A CMOS ANALOG-DIGITAL AUDIO PROCESSOR FOR A PORTABLE RADIOTELEPHONE

This paper describes a mixed analog-digital integrated circuit specifi cally designed to realize the audio processing functions needed for a portable radiotelephone (PRT) application. Multirate signal processing techniques are used to reduce the capacitance spread, and hence the o verall silicon area of the chip, as well as to minimize the settling r equirements of the amplifiers for lower power consumption. This, toget her with a programmable power-saving control circuitry also incorporat ed on-chip, considerably extends the lifetime of the battery. A semi-c ustom design methodology is employed to implement such an application- specific integrated circuit (ASIC) in a 3-mum CMOS double-poly process ing technology. Experimental results are presented to demonstrate the correct operation and functionality of the prototype chips.