US chip-related intellectual property company Opti has accused AMD of infringing three of its patents, all centring on techniques microprocessors can use to predict cache memory access requirements.

Opti's lawsuit, filed with the US District Court for the Eastern Texas, claims AMD is shipping CPUs that use such techniques and that AMD does so without its permission. It also claimed AMD "induced" other companies to infringe the patents too - in other words, by selling allegedly infringing processors to its customers.

The three patents at issue are US patents 5,710,906, 5,813,036 and 6,405,291, all entitled "Predictive Snooping of Cache Memory for Master-Initiated Accesses". The first two patents were awarded in 1998, the third in 2002. The later patents represent continuations of the first one.

Opti wants a jury trial, it said, and will ask the court to ban the sale of the AMD chips it claims infringe its patents and award damages.

Opti has form here. Just over two years ago, it filed a very similar complaint against Nvidia. The two companies reached a settlement in August this year: Nvidia will pay Opti $750,000 a quarter from February 2007 onwards for a three-year period, or simply cough up a one-off payment of $7m, Opti's most recent filing with the US Securities and Exchange Commission reveals. ®