Design of active RC filters simulating node equations of LC filters

An active filter design approach based on the simulation of an filter is proposed. In this approach, if node equations of an filter are given, an active structure is obtained which is described by the same equations. Then, the technique to decrease the number of operational amplifiers (OA\´s) is considered. The effect of gain-bandwidth products of the OA\´s used and that of changes in elements are discussed. For the design example, a fifth-order bandpass filter was selected. The experimental result showed good agreement with the theory.