Highly linear micropower class AB current mirrors using Quasi-Floating Gate transistors

Abstract

A design approach to achieve low-voltage micropower class AB CMOS cascode current mirrors is presented. Both class AB operation and dynamic cascode biasing are based on the use of Quasi-Floating Gate transistors. They allow high linearity for large signal currents and accurately set quiescent currents without requiring extra power consumption or supply voltage requirements. Measurement results show that dynamic cascode biasing allows a wider input range and a linearity improvement of more than 23dB with respect to the use of conventional biasing. A THD value better than −35dB is measured for input amplitudes up to 100 times the bias currents. Two class AB current mirror topologies are proposed, with slightly different ways to achieve class AB operation and dynamic biasing. The proposed current mirrors, fabricated in a 0.5µm CMOS technology, are able to operate with a supply voltage of 1.2V and a quiescent power consumption of only 36µW, using a silicon area <0.025mm2.