US Patent 9041389 Hall measurement system with rotary magnet

One or more embodiments are directed to a motor configured to rotate at least one magnet at a first frequency, a sensor configured to generate a reference signal of the at least one magnet's rotation, and a lock-in detection system configured to receive the reference signal, supply an excitation current at a second frequency to a device under test, measure a voltage from the device under test and demodulate the second frequency, and demodulate the first frequency from the measured voltage using the reference signal to obtain a Hall voltage associated with the device under test.