Cirrus Logic Prevails in Key Patent Infringement Suit; Mixed-Signal 'Delta-Sigma' Technology Validated.

AUSTIN, Texas--(BUSINESS WIRE)--May 17, 1999--

The Crystal Semiconductor division of Cirrus Logic Inc. (Nasdaq:CRUS) today won a key jury verdict in a patent infringment suit involving the company's popular Delta Sigma technology.

Delta Sigma technology plays an important role in the conversion of analog signals from sources such as microphones and sensors into the digital data streams utilized by audio products, modems, and other digital systems.

The defendants in the suit were OPTi Inc. of Milpitas, Calif., TriTech Microelectronics Pte Ltd. of Singapore and TriTech Microelectronics International Inc. of San Jose, Calif. The jury indicated the patents were valid, that both OPTi and Tritech infringed, and that Tritech's infringement was willful. Cirrus Logic's Crystal division will be asking the court to issue an injunction whereby sales of the TriTech and OPTi products employing this technology are barred within the United States.

"Obviously, we are pleased by the victory," said David French, president and CEO of Cirrus Logic. "Our portfolio of over 850 United States patents is one of our company's most important assets. We intend to defend our markets by vigorously asserting this intellectual property against infringing competitors. Over 50 of these patents are in the Delta Sigma area. In this particular case, we expect the parties will abide by the jury's decision and not use Cirrus Logic's technology."

The suit involved Patent Nos. 4,746,899; 4,851,841; and 5,220,483. The specific parts that infringed upon these patents were the OPTi 82C931 series and TriTech TR88015 series. One defendant, OPTi Inc., has already withdrawn from the market all of its products involved in the litigation.

"This judgement affirms the status of Cirrus Logic's Crystal Semiconductor division as the pioneer and leader in a technology that has now become pervasive," said Craig Ensley, vice president of marketing for Cirrus Logic. "Delta Sigma is generally considered the A/D and D/A technology of choice for signal processing and precision applications." He noted that this technology relies on standard CMOS wafer processing, and facilitates the design of high-integration systems-on-a-chip (SOCs) for the coming wave of information appliances and digital consumer products.

Since Cirrus Logic's seminal Delta Sigma patent for A/D conversion was granted in 1988, the company has extended the technology from its original use in modems to also include audio devices for computer, consumer and professional electronics, and for a wide variety of industrial applications. Starting in 1989, the company has also extended this proprietary technology to also include Delta Sigma D/A converters.

Eric Swanson, Cirrus Logic Chief Technical Officer and co-inventor of the '899 patent, said, "As one of the pioneering companies in high-integration CMOS mixed-signal design, it's gratifying to see years of hard work rewarded by this result."

Cirrus Logic is a premier supplier of high-performance analog circuits and advanced mixed-signal chip solutions. The company's products, sold under its own name and the Crystal product brand, enable system-level applications in mass storage, audio and precision data conversion. Additional information about Cirrus Logic is available at www.cirrus.com.

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