A CMOS integrated circuit for the digitally-controlled analog processing of dual-channel TV sound

A single-supply 4-μm silicon-gate CMOS IC for the processing of dual-channel TV sound transmitted with the West German two-carrier system is presented. Both transmission-mode identification and audio signal processing are performed. The processing functions are performed with continuous-time and sampled-data analog techniques and are digitally controlled by an external microprocessor through a serial bus, thus eliminating any need for analog controls or manual adjustments. The measured performance of the IC has demonstrated the effectiveness of the approach. Full integration of the required functions in a limited silicon area was achieved while retaining advantages resulting from the software programmability, in particular the elimination of any need for analog controls and manual adjustments, which result in improved factory productivity, better TV-set serviceability, and higher long-term stability and low temperature dependence of processing parameters