BiCMOS cascaded bandgap voltage reference

Abstract

A bandgap voltage reference with a circuit providing compensation of the thermal nonlinearity for the base-emitter voltage is described. The temperature dependence of V/sub BE/(T) is linearized using, as the bias current, a sum of two currents one of which is proportional to the third degree, and another to the fourth degree of absolute temperature. Two versions of the circuit are given, one is designed for 5 V, and another for 3 V supply voltage. Theoretical calculations show that the thermal instability of the output reference voltage can be reduced down to 0.2 ppm//spl deg/C. The simulation results for the circuits obtained by extraction from the layouts with non-protected pads give the figures of 4 ppm//spl deg/C (5 V power supply) and 8 ppm//spl deg/C (3 V power supply) in the range -50/spl deg/C to 180/spl deg/C.