Class Ab Rf Power Amplifier Non-linear Analysis And Research

For any wireless communication systems, transmitter is one of the important parts. And as the core device of transmitter, power amplifier has became the most important subject for communication system nowadays. Whether it's a mobile phone transmitting a few hundred milliwatts, a base station transmitting tens of watts, or a TV transmitter radiating hundreds of watts, the underlying principles in the power amplifier design are much the same. But, with the development of the wireless communication, the requirements for power amplifiers are more and more tougher, including the efficiency, linearity, output power and bandwidth. So how to build a high efficiency and high linearity power amplifier became a hotspot. Also it is important and meaningful to analyze the nonlinearity of radio frequency power amplifier. The nonlinearity of radio frequency power amplifier, especially the class AB power amplifier will be theoretically analyzed in this paper. Finally, a class AB power amplifier will be designed, and verified the theory.For the beginning, the basic theories of linear power amplifier will be introduced, including the classification, stability, nonlinear distortion, matching and load/source pull theory. Next, the analysis of waveform and the output terminal impedance for traditional reduced conduction angle power amplifier will be followed; also the introduction of"knee"effects in the amplifier transmission characteristic and the discussion of driving signal for power amplifier will be given. Base on these, the nonlinearity of radio frequency class AB power amplifier will be analyzed, including the ideal traditional class AB power amplifier, the nonlinearity for RF devices and effects as parasitic capacitance. After that, a class AB power amplifier for WCDMA base station will be designed. The amplifier will be simulated and optimized using ADS, and tuning to meet the specifications. Test and verification results will be given.