頻寬可調制之微波低通濾波器

Bandwidth-Tunable Microwave Low Pass Filter

黃家政(Chia-Cheng Huang)

指導教授 ： 陳念偉

元智大學/電機通訊學院/通訊工程學系/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00276

摘要

本論文提出一個由共平面波導(coplanar waveguide, CPW)組成之低通濾波器(low pass filter, LPF)，該濾波器具有相當高之頻寬可調範圍以及寬頻壓抑特性。該濾波器採用微波共振器結合變容二極體，以設計可調制(tunable)之微波共振器，此共振器可於低電壓操作下調制共振頻率，並使用該共振器實現共平面波導之低通濾波器。相較於至今所提出之相關設計，本文提出一個在設計上相對直觀的方法。經由實作與量測驗證，本文所提出之濾波器在低電壓操作下(0至5 V)具有相當高的半功率頻寬可調範圍(>65%)，在頻寬改變的過程中，通帶介入損耗皆小於0.7 dB，而濾波器選擇度(selectivity)幾乎維持不變，此外，該濾波器也具有寬頻壓抑之特性。

關鍵字

低通濾波器 ； 頻寬可調制

並列摘要

A coplanar waveguide low-pass filter (CPW-LPF) with high bandwidth tunability and wideband rejection is demonstrated. Compared to the reported design approaches, a relatively straightforward design with varactor-tuned microwave resonators is proposed for the realization of the tunable CPW-LPF. It is shown that the presented tunable CPW-LPF has a wide bandwidth tuning range(>65%) with a small bias tuning(0 to 5 V), low passband insertion loss(<0.7 dB), as well as wideband rejection. Furthermore, the filter roll-off remains unchanged while the cut-off frequency is tuned. The proposed tunable CPW-LPF is experimentally verified and expected to find applications in modern communication systems.

並列關鍵字

Low pass filter ； Tunable

參考文獻

[1] I. C. Hunter and J. D. Rhodes, “Electronically tunable microwave bandpass filter,” IEEE Trans. Microwave Theory Tech., vol. MTT-30, pp.1354–1360, Sep. 1982.

[2] B.-W. Kim and S.-W. Yun, “Varactor-tuned combline bandpass filter using step-impedance microstrip lines,” IEEE Trans. Microwave Theory Tech., vol. 52, no. 4, pp. 1279–1283, Apr. 2004.

[3] S.-J. Park and G. M. Rebeiz, “Low-loss two-pole tunable filters with three different predefined bandwidth characteristics,” IEEE Trans. Microwave Theory Tech., vol. 56, no. 5, pp. 1137-1148, May 2008.

[4] J. Lee and K. Sarabandi, “An analytic design method for microstrip tunable filters,” IEEE Trans. Microwave Theory Tech., vol. 56, no. 7, pp. 1699-1706, Jul. 2008.

[5] M. A. El-Tanani and G. M. Rebeiz, “A two-pole two-zero tunable filter with improved linearity,” IEEE Trans. Microwave Theory Tech., vol. 57, no. 4, pp. 830-839, Apr. 2009.