本論文利用雙模態環形共振器為基底，分別設計出微小化之可開關型寬止帶帶通濾波器與可調式的雙模態環形帶通濾波器。 利用奇偶模的分析方式，將可計算出所需要的耦合電容和傳輸零點所在的頻率位置，以及3-dB頻寬。適當的擺放p-i-n二極體將使得濾波器擁有可開關的特性。此外，利用混合型的低通濾波器來實現雙模態帶通濾波器，即能有效的縮小電路面積和提升止帶頻寬。整體電路面積為0.023λg2，在通帶開啟的情況，止帶在7.7倍的中心頻率以前能壓抑到20dB以下，而在通帶關閉的情況，止帶在7.48倍的中心頻率以前能壓抑到20dB以下。 由於傳統的環形共振器其中心頻率、耦合係數、外部品質因子皆可利用電容來單獨的控制，故利用變容二極體來取代電容，將可實作出可調式的雙模態環形帶通濾波器。可調整的中心頻率為0.88GHz到0.74GHz(17.35%)，而可調整的頻寬比為21.43%到4.24%(5.06:1)。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).
