具有功率分配比可調性之平衡式正交耦合器

Abstract

本論文為功率分配比可調性之平衡式正交耦合器首次設計及實現出來，該耦合器僅使用一個控制電壓和兩個變容二極體來控制耦合器的功率分配比。理論上，在調整功率分配比的所有情況下，該耦合器可以達成差模完美阻抗匹配及完美隔離度、完美共模及模態轉換的抑制。特別在耦合器裡增加一個多餘的變數，使頻寬更優化。 在實現上，工作頻率為1 GHz時，功率分配比可調整範圍為-3.24~18.39 dB。在此範圍內，最大的Insertion Loss約為-1.39 dB，差模反射係數與隔離度皆小於-15 dB，而差模輸出相位差為90°±5°，共模輸出散射參數皆小於-20 dB，而模擬與量測的值幾乎一致。

In this thesis, a balanced-to-balanced quadrature coupler with tunable power-dividing ratio is designed and implemented for the first time. This coupler uses only one control voltage and two varactors to control power-dividing ratio. For all tuning states, this coupler can theoretically realize perfect impedance matching and port isolation for the differential-mode operation, perfect common-mode rejection, and cross-mode conversion suppression. This coupler, especially, is given one more variable to optimize bandwidth. Practically, the range of power-dividing ratio can be tuned form -3.24 to 18.39 dB at the operating frequency 1 GHz. In this range of power-dividing ratio, the largest insertion loss reads about -1.39 dB, and both differential mode of reflection coefficient and isolation are less than -15 dB. As for differential mode of output phase, it reads 90 ° ± 5 °, and the common mode output suppressions are less than -20 dB. Measured and simulated results are in good agreement.