A 720 nW Current Sensor with 0-to-15 V Input Common-Mode Range and ±0.5% Gain Error from −40 to 85 °C
Roger Zamparette, Kofi A. A. Makinwa · 2023
This paper presents a nano-power high-side shunt-based current sensor (CS) that digitizes the voltage drop across an on-chip (±1A) or a lead-frame (±30A) shunt. A TC-tunable ADC reference compensates for the shunts’ large temperature coefficient (TC), resulting in ±0.5% gain error from −40 to 85°C. The CS employs a capacitively coupled gm-boosted front-end followed by a CCO-based $\triangle \Sigma$ ADC. Together with a floating input chopper, this results in an input common-mode range (ICMR) of 0-to-15V, the largest reported for a CS implemented in a standard CMOS process. It achieves high energy efficiency (164dB FoM) while consuming only 720nW, representing a $4 \times$ improvement on the state-of-the-art and making this the first ever reported sub-$\mu \mathrm{W}$ smart current sensor.