A self-calibrating on-chip temperature sensor for supply error based on PAFM technology

Abstract

This paper focuses on an on-chip integrated frequency-domain temperature sensor using a 0.18 μm CMOS process. Programmable load delay units and power feedback pulse width modulation technology are employed to reduce errors caused by process variations and power supply non-idealization. In detail, this paper uses a power average feedback modulator (PAFM) to detect changes in the power supply by converting the supply voltage into a fixed periodic pulse with varying duty cycle. In addition, the quantization time of the frequency digital conversion module is adjusted linearly, effectively reducing the power sensitivity of the temperature sensor from 0.0809°C/mV to 0.0099°C/mV. The sensor shows a measured inaccuracy of -0.66°C to +0.68°C from -70°C to 120°C, and occupies a compact area of 0.022 mm².