A low-voltage low-power bipolar automatic gain control (AGC) for heari
ng instruments that works in the current domain and operates on a sing
le 1.3-V battery is presented. In this AGC a large time constant (50 m
s) is realized on-chip. The AGC consists of a gain cell, a comparator
and a voltage follower. The active circuitry of the AGC has been integ
rated in the DIMES01 process and the total circuit demonstrates operat
ion down to 1 V with only 4 muW power consumption. The compression ran
ge amounts to 38 dB. The AGC has a dynamic range (DR) of 62 dB at the
output over a bandwidth of 10 kHz.