在本計畫中，將提出一全新設計架構的微小型平衡不平衡轉換器。傳統的馬群平衡不平衡轉換器(Marchand balun)採用了四分之一波長的耦合線，因而導致了寬頻的特性，且使得電路占據了相當的面積，特別是在低頻的應用，如DVB, GSM等。事實上在轉換器設計時，頻寬和電路的面積的決定是存在可取捨的空間的，尤其是並非所有的通訊應用皆需寬頻的設計。本計畫所將提出的轉換器設計，首先，將以一串聯的電容取代傳統轉換器的開路端。此電容可用來調整頻寬的大小。更進一歩，將開路以短路取代，則可得到面積非常小且窄頻的設計，此時耦合線可短至十分之一波長。此設計很適合低阻抗比(/1)的應用，但其響應容易受到輸出阻抗變化的影響。outZinZ≤ 考慮到輸出阻抗值的變化範圍，尤其在放大器的相關的設計中常會有複數阻抗的情形，在本計畫中，除了在縮小電路面積上做努力，亦將提出新的設計方式使轉換器對輸出阻抗值的敏感度降低(insensitivity)。此微小且不敏感的設計在不平衡端及平衡端將連結適當的電容電路。此設計將提供一範圍更大的阻抗轉換比，且所需的耦合線長度更可短至二十五分之一波長。在本計畫中第一年將以 FR4印刷電路板上完成適用於數位電視頻段(UHF 470-710MHz )的轉換器，並對整體電路設計的概念做全面且快速的檢驗。第二年將以低溫陶瓷製程技術(LTCC)實現適用於28~38GHz及5~7GHz的毫米波平衡不平衡轉換器，並於第三年完成系統的整合。所有的轉換器的量測結果將和HFSS數值模擬做比較，以逹成1dB的大小平衡(amplitude balance)及5度的相位平衡(phase balance)。 ; The novel miniaturized baluns designed for wireless communication applications will be presented in this project. Conventional Marchand baluns employ λ/4 coupled lines and yield broadband characteristics, these structures occupy large circuit areas, especially for lower frequency applications (ex, DVB, GSM). Some trade-offs exit between bandwidth and the size of the proposed circuit. Therefore, broadband design is not required to all commercial applications. The proposed design replaces the open-terminal of traditional Marchand balun with a series capacitor to ground plane. The capacitor regulates the bandwidth of the Marchand balun. Furthermore, by replacing the open-terminal with short-terminal, a narrow bandwidth characteristic is obtained. In the meantime, this design employs λ/10 coupled lines to shorten the electrical length substantially. This novel design is suitable for low impedance-transforming ratio (/outZinZ≤1) application, but it is sensitive to output impedance. In terms of the complex impedance component design (ex, amplifiers), circuit structures insensitive to output impedance are presented. The miniatured and insensitive balun is realized by using one series capacitor at unbalanced port and two shunt capacitors at balanced port. This design provides a wide impedance-transforming ratio /. The balun bandwidth is controllable, and the required coupled-line lengths of this balun structure can be made as short as λ/25. In the first year, DVB(470~710 MHz) Baluns are fabricated on FR4 substrate. In second and third years, RF(28~38 GHz) baluns and IF(5~7 GHz) baluns will be realized using LTCC techniques. All the measurements will be compared with simulations by HFSS. The proposed baluns are designed to achieve 1.0 dB amplitude balance and phase balance. ; 研究期間 9708 ~ 9807
