A US court has ruled that Hynix has in fact infringed upon patents held by rival Rambus, but a trial will still take place in March to determine whether the rest of Rambus' claims are valid.

Judge Ronald Whyte ruled in favour of Rambus on six of seven requests for summary judgement filed by both Rambus and Hynix. Rambus had asked the judge to declare that Hynix's memory chips infringed upon Rambus patents, while Hynix had asked the judge to rule that Rambus' patents are invalid.

A ruling of summary judgment essentially skips the trial phase of a case and holds that the issues in the case are clear enough to render a decision without a trial.

Hynix had filed six requests for summary judgment, asking the judge to throw out 59 claims within assorted Rambus patents. One of those requests was granted, dismissing nine of the claims, but the other requests to invalidate the remaining 50 claims were denied.

Rambus then identified 40 claims within its patents that the company believes are infringed by Hynix's products, and asked for rulings of summary judgment on those claims. Of those 40 claims, Judge Whyte ruled that Hynix's products infringe upon 29 of the claims, but the question of infringement on the remaining 11 claims will be debated at a trial starting 21 March.

The ruling is "a major step forward" in Rambus' goal to collect royalties on memory chips, said John Danforth, Rambus' general counsel, in a statement.

Rambus designs memory interfaces, the portion of a system's chipset that moves data from the processor to the memory. However, the company is better known for the legal saga that stems from a dispute over whether Rambus holds patents on the memory chips that can be found in the vast majority of the world's PCs, which could lead to billions of dollars in royalties.

Rambus believes that SDRAM chips contain technology that it patented. The SDRAM industry has vehemently protested the validity of Rambus' claims because Rambus was a member of the industry organisation that developed the SDRAM standard, and it did not disclose its patents while the group was debating what technology would wind up in the standard.

Infineon was the first target of Rambus' patent claims. In that trial, a Virginia jury originally convicted Rambus of fraud for failing to disclose its patents, but that verdict was overturned after an appeals court ruled that the disclosure policies of the standards-setting organisation did not specifically require Rambus to disclose its patents. Emboldened by that decision, Rambus is expected to press its original argument against Infineon in a new trial this year.

This particular case was filed by Hynix after Rambus sued Infineon. Hynix makes chips based on the same standard, and it sued Rambus in this case claiming that Rambus' patents on SDRAM technology were invalid.

Rambus is still involved in four other cases, including the Infineon trial. Micron has also sued Rambus claiming that its patents are invalid, and the US Federal Trade Commission has accused Rambus of unfair competition.

Rambus has also filed an anti-trust suit against Infineon, Micron, Hynix and Siemens claiming they conspired to keep the price of Rambus' own memory standard (RDRAM) high while keeping the price of SDRAM low, in an attempt to keep RDRAM from catching on as a standard. The memory makers deny that charge, but executives at Infineon and Micron plead guilty to conspiring to fix the price of SDRAM in a separate investigation involving the US Department of Justice.