A 60nW voltage reference circuit generating 1.0V using BJTs and subthreshold MOSFET

Abstract

An ultra low power voltage reference circuit generating 1.0V and consuming 60nW from power supply of 1.3V is fabricated in 0.13um CMOS 1P6M process. It can work from battery voltage of 1.3V to 3.6V. The proposed reference circuit uses BJTs and a MOSFET operating in subthreshold region to generate temperature stable reference voltage. The reference circuit proposed in this work generates 1.0V unlike the conventional bandgap circuit where it is 1.2V. Conventional bandgap circuits use baseemitter voltage (VBE) of BJT as CTAT signal while proposed reference circuit uses gate-source voltage (VGS) of a sub-threshold region biased MOSFET. The reference voltage is an estimate of threshold voltage extrapolated up to 0°K. Subthreshold MOSFET used in this circuit is a high voltage transistor having threshold voltage of 0.65V at room temperature, hence it generates 1.0V. Using a low voltage MOSFET having threshold voltage 0.35V, this circuit generates reference voltage of 0.5V.