Patent Document ID: 5422567
Application ID: 08174593
Patent Status: 1

Claim One:
1. A high frequency power monitoring circuit for an electrosurgical generator applied to a load to achieve an electrosurgical effect comprising: a source of high frequency electrosurgical energy including an electrosurgical generator and its active and return conductors connected to the output thereof; an inductive pick up for voltage connected between the conductors of the electrosurgical generator; an inductive pick up for current flowing through at least one of the conductors of the output from the electrosurgical generator; an inductive pick up for the inverse of current flowing through the one conductor of the electrosurgical generator output; a first adder circuit for computing the instantaneous inductively picked up voltage with the instantaneously inductively picked up current to provide a sum indicative instantaneously thereof; a second adder circuit for computing the inductively picked up voltage and the inverse of the instantaneously derived current providing a differential value thereof; a root mean square to direct current converter for the summation value to provide a signal of the instantaneous value of the summation as a root mean square summation value; a root mean square to direct current converter for the differential value to provide a signal of the instantaneous value of the differential as a root mean square differential value, and a microprocessor to periodically receive the root mean square summation and root mean square differential values and square those instantaneous root mean square summation and differential values for application to a formula wherein the squared root mean square summation values have subtracted therefrom the squared root mean square differential values so the result therefrom can be divided by four to provide the root mean square value of the actual power applied to the load.