Abstract: The characteristics of a full-tilt exponential waveform are developed through use of a charge burping model or through use of a transthoracic cell response model. These characteristics are implemented within a pulse delivery circuit, which itself is implemented within an internal defibrillator or within an external defibrillator. The pulse delivery circuit includes at least one switch which starts and stops the delivery of the defibrillation pulse. Delivery of the defibrillation pulse is started by the switch when there is sufficient stored energy to deliver a desired pulse. Delivery of the defibrillation pulse is stopped by the switch when the current flowing through the switch is substantially zero and the exponential waveform of the pulse is substantially fully decayed.