A 0.075 mm2 BJT-based temperature sensor with a one-point trimmed 3σ inaccuracy of ±0.97 °C from −40 °C to 120 °C

Abstract

This paper presents a bipolar junction transistor (BJT)-based CMOS temperature sensor for high accuracy, small-scale area, and low power consumption. A structure with a feedback amplifier biasing NPN transistors, combined with dynamic element matching (DEM), is proposed to avoid the effects of errors arising from the limited current gain of substrate PNP transistors in deep-submicron processes. Moreover, the switched capacitor (SC) integrators employ two single-stage cascode amplifiers for alternating cyclic sampling and integration, effectively simplifying the circuit design and reducing the operating voltage. The proposed sensor is fabricated with a standard 180 nm CMOS process, occupying an active chip area of 0.075 mm². It consumes 39.1 $\mu$W of power at room temperature, operating with a supply voltage of 1.8 V. The measurements indicate that the sensor exhibits an inaccuracy of ±0.97 °C (3$\sigma$) across the temperature range from −40 °C to 120 °C following a single-point temperature calibration.