Variable switched-capacitor filter capable of changing the filter characteristic thereof

Claim 1

A switched-capacitor filter comprising: an input terminal (101); an output terminal (104); first and second variable switched-capacitor filter (102 and 103, resp.) means/,each having a plurality of capacitors whose at (S 105 and S 106 , resp.) least one is selected responsive to a control signal and changing a filter characteristic thereof based on the selected capacitor or capacitors, the first and (102, 103) second filter means/being applied with an input signal coming in through said input terminal ( 101 ); (SA) first switching means/for, during a first state, delivering a first output signal from said first variable (102) switched-capacitor filter means/to said output terminal (104) either directly or via a sample and hold circuit and, during a second state, prohibiting the first output signal from reaching said output terminal (104); and (SB) second switching means/for, during said second state, delivering a second output signal from said second variable (103) switched-capacitor filter means/to said output terminal (104) directly or via said sample and hold circuit and, during said first state, prohibiting the second output signal from reaching said output terminal (104); said selection of at least one capacitor in said first variable switched-capacitor filter means (102) being performed during said second state, said selection of at least one capacitor in said second variable switched-(103) capacitor filter means/being performed during said first state.