Altering the Characteristics of Voltage Variable Capacitance Diodes

A network is deve loped which can be used with a voltage variable capacitance diode (varicap) to obtain a variety of capacitance versus voltage characteristics. This approach is useful when the shape of the capacitance versus voltage characteristic of available varicaps is not suitable for a particular application. A television color sub-carrier A.P.C. system is given as a practical example where this technique is used to produce symmetrical behavior with respect to hold-in and pull-in.