Low temperature coefficient CMOS voltage reference based on subthreshold operation

In this paper, a new low power, low temperature coefficient CMOS Voltage Reference Circuit independent of temperature and supply voltage is presented. The voltage reference circuit uses the V_GS difference between two MOSFETs operating in the weak-inversion region to generate the voltage with positive temperature coefficient. The reference voltage is obtained by combining the weighted V_GS difference with weak-inversion V_GS voltage, which has a negative temperature coefficient. This circuit provides a nominal reference voltage of 621 mV, a temperature coefficient of 11.5 ppm/°C in [20°C-120°C] from a 1.5 V supply voltage. The line regulation of the reference voltage is 6 mV/V when the supply voltage is increased from 1.5 V to 3 V.