Los Altos, Calif.-based Rambus announced Monday that it had filed suit against the world's largest memory manufacturer in the U.S. District Court of the Northern District of California. It also said it has added Samsung as a defendant in aoriginally filed against other memory manufacturers.
In all, the claims involve 35 patents. Rambus alleges the Samsung products that violate its patent include SDRAM (the most common type of PC memory used in the 1990s), DDR memory (the most common type now), DDR2 memory, and GDDR2 and GDDR3 graphics memory.
Samsung could not be reached for comment.
Samsung actually had a license to produce these types of memory. Under the terms of that agreement, the company was obliged to pay Rambus royalties unless a court invalidated the patents, according to now former Rambus executives. So far, courts have generally upheld the patents.
The license was set to expire at the end of the month. Rambus did not explain why it terminated the license agreement and sued now. Ironically, Samsung was more vocal in promoting RDRAM, a type of memory designed by Rambus, than any other major memory manufacturer.
"While we have regarded Samsung as a valuable licensee of our patents for certain applications, a number of issues now exist that have made the renewal and expansion of the Samsung SDRAM/DDR license difficult," Rambus CEO Harold Hughes said in a statement.
Samsung, however, remains a licensee for XDR memory, a different type of high-speed memory designed by Rambus. Sony will incorporate XDR in its PlayStation 3 games console, and Samsung will manufacture it for Sony.