An RF power package includes a substrate having a metallized part and an insulating part, an RF power transistor die embedded in or attached to the substrate, the RF power transistor die having a die input terminal, a die output terminal, an input impedance and an output impedance, a package input terminal formed in the metallized part or attached to the insulating part of the substrate, a package output terminal formed in the metallized part or attached to the insulating part of the substrate, and a first plurality of planar tuning lines formed in the metallized part of the substrate and electrically connecting the die output terminal to the package output terminal. The first plurality of planar tuning lines is shaped so as to transform the output impedance at the die output terminal to a higher target level at the package output terminal.