本論文主要係使用微波帶通濾波器作為迴授振盪器之選頻元件，以實現低相位雜訊振盪器。因帶通濾波器係以多共振器所合成，可提供較單一共振器佳之品質因數，用以設計振盪器，將可獲致較佳之相位雜訊。該新型振盪器之設計概念、實現方式及量測模擬結果皆於本論文中詳細討論。
本論文第二章將探討迴授振盪器的工作原理，並以實驗方式探討穩定輸出振盪器之穩定條件。另一方面，本論文將採用「複數品質因數」以估算振盪器之整體Q值，因該Q值不僅考慮相位響應隨頻率之導數，亦同時考慮振幅之影響，理論上較為完備，故可較精準推估振盪器之相位雜訊效能。
第三章則將第二章之理論應用於研製低相位雜訊振盪器。本章分別使用段枝帶通濾波器、步階阻抗T型濾波器及網狀式步階阻抗T型濾波器作為振盪器迴路中之選頻元件，以實現低相位雜訊振盪器。因使用步階阻抗T型濾波器所設計之振盪器操作於1 GHz，為了縮小電路面積尺寸，將步階阻抗共振器變形成網狀共振器，使整體振盪器電路縮小約38 %。另一方面，本論文亦使用步階阻抗T型濾波器設計5 GHz振盪器，以驗證該電路架構亦適用於較高之操作頻段。
由本論文之模擬及實驗結果得知，設計以濾波器為基礎之迴授式振盪器，其迴路上選頻濾波器可為具傳輸零點或不具傳輸零點之濾波器，只要該濾波器可提供較單一共振器高之Q值，即可應用於設計低雜訊振盪器。

The aim of this thesis is using a microwave bandpass filter as a frequency selective element of the feedback oscillator to implement a low phase noise oscillator. Since the bnadpass filter is synthesized by multiple resonators, it can provide a batter quality factor for the oscillator design. The detailed circuit design concept, implementation, and verification of the developed oscillator are presented in this thesis.
Chapter 2 will mention the design principle of the feedback oscillator and experimentally verify the condition of the stable oscillation. On the other hand, in this thesis the “complex quality factor” will be used to estimate the Q value of the overall oscillator. This type of Q factor not only considers the derivative with respect to frequency but also the effect of the amplitude. Hence, the complex Q factor is more rigorous to estimate the phase noise performance of the oscillator.
In Chapter 3, the design procedures in Chap 2 will be applied to implement low phase noise oscillators. Instead of using a simple resonator, the stub filter, T-shaped stepped-impedance resonator (SIR) bandpass filter and net-type T-shaped SIR bandpass filter are employed to be the frequency selective elements of the feedback loop oscillators. The oscillator with T-shaped SIR filter is designed at 1 GHz. To reduce the circuit size, the SIR resonator evolves into a net-type resonator to achieve a 38 % circuit size of the original one. On the other hand, this thesis also uses the T-shaped SIR bandpass filter to design a 5 GHz oscillator to demonstrate that the proposed circuit topology is also suitable for the high frequency application.
Based on the simulated and measured results of this thesis, regardless of having transmission zeros, as the bandpass filter can provide a peak value of the complex Q, it can be successfully utilized to design a low phase noise oscillator.

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