Composite right/left‐handed transmission lines in use for ultra‐wideband matching of front‐end amplifiers with modified cuckoo search optimization

Abstract

SummaryIn this work, the broadband capability of composite right/left‐handed transmission lines (CRLH TLs) in the balanced condition is exploited for ultra‐wideband matching of a compact single transistor front‐end amplifier. For this purpose, the LC element values and the number of identical asymmetric CRLH TL cells are taken as optimization variables. The minimum noise and maximum power delivery at each operation frequency of the chosen high technology transistor are considered as the feasible design target provided that the stability of the transistor is ensured. This feasible design target is expressed simply by a single objective function in terms of the port impedances of the input and output matching circuits together with the realization conditions of the CRLH TLs. Thus, human efforts for the design optimization process are reduced as much as possible. A novel metaheuristic algorithm ‘modified cuckoo search’ is used as a fast and accurate tool to find out ‘the global optimum’ within the feasible design variable space in the design procedure. In the study case, BPF640 is chosen as a high performance low‐noise microwave transistor. The design optimization results in a low‐noise amplifier using a single CRLH TL cell input and output matching circuits provided that a good agreement is obtained with the targetted performance and verified by Applied Wave Research, Inc. (AWR) simulation software. Thus, it can be concluded that CRLH TLs enable a designer to design high‐performance miniaturized low‐noise amplifiers. Copyright © 2016 John Wiley & Sons, Ltd.