Patent ID: 7956620

Claim:
An impedance monitoring circuit for an electrosurgical generator, the monitoring circuit comprising: an isolation transformer coupled to at least one of an active terminal and a return terminal of an electrosurgical generator, wherein the isolation transformer includes a primary winding coupled to a reference resistor and a secondary winding coupled to a load; a driver configured to transmit a sensor signal to the reference resistor and the load; a primary converter coupled to the reference resistor and the load and configured to detect a primary converted signal as a function of the sensor signal passing through the reference resistor and the load; a secondary converter coupled to the driver and configured to detect a secondary converted signal as a function of the sensor signal prior to passing through the reference resistor and the load; and a controller including a preprogrammed offset value, wherein the controller is configured to determine a fault condition based on the primary and secondary converted signals and the offset value.