AB类功率放大器的设计与仿真研究

在比较A类、B类、C类和介于A类、B类中间的AB类四类功放电路各自优缺点的基础上，提出功率放大器工作点的选取以及通过阻抗匹配来实现高效率的方法。讨论了放大器输入回路阻抗变换电路、晶体管放大电路以及输出回路阻抗变换电路的设计思想，运用电报方程从理论上推导出用于信号源和晶体管之间阻抗变换的传输线变压器输入输出阻抗计算公式，由此设计出模拟信号处理电路中非常重要的AB类高功率放大器。仿真和实验结果表明，放大器在1MHz～50MHz的范围内，输入0．1w时输出为1w，其增益达到10dB，并且失真率非常低。

Design and Simulation for AB Power Amplifier

A discussion on the advantages and disadvantages of four kinds of amplifying circuits such as class A, class B, class C and class AB is presented. A method is proposed for the operation point of the power amplifier and the implement of high efficiency through impedance match. The design for impedance converting circuit of input current, transistor amplifying circuit and converting circuit of output current is presented. The telegrapher equations are adopted to determine the impedance of transmission-line transformer, which is used to con- vert circuit impedance between signal source and transistor. A very important AB high power amplifier is designed. Experimental results are presented to verify the effectiveness of the proposed circuit. The results show that amplifier has 10 dB power gain and low distortion-rate.