Research And Design Of RF Power Amplifier

The Radio Frequency Power Amplifier (RFPA) is one of most important equipments in the modern wireless communications, and they are widely applied in the Radar, wireless communications, navigation, satellite communications system. As compared to traditional traveling wave amplifier, RF solid-state PA have high dynamic range, compactness, low power dissipation merits. RF PA have become very important in the military and personal communications system, and it becomes extremely important to develop the RF PA. Therefore, research and design RF PA have great significance.For RF PA, always require it can output a certain power within a range of frequency, at the same time meeting the system nonlinear requirements and have high conversion efficiency. RF PA almost working in large signal, so it's circuit design methods and transistor used are different from microwave small signal amplifier, these will led to RF PA design become more difficulty.The GaAs FET devices are widely used in design RF PA for the characteristics of low noise, High efficiency, good linearity. We discuss the model of active device in this paper, analyze the amplifier's gain and stability by use the S parameter. And point out the impedance matching network and bias network implement method, several major RF PA design methods is summarized. There are two development for the Middle Power Amplifier: the drive stage power amplifier and the last stage power amplifier. We simulate the circuit with the Agilent ADS, After select the most suitable topology structure of circuit,we simulate the biasing circuit,input and output matching circuit. Through the method of the small signal s parameters and the nonlinear designing method, we design and simulate the drive stage and last stage power amplifier with ADS software, point out some problem in the design procedure. At last, we analyze deficiency of the circuit and draw a summary.