Implantable cardiac defibrillator employing a switched capacitor filter stage having a low charge-injection induced offset voltage

摘要

An implantable cardiac defibrillator employing a switched capacitor filter stage having charge steering resistors connected in series with corresponding switched capacitors that are coupled to a sensitive node of an operational amplifier. The stored channel charges in associated switches when they are turned off are directed away from the sensitive node. The switches associated with the switched capacitors are operated by control signals having a generally trapezoidal shaped waveform so as to slowly turn off the same, thereby reducing clock feedthrough and charge injection induced offset voltage on the output of the operational amplifier.