A STEREO ASYNCHRONOUS DIGITAL SAMPLE-RATE CONVERTER FOR DIGITAL AUDIO

The design of an asynchronous digital sample-rate converter for digita l-audio applications is presented. The theory of asynchronous sample-r ate conversion is discussed using a signal-processing model that is ba sed on highly interpolated input samples. A novel closed-loop address- tracking system is disclosed that solves the problem of clock-edge arr ival estimation while at the same time providing a low-jitter selectio n of the correct polyphase filter for each output sample. Sample-rate ratio changes of up to 2:1 in either direction can be accommodated. Th e proposed signal-processing algorithm has been implemented in a 0.8-m um CMOS technology. Measurement results show excellent agreement with theory.