A CMOS Temperature Sensor Based on a Chopped Continuous-Time Delta-Sigma Modulator

Abstract

A resistor-based temperature sensor with a 2nd-order 1-bit continuous-time delta-sigma modulator (CTDSM) to realize an energy-efficient temperature sensor is presented. The chopping technique is applied to alleviate the offset and flicker noise of the 1st-stage amplifier. A finite impulse response (FIR) filter is incorporated in the feedback path to mitigate noise fold-back due to chopping operation. The proposed circuit, implemented in 0.18-μm CMOS, consumes 183.6 μW from a 1.8-V supply. With a single conversion time of 333.3 μs, the temperature resolution is less than 3.71 m°C (1δ), which leads to a Figure of merit (FoM) of 0.84 pJ°C2. The 3δ temperature inaccuracy of 8 chips under a range of −40 °C to 100 °C is 3.8 °C after 1-point and batch calibration.