Chip developer Rambus has filed patent infringement lawsuits against six chip makers including Broadcom and Freescale Semiconductor in the US, and said it is also seeking to ban the import of products that infringe its patents.

Rambus sued the companies, which also include LSI, MediaTek, Nvidia and STMicroelectronics, in the US District Court for the Northern District of California, while it is seeking an exclusion order barring the import of infringing products with the US International Trade Commission (ITC).

The ITC complaint also named companies whose products incorporate chips made by the six accused companies, including Hewlett-Packard, Hitachi, Motorola and Asustek Computer, in products ranging from servers and PCs to mobile phones, Blu-ray Disc players and set top boxes.

The lawsuits and complaint to the ITC are over a number of technologies Rambus developed, some controversial due to their being raised during meetings over the development of industry standard computer memory. The Rambus patents in question are used in a range of products, including PCI Express, Serial ATA and memory chip products from DDR (double data rate memory chips, first generation) to DDR2, DDR3, mobile DDR and GDDR3 (graphics DDR).

Rambus has spent over a decade in courts suing memory chip makers for the alleged infringement of its memory patents.

Nvidia in trouble

Some of the Rambus patents in question were a problem for Nvidia earlier this year. The ITC ruled in July that the graphics chip developer was infringing three Rambus patents and issued an order banning certain Nvidia chips from importation to the US. Nvidia appealed the case and started paying royalties on those products.

"The action against Nvidia was the first ever we have taken against a non-DRAM company. We had hoped by pursuing this action, other companies using our innovations and memory controllers on their chips would recognise our resolve to protect our patented innovations and further, would recognise the validity of our position given the ITC's decision in our favour."

"Yet rather than licensing the patents they were using, many chose instead to play the delay game," said Sharon Holt, senior vice president. She said Rambus took action after coming to the conclusion that it had no other recourse.

The US and European companies named by Rambus could not immediately be reached for comment. Taiwan's MediaTek declined to comment.

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