設計具寬截止頻帶的雙頻帶通濾波器

Abstract

本論文設計具寬截止頻帶的雙頻帶通濾波器，首先利用微小化髮夾式諧振器，設計具有類橢圓函數響應的交錯耦合雙頻帶通濾波器。依據髮夾式諧振器之諧振特性，改變諧振器的結構參數，使高階諧波頻率相互錯開，以產生寬截止頻帶響應。本論文第二部份使用步階式阻抗諧振器，設計雙頻帶通平行耦合濾波器，除了具有第一部分電路特性之外，更加入耦合級的傳輸零點以及雙頻阻抗轉換器擇定點產生的傳輸零點，衰減高階諧波，以大幅改善截止頻帶的響應。本論文製作的電路，量測結果與模擬結果相當一致。

This thesis presents two designs of bandpass filters with a dual-passband response and improved performance in extended upper stopband. One uses compact miniaturized hairpin resonators to design cross-coupled filters with a dual-passband elliptic function response. Based on the resonant characteristics, the hairpin resonators are designed to have identical fundamental resonant frequency, the higher order resonant frequencies are staggered by adjusting its structure parameters to suppress the spurious responses in the upper stopband. The other design was stepped-impedance resonators to design parallel-coupled filters with a dual-passband response. They are designed to possess similar resonant properties to those in the pervious structure. Inherent transmission zeros tuned by the coupling lengths of the coupled stages and by the tap positions of the dual-band transformers are used to enhance the rejection levels in the upper stopband. Measurement results show a good agreement with the simulations.