LOW-NOISE MAGNETORESISTIVE SENSOR HAVING MULTI-LAYER MAGNETIC MODULATION STRUCTURE

摘要

A low-noise magnetoresistive sensor having a multi-layer magnetic modulation structure that consists of a substrate (1) and a multi-layer magnetic modulation structure array located on the substrate (1). The multi-layer magnetic modulation structure comprises two ferromagnetic layers, an upper and a lower layer, each of which is comprised of a soft ferromagnetic material, and one layer of conductive metal in the middle. The two ends of the multi-layer magnetic modulation structure (21, 22, ..., 2N) are connected using conductive strips (31, 32, ..., 3N-1) to form a two-port excitation coil. Adjacent multi-layer magnetic modulation structures have opposite current directions. A magnetoresistive sensing unit is located above or below the multi-layer magnetic modulation structures, centered in the gap between the magnetic modulation structures. The sensitive direction of the magnetoresistive sensing units is perpendicular to the long direction of the multi-layer magnetic modulation structures. The magnetoresistive sensing unit array (41, 42, ..., 4N-2) is electrically connected to form a magnetoresistive sensor, and the sensor is connected to the sensor bond pads (7, 8). When measuring an external magnetic field, an excitation current is applied to the excitation coil, and the output of the voltage or current signal of the magnetoresistive sensor is demodulated to produce a low-noise voltage signal. This low-noise magnetoresistive sensor provides a compact structure with high sensitivity, low noise, and small size.