A DC to 25 MHz Current Sensing Interface for Hall-Effect Sensor

A dc to 25 MHz readout interface (ROI) design for Hall-effect sensors is presented. The current sensing system is comprised of a high-bandwidth aluminum gallium nitride/gallium nitride (AlGaN/GaN) or aluminum gallium arsenide/gallium arsenide (AlGaAs/GaAs) Hall-effect sensor and an on-chip fast ROI. The interface makes use of multisignal paths, utilizing a two-way current spinning technique to minimize offset at dc while using high- pass filtering to eliminate offset at the high frequencies. The usage of two sensors and signal paths makes it possible to take advantage of the full bandwidth of the sensor. The summed output is the desired high- bandwidth signal proportional to the current or the magnetic field to be detected. The system achieves a rise time of 40 ns in response to a current pulse, resulting in a noninvasive fast current detection solution. The die area of the ROI is 2850 by 200 mu m . When testing with a current trace at 1.5 mm from the sensor and using a ferrite-core magnetic field concentrator, the current sensitivity is observed to be 12.7 mV/A.