Harmonic load modulation in Doherty amplifiers

Abstract

In a Doherty amplifier employing a class-B main amplifier and a class-C peaking amplifier, harmonics are normally suppressed at each amplifier. If odd harmonic currents generated by the peaking amplifier are permitted to flow into the main amplifier, the loadline of the main amplifier is shaped in such a manner as to allow a lower supply voltage to be used.