Feedforward Power Amplifier Module And The Passive Components

The path of the rapid development of mobile communication depicts two trends: the first is that wireless communication systems are based on more complex RF signals with multiple carriers, high peak-to-average ratio and large dynamic range spectrum, which put more stringent requirements on RF power amplifier linearity, in particular the third-order inter-modulation distortion; the second is that people are more fond of short, small, light and thin terminal systems. Therefore, the academia and industry have invested more attention and funding for the research and development of RF power amplifier linearization and miniaturization techniques.In this paper, the feedforward power amplifier system and its negative modules are studied and discussed based on the theoretical analysis and comparison, which can be divided into the following three aspects:The first is a detailed analysis of nonlinear characteristics of power amplifier based on Taylor series model, introduces emphatically amplitude-amplitude and amplitude-phase modulation transforming distortion, especially those of the third-order and fifth-order inter-modulation distortion in the feedforward PA system, and then several linearizing technologies are delivered.Secondly, this paper briefly described the miniaturizing technology, working principle and implementation structure of passive components in the feed-forward amplifier module, and the process of designing and manufacturing 10dB and 30dB fixed attenuator, two-way and four-way homo-phase power divider, square 3dB hybrid coupler, and 10dB and 30dB directional coupler, using the software ADS, and the measured data verified the reliability of simulation results.And the third, built the verification system of the feedforward power amplifier module in ADS based on the measured data of the active modules and passive components. The simulation results achieve the project's design specifications, that is, not less than one watt in the output power, 40dB in power gain, better than -60dBc in the third-order inter-modulation through the operating frequency band.