低溫共燒陶瓷技術之非平衡至平衡及電容抽頭分接式交連濾波器暨射頻平衡輸入至平衡輸出帶通濾波器研究

Abstract

篇論文前段旨在已知的Marchan Balun結構中，利用輸入傳輸線的開路尾端(open end)直接接地，並於輸入端加上一對地電容使其產生共振腔而形成一帶通濾波器。此特性更別於以往傳統Marchan Balun，特別在輸出的平衡端點上跨接一電容器，使其輸出傳輸線經由地的連接串聯形成一段連續電感，並產生另一共振腔而形成一帶通濾波。因此這樣的兩個共振腔經由Marchan Balun的交連耦合特性就可以形成一個有帶通濾波器特性的Balun。由於為了提升其選擇性，使用電容抽頭Tapped-Capacitor的方試進行耦合交連，用升阻的方式來提升並聯共振Q值(circuit Q)，並且提升通帶的頻率響應特性且利用低溫共燒陶瓷多層架構的技術，來完成此一平衡式帶通濾波器的設計。平衡式射頻輸入至平衡式射頻輸出帶通濾波器由於中心頻率設計於2.4GHz，所以此帶通濾波器適用於藍牙或無線區域網路(IEEE 802.11b/g)之應用中。 在本篇論文的後段，則是利用已經知悉方式在Marchan Balun輸出的平衡端點上跨接一電容器和使其輸出傳輸線經由地的連接串聯，形成一段連續電感並產生一並聯共振，此外在輸入端以背靠背的方式建構另一平衡輸入端，經由兩個共振腔的交連耦合特性就可以形成一平衡式射頻輸入至平衡式射頻輸出帶通濾波器，並利用R/T Duroid/5880 substrate及high-Q discrete陶瓷電容來完成實驗印證。此一帶通濾波器可用於提升射頻信號能力，此一設計用於接續平衡射頻輸入如Dipole Antenna。由於2.4GHz的設計所以此帶通濾波器亦適用於藍牙或無線區域網路(IEEE 802.11b/g)之應用中。

This study proposes an unbalanced to balanced band-pass filter and a balanced input-output band-pass filter. Firstly, an unbalanced to balanced band-pass filter which is composed from a Marchand balun circuitry using Low Temperature Co-fired Ceramic (LTCC) technology is proposed and designed. Based on the Marchand balun, this work uses a shunt capacitor connecting the input port to ground, and then lets the open end of the input transmission line be short to ground, thus can derive a resonator. Besides, a capacitor is connected between the two balanced output ports of the Marchand balun, and remaining the other end of each output transmission line connected to ground. Therefore, it can form another resonator. For improving the performance of selectivity, tapped-C is used to enhance the circuit Q of the resonator and to couple the signal to the next stage. The proposed unbalance to balance band-pass filter which has low insertion loss at pass band and good attenuation at suppression area can be applied in Bluetooth or IEEE 802.11b/g WLAN (Wireless Local Area Network). Secondly, a balanced to balanced band-pass filter is proposed. Also based on the Marchand balun mentioned above, a capacitor is connected between the two balanced output ports, and thus forms a parallel-LC resonator by co-operating the grounded transmission line. After duplicating the same balanced ports with back-to-back structure, a balanced to balanced band-pass filter is derived. In order to verify the circuit simulation, we used low loss R/T Duroid/5880 substrate and high-Q discrete ceramic capacitors to implement the experiment circuit. The proposed balanced to balanced band-pass filter can also be applied in Bluetooth or IEEE 802.11b/g WLAN (Wireless Local Area Network).