Microwatt low-noise variable-gain amplifier

A fully integrated variable gain amplifier circuit is reported in this paper. The amplifier is based on an integrating topology allowing the gain to be controlled by the timing of a clock signal. The recording of physiological signals such as the electroneurogram (ENG) or electromyogram (EMG) is a targeted application. Therefore, low-noise performance and low power consumption are important. Simulated and measured results for a chip fabricated in 0.35μm CMOS technology show a gain range from 10-133 V/V, 169 nV/√Hz input spot noise, a NEF of 10.1 and an active area of 0.017 mm² with a power consumption of 1.44 μW using ±0.9 V supplies.