Automatic tuning of RC filters and fast automatic gain control for CMOS low-IF transceiver

Abstract

Automatic tuning of RC filters and fast automatic gain control (AGC) of cascaded programmable amplifiers were proposed and verified by a 0.18 /spl mu/m CMOS prototype IC. The tuning circuit includes a dummy 1st-order filter, a comparator and a simple digital circuit and tunes /spl plusmn/28 % time-constant variation of filters within /spl plusmn/4.4 % accuracy. The AGC circuit adopts a novel feedforward technique with a digital timing control, which enables one-shot gain control and thus a fast settling.