Analog base band processor with trimming-free filters for CDMA/FM cellular phone systems

This paper presents an analog base band processor for dual-mode code division multiple access (CDMA)/FM cellular phone systems. The processor interfaces between the intermediate-section and the digital processing circuitry of the telephone. By employing an unique filter circuitry technology, the precise and stable CDMA/FM filter characteristics in the RX/TX blocks have been realized with a trimming-free procedure. This analog base band processor has been designed and fabricated by using a 0.8 μm pure bipolar process named ECLA with npn type transistors performance with f_T as high as 14 GHz. By such technologies, its power consumption is reduced to as low as 132 mW at the CDMA RX/TX mode