Abstract: An analog to digital converter for use in an electrocardiogram device is provided that includes a voltage supply; an operational amplifier, including: a positive input pin; an inverting input pin; and an output pin; an output node, connected directly to the output pin and the inverting input pin; an ECG electrode, connected to the output node via a first resistor; a reference voltage, connected directly to the output node; and a feedback node, connected to directly to the positive input pin, connected to the voltage supply via a second resistor, and connected to a ground via a third resistor and a first capacitor, wherein the third resistor and the first capacitor are connected in parallel between the feedback node and the ground.