Sung Guo-Ming, Lin Wen-Sheng, Wang Hsing-Kuang
Department of Electrical Engineering, National Taipei University of Technology, Taipei 10608, Taiwan.
Sensors (Basel). 2017 Jan 10;17(1):126. doi: 10.3390/s17010126.
This paper presents a distance detector composed of two separated metal-oxide semiconductor field-effect transistors (MOSFETs), a differential polysilicon cross-shaped Hall plate (CSHP), and a readout circuit. The distance detector was fabricated using 0.18 μm 1P6M Complementary Metal-Oxide Semiconductor (CMOS) technology to sense the magnetic induction perpendicular to the chip surface. The differential polysilicon CSHP enabled the magnetic device to not only increase the magnetosensitivity but also eliminate the offset voltage generated because of device mismatch and Lorentz force. Two MOSFETs generated two drain currents with a quadratic function of the differential Hall voltages at CSHP. A readout circuit-composed of a current-to-voltage converter, a low-pass filter, and a difference amplifier-was designed to amplify the current difference between two drains of MOSFETs. Measurements revealed that the electrostatic discharge (ESD) could be eliminated from the distance sensor by grounding it to earth; however, the sensor could be desensitized by ESD in the absence of grounding. The magnetic influence can be ignored if the magnetic body (human) stays far from the magnetic sensor, and the measuring system is grounded to earth by using the ESD wrist strap (Strap E-GND). Both 'no grounding' and 'grounding to power supply' conditions were unsuitable for measuring the induced Hall voltage.
本文介绍了一种由两个分离的金属氧化物半导体场效应晶体管（MOSFET）、一个差分多晶硅十字形霍尔板（CSHP）和一个读出电路组成的距离探测器。该距离探测器采用0.18μm 1P6M互补金属氧化物半导体（CMOS）技术制造，用于感应垂直于芯片表面的磁感应强度。差分多晶硅CSHP使该磁性器件不仅能提高磁灵敏度，还能消除因器件失配和洛伦兹力产生的失调电压。两个MOSFET产生的两个漏极电流与CSHP处的差分霍尔电压呈二次函数关系。一个由电流-电压转换器、低通滤波器和差分放大器组成的读出电路被设计用于放大MOSFET两个漏极之间的电流差。测量结果表明，通过将距离传感器接地可消除静电放电（ESD）；然而，在不接地的情况下，ESD会使传感器灵敏度降低。如果磁性物体（人体）远离磁传感器，并且使用ESD腕带（腕带E-GND）将测量系统接地，则可以忽略磁场影响。“不接地”和“接地到电源”这两种情况均不适用于测量感应霍尔电压。
