| 摘要 |
PROBLEM TO BE SOLVED: To prevent an envelope waveform of a voltage waveform from ringing and rounding when producing high frequency power modulated such that the envelope waveform presents a waveform representing stepped level changes.SOLUTION: A series of periods of an envelope waveform is divided into a feedback control execution period and a feedback control suspension period. In each feedback control execution period, during a transitional period set immediately after the start of an interval period between adjacent level change timings of the envelope waveform, the control of equalizing a level of the envelope waveform with a target level is performed by open loop control, and subsequently during a stable period past the transitional period, the control of keeping the level of the envelope waveform at the target level is performed by feedback control. In each feedback control suspension period, on the other hand, during each entire interval period, the control of equalizing a level detected by a level detection section with a level detected during the stable period in the corresponding interval period of the most recent feedback control execution period is performed by open loop control. |
