Curvature-compensated CMOS bandgap reference with 1.8-V operation

Abstract

The typical current mode bandgap voltage circuit is built up by two currents, one is proportional to VBE across the base-emitter of the parasitic BJT in CMOS process, the other is proportional to VT. The negative temperature coefficient of the former term compensates the positive temperature coefficient of the latter. But the temperature dependence of VBE is not linear and therefore doesn't completely cancel the linear temperature dependence of DeltaVBE, which is proportional to absolute temperature (PTAT). A curvature-compensated bandgap reference (BGR) with 1.8-V supply voltage is presented, which utilizes the different temperature-dependent emitter of the BJT to obtain the nonlinear current INL to cancel the nonlinear term of IVBE. The simulation results indicate the temperature coefficient (TC) of 8ppm/ degC from -40 degC to 80 degC and a higher power supply rejection ration (PSRR) using 0.18mum CMOS process. A scaled-down bandgap reference voltage can also be obtained by setting the resistor and current mirror in the proposed BGR circuit