TECHNOLOGY : Silicon Systems Sues Exar Second Time for Patent Infringement

After a brief reconciliation, they’re back in court.

Silicon Systems Inc., a manufacturer of customer computer chips in Tustin, has filed a second patent-infringement lawsuit in federal court against competitor Exar Corp. in San Jose.

The suit, filed in federal court in San Francisco, alleges that Exar infringed on a patent despite a settlement agreement reached in October, 1991, between the two companies.

Silicon Systems charged that Exar copied the circuitry of Silicon Systems’ patented chip that enhances recovery of data in computer hard disk drives.

The data recovery chip costs less than $10 but is used widely in computers. It governs the process in which a reading device retrieves data on magnetic media, amplifies the signal and extracts the data in a code that a computer can understand.

Silicon Systems sued Exar over the same issue in December, 1990, but the companies reached an agreement that gave Exar a license to use the technology.

Silicon Systems is seeking a court injunction to stop Exar from making or selling the chip and is also seeking monetary damages.

Exar officials would not comment.