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: A phase adjusting circuit for adjusting phases of output powers from two high frequency power generators in a plasma processing apparatus comprises first and second synthesizing circuits for generating first and second high frequency signals of a predetermined waveform with frequencies of f0 and f0.+-..DELTA.f (.DELTA.f<<f0), a phase difference detection circuit for detecting a phase difference between detection signals of plate electrodes, a third waveform synthesizing circuit for generating a high frequency signal with frequency and waveform same as the first frequency signal which has a phase determined from a phase error between a set phase difference and an output from the phase difference detection circuit and a phase adjusting circuit which determines output powers of the two high frequency power generators base on outputs of the first and third waveform synthesizing circuits.

Abstract: In a microwave power source apparatus for a microwave oscillator for generating a microwave, a DC power source supplies a DC power for generating the microwave to the microwave oscillator. A measuring section of a voltage standing wave detector is mounted on a microwave transmission line connected between the microwave oscillator and a microwave load, and measures either one of an impedance seen looking toward the microwave load at a mounted point thereof and a reflection coefficient thereat by detecting a voltage standing wave of the microwave being generated by the microwave oscillator and propagating on the microwave transmission line.