Patent ID: 7332981
Filing Date: 2008-02-19
Classification: H03H

Abstract:
1. An impedance matching apparatus to be interposed between a high-frequency power source and a load, for changing an impedance of an impedance variable device so as to match an impedance of the high-frequency power source and an impedance of the load, comprising: a high-frequency wave information detector to detect information on a forward wave advancing from the high-frequency power source toward the load and information on a reflected wave advancing from the load toward the high-frequency power source, at an input terminal of the impedance matching apparatus; a variable device information detector to detect information on a variable value of the impedance variable device; a first storage unit to store therein a characteristic parameter of the impedance matching apparatus acquired through a preceding measurement, with respect to the information on a variable value of a plurality of the impedance variable devices, in correlation with the information on the variable value of the impedance variable device; a first calculator to calculate the information on the forward wave and the information on the reflected wave at an output terminal of the impedance matching apparatus, based on the information on the variable value of the impedance variable device detected by the variable device information detector, on the characteristic parameter stored in the first storage unit, and on the information on the forward wave and the information on the reflected wave detected by the high-frequency wave information detector; a third calculator to calculate a reflection coefficient at the output terminal of the impedance matching apparatus, based on the information on the forward wave and the information on the reflected wave at the output terminal of the impedance matching apparatus calculated by the first calculator; a fourth calculator to calculate a reflection coefficient at the output terminal of the impedance matching apparatus with respect to the information on the variable value of the plurality of impedance variable devices, based on a predetermined target input reflection coefficient and a plurality of the characteristic parameters stored in the first storage unit; a third storage unit to store therein a plurality of the reflection coefficients calculated by the fourth calculator in correlation with the information on the variable value of the impedance variable device; a second identifier to select a reflection coefficient closest to the reflection coefficient at the output terminal of the impedance matching apparatus calculated by the third calculator out of the plurality of reflection coefficients stored in the third storage unit, and to identify the information on the variable value of the impedance variable device corresponding to the selected reflection coefficient; and an adjustment unit to adjust an impedance of the impedance variable device, based on the information on the variable value of the impedance variable device identified by the second identifier.