BIPOLAR LSI CODEC FOR PCM EQUIPMENT.

A 1-chip LSI CODEC that can operate at speeds from single- to multi-channel on a time-shared basis was fabricated using the MOS bipolar process. The CODEC, which includes two sample and hold circuits, uses one common companding DA converter for tranceiving and its companding law can be switched between A-law and mu -law with an external control pin. Coupled with its analog compatible enhanced speed I**2L for successive approximation logics, the CODEC achieves ample speed for a multichannel time-shared operation up to 8 channels as an encoder only, 16 channels as a decoder only and 4 channels for bidirectional operation. Measured results show that S/N//Q and gain tracking characteristic curves are well within the limits specified in CCITT Recommendation G712.