Patent ID: 7501885

Claim:
An active filter circuit comprising: an active circuit including a voltage amplifier, an associated voltage amplifier power supply and a resistor connected to the voltage amplifier; a capacitor having a first electrode and a second electrode; a first analog switch connected between the first electrode and the active circuit and for receiving a switching control signal; and a second analog switch connected between the second electrode and the active circuit and for receiving the switching control signal, wherein each of the first and second analog switches is opened by the switching control signal when the associated voltage amplifier power supply supplies a supply voltage to the voltage amplifier and the voltage amplifier is turned on, is closed by the switching control signal when an output voltage of the voltage amplifier reaches a predetermined steady state value, and is opened by the switching control signal when the supply voltage from the associated voltage amplifier power supply to the voltage amplifier is interrupted and the voltage amplifier is turned off.