A low voltage low output impedance CMOS bandgap voltage reference

A low voltage bandgap architecture is proposed. The opamp in the proposed bandgap is used for both generating the output reference voltage (V_ref) and achieving low output impedance. To allow V_ref to have different values within the supply voltage limits, a transconductor is proposed and used in conjunction with the opamp to supply the biasing currents of the bipolar transistors. A 1V, ~33.5μW bandgap design example based on a 0.18μm CMOS process is presented. For a load current between 0mA and 50mA with a temperature range in between -20°C and 100°C, the variations on the nominal V_ref (632.94mV) was within -0.38% and +0.11% with a load regulation of <; 3.54μV/mA for different process corners. The temperature coefficient was <; 19.8ppm/°C. V_ref could be designed to have a value in between ~0.25V and ~0.85V and was limited only by the opamp output swing.