23.2 A 40 A Shunt-Based Current Sensor with ±0.2% Gain Error from -40°C to 125°C and Self-Calibration
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Abstract
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 circC) 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 (I textREF) source for shunt self-calibration. By employing a continuous-time (CT) front-end, it achieves an input noise density of 14textnV/sqrttextHz while consuming only 280mu A, making it > 10times more energy efficient than prior art [1], [2], with comparable gain error (pm0.2%) over a wider current (pm 40A) and temperature (-40 circC to 125 circC) range.