A high precision CMOS band-gap reference with exponential curvature-compensation

An exponential curvature compensation technique for the high precision band-gap reference (BGR) is presented in this paper, in order to reduce the temperature coefficient (TC) of the traditional band-gap reference, the circuit exploits the temperature characteristics of the current gain ß of BJTs, and generates the current which has non-linear relationship with the temperature to compensate for the higher-order term of the BGR. The compensation circuit adopts a different bipolar current mirror, which can reduce the current error greatly, and the use of native nmos instead of bipolar makes the BGR worked normally under a relatively low supply voltage and the MOST mirrored current can be more accurate. The whole BGR circuits are simulated by Spectre based on chartered 0.18μm 1P5M 1.8V CMOS technology. The simulation shows the temperature coefficient of the output voltage reaches 1.85ppm/K over the military temperature range of -40°C to +125°C, the Power Supply Rejection Ratio (PSRR) of the reference voltage achieves 58.8dB at low frequency(f=0.1Hz), the settling time is 370 ns and the band-gap reference can work normally in all process corners.