Patent ID: 6229307
Filing Date: 2001-05-08
Classification: G01R,G11B

Abstract:
A magnetic sensor, comprising:an oscillating circuit for allowing an a.c. magnetic field into a magnetic impedance element made of a ferromagnetic substance, having first and second electrodes on both ends thereof in a longitudinal direction thereof and having a structure in which a bias coil and a negative feedback coil are wound around the ferromagnetic substance through an insulator;a detecting circuit includes a detection diode detecting an a.c. voltage of said magnetic impedance element due to a change in the impedance of the magnetic impedance element which is caused by an applied external magnetic field;a peak holding circuit for holding the peak value of the output voltage of said detecting circuit; andan amplifying circuit for differentially amplifying the output of said peak holding circuit;wherein said detecting circuit allows a constant d.c. current to flow in the detection diode and differentially detects both of the positive side and the negative side of said a.c. voltage.