SigmaTel, Inc. (NASDAQ:SGTL), the Austin, Texas-based market leader for portable MP3 player technologies, today officially filed a formal complaint with the International Trade Commission (ITC) against Actions Semiconductor, based in Zhuhai, Guangdong, China, seeking to halt the infringement of SigmaTel's intellectual property rights. SigmaTel asserts that Actions Semiconductor infringed multiple SigmaTel patents in the design of System-on-Chip controllers for the Portable Digital Music player market. Actions' products have recently begun shipping into the United States retail market as components of MP3 players. SigmaTel seeks to stop shipment of products into the U.S. that use Actions Semiconductor integrated circuits or "ICs."...