Low-sensitivity active-RC high- and band-pass second-order Sallen & Key allpole filters

The design procedure of low-sensitivity, low-pass (LP) 2/sup nd/- and 3/sup rd/-order class-4 Sallen and Key active resistance-capacitance (RC) allpole filters, using impedance tapering, has already been published. In this paper desensitization using impedance tapering is applied to HP and BP 2/sup nd/-order filters. It is shown that HP filters have dual properties to LP filters in the sense of sensitivity. Among various topologies of BP filters, the best topology is proposed. The sensitivity of a filter transfer function to component tolerances is examined using the Schoeffler sensitivity measure as a basis for comparison. Monte Carlo runs are performed as a double-check. The component values, selected for impedance tapering, account for the considerable decrease in sensitivities to component tolerances for the LP as well as for the HP and BP filters.