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.

@en

Accurate current sensing is critical in many industrial applications, such as battery management and motor control. Precise shunt-based current sensors have been reported with gain errors of less than 1% over the industrial temperature range (-40°C to 85°C) [1]–[4]. However, since they are intended for coulomb counting, their bandwidth is limited to a few tens of Hz, making them unsuitable for battery impedance or motor-current sensing. This paper presents a current sensor with a wide (10kHz) bandwidth and a tunable temperature compensation scheme (TCS), which allows it to be flexibly used with different types of shunts while maintaining high accuracy. A low-cost room-temperature calibration scheme is proposed to optimize gain flatness over temperature by exploiting the shunt's self-heating at large currents. Over the industrial temperature range and a ±25A current range, it achieves state-of-the-art gain error (±0.25^%) with both low-cost PCB and stable metal-alloy shunts.@en

This article presents a versatile shunt-based current sensor for battery management applications. It digitizes the current-induced voltage drop across an external shunt resistor with the help of a 2 nd -order delta-sigma ( ΔΣ ) ADC, whose summing node is implemented as a low-noise capacitively coupled amplifier. To compensate for the shunt’s finite temperature coefficient (TC), the TC of the ADC on-chip voltage reference can be tuned. As a result, the sensor maintains high accuracy when used with low-cost high TC shunts, such as PCB traces, as well as with more expensive low TC shunts, such as metal-alloy resistors. Optimal gain flatness over temperature is achieved by a two-current room-temperature TC tuning scheme, which exploits the shunt’s self-heating at high current levels. Fabricated in a standard 0.18- μ m CMOS process, the current sensor occupies 0.36 mm 2 and draws 265 μ A from a 1.8-V supply. Over the industrial temperature range ( − 40 ∘ C to 85 ∘ C) and a ± 25-A current range, it achieves the state-of-the-art gain error ( ± 0.25%) with both PCB (1.6 m Ω ) and metal-alloy (2 m Ω ) shunts. With these shunts, it achieves 5.3-mA/4.3-mA (rms) resolution in a 10-kHz bandwidth.@en