EL SEGUNDO, CA. August 1998 - International Rectifier Corp. (IRF/NYSE) announced today that the Board of Patent Appeals of the U.S. Patent and Trademark Office notified the company of its decision upholding the company's U.S. Patent No. 4,959,699, believed by IR to cover all cellular power MOSFETs and IGBTs (two types of advanced power transistors), as well as many integrated circuits that incorporate cellular power MOSFETs. The '699 patent serves as one of the cornerstones of more than 20 licensing agreements under the company's field effect transistor patents.

The same patent is central to the company's legal action charging Samsung Semiconductor Inc. and Samsung Electronics Co. Ltd. with patent infringement. As part of that litigation, the U.S. Federal District Court in Los Angeles already issued a preliminary injunction affecting the sale of IGBTs designated by Samsung part number SGL60N90D (June 9, 1998). The Patent Board's latest decision upholds claims that International Rectifier believes apply to a much larger portion of Samsung's power transistor product line.

International Rectifier's '699 patent will expire in September, 2007.

International Rectifier is a major worldwide supplier of components and subsystems that convert electrical power to operate power supplies, motor drives, and lighting ballasts. Its patented HEXFET power MOSFETs and IGBTs make IR the world leader in field effect transistors. IR's technological advances improve the performance and energy efficiency of electronic and electrical equipment in automotive, consumer, computer/peripheral, industrial, lighting, telecom, and government/space applications.