A High-Precision, Low Offset Voltage, Delay Stability Comparator

Abstract

Comparators are widely used in DC/DC converters, some major design challenges are capabilities of the comparators to operate accurately, stably at all conditions. This paper proposes a voltage comparator circuit Based on 0.5μm BiCMOS process. In order to work stable in all temperatures, two kinds of temperature coefficient bias current are used, one is for BJT differential pair, and another is for CMOS differential pair. By using three-level amplifier and the special output stage to get a voltage gain of 123dB. The maximum voltage gain variation is 4dB which is fluctuated within 1.7% when the temperature from-40°C to 125°C. Compared with conventional PWM comparators, its advantages are fast response, low offset voltage, and delay stability. The proposed comparator is applied to a buck converter.