The relationship between computer memory designer Rambus Inc and one of its largest customers, Samsung Electronics Co Ltd, turned sour this week as the companies traded federal lawsuits over patents for computer memory chips.
Weeks before a five-year patent licensing agreement between Rambus and Samsung was set to expire, Rambus on Monday said it terminated the license pact and filed a patent infringement suit against Samsung in California.
A day later, Samsung sued Rambus in a Virginia court - the same court that in March handed Rambus a devastating blow in a separate case involving Germany's Infineon Technologies AG. Samsung asked the court to declare four Rambus patents "invalid and unenforceable."
Rambus, based in Los Altos, California, claims its intellectual property is used in standard computer memory chips, and has demanded billions of dollars in royalties from computer memory chip makers including Samsung, Infineon and Boise, Idaho-based Micron Technology Inc.
Samsung, based in South Korea, has paid Rambus royalties on memory chips since 2000, but has declined to pay royalties on a newer type of chip, called DDR2, that is becoming the new industry standard. Samsung accounted for more than 10 percent of Rambus's annual revenues, according to regulatory documents filed by Rambus.
In its lawsuit, Samsung asserts that Rambus used information it obtained as a member of a memory chip standards-setting body to secure additional patents, with the intention of later seeking to enforce those patents against the group's members. It also accuses Rambus of shredding documents related to the matter.
In March, Rambus agreed to settle its long-running patent case against Infineon after Infineon agreed to pay Rambus royalties.
The settlement, which some analysts said was very favourable for Infineon, came weeks after a federal judge in Virginia dismissed Rambus's patent infringement claims against Infineon. Rambus hinted it might appeal the ruling, but the case was settled before an appeal went forward.
Rambus shares fell 88 cents on Friday to $14.66 on Nasdaq, close to a $13.12 low reached in March.