低溫共燒陶瓷技術之串聯架構帶通濾波器暨射頻前端天線切換模組的研究

Abstract

本篇論文前段旨在利用低溫共燒陶瓷多層架構的技術，設計一串聯架構的帶通濾波器。別於以往傳統帶通濾波器利用耦合傳輸線架構的濾波器跨接一耦合電容形成一迴授路徑來產生有限傳輸零點；此串聯架構帶通濾波器乃是利用傳統耦合傳輸線架構的濾波器串接一個對地的電容，藉以形成一迴授路徑，因此而產生有限傳輸零點。改變此對地電容之容值，便可以控制有限傳輸零點的頻率，並且不影響通帶的頻率響應特性。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，則是利用低溫共燒陶瓷技術來設計一射頻前端天線切換模組，此模組把主動元件、被動元件以及內嵌式天線整合起來，形成一系統封裝之射頻前端模組。被動電路以及天線的部分都是內埋在低溫共燒陶瓷的基板裡面，主動元件則是黏著在基板的表面上，再利用磅線把內埋的被動元件與主動元件連結起來。因此在設計上，必須將磅線的影響加以考慮。由於磅線在高頻的時候近乎等效成電感，對於內埋的被動電路而言，輸入阻抗的匹配會被磅線破壞，所以整體的頻率響應會受磅線所影響。本篇論文把此磅線的效應加以考慮並利用磅線近似電感的現象設計所有內埋的被動電路與天線，讓此前端天線模組具有體積小、全向性輻射場型、以及被動電路特性良好之特色，頻段適合於無線區域網路(IEEE 802.11a)的應用中。

In front of this thesis, a band-pass filter of serial configuration using Low Temperature Co-fired Ceramic (LTCC) technology is proposed and designed. Different from the conventional band-pass filter, which uses a coupling capacitor between two I/O ports to form a feedback path and thus can generate finite transmission zeros; the proposed band-pass filter is based on an architecture of a conventional coupled-line filter, and incorporates a grounding capacitor to form the feedback path. By changing the value of the grounding capacitor, we can control the frequencies of the finite transmission zeros without affecting the frequency response of the pass band. The proposed band-pass filter which has low insertion loss at pass band can be applied in Bluetooth or IEEE 802.11b/g WLAN (Wireless Local Area Network). Additionally, we propose and design a RF front-end antenna switch module, which integrates an active component, two passive components, and an embedded antenna into a RF front-end System-on-Package (SOP). The passive circuits and the antenna are buried in the LTCC substrate, while the active component is mounted on the top surface of the substrate. Thus, bond wires are thus necessary for the connection among the active component and the buried circuits/antenna. Because the bond wire is similar to the inductor at microwave frequencies, we have to take the effect of the bond wire into account, in order to avoid the bond wire affecting the input impedance of the buried circuits. In this thesis, we utilize the bond wire for compensation on the input impedance matching of buried circuits. With proper design, the module has compact size, omni-directional radiation pattern, and low insertion loss of passive circuits. The proposed antenna switch module is suitable for applications of IEEE 802.11a WLAN.