Design of high efficiency frequency doublers based on Manley-Rowe´s energy relations

The paper describes a novel design technique for high efficiency microwave frequency doublers using a varactor diode. In the design technique the design parameters are derived analytically from Manley and Rowe\´s energy relations. First, the current and voltage of the varactor diode are represented by Fourier series as functions of the charge. Then the real and reactive powers of the varactor diode are evaluated as functions of the charge. From the real and reactive powers and from the current in the varactor diode at the fundamental frequency and the second harmonic, we derive the characteristic impedances of the frequency doubler\´s microwave structure for "matched" operation; furthermore, we derive the input and output powers and the distances between the varactor diode and the filters that reject the fundamental frequency and the second harmonic. These design parameters are all expressed as functions of the charge on the varactor diode.