New multifeedback type active RC filters

The multiple-amplifier type of filters are compared with their prototype filters and with others which are well known and compatible in terms of the number of passive and active elements. Two different nth-order active double-ladder filters are presented which are conceived from the structures of some multiple-amplifier filters introduced earlier. For each ladder filter, a synthesis algorithm is developed to derive the transfer function and a method of analyzing the effect of the gain-bandwidth product of the op amps is presented. These ladder filters are compared with a cascaded higher-order filter in which newly proposed second- and third-order multiple-amplifier filters are cascaded. The sensitivity of active RC filters is reviewed in detail, emphasizing what sensitivity functions should be taken into consideration, why they are chosen, and how they can be calculated for the given filter under study.