Curvature-compensated CMOS bandgap reference with 1.8-V operation

The typical current mode bandgap voltage circuit is built up by two currents, one is proportional to V
_BE
across the base-emitter of the parasitic BJT in CMOS process, the other is proportional to V
_T
. The negative temperature coefficient of the former term compensates the positive temperature coefficient of the latter. But the temperature dependence of V
_BE
is not linear and therefore doesn't completely cancel the linear temperature dependence of DeltaV
_BE
, 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 I
_NL
to cancel the nonlinear term of I
_VBE
. 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