Narrow BP active filters with reduced noise and sensitivity using current conveyors

This paper presents the low-sensitivity realization of narrow band-pass analog active filters using second-generation current conveyors. It is known that filters using multiple-feedback structures have reduced sensitivities to passive component tolerances. It was shown that using the follow-the leader (FLF) topology, the sensitivity of current transfer function magnitude was reduced when compared to the common cascade topology (CAS). The sensitivity reduction happens in the current mode in the same way as in the voltage-mode. Besides sensitivity, the output thermal noise is also reduced using the FLF topology. As an example, the design procedure and the Monte Carlo sensitivity, as well as output thermal noise analysis using PSpice were performed for a 4th-order Butterworth narrow BP filter.