A 1770-μ m² Leakage-Based Digital Temperature Sensor With Supply Sensitivity Suppression in 55-nm CMOS

This article presents a leakage-based digital temperature sensor with reduced supply sensitivity for on-chip thermal management. The sensor, featured with a novel supply sensitivity suppression mechanism, performs the temperature-to-frequency conversion by a leakage-dominated ring oscillator (LDRO) with exponential temperature dependence. Thanks to the proposed robust and reconfigurable Schmitt-trigger-based delay cell, both NMOS and PMOS leakage-based sensors can be evaluated in a single design. Fabricated in a standard 55-nm CMOS digital process, the proposed digital temperature sensor occupies a silicon area of only 1770 μm2and can operate under a supply ranging from 0.8 to 1.3 V, with the supply sensitivities of 2.53-5.22 °C/V and 2.84-5.76 °C/V in two working modes at room temperature, respectively. Measurement results show that the sensor achieves an inaccuracy of ±0.70 °C (3σ) from -40 °C to 125 °C after two-point calibration.