A monolithic NMOS filter and line balance chip

Abstract

A SINGLE CHIP FILTER, designed to replace passive LC and active RC filters in PCM telephony, has been presented earlier’. This paper will describe monolithic NMOS filter and line balance (FAB) chip intended for use in PCM D3/D4 quality line-circuit filtering applications. The FAB chip combines gain and fre uency trimmable transmit and receive switched-capacitor with a number of integrated line-circuit functions. These functions include external software controlled gain and derived from the loop detector circuit and is a function of the loop resistance.