TWI705736B

[SOLUTION] A radio-frequency power source 1 includes two DC-RF converting circuits 4A, 4B and an RF combining circuit 5 for combining the outputs from both DC-RF converting circuits 4A, 4B. The DC-RF converting circuits 4A, 4B amplify radio-frequency voltages va, vb inputted from a radio-frequency signal generating circuit 8, and output radio-frequency voltages vPA, vPB. The RF combining circuit 5 outputs radio-frequency voltage vPX at a ratio corresponding to the phase difference θ between the radio-frequency voltages vPA and vPB. A controlling circuit 9 switches the phase difference θ between θ1 and θ2. As a result, the power PX outputted from the RF combining circuit 5 becomes pulsed radio-frequency power having a high level period and a low level period. Since the switching of the phase difference θ can be performed at high speed, it is possible to output pulsed radio-frequency power with a high switching frequency between the first level and the second level.