3.8 A 0.65V 900µm² BEoL RC-Based Temperature Sensor with ±1°C Inaccuracy from −25°C to 125°C

To maintain high-performance computing capacity and prevent chip overheating, it is essential to minimize the gap between on-die thermal measurements and the actual temperature at hotspots. This relies primarily on the inherent accuracy of the temperature sensors and the distance to the heat sources. The latter factor is constrained by the physical footprint of the sensor, which is generally determined by the complexity of the sensor’s biasing and analog-to-digital conversion (ADC) schemes. In advanced FinFET nodes, the scaling of the supply voltage $( \mathrm{V}_{DD})$ and the decreasing of passive device types are other critical challenges for digital hot-spot sensors. Typical current-bias BJT sensors still need $\mathrm{V}_{DD}\ge 1\mathrm{V}$ [4–6]. A sub-1V capacitive-bias bulk-diode sensor has been reported in [9], but the extra keep-out zone between the bulk-diode and nearby PMOS logics may be required due to different N-well biases. Poly-resistor-based sensors [2, 3] can reach comparable accuracy to that of BJT sensors, but these resistors will not be available in advanced FinFET nodes.