Switched-capacitor band-pass filter of a discrete-time type, in particular for cancelling offset and low-frequency noise of switched-capacitor stages

摘要

Bandpass filter forms, and by operational amplifier (2) and passes through input circuit. The input circuit forms a capacitive filter element (C1), is connected to the operational amplifier of input terminal; Coupled switch (11) is coupled in input node (10) and capacitive filter element; The input terminal and input node of the filter coupled between condenser type sampling element (caesium); With sampling switch (16), couple in input node and reference potential line. The coupled switch and above-mentioned input sample switch approach reverse phase undesired component according to stream of samples and have detected step, condenser type sampling element is set to form sampler, for in the component to sampling the step of undesired component, undesired component in component not of interest, and in subtracter is from input signal step in a sense.