Patent ID: 7211081
Filing Date: 2007-05-01
Classification: A61B

Abstract:
1. An electrosurgical generator for supplying radio frequency (RF) power to an electrosurgical instrument for cutting or vaporising tissue, wherein the generator comprises an RF output stage having: at least one RF power device, at least one pair of output lines for delivering RF power to the instrument, and a series-resonant output network coupled between the RF power device and the said pair of output lines, and protection circuitry responsive to a predetermined electrical condition indicative of an output current overload substantially to interrupt the RF power supplied to the output network, the protection circuitry being responsive to application of a short circuit across the output lines, the protection circuitry being responsive to the said short circuit sufficiently quickly to disable the RF power device before the current passing therethrough rises to a rated maximum current as a result of the short circuit, wherein the output impedance of the output stage at the output lines is less than 200/√P ohms, where P is the maximum continuous RF output power of the generator in watts, and the protection circuitry is responsive to the application of a short circuit at the output lines with sufficient speed that the supply of RF power to the output network is interrupted within a time period corresponding to no more than 20 RF cycles of the delivered RF power.