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

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 autozeroing techniques for sensor interface applications. The design achieves a magnetic residual offset of 85 μT (mean) and 79 μT (1σ), while the offset drifts only 0.68 μT/°C (mean) and 0.27 μT/°C (1σ) 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 μT 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.