A 840-µm² low-power all-MOS temperature sensor front-end with real-time voltage calibration

Abstract

This letter presents an 840µm² 557nW temperature sensor front-end designed for system on chip (SoC) thermal monitoring. The circuit is implemented using MOS transistors exclusively, which enhances its scalability with process technologies and compatibility with digital circuit processes. To address MOSFETs circuit’s process variation issues, a differential voltage readout scheme is employed. Dynamic element matching (DEM) is used to minimize mismatch of the circuit. The sensor is self-referenced, eliminating the need for an external reference voltage. Real-time voltage calibration (RVC) scheme is used to improve the performance of supply sensitivity. It is fabricated using a 55nm process, and the measurement results showed an error of -0.69/0.85℃ across 16 samples over a temperature range of 0℃ to 100℃ with a low-cost one-point calibration at 30℃, while the maximum supply sensitivity is 3.3℃/V.