A High-Linearity Shunt-Based In-Line Current Sensor With Self-Heating Compensation and 14.4 V 2 MHz PWM Rejection

Abstract

This article presents a cost-effective, fully integrated shunt-resistor-based in-line current sensor that delivers high linearity and strong PWM rejection, enabling precise current measurement and control in dynamic driving systems like robotics, imaging, and audio. To mitigate the self-heating of the on-chip shunt resistor, which degrades linearity, a location-based thermal compensation technique is proposed. This technique reduces self-heating-induced distortion, improving THD+N by up to 23.6 dB over the full operating range without calibration. In addition, a floating transconductance (FG_m) stage is introduced to reject the high dv/dt, high-voltage PWM components at the switching node of the power stage, enabling robust current sensing with this PWM common mode voltage. The prototype is implemented in a 180 nm BCD process and demonstrates a peak THD+N of–87.2 dB and a dynamic range (DR) of 89.1 dB. It achieves up to 2 MHz, 14.4 V PWM rejection with 2 V/ns dv/dt, and supports a ±6 A bidirectional current range.