A Fast T&H Overcurrent Detector for a Spinning Hall Current Sensor With Ping-Pong and Chopping Techniques

Abstract

This paper presents a fast spinning-current Hall sensor with 568 ns overall delay for sub-microsecond overcurrent detection (OCD) in a magnetic current sensor. By combining the continuous-time chopping techniques and discrete-time dynamic offset cancellation techniques, the spinning frequency of 250 kHz does not limit the sensor speed. The proposed track-and-hold (T&H) ping-pong comparators extend the usage of auto-zeroing techniques for sensor interface applications. The design achieves a magnetic residual offset of $85~\mu \text{T}$ (mean) and $79~\mu \text{T}$ ( $1\sigma$ ), while the offset drifts only $0.68~\mu \text{T}/^{\circ }\text{C}$ (mean) and $0.27~\mu \text{T}/^{\circ }\text{C}$ ( $1\sigma$ ) from −40 °C to 150 °C. In addition, a background switched-capacitor filter breaks the limitation of high-frequency errors on conventional correlated double sampling techniques. The design thus reduces the input-referred noise to $136~\mu \text{T}_{\mathrm {rms}}$ with a bandwidth of 1.7 MHz, while consuming at least 30% less power than the other state-of-the-art designs. Moreover, the analog stress compensation with temperature coefficient (TC) correction guarantees an overall threshold error within ±4% over package stress and temperature.