具有源極電感回授之低雜訊放大器之研究

Abstract

本論文討論在低雜訊放大器之設計中，藉由源極電感性回授之技術以 使放大器電路能同時做到輸入端匹配及最低雜訊。首先根據雙埠雜訊理論 ，推導出元件加上源極電感回授後的變化，再經由簡化電路的分析，可以 了解電晶體天生的限制(即不能同時做到輸入端匹配及最低雜訊)以及加上 電感後如何補償這個限制。此外，最小雜訊指數 以及等效雜訊電阻 亦隨 電感的加入而有所變化，在本論文中箤取一電晶體的小訊號模型並且包含 了元件內部的雜訊源，籍由這個模型，可以了解 的變化情形。並根據以 上的討論，找出使用源極電感回授的限制，最後設計一個具有源極電感回 授的C-band放大器以印證本文的理論。 This thesis discusses the technique of source inductive feedback (SIF) in low noise amplifier design to achieve both input and noise matching. The behaviors of device with and without SIF are investigated by noisy two-port analysis. In the mean time, a simpli-fied noise model is proposed to verify the possibility for input/noise match. The variations of and with SIF are also examined. A full small signal model containing noise sources is presented to figure out the deteriorate factors for noise figure. The limitation for using SIF is also indicated. Finally, a C-band amplifier is designed to confirm our investigation.