A PCM transcoder circuit and remote metering generator for line circuit applications

The two functions are implemented in a custom integrated circuit (TCF). The system, circuit, and technological aspects of the design are described. The TCF chip performs transcoding from/to 13-bit linear to/from 8 bit, A-law or /spl mu/-law companded PCM, for 32 multiplexed channels. Every channel is transcoded, in both directions, every 125 /spl mu/s. A second function of the device is the generation of metering signal bursts free of audible clicks. The metering frequency is selectable at 12 or 16 kHz. In order to achieve low power consumption and minimal area, all the circuitry is implemented using fully dynamic CMOS.