MOS only nano-watt sub-bandgap voltage reference

This paper presents a nano-watt bandgap voltage reference (BGR). The self-cascode structure is provided as a proportional-to-absolute-temperature (PTAT) voltage. Due to the low slope of the PTAT voltage, a voltage divider consisting of five similar MOSFET transistors is presented. The resulting output voltage will be one-fifth of the complementary-to-absolute-temperature voltage and four-fifths of the PTAT voltage. All MOSFETs are standard CMOS transistors biased in the sub-threshold region where one of them is utilized as a diode. Post-layout simulation results using the standard 0.18 mu m CMOS process show a nominal output voltage of 0.132 V. The power consumption is 12.7 nW at 0.7 V of the power supply. The average temperature coefficient (TC) is about 28.5 ppm/degrees C over a temperature range of 0 degrees C-100 degrees C. The proposed BGR occupies a small area of 0.00083 mm(2).