Abstract
A monolithically-integrated two-dimensional (2D) magnetic field sensor consisting of two difference structures (DSІ and DSII) is proposed in this paper. The DSІ and DSII are composed of four silicon magnetic sensitive transistors (SMST1, SMST2, SMST3 and SMST4) and four collector load resistors (RL1, RL2, RL3 and RL4). Based on the magnetic sensitive principle of SMST, the integrated difference structure can detect magnetic fields’ component (Bx and By) along the x-axis and y-axis, respectively. By adopting micro-electromechanical systems (MEMS) and packaging technology, the chips were fabricated on a p-type <100> orientation silicon wafer with high resistivity and were packaged on printed circuit boards (PCBs). At room temperature, when the VCE = 5.0 V and IB = 8.0 mA, the magnetic sensitivities (Sxx and Syy) along the x-axis and the y-axis were 223 mV/T and 218 mV/T, respectively. The results show that the proposed sensor can not only detect the 2D magnetic field vector (B) in the xy plane, but also that Sxx and Syy exhibit good uniformity.
Highlights
At present, magnetic field sensors include the Hall element, giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), magnetic sensitive diodes (MSD), silicon magnetic sensitive transistors (SMST), and so on [1,2,3,4]
When the bias current was 100 mA and the supply voltage was 2.7 V, the results show that the optimum magnetosensitivity (SRI ), optimum sensitivity (S), minimum nonlinearity error (NLE) and minimum offset were 0.385 V/(A·T), 9.564 mV/T, 4.03% and 18.85 mV, respectively
In 2013, Guo-Ming Sung et al proposed a vertical Hall device (VHD) based on the combined magnetic effects between a bulk magnetotransistor (BMT), a vertical magnetoresistor (VMR) and a vertical magnetotransistor (VMT), which was sensitive to the magnetic induction in the plane [10]
Summary
Magnetic field sensors include the Hall element, giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), magnetic sensitive diodes (MSD), silicon magnetic sensitive transistors (SMST), and so on [1,2,3,4]. Based on the above references, the characteristics of sensitivity, uniformity and cross interference have been thoroughly studied These properties have been improved by technological improvement and structural optimization. In order to improve the magnetic sensitivity and uniformity, we integrated two difference structures (DSI and DSII) with four SMSTs and four collector resistors as a magnetic sensitive structure along the direction of the x-axis and y-axis, respectively. On this basis, theoretical analysis shows the effect of the magnetic field component (Bx and By ) on the output voltage of the proposed sensor. The IC -V CE characteristics of SMSTs and the magnetic sensitivity of DSI and DSII were tested, and we studied the uniformity and cross interference of the magnetic sensitivity (Sxx and Syy )
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