Patent ID: 7180311

Claim:
A physical quantity sensing device comprising: a bridge circuit including: first and second input points, to which an AC voltage is applied; first and second output points, which are connected to a differential amplifier; a first bridge arm arranged to electrically connect the first input point to the first output point; a second bridge arm arranged to electrically connect the first output point to the second input point; a third bridge arm arranged to electrically connect the first input point to the second output point; and a fourth bridge arm arranged to electrically connect the second output point to the second input point; wherein the first bridge arm includes a first sensor element, an impedance of which changes with a physical quantity to be measured, and the second bridge arm includes a second sensor element, an impedance of which changes with the physical quantity to be measured; a total impedance of the first and second bridge arms is smaller than that of the third and fourth bridge arms; and each of the first and second sensor elements is a magnetostrictive sensor element, an impedance of which changes according to a given load, and the physical quantity to be measured is a load that has been placed on one of the first and second sensor elements.