Note on the Determination of the Offset Lines in Doherty Power Amplifiers

This letter shows how to find by inspection, the values of the characteristic impedances and the electrical lengths of the offset lines of the main and auxiliary amplifiers constituting a Doherty power amplifier. This letter focuses on the easiest determination of these offset lines using the ABCD matrix coupled with the formalism of image parameters to describe the output matching circuits of the main and auxiliary amplifiers.