摘 要
随着通讯技术的不断发展与成熟，射频技术也越来越多的服务于各个领域。从最初的无线收发到激光上的调制，再到现在的医疗事业的射频治疗，无不加入了射频技术。其中短波线性功率放大器普遍应用在各类型的发射机中，而且在许多电子设备如高频加热装置、高频换流器及微波功率源中，射频功放也得到广泛应用。功率放大的实质是一个能量转换器，即把电源供给的直流能量转化为高频功率输出。本次毕业设计课题所究的是27MHz的信号通过该放大器放大，获得增益大于37dB功率输出。
在本文第一部分射频功率放大器原理和特性部分，描述了射频功放的基本理论；并着重阐述了指标涉及的功率放大器线性以及非线性指标，分析了高频功放的工作原理；最后，在研究了射频功放的工作状态后，对其负载、振幅和调谐等外部特性也作了分析。
在第二部分功放的实际电路设计部分，根据工作指标要求结合原理图，选择了高频发射晶体管2SC1972，2SC2538和C1946A，然后根据晶体管确定电源电压数值及偏置电阻的阻值，计算并确定输出、输入以及级间匹配电路及其有关电抗元件值，接着根据以上数值对偏置电路和匹配网络进行了调整。最后根据以上分析和设计，使用ADS进行了仿真并用PROTEL99SE制作了10W(27MHz)功率放大器的电路图制作了电路板。
经过调谐,测试的实验结果表明，本功率放大器在高频工作状态下，能产生符合要求的高频功率输出，线性度也比较好，具有比较高的转换效率，并且达到了预期的工作指标。
关键词：功率放大器；偏置；匹配网络；计算机辅助设计；
Abstract
Along with the developping and growning up of communication technology,the short-wave line power amplifier have beening applied in various of area. Aboriginally since wireless receive and laser confection, to radio teatment it was applied at anywhere.types transmitter ,many electronic equipments like high-frequency heating machine , the high frequency converter and the microwave power source also all widely apply it. Substantially, the high frequency power amplifier is an energy switch. It converts direct current energy from electrical source to high frequency energy. The research topic of the paper is the radio frequency power amplifier and requests the center frequency in 27 MHz, and the plus of output power is more than 37dB.
At the first part, we deepened understanding to some basic concepts and the basic function high frequency power amplifier in the part of the high frequency power amplifier principle and the characteristic. Then, we emphatically analyze the principle of the high frequency power amplifier, mainly is the triode transistor signal amplification principle and the high frequency power amplifier principle. In the end, after studied the active status of the high frequency power amplifier, we study its external function also, for example, the load, the oscillation amplitude and harmonious and so on .
And the second part ,in circuit design part of the radio frequency power amplifier, on the basic of principle analysis and technical specification request before, we determined that use 2SC1972 2SC2538 and C1946A, the supply voltage value and the direct current operating point. Then we computed and determined its output, input match circuit and other related part values, and after that, to the electric power-supply circuit, the bias electric circuit and the matching network has carried on the design. In the end, according to the above analysis and design, we have manufactured 10W (27MHz) the power amplifier using Protel99se. After harmonious with adjustment, it completely conforms to the design requirement.
