A 19-nW sub-bandgap reference with 15ppm/°C temperature coefficient

Driven by the increasing research interest in micro-power devices such as implantable medical devices with battery operation and wirelessly powered wearable devices, voltage reference circuit which consumes power in the nW range has become important. In this paper, a 19-nW sub-bandgap reference circuit designed in 0.18-μm CMOS process is presented. The sub-bandgap reference utilizes the difference of the gate-to-source voltage between a thick and a thin gate MOSFET to generate the temperature independent reference voltage output. Post-layout simulation shows that the sub-bandgap reference generates an output voltage of 201 mV with temperature coefficient of 15.4ppm/°C. It achieves a line regulation of 2%/V and a PSRR of -48dB at 10 kHz frequency. The functionality of the circuit has been verified in measurement.