SINGLE-CHIP N-M. O. S. CODEC.

Design of a new Codec is reported for use in telephone systems and similar applications which converts low-frequency (audio) signals into pulse-code modulated signals and vice versa. The Codec is divided into three main functional blocks; the transmit channel, which consists of an A/D converter (encoder), the receive channel, which consists of a D/A converter (decoder), and a section containing circuits common to the two channels. Each block has its own clock and data, and can operate independently of the other two. The blocks can also operate asynchronously, but the two channels are normally synchronized so that fewer clock lines need to be distributed.