Novel low-sensitivity, third-order LP active Leap-Frog filter

This paper presents the realization of third-order low-pass (LP) active-RC filters using new simplified Leap-Frog (LF) topology. It has the reduced number of components, reduced complexity and straightforward design procedure. It is well known that the passive ladder-RLC filters, terminated with equal resistors at both ends have very low sensitivity to component tolerances in the pass-band. If active-RC filter are built using structures which simulate ladder-RLC using signal-flow-graphs (SFG), their sensitivities are significantly decreased. The leap frog structure follows readily from this simulation and has minimum sensitivity. The new structure presented here is a simplified LF structure with the elements calculated directly from the transfer function coefficients. As an illustration of the efficiency of the proposed modified LF filter, the sensitivity analysis with Monte Carlo runs using PSpice is performed for a third-order Butterworth and Chebyshev LP filters with various pass-band ripples.