Realization of leapfrog filters using current differential buffered amplifiers

In this paper, is shown an approach to realize leapfrog structures obtained from proto-type passive RLC ladder filters using current differencing buffered amplifiers (CDBA) as active elements. The use of the CDBA's provides advantages that the realization procedure is simplified and the number of active components required is reduced. The approach is quite suitable for the realization of band-pass ladder filters, which generally requires a complicated structure to simulate LC series and/or parallel resonant branches by the conventional opamp-based leapfrog filters. A simple circuit configuration of the CDBA suitable for high frequency and low power supply voltage applications is also presented. As design examples, a fifth-order Butterworth low-pass ladder filter and a sixth-order Chebyshev bandpass ladder filter are designed. The effectiveness and the correctness of the proposed approach and the characteristics of the proposed filters are verified and examined through computer simulation.