Circuits and methods related to power amplifier efficiency based on multi-harmonic approximation. In some embodiments, an output network circuit can be provided for multi-harmonic control of a radio-frequency (RF) power amplifier. The output network circuit can include an impedance matching network configured for a fundamental frequency of the power amplifier. The output network circuit can further include a broadband harmonic trap in communication with the impedance matching network. The broadband harmonic trap can be configured to substantially trap a plurality of harmonics associated with the fundamental frequency. The output network circuit can further include a dipole network in communication with the broadband harmonic trap. The dipole network can be configured to tune reactances resulting from the operation of the broadband harmonic trap.