New vocoder CMX638 and its application design

This paper introduces a new and high-performance vocoder CMX638 and its application circuit design.The paper also describes the main features,internal structure and control theory of CMX638.The chip is flexible which is integrated analog input/output channels,and can sample analog voice signal directly,or works with external analog-to-digital and digital-to-analog converters.Besides,The chip is a full-duplex vocoder,offering near toll quality voice at very low bit rates.