Chip technology designer Rambus has won a $307m (£172m) court battle with South Korean rival Hynix Semiconductor.
Hynix has said it will appeal against the court ruling
A jury in San Jose, California, found Hynix - the world's second-biggest maker of memory chips - had violated Rambus patents.
Hynix has to pay $30.5m in damages over patents for computer memory called SDRAM and $276.4m on one called DDRSD.
Rambus has suits pending against other memory chip makers such as Samsung Electronics and Micron Technology.
Rambus specializes in technology that speeds the transmission of data between computer chips.
Shares in Hynix fell 1.92% to 33,250 won following the decision while Samsung, the
world's biggest maker of memory chips, fell 1.93%.
After the legal ruling Hynix said it would appeal against the federal court decision.
It said its appeal would focus on "whether or not Rambus violated anti-trust laws in acquiring and enforcing these patents".
"In the next phase, scheduled for this summer, Hynix will seek to have all of the Rambus patents in dispute held (to be) unenforceable," Hynix said.
The damages cover Hynix memory chip sales between the summer of 2000 and the end of 2005, Rambus said.
"We continue to hold out an olive branch to resolve these matters short of full scale trials," said Rambus general counsel John Danforth.
"By doing this, we give defendants and potential defendants a way to avoid significant exposure to antitrust and patent cases," he added.
The Hynix case went to trial a month ago after six years of legal wrangling.