A 0.9-V supply, 16.2 nW, fully MOSFET resistorless bandgap reference using sub-threshold operation

A nano-watt bandgap voltage reference (BGR) is presented. To provide a low-voltage and low-power BGR, the circuit has been biased in the sub-threshold region; thereby, drawing a few nano-amperes current from the source, has been achieved. In order to reduce die area and also power consumption, instead of resistor, transistor is used. To generate PTAT voltage, self-cascode composite structure is used for the transistors. The results from post-layout simulation using 0.18-mu m standard CMOS technology show that the proposed BGR circuit generates a reference voltage of 625 mV, obtaining temperature coefficient of 13 ppm/ degrees C in the temperature range of - 25 degrees C to 110 degrees C. The simulated power supply rejection ratio is 42 dB. Fully designed with MOS transistors, the circuit draws 18 nA from a 0.9-V supply. The active area of the proposed BGR is 0.00067 mm(2).