SWITCHED CAPACITOR FILTER

摘要

PURPOSE:To increase the filter characteristics and to improve the space coefficient, by setting nearly the same integral constant for integrators of higher- order switched capacitor filters. CONSTITUTION:The integral constant of switched capacitor filters 11 and 12 are set at beta1 and beta2 respectively (K0 and S showing the gain of an operational amplifier and the S function respectively in the diagram). Then a constant K1 is selected to satisfy beta1/K1=K1beta2. Thus beta1'=beta2'=W0 is satisfied for new integral constants beta1'=beta1/K1 and beta2'=K2beta2. Accordingly the area can be reduced for the capacity occupying on an integrated circuit pattern with an improved space coefficient by providing switched capacitor filters 11' and 12' having equal integral constants beta1' and beta2'.