Picowatt 0.3-V MOS-only voltage reference based on a picoamp cascode current generator

Abstract

A tiny-size ultra-low voltage CMOS voltage reference operating at quiescent picoamp scale has been proposed in this paper to fit the high standards of modern wireless microsystems. Without any on-chip resistor or operational amplifier (opamp), the sensitive core of the proposed voltage reference is protected from the glitches of the power supply via a temperature-dependent cascode current source biased by the output. The upper limit of the output temperature range is broadened by the increased diode leakage current of the proposed current generator. The case study deals with implementation of the new circuit and post-layout simulation results in 0.18-μm CMOS technology. The circuit occupies an active area of 629 μm2, consuming almost 690 pA from 0.3 V minimum supply voltage at room temperature. The untrimmed 229 mV output voltage exhibits an average temperature coefficient (TC) of 47.39 ppm/°C over the −40 °C–140 °C temperature range. The line-voltage sensitivity (LS) is 0.17%/V when the input supply is varied from 0.3 V to 1.8 V, and can be improved by 9 × if the lower limit of the power supply is increased to 0.4 V. The DC power supply ripple rejection (PSRR) is lower than −80 dB for the line voltage beyond 0.5 V.