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.