帶通功率放大器設計

Bandpass Power Amplifier Design

黃雅純(Ya-chun Huang)

指導教授 ： 林祐生

國立中央大學/資訊電機學院/電機工程學系/碩士(2012年)

摘要

本論文的研究方向為微波帶通功率放大器的研製，藉由整合帶通濾波器與功率放大器，希望能達到元件的多功能化並縮小發射端電路面積，以提高射頻前端的系統整合度。實現方式為將帶通濾波器的設計引入功率放大器的匹配電路設計中，並以兩個設計實例驗證成果。
首先，1.95 GHz A類帶通功率放大器設計部分，使用二階Chebyshev響應來進行輸出與輸入端帶通濾波器的設計，為了增加設計的自由度，採用阻抗轉換器與導納轉換器的架構實現此電路，以利用集種元件實現於微波基板上。量測結果顯示，帶通功率放大器的30 dB止帶頻寬可達5倍頻，對於2次與3次諧波有45 dBc與60 dBc以上的抑制。
接著進行1.95 GHz AB類帶通功率放大器設計，設計與實現方式皆與前一電路相同。從量測結果可看出帶通功率放大器的25 dB止帶頻寬可達5倍頻，對於2次與3次諧波有50 dBc以上的抑制，4次與5次諧波也有70 dBc以上的抑制。
本研究將帶通濾波器設計於功率放大器的匹配電路中，並提出了完整的設計流程，由電路實作結果可看出在電路面積差不多的情況下，帶通功率放大器不僅將功率放大，更具有高選擇度、寬止帶與諧波抑制效果。

關鍵字

功率放大器 ； 帶通濾波器

並列摘要

This thesis focuses on the design of novel microwave bandpass power amplifier. By integrating the functions of bandpass filter and power amplifier, novel multi-functional RF component is achieved, which can help reduce the circuit size and improve the level of integration of RF transmitter. The proposed method of realization is based on introducing the bandpass filter design flow into the matching network design of power amplifier. Two design examples are present to validate the effectiveness of proposed design method and the circuit performance.
First, at 1.95 GHz class A bandpass power amplifier is implemented, in which the 2nd-order Chebyshev bandpass response is used to design the input and output matching networks. In order to enhance the design flexibility of bandpass matching network, immittance inverters are adopted in the proposed circuit structure. The bandpass power amplifier is implemented on printed circuit board using packaged HEMT and chip components. Due to the bandpass matching networks used, very good harmonic suppression is achieved. The 30 dB upper stopband rejection is up to 5f0. Especially, the second and the third harmonic levels are below −45 dBc and −60 dBc, respectively.
Next, the 1.95 GHz class AB bandpass power amplifier design is implemented using the same technique. The measured results show that 25 dB upper stopband rejection is also up to 5f0. Notably, the second and the third harmonic levels are below −50 dBc and the fourth as well as the fifth harmonic levels are below −70 dBc.
The proposed bandpass power amplifier is composed of the functions of bandpss filter and power amplifier with complete and systematic design procedure. Compared with conventional ones, the propsoed bandpass power amplifier features better selectivity, wider upper stopband, and better harmonic suppression with about the same circuit area.

並列關鍵字

Power Amplifier ； Bandpass Filter

參考文獻

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