A ±50-A Shunt-Based Current Sensor With ±0.2% Gain Error From-40 °C to 125 °C

초록

This paper presents a shunt-based low-side current sensor that consists of an off-chip PCB trace shunt resistor and a readout circuit. A temperature-dependent reference voltage, composed of a proportional-to-absolute-temperature voltage and a tunable complementary-to-absolute-temperature (CTAT) voltage, is used to compensate for the shunt's temperature-dependent resistance variation. To compensate for both the first-and higher-order temperature dependence of the shunt resistor, this paper proposes a CTAT voltage generation technique based on a temperature-coefficient (TC)-adjustable current source and a CTAT resistor. This technique enables the shunt's temperature-dependent resistance variation to be compensated over a wide temperature range using only a single batch-calibration parameter. In addition, this paper proposes a dual-mode amplifier for the first integrator of the discrete-time Delta Sigma ADC-based readout circuit to improve power efficiency and reduce sensitivity to PVT variation. The current sensor was fabricated in a 0.18-mu m CMOS process occupying 0.43 mm(2) and consumes 374 mu W from a 1.8-V supply. Over the automotive temperature range (-40 C-degrees to 125 C-degrees) and for currents up to +/- 50 A, it achieves a gain error of +/- 0.2% after a one-point gain trim at room temperature.

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