High-frequency power supply apparatus
A high-frequency power supply apparatus includes the following elements. A first power supply supplies first power to a load by outputting a first voltage whose fundamental frequency is higher than a second voltage output by a second power supply. A period signal generation circuit generates a period signal matching a frequency and a phase of the second voltage. A waveform control circuit generates a modulation signal for performing frequency modulation on a fundamental wave signal of the first voltage, and adjusts an output timing of the modulation signal in accordance with a timing of the period signal. The first power supply generates a first frequency signal by performing frequency modulation on the fundamental wave signal of the first voltage by using the modulation signal. The first power supply performs power amplification on the first frequency signal and outputs, to the load, the first frequency signal as first power.
1. A high-frequency power supply apparatus comprising:
a first power supply configured to supply first power to a load by outputting a first voltage with a first fundamental frequency;
a second power supply configured to supply second power to the load by outputting a second voltage with a second fundamental frequency being lower than the first fundamental frequency;
a first matching circuit connected between the first power supply and the load;
a second matching circuit connected between the second power supply and the load;
a detection circuit configured to output a detection signal representing the first voltage;
a period signal generation circuit configured to generate a period signal matching a frequency and a phase of the second voltage, the period signal being generated by performing predetermined processing after generating a square signal by squaring the detection signal; and
a waveform control circuit configured to
generate a modulation signal for performing frequency modulation on a fundamental wave signal of the first voltage, and
adjust an output timing of the modulation signal in accordance with a timing of the period signal,
wherein the first power supply is further configured to
generate a first frequency signal by performing frequency modulation on a fundamental wave signal of the first voltage by using the modulation signal,
perform power amplification on the first frequency signal, and
output, to the load, the first frequency signal as the first power.
2. The high-frequency power supply apparatus according to claim 1 , wherein the period signal generation circuit includes:
a squaring circuit configured to generate the square signal;
a low-pass filter circuit configured to output a high-frequency component removal signal representing an amplitude component of a fundamental wave of a voltage of the first power;
an averaging circuit configured to output an averaged signal obtained by averaging the square signal; and
a comparison circuit configured to output, as the period signal, a signal representing a comparison result obtained by comparing the high-frequency component removal signal and the averaged signal.
3. The high-frequency power supply apparatus according to claim 1 , wherein the period signal generation circuit includes:
a differential squaring circuit configured to generate the differential square signal by squaring the detection signal;
a differential low-pass filter circuit configured to output a high-frequency component removal signal representing an amplitude component of a fundamental wave of a voltage of the first power; and
a comparator configured to output, as the period signal, a signal representing a comparison result obtained by comparing a signal on a positive side and a signal on a negative side in the high-frequency component removal signal.
4. The high-frequency power supply apparatus according to claim 1 , wherein the waveform control circuit is configured to
generate the modulation signal based on modulation waveform data, the modulation waveform data being constituted by pieces of amplitude information and being stored in a memory,
sequentially output, every control cycle, the pieces of the amplitude information of the modulation waveform data, and
adjust an output timing of the modulation waveform data to synchronize with a timing of a predetermined phase of the period signal.
5. The high-frequency power supply apparatus according to claim 2 , wherein the waveform control circuit is configured to
generate the modulation signal based on modulation waveform data, the modulation waveform data being constituted by pieces of amplitude information and being stored in a memory,
sequentially output, every control cycle, the pieces of the amplitude information of the modulation waveform data, and
adjust an output timing of the modulation waveform data to synchronize with a timing of a predetermined phase of the period signal.
6. The high-frequency power supply apparatus according to claim 3 , wherein the waveform control circuit is configured to
generate the modulation signal based on modulation waveform data, the modulation waveform data being constituted by pieces of amplitude information and being stored in a memory,
sequentially output, every control cycle, the pieces of the amplitude information of the modulation waveform data, and
adjust an output timing of the modulation waveform data to synchronize with a timing of a predetermined phase of the period signal.