A CMOS Temperature Sensor With Versatile Readout Scheme and High Accuracy for Multi-Sensor Systems

Abstract

In this paper, a smart CMOS temperature sensor with a versatile readout scheme is presented. A digital-assisted readout solution is proposed to improve the compatibility of the circuit and maintain the performance of a traditional smart temperature sensor. In addition, the potential multi-operating points of the analog front-end are analyzed, and a compact start-up circuit is designed to make the analog front-end work properly. Fabricated in a standard 0.13 $\mu \text{m}$ CMOS process, the proposed temperature sensor occupies a silicon area of 0.29 mm2 and draws a current of $95~\mu \text{A}$ from a 2 to 3.6 V supply voltage at the room temperature. Measured results show that the proposed design has the inaccuracy of ± 0.47 °C ( $3\sigma $ ) from −40 °C to 125 °C after a single-point temperature calibration. It achieves a resolution of 16 mK at a conversion time of 5.12 ms and a supply sensitivity of less than 0.05 °C/V. Thanks to the versatile readout scheme, the proposed temperature sensor is compatible with multi-sensor systems where the readout-circuitry can be shared between different input signals.