A new method to design broadband amplifiers by using genetic algorithm

摘要

In recent years microwave techniques take more in to consideration. In most applications wide broadband amplifier is need. One of these circuits which used for broadband amplifier designing is reactively matching circuit. In designing of reactively matching circuit, in method which is named compensated matching, with making a small unmatching in input and output of matching network changing gain are decrease as for as possible along the band. The small unmatched in designing of matched circuit in compensated matching method call matching error. Changing of amplifier gain along the spectrum totally depended on matching error. So we should decrease matching error until gain amplifier be constant along the spectrum. We can assign suitable elements in matching circuit to achieve wide band and small matching error broadband amplifier but, it is difficult and time-consuming to assign proper elements. Hence, make a new method in order to determine proper elements for maximum decrease of matching error with high speed looks necessary. The goal of this paper is presentation a new method for designing broadband amplifier to either cause the sever decrease in matching error or increase the designing speed. In the new presentation method an equation is achieve to accounting matching error which is base on S transistor parameters and matching circuit elements. Then in order to reduce the matching error, genetic algorithm method is used. In order to consider application of the new proposed method, a matching circuit is designed with five elements. This design is with use of compensated matching methods and proposed method. The results show designing time and matching error of the new method is decreased dramatically.