Design of Compact Complex Impedance Transformer with Frequency and Terminal Impedance Tunability

In the paper, a compact complex impedance transformer (CIT) composed of cascading three varactors loaded coupled lines and two variable shunt susceptances was proposed. Highly flexible tunability functions including only frequency tunable, both tunable can be achieved by tuning capacitance types value susceptance. Design equations were derived using even–odd mode analysis examples are given for descripting design procedures. For validation, prototype designed fabricated. During measurement, cases exhibited. When termination fixed, measured center tuned in range 1.1–2.1 GHz (62.5%). determined, different terminal impedances matched prototype. The function at is also trated results. After comparison, potential proposed CIT applications radio front-end demonstrated.