Distortion and its compensation in a varactor-controlled frequency modulator

The nonlinearity of the voltage-frequenc characteristic of a frequency modulator is a factor of primary importance when designing, for example, high-quality modulators for large-capacity microwave links. The nonlinearities of a varactor-controlled oscillator are derived. A theory of various distortion-conpensation circuits is developed. Distortion compensation is applied to push-pull modulator, and 1800¿2700-channel radio links, are shown.