A 0.8-V, 593-pA Trim-free Duty-cycled All CMOS Current Reference for Ultra-Low Power IoT Applications

This paper presents a sub-1V, 593 pA current reference without using resistors and amplifiers. Temperature compensation is achieved by incorporating a CTAT gate to source voltage and a PTAT drain to source voltage in an NMOS-based sub-threshold biased circuit. The proposed architecture achieves $\pm 3 \sigma /\mu$ process variation of ±0.75%, which enables seamless trim-free operation. Implemented in the 90nm CMOS process, the temperature-compensated current reference achieves a temperature coefficient of 378 ppm/°C over a high-temperature range of −40 to 100°C and a line sensitivity of 0.198%/V in a supply voltage range from 0.8 to 2.5 V. Duty cycling technique is adopted in the CTAT generator to reduce the total average power consumption. The proposed circuit occupies an area of 0.074 mm
²
while consuming only 3.3 nW at a typical corner of 27 °C and 0.8 V supply.