Joint news release by Infineon Technologies and SigmaTel

SigmaTel and Infineon Bring Enhanced Connectivity to Portable Media Players; Companies Will Jointly Develop Bluetooth Solutions Optimized for Digital Multimedia Devices

Austin, Texas and Munich, Germany – March 7, 2006 – SigmaTel, Inc. (NASDAQ: SGTL), a leader in mixed-signal multimedia semiconductors, and Infineon Technologies AG (FSE/NYSE: IFX), a leading communication semiconductor company, today announced that they have entered into an agreement to offer Bluetooth® solutions for portable digital multimedia devices. Under the terms of the agreement, the companies will jointly develop a Bluetooth chip that is optimized for use in digital multimedia devices based on SigmaTel’s portable multimedia System on Chip (SoC) solutions. The new chip will make use of SigmaTel’s optimized radio architecture and Infineon’s expertise in Bluetooth technology, chip design, CMOS process technology, and manufacturing know-how. SigmaTel and Infineon believe this solution will enable widespread adoption of Bluetooth technology in even the most cost sensitive, power and space constrained applications, such as MP3 players or stereo headsets. The new chip will be exclusively marketed by SigmaTel. “Wireless technologies are strategic to SigmaTel and our customers, who view wireless connectivity as the next ‘must have’ feature that will enhance the end-user experience. SigmaTel is working on both internal developments as well as relationships with world-class companies like Infineon to offer customers wireless capabilities in conjunction with our industry-leading SoC solutions,” said Ron Edgerton, president and CEO of SigmaTel. “After an extensive evaluation, SigmaTel determined that Infineon offers the best performing, low power Bluetooth solution on the market. Infineon’s technology will allow us to meet our customers’ needs today, and will be integral in helping SigmaTel develop tomorrow’s leading-edge wireless technologies for portable multimedia devices.” “The new Bluetooth chip is optimized for low power consumption and minimum size,” said Thomas Pollakowski, vice president and general manager of the Connectivity business unit at Infineon Technologies. “Based on our state-of-the-art chip IP and excellent CMOS manufacturing capability, we are one of the world’s very few semiconductor companies offering radio frequency (RF) foundry services enhanced with RF IP blocks. We are pleased to provide connectivity solutions that will contribute to the success of Sigmatel’s portable SoC products.” Infineon’s BlueMoon UniCellular supports basic and enhanced data rate together with minimized power consumption and excellent RF performance, providing an outstanding receiver sensitivity of -90 dBm (decibel milliwatts). Prior to the availability of the new optimized Bluetooth solution, SigmaTel will begin offering Infineon’s BlueMoon UniCellular (PMB8753) Bluetooth 2.0 solution featuring Enhanced Data Rate (EDR) functionality as part of its STMP3600 MP3 player Reference Design Kits (RDKs). The reference design will provide a turnkey system, including the Bluetooth upper stack software and relevant Bluetooth profiles. The design will also be BQB certified and UnplugFest tested, reducing customer development costs and time to market. SigmaTel’s customers can expect a smooth transition from the PMB8753 to the optimized SigmaTel Bluetooth solution.   The addition of Bluetooth to SigmaTel solutions will allow MP3 and portable multimedia device manufacturers to provide seamless interoperability with the rapidly expanding universe of Bluetooth-enabled products, including stereo headsets, headphones, cellular handsets, and car audio systems. New and compelling usage scenarios include: Wireless streaming of high-quality digital audio from a portable player to a car stereo, including control of the portable player from the car stereo’s built-in user interface. No cables, adapters, or custom installations are required. Sharing of one wireless headset between a portable player and a cell phone, allowing the user to effortlessly switch between phone calls and music playback. Using wireless headphones for sports or other activities, eliminating the dangling wire, and allowing for convenient control of the portable player directly from the headphone. SigmaTel's portable multimedia SoC solutions provide high quality audio playback for portable devices such as MP3 players, language learners, and jukeboxes. The company's solutions offer market-leading benefits, including as much as a 30 percent lower bill of materials cost, Hi-Speed USB 2.0, 70 hours of battery life on a single AA battery, and a 14.5 square cm PCB footprint enabling incredibly small form factor products. With flexible software support and upgrade options, the SigmaTel SoC solution offers support for MP3 and WMA audio formats as well as WMA Digital Rights Management (DRM) security. Availability SigmaTel’s STMP3600 RDK with the Infineon PMB8753 Bluetooth solution is now sampling to SigmaTel's beta customers for production in the second quarter. Customers interested in ordering the RDK should contact their local sales office listed on the SigmaTel web site at www.sigmatel.com or contact sales at sales@sigmatel.com. For more information on SigmaTel, please visit www.sigmatel.com. For more information on Infineon’s Bluetooth and wireless solutions, please visit www.infineon.com/wireless. About SigmaTel SigmaTel, Inc. a fabless semiconductor company headquartered in Austin, Texas, designs, develops, and markets proprietary, analog intensive, mixed-signal ICs for a variety of digital multimedia products in the consumer electronics and computing markets, including portable compressed audio players, such as MP3 players, notebook and desktop PCs, digital video cameras, multi-function peripheral products, digital televisions, and set-top boxes. SigmaTel provides complete, system-level solutions that include highly-integrated ICs, customizable firmware and software, software development tools, reference designs, and applications support. The Company’s focus is on providing system-level solutions that enable customers to rapidly introduce and offer electronic products that are small, light-weight, power-efficient, reliable, and cost-effective. SigmaTel is ISO 9001:2000 certified and is committed to providing customers with high performance, quality products along with superior customer service. Cautionary Language: This press release contains forward-looking statements based on current SigmaTel expectations. The words “expect,”  “will,” “should,” “would,” “anticipate,” “project,” “outlook,” “believe,” “intend,” and similar phrases as they relate to SigmaTel or future events are intended to identify such forward-looking statements.  These forward-looking statements reflect the current views and assumptions of SigmaTel, but are subject to various risks and uncertainties that could cause actual results to differ materially from expectations.  A number of important factors could cause actual results to differ materially from those in the forward-looking statements, and there will be events in the future that SigmaTel is not able to accurately predict or control. For a discussion of factors that could impact SigmaTel's financial results and cause actual results to differ materially from those in the forward-looking statements, please refer to recent SigmaTel filings with the SEC, particularly the Form 10-K that was filed on February 24, 2006. SigmaTel is a registered trademark of SigmaTel, Inc. All other products and brand names as they appear in this release are trademarks or registered trademarks of their respective holders. All specifications may be changed without notice.

About Infineon Infineon Technologies AG, Munich, Germany, offers semiconductor and system solutions for automotive, industrial and multimarket sectors, for applications in communication, as well as memory products. With a global presence, Infineon operates through its subsidiaries in the US from San Jose, CA, in the Asia-Pacific region from Singapore and in Japan from Tokyo. In fiscal year 2005 (ending September), the company achieved sales of Euro 6.76 billion with about 36,400 employees worldwide. Infineon is listed on the DAX index of the Frankfurt Stock Exchange and on the New York Stock Exchange (ticker symbol: IFX). Further information is available at http://www.infineon.com