Iterative design of a harmonically tuned multi-octave broadband power amplifier

This article presents the design approach, realization and measurement results of a highly efficient double octave wideband power amplifier using a GaN-HEMT bare-die. An iterative approach to obtain the optimum source and load impedances is described. Multiple harmonics are analyzed using harmonic load-pull simulation and a reliable large-signal device model. The design was realized exploiting a transition between two substrates and a vertical impedance step transformation. From 1.5 GHz to 6 GHz, a constant high output power and remarkable efficiency were achieved. More than 20 W saturated power and 50 % drain efficiency were measured up to 5.5 GHz.