The TCM4400E global system for mobile communication (GSM) baseband RF interface circuit is designed for GSM 900 , PCS1900, and DCS 1800 European digital cellular telecommunication systems. It performs the interface and processing of voice signals, generates baseband in-phase (I) and quadrature (Q) signals, and controls the signals between a digital signal processor (DSP) and associated RF circuits. The TCM4400E includes a second serial interface for use with a microcontroller. Through this interface, a microcontroller can access all the internal registers that can be accessed through the DSP digital serial interface. This option is intended for applications in which part of the L1 software is implemented in the microcontroller.