Effect of Embedding Impedances on the Efficiency of Varistor Schottky Diode Frequency Multipliers

Numerical modelling of varistor Schottky diode frequency multipliers reveals their optimum operating conditions. In the case of doublers the minimum conversion loss is provided by open-circuiting of the unused harmonics. The choice of the embedding impedances is of particular importance in the case of triplers where the conversion loss difference between the best and the worst case may attain 7 dB. The minimum conversion loss circuit requires an optimum inductive load at the second harmonic and open circuits at the remaining unused harmonics. Short-circuiting of the harmonics ensures the best conditions for broadband operation of both frequency doublers and triplers.