Narrow-band switched-capacitor bandpass filters

Novel circuits, based on the
N
-path (or pseudo-
N
-path) configuration, are described for the design of narrow-band switched-capacitor (SC) bandpass filters. For noncritical applications very simple and economical circuits, based on the simulation of passive or active
RC
circuits, can be used; for high-accuracy filtering tasks, more elaborate circuits (obtained from doubly terminated reactance ladders) are proposed. The resulting filters provide stable passband responses and low sensitivities to element-value variations even for extremely narrow relative bandwidths, where other design approaches fail.