Closed-Form Analysis of the Abrupt Junction Varactor Doubler

Circuit equations of the abrupt junction varactor doubler have been consolidated into one implicit equation in one unknown. For tuned input and output circuits, this equation reduces to a cubic equation that is solved explicitly as a function of available input power and circuit loading. Optimum loading conditions for maximum power output are functions of only a single composite parameter. For general terminating impedances at input and output frequencies, the consolidated equation is readily solved numerically using the tuned results as a starting point. As examples, doubler frequency responses, with single-and double-tuned load circuits, have been calculated. Surprisingly, double tuning is of Iimited value in enhancing the instantaneous bandwidth. In addition, for single-tuned load circuits, the frequency response as a function of bias voltage has been calculated, showing the potentiality of greater than 20-percent frequency tunability.