The case is one of a number of similar pending cases against Rambus, and was brought by memory manufacturers Hynix Semiconductor, Micron Technology and Nanya Technology Corporation.

In Wednesday’s decision, a San Francisco jury said that the plaintiffs had not met their burden of proving antitrust and fraud claims, according to a Rambus statement.

In 2006, the US antitrust watchdog, the Federal Trade Commission (FTC), found Rambus guilty of unlawfully monopolizing computer memory markets through deceptive conduct, and in February 2007 capped the royalty rate Rambus can collect from licensing its patents. The FTC said that Rambus had deceived the Joint Electron Devices Engineering Council (JEDEC) by failing to disclose that it was actively working to develop, and possessed, a patent and several pending patent applications that involved specific technologies ultimately adopted in the standards for DRAM.

In August 2007, the company also came under fire in Europe, when the European Commission sent Rambus a Statement of Objections accusing it of breaching Article 82 of the EC Treaty by claiming unreasonable royalties for the use of the same patents.

Last week Hynix Semiconductor said that several of the patents at issue in the San Francisco litigation are also being reexamined by the USPTO, and that another Rambus patent was recently rejected by the PTO in a preliminary ruling.

In a statement issued by Rambus last week, Tom Lavelle, senior vice-president and general counsel at Rambus, said: "This ruling should put to rest a series of ongoing allegations Rambus has endured for many years. Our business is to license our revolutionary technology to the industry for fair compensation. We are pleased to have this decision behind us as we continue to engage with the industry to deliver compelling products to the market."

But Micron Technology said that it disagrees with last Wednesday’s jury decision and emphasized that the case represents just one phase in a slew of pending litigation between the two companies. Rod Lewis, Micron’s vice-president of legal affairs and general counsel said: “Micron believes that Rambus has engaged in a pattern of deception, destruction of evidence, false testimony and other improper activities designed to mislead and to extract unjust patent licensing fees and damages. We will continue to vigorously advance our claims that Rambus has engaged in a variety of illegal activities designed to injure Micron.”