(A) study on the low-sensitivity multiple-loop feedback active filters

Abstract

A new topology for the design of multiple-loop feedback active filter is proposed. Using the topology, the theory of design of symmetric bandpass filter of any type and any order whose lowpass prototype function is known is developed. And its performance is compared with respect to the sensitivity measure with the Follow-the-Leader Feedback (FLF), Double-Skipped-Feedback(DSF), and cascade case. The result is that proposed topology is less sensitive than the others. This topology needs one more active device than FLF, but it can be applied to any type and any order filter like FLF. Experimentally an 8th-order Butterworth filter is built and tested. And its frequency characteristic is reported.