Two-electrode ECG devices have gained popularity in the recent past to enable comfortable and long-term monitoring of cardiovascular health. As a ground or bias electrode is not used in a two-electrode ECG device, common-mode interference (CMI) caused by powerline coupling to the human body can be as large as a few tens of volts. Such a large CMI ruins the ECG recording, and thus the analog front-end of the ECG device must be immune to large CMI.