23.2 A 40A Shunt-Based Current Sensor with ±0.2% Gain Error from −40°C to 125°C and Self-Calibration

Low-cost metal (e.g., PCB trace) shunts can be used to make accurate current sensors ($<$ 1 % gain error) [1–3]. However, their reported maximum operating temperature $(85^{\mathrm{\circ}}\mathrm{C})$ is not high enough for automotive applications, and at higher temperatures, shunt resistance may exhibit increased drift, especially at high current levels. This paper presents a metal-shunt-based current sensor with a wide temperature range and a stable on-chip reference current $(\mathrm{I} _{\text{REF}})$ source for shunt self-calibration. By employing a continuous-time (CT) front-end, it achieves an input noise density of $14\text{nV}/\sqrt{}\text{Hz}$ while consuming only $280\mu \mathrm{A}$, making it $> 10\times$ more energy efficient than prior art [1], [2], with comparable gain error $(\pm0.2\%)$ over a wider current $(\pm 40\mathrm{A})$ and temperature $(-40^{\mathrm{\circ}}\mathrm{C}$ to $125^{\mathrm{\circ}}\mathrm{C})$ range.