Research Of Microwave Linear Power Amplifier

In recent years, with the development of communication and microelectronics technology. Modern communication is developing towards adding channel capability, multi-carrier, multi-level, wide-band and high efficiency. All these changes make the design of communication equipment more difficulty. As the core of the transmitter, the performance of RF power amplifier restricts the performance and technique level of the whole system. Therefore, analysis, design and linearization of the power amplifier have become very important in the construction of RF/microwave systems.This paper discusses the design of power amplifier and linearization technology in Ku-band. This paper has designed two different types of diode pre-distorter to improve the linearity of power amplifiers. One is microwave diode transmission-type pre-distorter and the other, it is microwave diode reflective-type predistorter. By simulating with ADS simulation software, The simulation results show that it can inhibit both third-order and fifth-order inter-modulation effectively. In the large-signal condition, microwave semiconductor devices normally work on the nonlinear region. So the traditional linear circuit analysis and design methods can not meet the requirements of non-linear circuit analysis and design. In order to maximize the output power, gain and efficiency of large-signal power amplifier, this paper began with the modeling of microwave semiconductor power devices and nonlinear analysis (harmonic balance) method, analyzed and designed the power amplifier. The specific size of the Large and Small signal equivalent model was discussed along with its validation. The results show that the model fits well with the characteristics of the device. By using harmonic balance method, the optimization and design of GaAs MESFET power amplifier was achieved.. Finally, based on technical criteria of designing linear power amplifier, the scheme of the overall designing power amplifier was proposed, and simulation was made.Above all, modeling of microwave semiconductor device and nonlinear circuit, pre-distortion linearization technology have played a very important role in improving the performance of microwave power amplifiers.