A Push-Pull Power Amplifier Using Novel Impedance-Transforming Baluns

A novel impedance-transforming balun technique has been applied to the design of a push-pull GaAs FET power amplifier for the first time. By employing a multilayer structure which gives very tight coupling, the balun can transform from 50 Ωto the very low impedance required by power transistors. The power amplifier delivers 2.9 W with a 41% PAE at 1 dB gain compression, at a frequency of 1.8 GHz.