應用於巨磁阻磁場感測器之CMOS同步偵測電路設計與特性測定

Design and Characterization of the CMOS Synchronous Detection Circuit for GMR Magnetic Field Sensors

廖唯佐(Wei-Zuo Liao)

指導教授 ： 呂志誠 ； 鄭振宗

國立臺北科技大學/機電學院/機電整合研究所/碩士(2014年)

摘要

巨磁阻感測器的輸出電壓對感測軸上磁場分量的響應為單極性(unipolar)且俱有磁滯(magnetic hysteresis)。以交流磁場驅動並對奇次諧波作同步偵測(synchronous detection)，可使其輸出電壓響應成為雙極性(bipolar)且降低磁滯，成為俱有較大的線性範圍的磁場感測器。本研究探討應用於巨磁阻磁場感測器的交流磁場驅動與同步偵測電路設計及製作， 晶片電路利用CIC提供TSMC 0.18 μm 1P6M CMOS製程來完成，並透過印刷電路板驗證部份的電路架構。電路架構區分激發輸出與感應訊號偵測電路，以10 kHz的方波磁場激發，能偵測巨磁阻感測器的電壓-磁場曲線受到外磁場影響而產生的偏移量，得到與磁場呈線性關係之直流輸出電壓。由於感測器輸出的相位受許多因素影響而變動，電路設計中包含移相器以使輸出電壓響應達到最大。未來將與驅動電路和激磁線圈整合在同一顆晶片上，來探討其特性與應用範圍，以便實現SOC〈System-on-a-chip〉之目的。

關鍵字

巨磁阻 ； 磁滯 ； 磁場調變 ； 同步偵測

並列摘要

The response of GMR output voltage’s component of the vector equal to the sensing axis is unipolar and has a magnetic hysteresis phenomenon. When driving by an AC magnetic field and detecting the odd harmonic signal synchronously, the response of the output voltage becomes bipolar and the magnetic hysteresis decreases. These results make the GMR become a sensor with a wider linear range. In the study we discuss about circuit design and fabrication of AC magnetic field driver and synchronous detection which can be applied on GMR magnetic. We use CIC TSMC 0.18 μm 1P6M CMOS processes to complete the circuit on chip. The circuit contains two parts: Excitation output circuit and sensing signal circuit. We use a 10 kHz square wave as an excitation field, and it can detect the offset between the GMR sensor Voltage-Magnetic curve affected by the outside magnetic. Finally, we can derive the DC output voltage linear to the magnetic field. Because the phase of the sensor output is easy to be affect by many factors, the circuit design contains a phase shifter to enhance the response of output voltage. In the future, we can integrate the driving circuit and the excitation coil into a single chip to complete the target of the “SOC” System on a chip.

並列關鍵字

GMR ； Magnetic Hysteresis ； Field Modulation Techniques ； Synchronous Detection

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