A 0.9-V 6400-μm² Resistor-Based Temperature Sensor With a One-Point Trimmed 3σ Inaccuracy of ±0.64 °C from −50°C to 125 °C

This brief describes a compact and precise resistive temperature sensor based on a frequency-locked loop (FLL) intended for thermal monitoring in system-on-chips. The FLL incorporates a switched-capacitor loop filter improving the sensor’s inaccuracy and FLL outputs are converted into a digital code with an edge-combined counter for efficient frequency-to-digital conversion. A prototype sensor is fabricated in 65-nm CMOS process and occupies only 6, $400 \mu \text{m} ^{\mathrm{ 2}}$ . It achieves a one-point trimmed $3\sigma $ inaccuracy of ±0.64 °C over a wide temperature range of −50 to 125 °C. Operating at 0.9 V supply, it consumes $40 \mu \text{W}$ and achieves 2.2 mK resolution in a 1-ms conversion time, which corresponds to a resolution FoM of 0.19 pJ $\cdot \text{K} ^{\mathrm{ 2}}$ .