BACKGROUND: The defibrillator is a device that instantaneously discharges the high energy stored in the capacitor to the human body to help revitalize the heart. The circuit for charging the capacitor uses the same power source as the biosignal measurement unit. Therefore, variation in main power supply voltage, ground noise, and electromagnetic interference from the charging circuit can induce distortion into the biosignal at the initial stage of charging. OBJECTIVE: In this study, a simple method is proposed for removing the initial irregularity of an electrocardiogram due to the transient state of a power supply. METHODS: To evaluate the method, a 1-channel electrocardiogram measurement unit and peripheral units were separated from the main control module using galvanic isolation. An isolated push-pull converter was designed to power the secondary side. The method was tested under steady-state and transient conditions. RESULTS: The obtained results proved that biosignal distortion can be significantly reduced. CONCLUSION: This method could be another simple implementation approach for solving signal distortions due to the transient status of power supplies used in medical devices.
