An Integrated Interpolative PCM Decoder

The technique of time-averaging interpolation provides a means for obtaining telephone quality digital-to-analog conversion using conventional digital integrated-circuit processing. This approach has been adopted in a monolithic circuit that decodes the 8-kHz companded PCM commonly used in voiceband communication systems. The circuit, realized in a standard buried collector bipolar technology, contains 300 integrated injection logic gates together with a current-driven resistive ladder network. The performance of the decoder exceeds typical toll network objectives.