Patent ID: 6809580
Filing Date: 2004-10-26
Classification: H03H

Abstract:
A switched capacitor filter circuit comprising:an input capacitor; a first switching transistor provided at one terminal side of the input capacitor to perform switching operation when a switching control signal is inputted to a gate thereof; a second switching transistor provided at the other terminal side of the input capacitor to perform switching operation when the switching control signal is inputted to a gate thereof; an operational amplifier to which an input voltage is applied to an input terminal thereof via the second switching transistor; an integration capacitor provided between the input terminal and an output terminal of the operational amplifier to allow application of a voltage across the input terminal and the output terminal; and a first noise compensation transistor connected in series to the second switching transistor between the second switching transistor and the input terminal of the operational amplifier in order to cancel feedthrough noise associated with the input voltage applied to the input terminal, the feedthrough noise being generated by the second switching transistor when a signal of a polarity inverted from the switching control signal is applied to a gate thereof.