CIRCUIT FOR DRIVING GEOMAGNETIC SENSOR USING IMPEDANCE CHANGE, ESPECIALLY CONSTRUCTING DRIVING CIRCUIT EASILY WHEN AMPLIFICATION UNIT IS DESIGNED WITH ACTIVE DEVICE

摘要

PURPOSE: A circuit for driving the geomagnetic sensor using an impedance change is provided to obtain a high amplification ratio although a cheap active device is used when the amplification unit is constructed with an active device. CONSTITUTION: A circuit for driving the geomagnetic sensor using an impedance change includes an oscillation unit, a bridge unit, a detection unit and an amplification unit. The output voltage of the bridge unit depending on the impedance change in response to the applying of the external magnetic field is converted into a direct current component by using a detector or a low pass filter. The driving circuit amplifies the output voltage of the direct current component.