Texas Instruments Incorporated
Transimpedance amplifier-based reduction of hall sensor parasitic impedance

Abstract:

A first amplifier has an input to receive a Hall-signal output current from a first Hall element and has an output to output feedback current in response to the received Hall-signal output current. The Hall-signal output current is impeded by an impedance of the first Hall element. The feedback current is coupled to counterpoise the Hall-signal output current at the input, and a voltage at the output is an amplified Hall output signal. A second amplifier generates a high-frequency portion output signal in response to a difference between the amplified Hall output signal and a Hall-signal output signal from a second Hall element. A filter reduces high-frequency content of the high-frequency portion output signal and generates an offset correction signal. A third amplifier generates a corrected Hall signal in response to a difference between the amplified Hall output signal and the offset correction signal.