Characteristics of a Magnetic Field Sensor with a Concentrating-Conducting Magnetic Flux Structure

Abstract

A magnetic field sensor with a new concentrating-conducting magnetic flux structure (CCMFS) is proposed in this paper, using a silicon-on insulator (SOI) Hall element fabricated by complementary metal oxide semiconductor (CMOS) technology as a magnetic sensitive unit. By fixing the CCMFS above the Hall element packaged on a printed circuit board (PCB) based on inner-connect wire bonding technology, a non-magnetized package can subsequently be obtained. To analyze the inner magnetic field vector distribution of the CCMFS, a simulation model was built based on a finite element software, where the CCMFS was processed using Ni-Fe alloys material by a low speed wire-cut electric discharge technology. The test results showed that the measurement of magnetic fields along a sensitive and a non-sensitive axis can be achieved when VDD = 5.0 V at room temperature, with magnetic sensitivities of 122 mV/T and 132 mV/T in a testing range from −30 mT to 30 mT, respectively. This study makes it possible to not only realize the detection of magnetic field, but also to significantly improve the sensitivity of the sensor along a non-sensitive axis.

Magnetic Micro Sensors with Two Magnetic Field Effect Transistors Fabricated Using the Commercial Complementary Metal Oxide Semiconductor Process

“…The MMS had a sensitivity of 0.69 V/T in the x-axis MF and a sensitivity of 0.55 V/T in the y-axis MF. The sensitivity of the MMS exceeded that of Li [16]. Osberger [19] presented an MMS fabricated using a standard CMOS process.…”

“…Many MMSs have also been developed using the standard CMOS process. For example, Li [16] developed an MMS with a conducting magnetic structure using a CMOS process. The MMS was bonded on a printed circuit board.…”

“…The experimental results showed that the MMS had a sensitivity of 6.5 mV/T in the x-axis MF and a sensitivity of 6.5 mV/T in the y-axis MF. The sensitivity of the MMS was lower than that of Li [16] and Lin [18]. A fluxgate MMS, which was presented by Lu [21], was produced using CMOS-MEMS technology.…”

“…The MMS was a 16 × 16 array of the Hall element, and the average sensitivity of the MMS was 0.140 mV/mT. The sensitivity of MMS approached that of Li [16] but was smaller than that of Lin [18].…”

“…These magnetic micro sensors [16][17][18][19]21,23,25,26] fabricated by CMOS technology were 1-axis MF sensors. The MMS developed by Lin [18] was a three-axis sensor, but its cross-sensitivity was high because the structure of the MMS had only one magnetotransistor.…”