Reconfigurable dual-mode bandpass filters

• Main Authors: Ming-Ju Tsou, 鄒明儒
• Other Authors: Wen-Hua Tu
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/81801168975856322212

碩士 === 國立中央大學 === 電機工程研究所 === 100 === Based on dual-mode ring resonator, compact switchable bandpass filter with wide stopband and tunable dual-mode ring bandpass filter are designed individually in this thesis. By using even- and odd-mode technique, we can calculate the value of required coupling capacitor, the positions of transmission zeros, and where 3-dB bandwidth is. When p-i-n diodes are loaded on the circuits appropriately, the proposed filters feature switch abilities. In addition, dual-mode bandpass filter is implemented using mixed lowpass filter so that the circuit size can be miniaturized effectively and widen the stopband further. The overall circuit size is 0.023λg2. The stopband can reach up to 7.7f0 with 20-dB rejection level when the passband is turned on. On the other hand, the stopband is 7.48f0 with 20-dB rejection level when the passband is shut down. In the case of conventional ring resonator, center frequency, coupling coefficients, and external quality factor can be controlled by capacitors separately. Therefore, varactors are used to take the place of capacitors to fabricate the proposed tunable dual-mode ring bandpass filter. Adjust range of center frequency varies from 0.88GHz to 0.74GHz (17.35%) and that of bandwidth differs from 21.43% to 4.24% (5.06:1).