橋式串接高頻電容值量測電路

A Bridge Type Serial-Connected High Frequency Capacitance Measurement Circuit

本文提出一種傳輸線的橋式結構，可應用在表面黏著元件電容值的量測。電路結構因具有對稱性，電路特性以奇偶模分析方式進行以求得。文中並分析不同阻抗及電氣長度之傳輸線和負載電容值，對散射參數S11、S21的影響。本電路可應用在高頻的電容值量測。電路特性並以電磁模擬軟體MicrowaveOffice V2.66及IE3D 進行模擬驗證且使用MATLAB驗證推導公式之正確性，實際電路以FR-4 雙面板製作。由模擬與實際電路量測結果顯示，本電容值測定器之模擬與量測結果均具有良好的一致性。

A novel transmission line bridge planar type circuit for surface mountdevice capacitance measurement in microwave frequency bands isproposed. The circuit possesses a symmetrical structure and can be usedfor even-odd mode analysis to obtain two-port scattering parameters interms of physical parameters. The influences of various transmission lineimpedance values, electrical lengths and load capacitances on the scatteringparameters are widely investigated. The analysed results are helpful foractual circuit design. One prototype circuit has been designed at 1 GHz,simulated by Microwave Office V2.66 and IE3D microwave simulators,and fabricated on FR-4 substrate. The simulated and experimental resultsshow good agreement in the frequency of interest.