A circuit is provided for isolating noise from an input signal to an Analog/Digital (A/D) converter. The circuit includes a plurality of multiplexers and a capacitor connected between the poles of two Single-Pole Multi-Throw (SPMT) multiplexers. A method is also provided for isolating noise from an input signal to the A/D converter using the circuit. The method includes storing a charge in the capacitor and discharging the charge to an A/D converter used to control a system or device.