使用低溫共燒陶瓷設計一非平衡至平衡帶通濾波器

Abstract

本篇論文提出一個新型非平衡至平衡帶通濾波器的電路架構。首先以一個電感性帶通濾波器並聯一個異相位的電容性帶通濾波器，組成一個新的非平衡至平衡帶通濾波器電路架構。之後提出一個微型化的非平衡至平衡帶通濾波器電路架構，這個電路架構是由上述電路改善而來的，為了證實所提出之電路的可行性，因此以此電路架構為基礎並藉由電路及全波電磁模擬軟體來設計一個尺寸為2.0 mm x 1.2 mm x 0.7 mm，操作在2.4 GHz的非平衡至平衡帶通濾波器，並將該電路實現於低溫共燒陶瓷中，實際量測實作後的非平衡至平衡帶通濾波器，其量測結果與模擬結果十分吻合，由量測結果可知所設計的濾波器在通帶內其最大介入損失為1.65 dB，平衡振幅差異可以控制在0.32 dB，而平衡相位差異可以控制在3度以內。

This thesis proposes a novel compact circuit structure of balanced-to-unbalanced bandpass filter. Firstly, a pre-design circuit is presented, which is composed of an inductive coupled-line (ICL) bandpass filter and an out-of-phase capacitive coupled-line (CCL) bandpass filter. A novel compact circuit with three coupled lines configuration, derived from the pre-design circuit, is then proposed for miniaturizing the balanced-to-unbalanced bandpass filter. In order to verify the feasibility of the proposed structure, a 2.4 GHz multilayer ceramic chip type balanced-to-unbalanced bandpass filter with size of 2.0 mm x 1.2 mm x 0.7 mm is developed. The filter is designed by using circuit simulation as well as full-wave electromagnetic (EM) simulation softwares, and fabricated by the use of low-temperature co-fire ceramic (LTCC) technology. The measured results agree quite well with the simulated ones. According to the measurement results, the maximum insertion loss is 1.65 dB, the maximum in-band phase imbalance is within 3 degrees, and the maximum in-band magnitude imbalance is less than 0.32 dB.