Right after Judge Payne's decision Friday, trading in Rambus stock was halted. The stock had dropped below $15 just before trading was stopped. It had hit a high of $152 late last year.