A BJT-based CMOS Temperature Sensor With a ±0.4° 9C 3σ-inaccuracy From-0° 4C to +10° 5C

초록

This paper presents a BJT-based CMOS temperature sensor designed for an extended temperature range. In the sensing frontend, a /3-compensation technique is employed to mitigate the effects of the finite current gain (/3) of PNP transistors. Additionally, bitstream-controlled dynamic element matching (DEM) is applied to address mismatch errors in current sources and PNP transistors. The readout circuit based on 1-bit second-order incremental Delta Sigma ADC is configured with a minimum number of sampling switches to mitigate the impact of increasing switch leakage currents at high temperatures. Furthermore, system-level low-frequency chopping (CHL) is implemented digitally, removing the need for extra switches. Fabricated in a 0.18-mu m CMOS process, the proposed sensor occupies an area of 0.63 mm2. The sensor is accurate to within +/- 0.94 degrees C (3 sigma) after one-point trimming from-40 degrees C to +150 degrees C. It achieves a resolution figure of merit (FoM) of 21.17 pJ<middle dot>K2 at 27 degrees C, with a conversion time of 20 ms and a power consumption of 22.23 mu W from a 1.8 V supply.

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