A universal single chip analog CMOS speech processor for analog mobile cellular phones

A single-chip analog CMOS speech processor for advanced mobile-phone system (AMPS), total access communication system (TACS), NMT900, and NMT450 mobile cellular phones is represented. The circuit includes all necessary speech processing functions including compressor, expander, and deviation limiters. It includes a multi-frequency generator and buzzer driver for DTMF and general purpose signaling. The circuit is integrated in a standard 2- mu m CMOS double-poly double-metal process and requires 32.8 mm/sup 2/.<>