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

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 <inline-formula> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process, the proposed temperature sensor occupies a silicon area of 0.29 mm<sup>2</sup> and draws a current of <inline-formula> <tex-math notation="LaTeX">$95~\mu \text{A}$ </tex-math></inline-formula> 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 (<inline-formula> <tex-math notation="LaTeX">$3\sigma $ </tex-math></inline-formula>) 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.

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