Summary In 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.

This paper presents the design optimization and analysis of Matching Circuits (MCs) composed of identical Composite Right/Left-Handed (CRLH) transmission cells in the balanced conditions. For this purpose, noise matching is considered as the Feasible Design Target (FDT) throughout the available bandwidth for a chosen low-noise microwave transistor which is BPF640 and the L, C element values, number of identical asymmetric CRLH TL cells are taken as the optimization variables. This FDT is expressed simply by the two alternative objective functions which are the expressions for the gain and port impedance approaches together with the balanced condition. Furthermore, the effect of transition frequency on the matching vs frequency characteristics is investigated. A novel metaheuristic algorithm "Cuckoo Search" (CS) combined with the Lévy flight is used as a fast and accurate tool to find out "the Global Optimum" within the Feasible Design Variable Space (FDVS) in the design procedure. The computed results are given in details which are also verified by AWR circuit simulator. It can be concluded that the CRLH transmission cells can be employed in the design of the miniaturized ultra-wide band microwave amplifiers due to their broadband matching capabilities.

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