A 0.8-V Resistor-Based Temperature Sensor in 65-nm CMOS With Supply Sensitivity of 0.28 °C/V

Abstract

A 0.8-V resistor-based CMOS temperature sensor in 65-nm CMOS process with low supply sensitivity is presented. The temperature-to-voltage conversion gain is maximized by utilizing two types of on-chip resistors with positive and negative temperature coefficient. Reusing the resistor sensor frontend as a reference, the voltage generator of the subsequent A/D converter inherently removes the supply dependence of temperature-to-digital conversion. A 10-bit sub-ranging A/D converter employing 5-bit amplifying interpolation D/A converter enables low-voltage and low-noise A/D conversion. Over a range of -45 °C ~ 85 °C, the proposed sensor achieves 0.12 °C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> temperature resolution with a conversion time of 10 μs. After a 2-point calibration, the sensor achieves an inaccuracy of less than +1.6/-1 °C while consuming 47 μW from 0.8-V supply voltage. Measured supply sensitivity is 0.28 °C/V over 0.6 ~1.2 V, which is one of the lowest ever reported among sub-1-V temperature-to-digital converter designs.