Computer-Aided Design of Highly Linear, High-Power Varactor-Tuned Frequency Modulators

A systematic approach to the design of linear high-power varactor-tuned frequency modulators is presented. It is shown that a few simple measurements on the free-running oscillator together with a suitable use of modern general-purpose optimization programs allow the designer to predict and control all aspects of the design problem, including linearity of the frequency-voltage characteristic, the R.F. voltage swing across the varactor junction, and the optimum choice of the varactor diode itself.