The Hardware Design Of Adaptive Feedforward Linear Power Amplifier

In the system of modern wireless communication, the transmission of information is developing toward multi-carrier, great-capacity and high-speed. This needs the RF components to provide higher linear in the systems of communication. Especially the linearity of power amplifier will affect the performance of the whole system. Feed-forward power amplifiers are more concerned by RF engineers because of its high linearity and stability.This paper summarizes the domestic and foreign development of linear power amplifier systemically, analyzes the non-linear characteristic of power amplifier in detail, compares and evaluates linear technologies used widely. E.g,feedback, pre-distortion, feed-forward. This paper also gives an adaptive feed-forward power amplifier scheme, and illustrates the feasibility in theory; also it introduces the ADS design of all the modules of the adaptive feed-forward power amplifier in detail:main power amplifier, error power amplifier,loop circuit,down-convert circuit .Also, it gives all the test result. The result shows that:The kill of error signal is obvious in adaptive feed-forward power amplifier from test result, the purpose is achieved. But the guide line is lower than the simulation result. For example, lower output power,lower efficiency. It needs to be improved later.The adaptive algorithms is one of the key techniques of adaptive control feed-forward power amplifier, and it influences the performance and price of the whole system This paper analyses and demonstrates the algorithms of adaptive control feed-forward power amplifier—minimum power algorithm and minimum relativity algorithm .The results of theory analysis and simulation both prove that the effect of them is the same, but minimum power algorithm costs less than minimum relativity algorithm, and is more appropriate in practical application.