Differential amplifier circuit for enhancing small voltage signals

Abstract

A differential amplifier circuit suitable for amplifying a faint signal, such as the output of a magnetic sensor including a Hall element. The differential amplifier circuit includes switching units which are provided at the input and output terminals of a differential amplifier to switch the polarity of the input and output signals, and low pass filters which are provided at the output terminals to remove the switching frequency component from the output signal, thus working as an ideal amplifier with no offset voltage. Furthermore, by alternating the polarity of driving current of the Hall element for inverting the polarity of the input signal of the differential amplifier, an error voltage of the Hall element caused by location error of the output electrodes and the voltage drop across them can be eliminated at the same time.

Dependencies are inferred from the claim text.