Patent ID: 6259334
Filing Date: 2001-07-10
Classification: H01J,H01P,H03H

Abstract:
A method for tuning an impedance matching network toward a tune point where power reflection is at a minimum, the impedance matching network being coupled between an rf generator and a load to transmit rf power to the load, the impedance matching network including a set of variable impedance elements, the method comprising:(a) measuring a network impedance value of the impedance matching network including the load at current values of the variable impedance elements;(b) determining directions and relative rates of change for the variable impedance element values in response to the network impedance of the network, wherein network impedance values are computed at a plurality of neighboring values of the current values of the variable impedance elements in response to an impedance of the load, wherein a set of neighboring values having the lowest reflected power among the plurality of neighboring values is selected from the plurality of neighboring values;(c) driving the variable impedance elements by adjusting the variable impedance elements in the computed directions by the computed relative rates of change such that the variable impedance elements are driven to new current values in the direction of the selected set of neighboring values; and(d) repeating operations (a) through (c) until a desired level of tuning precision is obtained at the current values of the variable impedance elements.