A −40 °C to 120 °C, 169 ppm/°C Nano-Ampere CMOS Current Reference

Abstract

This brief presents a nano-ampere CMOS current reference (CCR) for low power application with a wide temperature range from −40°C to 120°C. The current reference is generated by the division of a temperature-independent voltage and resistance in a simple way. The low temperature-independent voltage is generated based on the threshold voltage difference between two same-type NMOS transistors with different channel lengths working in the subthreshold region, while the temperature-independent resistance is made up by two poly resistors, whose temperature coefficients are opposite. By designing a low voltage to allow for a small resistance, the CCR circuit takes a small chip area while generating nano-ampere current. The proposed CCR circuit was implemented in a standard 0.18- ${\mu }\text{m}$ CMOS process and its active area is 0.054 mm2. Among the measured 10 samples, the average output current is 11.6 nA and the average temperature coefficient is 169 ppm/°C.