Patent ID: 6996436

Claim:
A defibrillator comprising first and second electrodes for application to a patient, a voltage source, and an output circuit for connecting the voltage source across the electrodes upon the occurrence of at least one control signal, wherein the output circuit includes a first current path connecting one side of the voltage source to the first electrode and a second current path connecting the other side of the voltage source to the second electrode, a third current path connecting the one side of the voltage source to the second electrode, and a fourth current path connecting the other side of the voltage source to the first electrode, each of the first to fourth current paths containing at least one solid state switching device that is an uncontrolled two-terminal device which automatically undergoes a transition from a high impedance state to a low impedance state when a voltage greater than a predetermined threshold is applied across its terminals, the at least one switching device in the first current oath transitioning to a low impedance state unconditionally when the applied voltage exceeds a predetermined threshold, and the at least one switching device in the third current oath transitioning to a low impedance state if the applied voltage exceeds a predetermined first threshold but not a second, higher threshold.