A low power time-domain CMOS temperature sensor

Abstract

The proposed temperature sensor is composed of serial inverter chain and time-to-digital converter(TDC) instead of proportional to absolute temperature(PTAT) and analog-to-digital converter(ADC) for reducing current consumption. The generated temperature dependent delay is compared with temperature insensitive clock. The proposed temperature sensor's temperature resolution is under 0.2°C and draw current is under 800 nA from a 1.8V supply voltage. The simulated temperatre range is 0∼100°C and temperature error is -within ±2°C. The simulated results are trimmed by 2-point calibration. The chip is fabricated using a 0.18 µm CMOS process.