.225-450mhz Broadband Linear Power Amplifier Developed

In modern wireless communication,linear power amplifer is necessary and play a critical role,and even the whole communication system will be affected by its performance.This subject aim at designing a linear power amplifer whose output power is 40W for 225-450MHz band.but it seems not easy to finish the task because of this power amplifier own unique requirements including high output power,broad working frequency band,high linearity,and flat gain.Due to the complexity involved, Theoretically several soltuions are derived in the final scheme such as broadband matching technology, power-retreat,power synthesize, Automatic Power Control and negative feedback.In addition,the design will be optimized by EDA software and the final test result indicates that our design is successful.The principle of power amplifier is introduced at first in this paper, especially its nonlinearity characteristic under the condition of Large signal.Subsequently linearization technology such as power-retreat, negative feedback, pre-distortion and feed-forward are discussed.and then broadband matching technology is introduced.At last, the scheme of subject, the functional realization of each module, some questions which must be pay much attention in the system design, and the ultimate testing result of this subject is represented and analyzed in detail.