An Energy-Efficient Capacitively Biased Diode-Based Temperature Sensor in 55-nm CMOS

This work presents an energy-efficient diode-based CMOS temperature sensor. It is based on the capacitively biased diode (CBD) working principle and can operate with a 1-V supply voltage. Instead of using a separate CBD front-end and ADC, a new architecture is proposed in which the CBD front-end is directly embedded into the 1st stage of a 1-bit 2nd-order switched-capacitor $\Sigma \Delta $ -ADC, thereby improving both energy efficiency and accuracy. The circuit was fabricated in a standard 55-nm CMOS process and occupies an active area of 0.021 mm2. The measured inaccuracy is ±0.6 °C ( $3\sigma $ ) from −55 °C to 125 °C after a 1-point calibration. Furthermore, it consumes $2.2~\mu \text{W}$ and achieves a resolution of 15 mK in a conversion time of 6.4 ms, which corresponds to a competitive resolution FoM of 3.2 pJ $\cdot \text{K}^{2}$ .