Abstract: [OBJECT] To provide a radio-frequency power source capable of outputting radio-frequency power having a desired waveform changing at high speed. [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 ? between the radio-frequency voltages vPA and vPB. A controlling circuit 9 switches the phase difference ? between ?1 and ?2. 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.

Abstract: [OBJECT] To provide a radio-frequency power source capable of outputting radio-frequency power having a desired waveform changing at high speed. [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 ? between the radio-frequency voltages vPA and vPB. A controlling circuit 9 switches the phase difference ? between ?1 and ?2. 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.

Abstract: A phase difference detector detects the phase difference between two AC signals at a high speed and with high accuracy. A phase difference computation unit computes the phase difference ?r(=?2??1) between two detected voltages v1 (phase angle: ?1) and v2 (phase angle: ?2). The phase difference computation unit uses a sine wave vs and a cosine wave vc generated separately and having the same frequency as the fundamental frequency of the voltages v1 and v2, to perform computation of v2s=v2×vs, v2c=v2×vc, v1s=v1×vs, v1c=v1×vc, and then extracts DC components I2=(?A2/2)·sin(?2), R2=(A2/2)·cos(?2), I1=(?A1/2)·sin(?1), R1=(A1/2)·cos(?1) at low-pass filters. The phase difference computation unit computes R3=R1×R2+I1×I2 at a complex multiplying unit to obtain R3=(A1·A2/4)·cos(?r), computes I3=R2×I1?R1×I2 to obtain I3=(A1·A2/4)·sin(?r), and computes ?r=tan?1(I3/R3) at the arctangent calculation unit, thereby obtaining the phase difference ?r.

Abstract: A phase difference detector detects the phase difference between two AC signals at a high speed and with high accuracy. A phase difference computation unit computes the phase difference ?r(=?2??1) between two detected voltages v1 (phase angle: ?1) and v2 (phase angle: ?2). The phase difference computation unit uses a sine wave vs and a cosine wave vc generated separately and having the same frequency as the fundamental frequency of the voltages v1 and v2, to perform computation of v2s=v2×vs, v2c=v2×vc, v1s=v1×vs, v1c=v1×vc, and then extracts DC components I2=(?A2/2)·sin(?2), R2=(A2/2)·cos(?2), I1=(?A1/2)·sin(?1), R1=(A1/2)·cos(?1) at low-pass filters. The phase difference computation unit computes R3=R1×R2+I1×I2 at a complex multiplying unit to obtain R3=(A1·A2/4)·cos(?r), computes I3=R2×I1?R1×I2 to obtain I3=(A1·A2/4)·sin(?r), and computes ?r=tan?1(I3/R3) at the arctangent calculation unit, thereby obtaining the phase difference ?r.

Abstract: The microwave generator with use of a magnetron comprises a microwave detector for detecting microwave output from the magnetron and a filament life diagnostic circuit for judging the life of filament of the magnetron by decreasing an input power to a filament of the magnetron from a normal state of the magnetron while monitoring the microwave output from the magnetron by the microwave detector, comparing the input power in the normal state of the magnetron with that just before the magnetron becomes unstable and judging the filament life based on the difference between the input power of the normal state and that just before the unstable state.