An energy-efficient capacitively biased diode-based temperature sensor in 55-nm CMOS
Zhong Tang (Zhejiang University - Hangzhou, TU Delft - Electronic Instrumentation, Eindhoven University of Technology)
Yun Fang (Zhejiang University - Hangzhou)
Xiao Peng Yu (Zhejiang University - Hangzhou)
Nick Nianxiong Tan (Zhejiang University - Hangzhou)
Zheng Shi (Zhejiang University - Hangzhou)
Pieter Harpe (Eindhoven University of Technology)
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Abstract
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 ΣΔ-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 (3σ) from -55 °C to 125 °C after a 1-point calibration. Furthermore, it consumes 2.2 μW 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·K2