An investigation into the effects of charge storage on the efficiency of a varactor diode doubler

A paper on power dissipation in fourpole networks by A. Weissfloch is adapted to calculate the power dissipation in the input and output matching networks of an experimental varactor doubler and therefore to calculate the true input and output powers from semiconductor bulk material. Experimentally measured values of input and output power for specified biases are then compared with predicted values for the same biases calculated using an approximate analysis suggested by D. B. Leeson which assumes a non-linear depletion layer capacitance mechanism for harmonic generation. Reasonable agreement was achieved at power levels and biases which did not involve forward conduction. At higher power levels the results show that if charge storage does occur when forward conduction takes place then it does not enhance the efficiency to any greater extent than could be accounted for by depletion layer non-linearities. An analysis of the impedance changes of the varactor diode under high power conditions shows that this could account for the decrease in power loss in the surrounding circuits and could well explain the large increases in overall efficiency of the harmonic generator under these conditions.