A wide range dB-linear variable gain CMOS amplifier

A 10 MHz 6-stage CMOS amplifier with variable gain from 0 dB up to 80 dB is presented. Differential inputs and outputs provide a high PSRR. The gain is controlled by a dB-linear differential voltage. At a single power supply voltage of 5 V the maximum linear input and output swing is 600 mV. The amplifier has been fabricated in a 1.6µm CMOS process and covers a chip area of 0.72 mm². Measurements of a fully integrated automatic gain control are presented.