Wideband Two-Section Impedance Transformer With Flat Real-to-Real Impedance Matching

This letter presents the design of an impedance transformer with wideband, maximally flat real-to-real impedance matching. The design formulas for two-section quarter-wave transformer are presented and exact solutions for transmission lines' parameters are derived in explicit form for any impedance transformation ratio. The results of this study are useful for a number of practical design problems, especially power amplification circuits. To validate the design formulas, three impedance transformers terminated in a fixed impedance of 50 Ω and three target impedances of 100, 150, and 200 Ω are fabricated and measured. Measurements show a good agreement with theory and simulations.