縮小化功率放大器輸出級平面式巴倫濾波器

Abstract

本論文為設計一個巴倫(balance to unbalance transformer)作為功率放大器的輸出級，對於要把一個功率放大器的平衡訊號轉換為單端訊號的輸出級裝置來說，傳統的方法均為使用一平面電感式變壓器形式之輸出級，其中中央抽頭式變壓器型式易有高磁場耦合，在單晶片系統上，不論是VCO與PA都會產生磁場耦合的雜訊效應，例如互調訊號(inter-modulation signal)、注入鎖定(injection lock)、注入牽引(injection pulling)等干擾。為了解決這樣的情況，於是我們朝著巴倫式的輸出級作研究，以公式分析並推演出不對稱耦合線(asymmetric coupled line)所該有的寬與間隔，並以折疊式佈局以期更小的面積，還有之後量測電路也是考量整體計畫，的一個重點。根據這個方法，也可以在各板材，各頻率上設計想要的縮小化balun。

This thesis introduces a design of balun (balance to unbalance transformer) as an output of a power amplifier. A conventional power amplifier output network uses a center-tapped spiral transformer to transform the balanced signal to a single ended signal with specific impedance transformation ratio. The center-tapped spiral transformer always comes with a strong magnetic coupling with nearby spiral inductors. For the SOC (System On Chip), both VCO and power amplifier are interfered by noise from magnetic coupling, such as inter-modulation signal, injection lock, injection pulling. To solve this problem, a novel balun filter for power amplifier output network is proposed in this thesis. An analytical method is developed to calculate the width and gap of the asymmetric coupled-line with respect to balun filter specifications. A folded layout is applied to meet the smaller size. Measuring is also a critical issue in the project. The proposed balun filter can be applied to any substrate at any frequency.