A dual vertical Hall latch with direction detection

A chopped vertical Hall sensor for detecting the speed and motion direction of magnetic encoder wheels is presented. It achieves low offset and low noise even in the case of the low intrinsic sensitivity and high voltage dependency of offset common to the vertical Hall devices. It features a combination of spinning and stacking techniques together with mixed sampled and continuous time processing, capable of reaching 36μT switching noise at 25°C and typical 0.25mT offset in a temperature range from -40 °C to 150 °C. Additionally, it employs sensitivity compensation of mechanical stress for reducing packaging influences on the sensor. This allows switching point measurement at wafer level, based on injecting current in an integrated wire on chip.