相位可調之本地震盪架構應用於相位陣列設計

Abstract

本論文利用四層ＰＣＢ製程實現一個相位可調之本地震盪電路，並利用它來設計一個１ｘ４的相位陣列天線。此電路利用相位調變器(vector modulator)來取代昂貴的移相器並證明其能夠準確的控制輸出相位。在電路中我們加入了一個相位校正機制來確保在做相位調整前四路訊號輸出能為同相位。為了使相位調變器有最好的表現，我們也提出了一個方法來最佳化相位調變器的偏壓點。最後，我們利用此電路來設計相位陣列，量測場型顯示此電路能夠準確的控制相位產生出理想的輻射場型。

In this thesis, we propose a 4-channel phased-local circuit with calibration mechanism operating at 2.4 GHz which can be used in phased-array and communication systems. The circuit is realized using 4-layer printed circuit board (PCB) process. We replace expensive RF ferrite phase shifters in the phased-array system with vector modulators. We show in this thesis that vector modulator can control the output phase precisely so it is able to take the place of RF ferrite phase shifter. A phase calibration technique called power combination technique is introduced and verified experimentally. We also propose a method to optimize the bias point of the vector modulator. Finally we use this circuit to design a 4-element phased array and the measured radiation patterns show that this circuit works well as a phased-local oscillator.