A 3.4-pW 0.4-V 469.3 ppm/°C Five-Transistor Current Reference Generator

This letter presents a near-zero power constant with temperature (CWT) current reference generator that utilizes only live transistors in standard CMOS technology. By operating an off-state nMOS transistor as a self-biased current source driving an nMOS transistor in the subthreshold region, a temperature stabilized voltage is generated, which is then buffered by a third nMOS and applied to a gate-leakage transistor. To improve line regulation, a lifth nMOS operating in off-state is employed, constructing a live-transistor (5T) IREF generator. Measurement results of 13 5T IREF generator samples fabricated in 65-nm CMOS revealed an average temperature coeflicient of 469.3 ppm/°C from -20 °C to 60 °C when operating at a supply voltage of 0.4 V. Measured with a supply voltage from 0.4 to 1.2 V, the proposed 5T IREF generator achieved an average line regulation of 2.5%/V. The 5T IREFgenerator consumed 3.4 pW at 20 °C and occupied an area of 0.008 mm2, thereby enabling a near-zero-power, low-cost CWT IREF generation for next-generation Internet of Things applications.