Quantative analysis of output power improvement using output reflector network in microwave frequency doublers

This paper quantatively analyzes the improvements of output power at two times fundamental frequency (fo) employing fo and 3fo reflector networks at the output of an active microwave frequency doubler. The output equivalent circuit of the active device is characterized by an ideal current source having a nonsinusoidal waveform in shunt with a nonlinear resistor. Harmonic balance analysis of this model is utilized to quantatively analyze the theory that an increase of output power at 2fo can be achieved due to the nonlinearity and mixing of fo and 3fo components in the resistor. Power increase by up to 3 dB is observed.