本研究主要預測GaAs pHEMT於不同負載條件之非線性響應。X參數模型由PNA-X量測而得。50歐姆大訊號X參數模型預測史密斯圖的輸出功率特性被限制於0.5"Z" _"0" 到2"Z" _"0" 。也就是X參數模型預測能力被限制於1/3反射係數，因此藉由量測特定負載之大信號X參數模型來預測史密斯圖的等功率圓特性。等功率圓與最佳負載阻抗之預測能力可應用於功率放大器設計。

This thesis proposes a method to predict nonlinear responses of GaAs pHEMT with X-parameter models by tuning load impedances. The X-parameter models are directly measured by the nonlinear vector network analyzer instrument. The power prediction by using X-parameter models with "R" _"L" of 50 Ohm is limited in the regime from 0.5"Z" _"0" to 2"Z" _"0" . Due to the restriction of reflection coefficients in 1/3, the power contour characteristics on the Smith chart should be determined by measuring X-parameters at different load impedances. The prediction of power contours and the optimum load impedance is useful for power amplifier design.

論文審定書 i
致謝 ii
中文摘要 iii
Abstract iv
目錄 v
圖目錄 vii
第一章 緒論 1
1.1 簡介 1
1.2 章節規劃 2
第二章 雙埠網路 4
2.1 傳輸線原理 4
2.2 網路模型 6
2.3 散射參數矩陣(Scattering Matrix) 7
2.4 廣義散射參數 9
2.5 大訊號散射參數(X-Parameter)基本原理 10
第三章 行為模型量測系統與驗證 13
3.1 簡介 13
3.2 電晶體電流電壓特性量測 13
3.3 高頻功率量測 15
3.4 大訊號散射參數量測與驗證 17
第四章 X參數模型預測能力 21
4.1 簡介 21
4.2 大訊號輸出電壓波之預測能力 21
4.3 X參數模型之預測能力 28
4.4 X參數模型之預測最大功率特性之阻抗 36
第五章 結論 39
參考文獻 40

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