switched capacitor (SC)

An SC filter, switched capacitor, is a discrete-time filter whose cutoff frequency is varied by changing the capacitance. In contrast to known analog filters, the cutoff frequency of the SC filter is changed by switching one or more capacitors on or off.

In the switched capacitor filter, the capacitor is switched on and off at a specific clock frequency as the frequency-determining component. The switching frequency used for this is many times higher than the cutoff frequency of the filter. The switching function is performed by an operational amplifier or a transistor. By changing the clock frequency at which the capacitors are switched on and off, the frequency-related filter characteristics can be changed.

SC filters are characterized by a large frequency variation, they can have different ordinal numbers and Q and reach slopes of 100 dB/ octave.