Compensation of Parasitic Capacitances in Broadband Filters

Methods are presented to anticipate the effect of the coils parasitic capacitances in the implementation of broadband filters. The case of uniform parasitic capacitances leads to a process in some respect analogous to the classical predistortion theory for losses: the compensation problem can be solved by operating solely on the transmittance function. Limits of realizability, independent of the filter structure, have been found for the cases of finite terminations and short-circuited output. In the case of nonuniform capacitances, methods are described to generate equal shunt capacitances and to equalize the values of the inductances. A numerical example has been treated which allows a comparison of the various methods described.