Rambus, a memory and interface design firm, on Monday said it had terminated license agreement with the world’s largest memory maker Samsung Electronics and added it to the list of defendants in its pending patent infringement suit in the U.S. District Court for the Northern District of California and also filed in an additional suit against the DRAM 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,” said Harold Hughes, chief executive officer at Rambus.

In its claims filed on Monday, Rambus asserts infringement of 14 of its patents by DDR2, GDDR2 and GDDR3 devices that are currently shipping in the marketplace by Samsung. Rambus is also asserting infringement of 10 of its patents by SDRAM and DDR DRAM memory and controller products. Today’s action does not affect Samsung’s role as a licensee of RDRAM and XDR DRAM memory types, though.

“These issues have caused us to terminate that license prior to its scheduled June 30, 2005 end date. We continue to value our relationship with Samsung as one of the primary manufactures of memory using our XDR DRAM and RDRAM designs. We very much hope that there is an opportunity in the near future to normalize all other aspects of our relationship as well,” Mr. Hughes added.

Rambus did not elaborate about the issues that caused it to terminate the license agreement with Samsung.