Parametric up-conversion by the use of non-linear resistance and capacitance

The power gain of parametric up-converters using both nonlinear resistance and capacitance is found for the condition of conjugate matching at the output termination only. It is shown that for the elements pumped in quadrature it is possible to obtain input impedances with a negative real part, and that under these conditions the gain may be arbitrarily large in principle for any value of pump frequency greater than zero. It is also shown that the device may be used as a negative-resistance parametric amplifier in which the pump frequency is lower than the signal frequency. Previous results showing that the up-converters may be made unidirectional in operation are confirmed, and it is shown that the gain under these conditions may be optimized by suitable adjustment of the mark/space ratio of the resistance variation. Attempts are made on physical grounds to explain both the unidirectional operation and also the high gain possible with R-C converters. Finally, some experimental confirmation of the theory is given