The Lucent Technologies Microelectronics Group T7570 Programmable PCM Codec with Hybrid-Balance Filter is a programmable PCM codec with an internal hybrid-balance network filter. It provides analog-to-digital and digital-to-analog conversion, as well as the transmit and receive filtering necessary to interface a voice telephone circuit to a time-division multiplexed (TDM) system. Programmable features include transmit gain setting over a 19.4 dB range and receive gain setting over a 19.4 dB range. An internal filter can be programmed to provide hybrid balancing over a wide range of loop impedances for both active and transformer subscriber line interface circuits (SLIC).