A Low-Power CMOS Bandgap Voltage Reference for Supply Voltages Down to 0.5 V

A voltage reference is strictly required for sensor interfaces that need to perform nonratio-metric data acquisition. In this work, a voltage reference capable of working with supply voltages down to 0.5 V is presented. The voltage reference was based on a classic CMOS bandgap core, properly modified to be compatible with low-threshold or zero-threshold MOSFETs. The advantages of the proposed circuit are illustrated with theoretical analysis and supported by numerical simulations. The core was combined with a recently proposed switched capacitor, inverter-like integrator implementing offset cancellation and low-frequency noise reduction techniques. Experimental results performed on a prototype designed and fabricated using a commercial 0.18 mu m CMOS process are presented. The prototype produces a reference voltage of 220 mV with a temperature sensitivity of 45 ppm/degrees C across a 10-50 degrees C temperature range. The proposed voltage reference can be used to source currents up to 100 mu A with a quiescent current consumption of only 630 nA.