A Positive Feedback-Based Op-Amp Gain Enhancement Technique for High-Precision Applications

Abstract

A power-efficient, voltage gain enhancement technique for op-amps has been described. The proposed technique is robust against Process, Voltage and Temperature (PVT) variations. It exploits a positive feedback-based gain enhancement technique without any latch-up issue, as opposed to the previously proposed conductance cancellation techniques. In the proposed technique, four additional transconductance-stages (gm stages) are used to boost the gain of the main gm stage. The additional gm stages do not significantly increase the power dissipation. A prototype was designed in 65[Formula: see text]nm CMOS technology. It results in 81[Formula: see text]dB voltage gain, which is 21[Formula: see text]dB higher than the existing gain-boosting technique. The proposed op-amp works with as low a power supply as 0.8[Formula: see text]V, without compromising the performance, whereas the traditional gain-enhancement techniques start losing gain below a 1.1[Formula: see text]V supply. The circuit draws a total static current of 295[Formula: see text][Formula: see text]A and occupies 5000[Formula: see text][Formula: see text]m2 of silicon area.