Patent attributes
An impedance matching device is to be provided between a load and a high frequency power supply in which output power is modulated to a high output and a low output alternately. The impedance matching device calculates an impedance or a reflection coefficient of a case where the load side is viewed from an output end of the high frequency power supply. The impedance matching device performs, based on results of the calculations performed in a first period in which the output power is the high output and in a second period in which the output power is the low output, operations for the impedance matching in the subsequent second period and first period respectively. The impedance matching device achieves, based on results of these operations, the impedance matchings in the subsequent first period and second period respectively.
