A two-chip CMOS CODEC

A staightforward answer to the per-channel CODEC question has been obtained by a CMOS chip pair operating on the capacitive charge redistribution technique. Designed especially for the D4 channel bank, but ideal for various PCM telephone systems and other applications, the compressing A/D converter and expanding D/A converter produce the standard digital approximation to the μ-255 characteristic without the requirement of external components; all analog and digital functions are integrated. The advantages of the per-channel over the shared CODEC are manifest; the configuration separating the two asynchronous conversions maximizes versatility and ease of application.