A Sub-1-V Linear CMOS Bandgap Voltage Reference

Abstract

Reference voltage generators with low sensitivity to the temperature and supply are commonly required both in analog and digital circuits. Since in the conventional bandgap reference circuit, the output voltage Vref is the sum of the built-in voltage of the diode Vf and the thermal voltage VT of KT/q multiplied by a constant, thus Vref is usually about 1.25 V, which limits a low supply-voltage operation below 1V. This paper presents a precise linear CMOS bandgap voltage reference circuit, which has low supply voltage. The proposed circuit is based on a novel architecture of two currents sum, one of which is proportional to Vf and the other of which is proportional to VT. In addition, by properly selecting input voltage node for operational amplifier, the problem of low supply voltage is solved without complex low supply voltage amplifier. The simulated results for this circuit using Spectre of Cadence Corporation show that the temperature coefficient is about 30.67ppm/degC and that the whole circuit can successfully operate with sub-1-V supply