高效率高功率放大器

Abstract

在傳統的A類、B類及AB類功率放大器中，有部分的功率被功率晶體給消 耗掉， 我們很難將功率轉換效率提高。我們改良傳統AB類功率 放大器，設計出一切換式 電壓調整器當作功率放大器輸出級的電 壓電源，使這電壓電源隨功率放大器的輸入訊號變動而變動，且不影響輸 出電壓的品質與效率，以改善功率轉換效率。從實驗結果中我們將改良後 的功率放大器與傳統功率放大器做比較，可以發現改良後的功率放大器的 確能將效率大幅度的提升，原因是因為功率電晶體所消耗的功率比在傳統 功率放大器中要減少很多。而在切換式電壓調整器中的我們選用MOSFET功 率晶體當做開關，由於MOSFET 功率晶體本身限制的關係，所以我們將 功率晶體以並聯的方式處理，以提高輸出功率。 In the conventional class A, B, and AB power amplifiers, much power are dissipd by the output transistors. Therefore, the power conversion efficiency are greatly reduced by their output stages. In this thesis we propose a new design for power amplifiers, where two switching regulators are used for the power voltage sources of output stages power amplifiers. Using this new design, one can promote the output power conversion efficiency much higher than the conventional power amplifiers without any loss of the output quality. In our experiments wecompare conventional power amplifiers with ours. The results show that our new power amplifier really has high power conversion efficiency and the output transistors dissipate very few power. In the swtiching regulators, power MOSFETs are used as switches, and the output frequency bandwidth can be as high as 5kHz.