SAN JOSE -- The International Trade Commission has issued a final ruling affirming certain patents issued to Tessera Technologies, but also said that the chip package designer did not prove infringement on the part of its DRAM competitors.

In a statement, Tessera said the ITC determined that the methodology used by Tessera's expert was insufficient to prove infringement by the respondents of two of the asserted patents. The notice indicated that infringement was proven as to some but not all of the accused products regarding the third contested patent but due to patent exhaustion, there was no violation.

Tessera said has not yet received the Commission's final determination and therefore does not yet know the details of any reasoning behind the ITC's conclusions. 

In a statement, Tessera president and CEO Henry R. Nothhaft said, "Once again, the ITC affirmed the validity of our asserted patents. We are disappointed, however, with the determinations regarding our infringement methodology and patent exhaustion."

Tessera said it could appeal the ruling.

Respondents in the DRAM ITC action include Acer, Centon Electronics, Elpida Memory, Kingston Technology, Nanya, Powerchip Semiconductor, ProMOS Technologies, Ramaxel Technology and Smart Modular Technologies.

Tessera asserted infringement of three Tessera patents, US Patent No. 6,133,627 ('627), US Patent No. 5,679,977 ('977), and US Patent No. 5,663,106 ('106).