Advanced Power Technology Hosts Senator Gordon Smith for Silicon Carbide Launch; Commitment to Silicon Carbide Fabrication Facility Formally Kicked Off at APT's Bend, Oregon, Site

Business Wire, April 21, 2006

BEND, Ore. -- Advanced Power Technology, Inc. (Nasdaq:APTI), a leading supplier of high performance power semiconductors, has formally launched the construction of its SiC manufacturing fab with an inauguration event featuring a keynote address by U.S. Senator Gordon Smith (R-OR).

This event follows the previous announcement (February 22, 2006) by APT of a licensing agreement with Northrop Grumman Corporation regarding certain silicon carbide manufacturing technology.

Other local dignitaries and senior company management were present, including James J. Peterson, Chairman and CEO of Microsemi Corporation. Microsemi (Nasdaq:MSCC) is in the final stages of acquiring APT.

Senator Smith lauded both companies for their commitment to advanced semiconductor technology which has been developed, in part, for the Defense Department's electronics programs. Senator Smith said, "The efforts here at APT are playing a key role in supporting our efforts to maintain peace around the world through the supply of components for communications, monitoring, and surveillance systems."

The driving force for the adoption of silicon carbide for military as well as civilian applications is the need to reduce weight and size of power control and management systems and their associated support equipment, in particular cooling systems and heat dispersing packaging. SiC semiconductors have demonstrated large performance advantages in numerous test beds over the most advanced silicon components.

Military applications include radar, hybrid power systems, electric power control and distribution, electronic jamming, and wideband communications systems.

Potential non-military applications that can benefit from silicon carbide's military-level performance include hybrid vehicles, electric power transmission, computer/servers, medical systems, and alternative energy.

About Advanced Power Technology:

With operations in Bend, Oregon, Santa Clara, California, Montgomeryville, Pennsylvania, Boulder, Colorado, and Bordeaux France, Advanced Power Technology is a leading supplier of power semiconductors for RF, Microwave, Linear, and Switchmode Applications. For additional information on Advanced Power Technology, visit its website at www.advancedpower.com.

About Microsemi Corporation:

Microsemi Corporation, with corporate headquarters in Irvine, CA, is a leading designer, manufacturer and global supplier of high performance analog and mixed signal integrated circuits and high reliability semiconductors. For additional information on Microsemi Corporation, visit its website at www.microsemi.com.

About the Acquisition:

Microsemi Corporation has filed a registration statement (including a prospectus) with the SEC for the issuance of Microsemi shares to APT shareholders in connection with the acquisition of APT. The prospectus in that registration statement, and the other documents Microsemi has filed with the SEC in connection with that registration statement, contain additional material information about APT, Microsemi, and the terms of the acquisition. You may get these documents for free by visiting EDGAR on the SEC Web Site at www.sec.gov. Alternatively, you may request Microsemi to send you the prospectus by calling 949-221-7101.

Safe Harbor Statement

Except for historical information contained herein, the matters discussed in this press release are forward-looking statements made pursuant to safe harbor provisions of the Private Securities Litigation Reform Act of 1995. APT cautions that such statements, including statements concerning the potential benefits of this contract, are subject to a number of uncertainties, and actual results may differ materially. Factors that could affect the Company's actual results include the ability of subcontractors to meet their delivery commitments; unfavorable changes in industry and competitive conditions; the Company's mix of product shipments; the accuracy of customers' forecasts; the effectiveness of the Company's efforts to control and reduce costs; and other uncertainties disclosed in the Company's filings with the Securities and Exchange Commission, including our Form 10-K filed on March 8, 2005. The Company assumes no obligation to update the information in this release.