JP5963632B2 - High frequency power supply device and control method thereof - Google Patents

Description

  The present invention relates to a high-frequency power supply apparatus that outputs high-frequency power having a voltage waveform modulated by a signal indicating a step-like level change, and a control method thereof.

  In processing various objects to be processed, a technique for converting a gas into plasma by radiation of high-frequency power is used. For example, in an etching process performed in a semiconductor manufacturing process, a high-frequency power is supplied to an electrode disposed in a process chamber and the high-frequency power is radiated into the chamber, whereby the gas in the chamber is converted into plasma, and the plasmaized gas Is supplied to the object to be processed. A high-frequency power supply device used for this kind of application includes a high-frequency signal generator that generates a high-frequency signal, a high-frequency signal generator / amplifier having an amplifier that amplifies the high-frequency signal and outputs high-frequency power, and a high-frequency signal generator / amplifier. And a control unit that controls the level of the high-frequency voltage detected at the output terminal of the unit to be maintained at the target level.

  In recent years, in a semiconductor manufacturing process, in order to enable fine etching processing, high-frequency power modulated by a pulse waveform is radiated into a process chamber. The high frequency power modulated by the pulse waveform can be obtained by on / off control of the level of the high frequency signal input to the amplifier.

  When high-frequency power modulated by a pulse waveform is used for plasma processing, it is necessary to strictly manage the frequency, level (amplitude value), duty, and repetition period of the envelope waveform (pulse waveform) of the voltage waveform. In addition, with the miniaturization of processing, it is required to supply high-frequency power to the electrodes in the process chamber, in which the waveform of the envelope of the voltage waveform exhibits a more precise and stable waveform. .

  Recently, there are a plurality of level change timings that cause a step-like level change in one cycle, and the interval period between each level change timing and the next level change timing is to hold the level. It has also been studied to radiate high-frequency power modulated by a step waveform whose level takes a plurality of different values during one period into the process chamber.

  As a high-frequency power supply device that obtains high-frequency power modulated by a pulse waveform, for example, the one disclosed in Patent Document 1 is known. In the high-frequency power supply device disclosed in Patent Document 1, a pulse modulation unit that generates a pulse-modulated high-frequency signal by modulating a high-frequency signal with a pulse signal having a frequency lower than that frequency, and the pulse-modulated high-frequency signal A high-frequency power converter (amplifier) that amplifies the signal and converts it into pulse-modulated high-frequency power, an output detector that detects a high-frequency voltage output from the high-frequency power converter, and an output voltage detected by the output detector A detection unit that detects and generates a detection voltage indicating the envelope, a sample and hold unit that samples the detection voltage according to the sample and hold signal and outputs a sampling voltage, and generates the pulse signal and the sample and hold signal A control unit and an error amplifying unit that compares the sampling voltage with the reference voltage and outputs an error voltage are provided. The level of the high-frequency voltage is controlled by feedback control of the high-frequency power converter so as to minimize the gap.

  In the high frequency power supply device disclosed in Patent Document 1, a period from a timing delayed by a certain time from each rising edge of a pulse signal waveform that modulates high frequency power to a timing earlier by a certain time than each falling edge is sampled and held. The sampling period of the sample hold signal is set in accordance with the duty ratio of the pulse signal so as to be the on period of the signal. Then, during the on-period of the sample hold signal, the sample hold unit provides the detection voltage obtained from the detection unit as it is as the sampling voltage to the error amplification unit, and feeds back the level fluctuation of the high frequency voltage, thereby providing a voltage of the high frequency power. Control is performed to maintain the waveform envelope level at a predetermined level. During the off period of the sample and hold signal, the detection voltage at the timing when the sample and hold signal switches from the on period to the off period (timing immediately before the pulse signal falls) is held. At the start of the on-period of the pulse signal, the held sampling voltage is applied to the error amplifying unit so that the error voltage is output and feedback control is performed. After the pulse signal waveform has risen, a certain delay time has elapsed. When the elapsed time elapses, the hold signal is turned on, and a sampling voltage equal to the detection voltage is supplied to the error amplification unit, thereby feeding back the level fluctuation of the high frequency voltage during the on period of the pulse signal and feeding back the high frequency voltage during the on period of the pulse signal. Is controlled to keep the level at a predetermined level.

  According to the high frequency power supply device disclosed in Patent Document 1, when the level fluctuates after the waveform (pulse waveform) of the voltage waveform of the high frequency power rises, the level fluctuation is fed back and the high frequency voltage is fed back. It is possible to perform control to keep the level at a predetermined level.

JP 2010-263352 A

  In the high frequency power supply device disclosed in Patent Document 1, the sampling value of the detection voltage indicating the level of the envelope of the voltage waveform of the high frequency power is maintained at the reference value at the rise and fall of the pulse signal that modulates the high frequency power. Thus, feedback control is performed. Since the level of the high-frequency voltage fluctuates sharply at each rise and fall of the pulse signal, ringing or waveform dullness occurs at each rise and fall of the pulse signal unless the control tracking is improved. become. If the time axis of the pulse signal that modulates high-frequency power is long (when the pulse width is wide), it will not be noticeable even if ringing or waveform dullness occurs at the rise and fall of the pulse signal, so the load will be greatly affected. However, if the pulse signal repetition period is shortened and the pulse signal ON period is shortened or the amplitude of the pulse signal is large, ringing or waveform dullness that occurs in the high-frequency voltage at the rise and fall of the pulse signal The effect of these transient waveforms on the load becomes a problem.

  In particular, when the waveform that modulates high-frequency power is not a simple pulse waveform, but a step waveform that shows a step-like level change up and down at short intervals during each period, at each rising edge of the step waveform Since the ringing or waveform dullness generated in the high frequency voltage and the ringing or waveform dullness generated in the high frequency voltage at each falling edge appear in a short time interval, the ringing or waveform dullness cannot be ignored. Therefore, when the waveform that modulates high-frequency power is a pulse waveform or step waveform having a high frequency, it becomes a problem to improve the follow-up of control at each rising and falling of the modulation waveform.

  If a control loop that feedback-controls the level of the high-frequency voltage based on the detection data obtained from the detector that detects the high-frequency voltage output from the amplifier that amplifies the high-frequency signal as in the prior art, modulation is performed. If the waveform level changes at a high speed, it is inevitable that the followability will deteriorate, and if you try to control it by force, ringing and waveform dullness will occur at the rise and fall of the modulation waveform level. Will adversely affect the load.

  For example, as shown in FIG. 9A, a plurality of level change timings indicating step-like level changes (three level change timings ta, tb, tc in the illustrated example) are provided in one cycle. When obtaining a high-frequency power having a voltage waveform modulated by a multi-value step waveform (three-value step waveform in the illustrated example) whose level takes a plurality of values (three in the illustrated example) during one cycle, When feedback control is performed based on the detected value of the high-frequency voltage level at each rise and fall of the step waveform, when the control gain is too large, the level change of the step waveform as shown in FIG. At the timing, the overshoot and the downshoot are repeated and ringing L occurs. Further, when the control gain is insufficient, as shown in FIG. 5C, the control is not in time at each level change timing of the step waveform, and the waveform dullness D occurs.

  Although there is a state in which neither ringing nor waveform blunting occurs between the state of FIG. 9B and the state of FIG. 9C, the time interval of the timing at which the modulation waveform shows a level change is short. In some cases, it is difficult to configure the control system so that neither ringing nor waveform dullness occurs.

  As shown in FIG. 10A, when obtaining a high-frequency power having a voltage waveform modulated by a high-speed step waveform in which the repetition cycle of level change is made shorter than in the case shown in FIG. 9A. When the feedback control system has the characteristic of causing ringing, as shown in FIG. 10B, the ringing L generated at each rising and falling of the envelope waveform of the voltage waveform of the high frequency power is level. The waveform cannot be ignored with respect to the length of the level holding period between the change timings. Further, as shown in FIG. 10A, the feedback control system has a characteristic of causing waveform dullness when obtaining high-frequency power having a voltage waveform modulated by a high-speed step waveform with a short cycle of level change. As shown in FIG. 10C, the waveform dullness D generated at each rise and fall of the envelope waveform of the voltage waveform of the high frequency power is the length of the level holding period between the level change timings. On the other hand, the waveform cannot be ignored.

  As described above, when it is necessary to supply high-frequency power modulated by a pulse waveform or step waveform to the load, the detected value of the envelope level even at the timing when the envelope of the high-frequency voltage shows a level change. When using a conventional high-frequency power supply that performs feedback control of the output level based on the deviation (error) from the target value, the voltage waveform of the resulting high-frequency power becomes a waveform in which ringing or waveform dullness is conspicuous, and the desired However, there is a problem that high-frequency power having a voltage waveform that meets the requirements cannot be supplied to the load. The problem of ringing and waveform blunting when the level changes stepwise and adversely affecting the load occurs not only when the waveform that modulates high-frequency power is a pulse waveform or step waveform. The same problem occurs when the waveform for modulating the high-frequency power is another waveform with a step-like level change.

  An object of the present invention is that the envelope of the voltage waveform has a plurality of level change timings indicating step-like level changes in one cycle, and the period between each level change timing and the next level change timing is When obtaining high-frequency power modulated so as to exhibit a waveform having an interval period that maintains a certain level, the envelope of the voltage waveform of the high-frequency power is whatever the level change speed of the waveform to be modulated. To provide a high-frequency power supply apparatus and a control method thereof capable of obtaining high-frequency power having a stable voltage waveform by preventing ringing and waveform dullness during a transient in which the waveform of the line shows a step-like level change. It is in.

  In the first invention disclosed in the present application, the waveform of the envelope of the voltage waveform (hereinafter referred to as the envelope waveform) has a plurality of level change timings indicating a step-like level change in one cycle, and is adjacent to each other. The present invention is directed to a method for controlling a high-frequency power supply device that outputs high-frequency power modulated so as to exhibit a step waveform in which a period between level change timings is an interval period in which a constant level is maintained.

  In the present invention, a level detector that detects the level of the envelope waveform is provided, and control is performed to keep the level detected by the level detector at the target level. In this control, each interval period of each cycle of the envelope waveform is divided into a transition period set immediately after the start and a stable period after the transition period has elapsed, and the envelope is set in the transition period of each interval period. Control for matching the level of the waveform to the target level is performed by open loop control, and control for matching the level of the envelope waveform to the target level is performed by feedback control during the stable period.

  In the present invention, in order to perform the above-described control, the set value of the level to be taken in each interval period that the envelope waveform of the voltage waveform of the high frequency power output from the high frequency power supply device has in one cycle is set for each interval period. The set target level is stored in the set target level storage unit.

  In addition, the first cycle of the envelope waveform when the high-frequency power is first output from the high-frequency power supply device with the envelope waveform of the voltage waveform being set as the target level for each interval period of the cycle is the first cycle. As for each period from the first period of the envelope waveform to the (m-1) th period (m is a set value consisting of an integer of 2 or more), each of the period from the first period to the current period A level obtained by averaging the levels detected by the level detection unit in the stable period of each interval period corresponding to the period is calculated as an average detection level of each interval period, and in each period after the mth period of the envelope waveform , A level obtained by averaging the m levels detected by the level detection unit in the stable period of each interval period corresponding to each cycle from the previous cycle to the current cycle. Calculated as the average detection level of the interval period, and calculated the average detection level of each interval period as the target level that the envelope waveform should take in the corresponding interval period of the period following the period of calculation of the average detection level. This is stored in the periodic target level storage unit.

  In each interval period of the first cycle of the envelope waveform, the level detected by the level detection unit is equal to the corresponding set target level stored in the set target level storage unit until the transition period elapses. After performing the control by open loop control, during the stable period, control to maintain the level detected by the level detection unit at the corresponding set target level stored in the set target level storage unit is performed by feedback control, and the envelope waveform In each interval period of each period after the second period, control for making the level detected by the level detection unit until the transition period elapses equal to the corresponding target level stored in the next period target level storage unit Is performed by open loop control, and the level detected by the level detection unit is stored in the next cycle target level storage unit during the stable period. The corresponding is performed by feedback control of the control to keep the target level.

  During the above transition period, the feedback control system can stably perform the feedback control after performing control to make the level of the envelope of the voltage waveform of the high-frequency power equal to the target level at each level change timing by open loop control. It is set equal to the time required until the state is reached (the time required until the detected value of the voltage level detected by the level detection unit becomes stable).

  As described above, when obtaining a high-frequency power having a voltage waveform modulated by a waveform indicating a step-like level change, a transient immediately after the start of each interval period of each cycle of the envelope waveform of the voltage waveform of the high-frequency power During the stable period after the transition period of each interval period of each cycle of the envelope waveform of the high-frequency power voltage waveform is performed by level control during the period not by feedback control but by open loop control If the control that keeps the level detected by the level detection unit at the target level is performed by feedback control, the level change at any level change timing and at any level change cycle No ringing or waveform dullness occurs at the timing, and in the stable period of each interval period There are levels of the envelope can be obtained a high-frequency power having a precise voltage waveform was maintained at a target level.

  In addition, as described above, the level detection unit detects the target level that the envelope waveform should take in each interval period of each cycle of the envelope waveform of the voltage waveform, and the stable period of the corresponding interval period of the most recent cycles. Assuming that the detected level is an average level, the target level in each interval period can be made equal to the average value of the stable levels actually feedback controlled in the corresponding interval period of the most recent period, The level of the envelope of the voltage waveform of the high-frequency power that is output from the amplifier by performing open-loop control during the transition period in each interval period, and the level of the envelope of the voltage waveform of the high-frequency power that is output at the moment of switching to feedback control It is possible to make almost no difference between the two. Therefore, according to the present invention, it is possible not only to prevent ringing and waveform dullness at each level change timing, but also to prevent voltage fluctuation when the control is switched from open loop control to feedback control. High-frequency power with a clean waveform can be obtained.

  Also, according to the above method, ringing and waveform dullness do not occur at each level change timing of the envelope waveform of the voltage waveform of the high frequency power, so that the excessive period can be shortened, and the detection speed of the envelope of the high frequency voltage Can be increased. For this reason, even when the level change of the waveform that modulates the high frequency power is high speed, the level control during the transition period from each level change timing and the level control during each interval period can be accurately performed. It is also possible to cope with the case where high-frequency power is modulated by the pulse waveform or step waveform.

  The second invention disclosed in the present application relates to a high-frequency power supply apparatus that implements the control method according to the first invention, and the envelope waveform of the voltage waveform has a level change timing of 1 indicating a step-like level change. A plurality of high-frequency signal generators and high-frequency signal generators each having high frequency power modulated so as to exhibit a step waveform having an interval period in which a period between adjacent level change timings holds a constant level. A high-frequency power supply apparatus that outputs from a high-frequency signal generation / amplification unit including an amplifier that amplifies a high-frequency signal generated by a signal generator is an object.

  In the present invention, the level detector that detects the level of the envelope waveform, and the level to be taken in each interval period that the envelope waveform of the voltage waveform of the high-frequency power output from the high-frequency power supply device has during one cycle thereof. A set target level storage unit stored as a set target level for the interval period, and a high frequency power having the envelope waveform of the voltage waveform to be taken in each interval period of each cycle as a set target level are first output from the high frequency power supply device The first period of the envelope waveform at the time is the first period, and each interval period of each period of the envelope waveform is set to a transient period set immediately after the start and a stable period after the transient period has elapsed. Separately, in each period from the first period of the envelope waveform to the (m-1) th period (m is a set value consisting of an integer of 2 or more), the first The level obtained by averaging the levels detected by the level detection unit in the stable period of each interval period corresponding to each period from the period to the current period is calculated as the average detection level of each interval period, and the mth of the envelope waveform In each cycle after the first cycle, a level obtained by averaging the m levels detected by the level detection unit in the stable period of each interval period corresponding to each cycle from the cycle before m−1 to the current cycle is obtained. The average detection level calculation unit that calculates the average detection level of each interval period, and the average detection level of each interval period that is calculated by the average detection level calculation unit in each cycle of the envelope waveform, and the cycle in which the average detection level is calculated A next cycle target level storage unit for storing the envelope waveform as a target level to be taken in each interval period of the next cycle, A high frequency power control unit for controlling the high-frequency signal generator and amplification unit to a level that Le detecting unit detects the target level is provided.

  The high frequency signal generation / amplification unit stores the level detected by the level detection unit in the set target level storage unit until the transition period elapses in each interval period of the first cycle of the envelope waveform. After performing control to equalize the corresponding set target level by open loop control, feedback that controls to maintain the level detected by the level detection unit at the corresponding set target level stored in the set target level storage unit during the stable period In each interval period of the second and subsequent cycles following the first cycle, the level detected by the level detection unit until the transition period elapses is stored in the next cycle target level storage unit. After performing control to make it equal to the stored target level of the corresponding interval period by open loop control, each input During the stabilization period of Baru period, configured to perform the feedback control of the control to maintain the level of the level detection unit detects the corresponding target level is stored in the next cycle target level storage section.

  In the third invention disclosed in the present application, the waveform of the envelope of the voltage waveform (hereinafter referred to as an envelope waveform) has a plurality of level change timings indicating a step-like level change in one cycle, and is adjacent to the waveform. A high-frequency signal generator and a high-frequency signal generated by the high-frequency signal generator are amplified with a high-frequency power modulated so as to exhibit a step waveform in which a period between matching level change timings is an interval period that maintains a constant level. The present invention is directed to a high-frequency power supply device that outputs from a high-frequency signal generation / amplification unit including an amplifier that performs the above-described operation.

  In the high frequency power supply device according to the present invention, the level detector that detects the level of the envelope waveform and the interval waveform that the envelope waveform of the voltage waveform of the high frequency power output from the high frequency power supply device has in one cycle. A set target level storage unit that stores a level to be taken as a set target level for each interval period; and a high-frequency power source that uses the envelope waveform of the voltage waveform as a set target level for each interval period of each cycle The first period of the envelope waveform at the time of first output from the device is the first period, and each interval period of each period of the envelope waveform is set immediately after the start of the transient period and the transient period has elapsed. Divided into later stable periods, each of the envelope waveform from the first cycle to the (m-1) th cycle (m is a set value consisting of an integer of 2 or more) In the period, the level obtained by averaging the levels detected by the level detection unit in the stable period of each interval period corresponding to each period from the first period to the current period is calculated as the average detection level of each interval period. In each cycle after the m-th cycle of the envelope waveform, m detected by the level detection unit in the stable period of each interval period corresponding to each cycle from the m-1 previous cycle to the current cycle. An average detection level calculation unit that calculates a level obtained by averaging the individual levels as an average detection level of each interval period, and an average detection level of each interval period calculated by the average detection level calculation unit in each cycle of the envelope waveform Stored as the target level to be taken by the envelope waveform in each interval period following the period in which the average detection level is calculated And the next cycle target level storage unit, and a high frequency power control unit for controlling the high-frequency signal generator and amplification unit is provided so that the level detector is a target level the likelihood of detecting.

  The high-frequency signal generation / amplification unit is configured to have a function of adjusting a voltage level of high-frequency power output from the amplifier according to given level data.

  In addition, the high frequency power control unit is configured to store the level detected by the level detection unit in the set target level storage unit until the transition period elapses in each interval period of the first cycle of the envelope waveform. Open the control to make the envelope waveform level equal to the set target level by giving the high-frequency signal generator / amplifier the level data necessary to output the high-frequency power equal to the target level from the high-frequency signal generator / amplifier. After performing the loop control, during the stable period, the envelope is obtained by giving level data to the high frequency signal generation / amplification unit so that the deviation between the level detected by the level detection unit and the set target level of the corresponding interval period becomes zero Control that keeps the level of the line waveform at the set target level is performed by feedback control, and the second cycle following the first cycle is performed. In each interval period of each period after the period, the level necessary to make the envelope waveform level equal to the corresponding target level stored in the next period target level storage until the transition period elapses By applying data to the high-frequency signal generator / amplifier, the level of the envelope waveform is controlled to be equal to the target level by open loop control, and then the level detected by the level detector during the stable period and the next cycle target Control that keeps the envelope waveform level at the target level by giving level data to the high-frequency signal generator / amplifier so that the deviation from the corresponding target level stored in the level storage unit becomes zero is performed by feedback control. Configured.

  The fourth invention disclosed in the present application is applied to the third invention. In the present invention, the high-frequency signal generation / amplification unit sets the level of the high-frequency signal supplied from the high-frequency signal generator to the amplifier. A high-frequency signal generator is provided with a level adjusting unit that adjusts according to data, and the high-frequency signal generator is configured by a direct digital synthesizer (DDS) that outputs a high-frequency signal having a level indicated by level data given from the outside.

  The high frequency power control unit stores the envelope level of the voltage waveform of the high frequency power output from the amplifier in the set target level storage unit until the transition period of each interval period of the first cycle elapses. The open loop control in the first cycle is performed by giving level data to the DDS so as to be equal to the corresponding set target level, and the level detection unit performs the stable period of each interval period in the first cycle. Feedback control is performed in each interval period of the first period by giving level data to the level adjustment unit so that the deviation between the detected level and the set target level of the corresponding interval period becomes zero, High frequency output from the amplifier until the transition period of each interval period of each period after the 1st period elapses The level data is supplied to the DDS so as to make the level of the envelope of the voltage waveform of the power equal to the target level of the corresponding interval period stored in the next cycle target level storage unit, so that each of the subsequent cycles Performs open loop control in each interval period of the cycle, and is stored in the level detected by the level detection unit and the next cycle target level storage unit during the stable period of each interval period of each cycle after the second cycle By providing level data to the level adjuster so as to make the deviation from the target level of the corresponding interval period zero, feedback control is performed in each interval period of each period after the second period.

  The fifth invention disclosed in the present application is also applied to the third invention. In the present invention, the high-frequency signal generation / amplification unit includes a level adjustment unit that adjusts the level of the high-frequency signal supplied from the high-frequency signal generator to the amplifier according to the level data. In this case, the high frequency power control unit stores the envelope level of the voltage waveform of the high frequency power output from the amplifier in the set target level storage unit until the transition period of each interval period of the first cycle elapses. The open loop control in each interval period of the first cycle is performed by giving level data to the level adjuster so as to be equal to the set target level of the corresponding interval period, and each interval period of the first cycle Feedback control in each interval period of the first cycle by providing level data to the level adjuster so that the deviation between the level detected by the level detector and the corresponding set target level is zero during the stable period Until the transition period of each interval period of each period after the second period elapses Providing level data to the level adjusting unit so as to make the level of the envelope of the voltage waveform of the high frequency power output from the amplifier equal to the target level of the corresponding interval period stored in the next cycle target level storage unit Performs the open loop control in each interval period of each period after the second period, and the level detected by the level detection unit during the stable period of each interval period after the second period and the next period target Feedback control in each interval period of each cycle after the second cycle by giving level data to the level adjustment unit so that the deviation from the target level of the corresponding interval period stored in the level storage unit becomes zero Configured to perform.

  The sixth invention disclosed in the present application is also applied to the third invention. In the present invention, the high-frequency signal generator provided in the high-frequency signal generating / amplifying unit is constituted by a direct digital synthesizer (DDS) that outputs a high-frequency signal having a level indicated by level data given from the outside. .

  In this case, the high frequency power control unit stores the envelope level of the voltage waveform of the high frequency power output from the amplifier until the transition period of each interval period of the first cycle elapses, in the set target level storage unit. By providing level data to the DDS so as to be equal to the set target level of the corresponding interval period, open loop control of each interval period in the first period is performed, and the stable period of each interval period in the first period is set. Meanwhile, feedback control in each interval period of the first cycle is performed by giving level data to the DDS so that the deviation between the level detected by the level detection unit and the set target level of the corresponding interval period becomes zero, Until the transition period of each interval period of each period after the second period elapses The level data is supplied to the DDS so that the level of the envelope of the voltage waveform of the high frequency power output from the amplifier is equal to the target level of the corresponding interval period stored in the next period target level storage unit. Performs open loop control in each cycle after the second cycle, and stores the level detected by the level detection unit and the next cycle target level storage unit during the stable period of each interval period of each cycle after the second cycle The feedback control in each cycle after the second cycle is performed by giving level data to the DDS so that the deviation from the target level in the corresponding interval period is zero.

  According to the present invention, when high-frequency power having a voltage waveform modulated by a waveform indicating a step-like level change is obtained, immediately after the start of each interval period of each cycle of the envelope waveform of the voltage waveform of the high-frequency power. Level control during the transition period is not performed by feedback control but by open loop control, and the stable period after the transition period of each interval period of each period of the envelope waveform of the high-frequency power voltage waveform is passed. Since the control for maintaining the level detected by the inter-level detection unit at the target level is performed by feedback control, ringing or waveform dullness does not occur at each level change timing, regardless of the level change cycle, and each High frequency with a voltage waveform in which the envelope level is accurately maintained at the target level in the stable period of the interval period It is possible to obtain the power.

  According to the present invention, the target level in each interval period of each cycle of the envelope waveform is made equal to the average value of the stable levels actually feedback-controlled in the corresponding interval period of one or more cycles. Therefore, there is almost no difference between the level of the envelope waveform of the voltage waveform of the high frequency power output from the amplifier during the transition period of each interval period and the level of the envelope waveform of the high frequency power output from the amplifier during the stable period. Since it can be prevented from occurring, it is possible not only to prevent ringing and waveform dullness at each level change timing, but also the control is switched from open loop control to feedback control regardless of the level change period. In this case, it is possible to obtain high-frequency power having a clean waveform by preventing voltage fluctuations.

  Further, according to the present invention, it is possible to prevent ringing and waveform dullness from occurring at each level change timing of the envelope waveform of the voltage waveform of the high-frequency power. The detection speed can be increased. Therefore, even when the level change of the step waveform that modulates the high-frequency power is fast, the level control in the transition period of each interval period and the level control in the stable period can be performed accurately, and the high-speed pulse waveform Alternatively, it is possible to cope with the case where high-frequency power is modulated by a step waveform.

1 is a block diagram showing a configuration of a first embodiment of a high-frequency power supply device according to the present invention. It is the block diagram which showed the structure of 2nd Embodiment of the high frequency power supply device concerning this invention. It is the block diagram which showed the structure of 3rd Embodiment of the high frequency power supply device concerning this invention. It is the wave form diagram which showed typically an example of the waveform which modulates high frequency electric power. (A) is the wave form diagram which showed typically the voltage waveform of the high frequency electric power which the high frequency power supply device concerning this invention outputs. (B) is a wave form diagram explaining the method of level control of the high frequency voltage in this invention. FIG. 6 is an enlarged waveform diagram showing a part of the waveform shown in FIG. FIG. 6 is an enlarged waveform diagram showing another part of the waveform shown in FIG. It is the wave form diagram which showed typically the other example of the waveform which modulates high frequency electric power. (A) is the wave form diagram which showed typically an example of the voltage waveform of the high frequency electric power which should be output from a high frequency power supply device, (B) generated the high frequency electric power which has the voltage waveform of (A) with the conventional high frequency power supply device. FIG. 6C is a waveform diagram schematically showing an example of the actual waveform of the envelope of the voltage waveform obtained in the case where the high frequency power having the voltage waveform of FIG. It is the wave form diagram which showed typically the other example of the actual waveform of the envelope of the voltage waveform obtained. (A) is a waveform diagram schematically showing the waveform of the envelope of the voltage waveform when the frequency of the modulation waveform is made higher than that of the example shown in FIG. 9 (A), and (B) is a diagram of a conventional high-frequency power supply device. The waveform diagram which showed typically an example of the actual waveform of the envelope of the voltage waveform obtained when the high frequency electric power which has the voltage waveform of (A) was generated, (C) is (A) by the conventional high frequency power supply device. It is the wave form diagram which showed typically the other example of the actual waveform of the envelope of the voltage waveform obtained when the high frequency electric power which has this voltage waveform was generated.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
The high-frequency power supply device to which the present invention is applied has a plurality of level change timings in one cycle in which the waveform of the envelope of the voltage waveform (envelope waveform) indicates a step-like level change, and the adjacent level change A high-frequency power modulated by a step waveform that periodically repeats a waveform that is an interval period in which a period between timings keeps a constant level is output.

  In the present embodiment, as shown in FIG. 4, high-frequency power is modulated by a ternary step waveform having three level change timings during one cycle (takes three levels during one cycle). . Therefore, the high-frequency power output from the high-frequency power supply device according to the present embodiment has an envelope waveform of the voltage waveform (referred to as an envelope waveform), and one cycle is composed of three interval periods as shown in FIG. Presents a step waveform (stepped waveform).

  In FIG. 4, Tn (n = 1, 2, 3,...) Is the nth cycle, tan, tbn, tcn are the level change timings existing in the nth cycle, and t1n, t2n, t3n are the nth cycle. Are the first to third interval periods. P1n, P2n, and P3n (P1n> P2n> P3n in the illustrated example) are the levels of the envelope of the voltage waveform of the high-frequency power in the first to third interval periods t1n, t2n, and t3n of the nth cycle, respectively. . The lengths of the interval periods t1n, t2n, and t3n in the nth cycle do not have to be equal, but in the example shown in FIG. 4, all these interval periods are set equal. That is, t1n = t2n = t3n. In the present embodiment, the envelope levels P1n, P2n, P3n of the voltage waveform of the high frequency power in the interval periods t1n, t2n, t3n of the nth cycle are set equal to the corresponding levels in the interval periods of other cycles. ing.

  In the control method of the present embodiment, as described above, the envelope waveform (envelope waveform) of the voltage waveform has a plurality of level change timings indicating step-like level changes in one cycle, and each level change High-frequency signal generated from high-frequency power modulated (modulated with a step waveform) so as to exhibit a step waveform in which the period between the timing and the next level change timing is an interval period that maintains a constant level When the high-frequency signal generator / amplifier is provided with an amplifier and an amplifier that amplifies the high-frequency signal generated by the high-frequency signal generator, the envelope waveform is maintained at a target level at each interval period of each cycle. To control.

  Therefore, in this embodiment, a level detection unit that detects the level of the envelope waveform of the voltage waveform of the high frequency power output from the high frequency power supply device is provided, and the envelope waveform of the voltage waveform of the high frequency power output from the high frequency power supply device is provided. Is stored in the set target level storage unit as a set target level for each interval period. This set target level may be set only once when high-frequency power is supplied to the load, or may be appropriately updated while high-frequency power is being supplied to the load.

  In the present embodiment, when performing control to keep the level of the envelope waveform to be taken in each interval period of each cycle at the target level, each interval period of each cycle of the envelope waveform is set to a transient period set immediately after the start. And the stable period after the transition period elapses, and different control is performed in the transient period and the stable period.

  In the present embodiment, the first cycle of the envelope waveform when the high frequency power is first output from the high frequency power supply device with the voltage waveform envelope waveform set to the set target level for each interval period of the cycle is the first cycle. As the first cycle, in each cycle from the first cycle of the envelope waveform to the (m-1) th cycle (m is a set value consisting of an integer of 2 or more), the first cycle to the present A level obtained by averaging the levels detected by the level detection unit in the stable period of each interval period corresponding to each period up to the period is calculated as the average detection level of each interval period, and thereafter the mth period of the envelope waveform In each cycle, m levels detected by the level detection unit in the stable period of each interval period corresponding to each cycle from the previous cycle of m−1 to the current cycle are displayed. The average level is calculated as the average detection level for each interval period, and the calculated average detection level for each interval period is taken by the envelope waveform in the interval period corresponding to the period following the period for which the average detection level is calculated. The target level is stored in the next cycle target level storage unit.

  The “first period” is an envelope when the high-frequency power is first output from the high-frequency power supply device with a predetermined set target level for the envelope waveform of the voltage waveform that should be taken in each interval period of each period. This is the first period of the waveform, and when the set target level is updated, the first time when high-frequency power is output for the first time, the envelope waveform is equal to the set target level at which the level to be taken in each interval period of each period is updated. It is a cycle.

  And in the control method of this embodiment, in each interval period of the first cycle of the envelope waveform, the level detected by the level detector until the set transient period elapses is set as a target level storage unit After performing the control to be equal to the corresponding set target level stored in the open loop control, the level detected by the level detection unit during the stable period is set to the corresponding set target level stored in the set target level storage unit. Control for maintaining is performed by feedback control, and in each interval period of each cycle after the second cycle of the envelope waveform, the level detected by the level detection unit until the transition period elapses is stored in the next cycle target level storage unit. After performing control to equalize the corresponding target level stored by open loop control, the level detection unit detects during the stable period Performed by the feedback control of the control to keep the bell corresponding target level is stored in the next cycle target level storage section.

  FIG. 1 shows a configuration of a first embodiment of a high-frequency power supply apparatus according to the present invention that implements the above control method. In FIG. 1, 1 is a high-frequency signal generating / amplifying unit that amplifies a high-frequency signal and outputs high-frequency power, and 2 is a level detected by the level of the voltage waveform envelope of the high-frequency power output from the high-frequency signal generating / amplifying unit A level detection unit, 3 is a set target level storage unit, 4 is an average detection level calculation unit, 5 is a next cycle target level storage unit, and 6 is a level of an envelope waveform detected by the level detection unit 2 as a target level. Thus, the high frequency power control unit controls the high frequency signal generation / amplification unit.

  Each part will be described in more detail. The high-frequency signal generating / amplifying unit 1 determines the frequency indicated by the frequency data (digital value) given from the outside and the voltage level indicated by the level data (digital value) given from the outside. A high-frequency signal generator 101 for generating a high-frequency signal, an amplifier 102 for amplifying the high-frequency signal generated by the high-frequency signal generator 101, and inserted between the high-frequency signal generator 101 and the amplifier 102 and supplied from the outside. In accordance with the level data (analog signal), the level adjustment unit 103 that adjusts the voltage level of the high-frequency signal input from the high-frequency signal generator 101 to the amplifier 102, and the level data (digital value) given from the outside to the analog signal It comprises a D / A converter 104 that converts it and supplies it to the level adjusting unit 103.

  In this embodiment, the high frequency signal generator 101 generates a high frequency signal having a frequency as indicated by frequency data (digital value) and a voltage level as indicated by level data (digital value) given from the outside. A direct digital synthesizer (DDS) is used.

  The level adjustment unit 103 is composed of, for example, an electronic volume, and adjusts the level of the high-frequency signal input to the amplifier 102 in accordance with a control signal (voltage signal) given from the A / D converter 104. In the present embodiment, the output of the high-frequency signal generating / amplifying unit 1 can be adjusted by both the level adjustment by the level adjustment unit 103 and the adjustment of the output level of the DDS 101 by the DDS level data.

  The output of the high frequency power output from the amplifier 102 can be adjusted by either the level adjustment by the level adjustment unit 103 or the adjustment of the output level of the DDS 101 by the DDS level data, but in this embodiment, the waveform for modulating the high frequency power has a waveform. In the period from the level change timing indicating the step-like level change until the set transient period elapses, the output of the high frequency power output from the amplifier 102 is adjusted according to the level data level applied to the DDS 101, and each level is adjusted. In the interval period after the transition period has elapsed from the change timing, the output of the high frequency power output from the amplifier 102 is adjusted according to the level data level applied to the level adjusting unit 103.

  In the present embodiment, the D / A converter 104 is configured such that digital data is inputted in parallel and can perform D / A conversion at high speed. On the other hand, as the DDS 101, a level data composed of digital values is serially input.

  The level detection unit 2 is inserted between the output terminal of the amplifier 102 and the cable connected to the load, and separates a part of the high-frequency voltage output from the amplifier 102. A filter 202 that removes an unnecessary component such as a wave component and extracts a fundamental frequency component of a high-frequency voltage, a detector 203 that detects an envelope by detecting the high-frequency voltage output from the filter 202, and a detector 203 The level detector 204 for detecting the output level of the signal and the A / D converter 205 for converting the output of the level detector 204 into a digital value, and the high-frequency power output from the high-frequency signal generating / amplifying unit 1 Detect the envelope level of the voltage waveform.

  The set target level storage unit 3 sets the set value of the level to be taken in each interval period that the envelope waveform of the voltage waveform of the high frequency power output from the high frequency power supply device has during one cycle as the set target level for each interval period. Remember. In this embodiment, the first cycle of the envelope waveform when the high-frequency power is first output from the high-frequency power supply device with the set target level being the level that the envelope waveform of the voltage waveform should take in each interval period of each cycle is the first cycle. As the first cycle, when controlling the level of the envelope waveform in each interval period of the first cycle, the set target level of each interval period stored in the set target level storage unit 3 is used as the envelope waveform. Is the target level to be taken in each interval period. In the example shown in FIG. 5, the target level (P11, P21, P31 in the example shown in FIG. 5) that the envelope waveform of the voltage waveform of the high frequency power should take in the interval periods t11, t21, t31 is set as the set target level. Stored in the level storage unit 3. The set target level storage unit 3 includes a memory provided in a microprocessor constituting the main part of the high-frequency power control unit 6, and a program for writing data to the memory and reading data from the memory. Is done.

  In the present embodiment, the first cycle of the envelope waveform when the modulated high-frequency power is first output is the “first cycle”. However, the envelope waveform is generated in the interval period of each cycle of the envelope waveform. When changing the set target level to be taken in the middle of supplying high frequency power to the load, the set target level that the envelope waveform should take in each interval period of each cycle has been changed (updated) The first cycle of the envelope waveform when the first is output is the “first cycle”.

  The set target level to be stored in the set target level storage unit 3 can be written from the outside by a keyboard, a digital switch, or the like.

  The average detection level calculation unit 4 first outputs the envelope waveform when the envelope waveform of the voltage waveform is first output from the radio frequency power supply device with the high frequency power whose level to be taken in each interval period of each cycle is the set target level. The cycle is the first cycle, and each interval period of each cycle of the envelope waveform is divided into a transient period set immediately after the start and a stable period after the transient period has elapsed, In each cycle from the first cycle to the m-1st cycle (m is a set value consisting of an integer of 2 or more), each interval corresponding to each cycle from the first cycle to the current cycle A level obtained by averaging the levels detected by the level detection unit in the stable period is calculated as an average detection level for each interval period, and in each cycle after the mth cycle of the envelope waveform, m− Each cycle of the corresponding level of the level detector in the stable period has averaged the m levels detected for each interval period from pieces previous cycle to the current cycle is calculated as a mean detection level in each interval period.

  That is, when there is no set number m of cycles from the first cycle to the current cycle, the average detection level calculation unit 4 corresponds to the interval corresponding to each cycle from the first cycle to the current cycle. After averaging the levels detected by the level detection unit 2 in the stable period, the average detection level is calculated, and after the first cycle to the current cycle, there are more than a set number m of cycles. Calculates a simple moving average value of the level detected by the level detection unit in the stable period of the interval period corresponding to the latest m cycles as the average detection level.

  The next cycle target level storage unit 5 displays the average detection level of each interval period calculated by the average detection level calculation unit 4 in the interval period corresponding to the next cycle of the cycle in which the average detection level is calculated. Memorize as the target level to be taken.

  Specifically, in the example shown in FIG. 5, in the first period T1, constant transient periods Δt11 to Δt31 are set immediately after the start of the first to third interval periods t11 to t31, respectively, and t11− Δt11, t21-Δt21, and t31-Δt31 are the stable periods of the first to third interval periods t11 to t31, respectively. Similarly, in the second period T2, transient periods Δt12 to Δt32 are set immediately after the start of the first to third interval periods t12 to t32 (t32 is not shown), and t12−Δt12, t22−Δt22. And t32−Δt32 are the stable periods of the first to third interval periods t12 to t32.

  Here, if m = 2, for example, in the first period T1, the average detection level calculation unit 4 performs the stable period t11−Δt11 of the first interval period t11, the stable period t21−Δt21 of the second interval period t21, and The levels detected by the level detection unit 2 during the stable period t31-Δt31 of the third interval period t31 are set as the average detection level of the first interval period to the third interval period. These average detection levels are stored in the next cycle target level storage unit 5 as target levels that the envelope waveform should take in the first to third interval periods t12 to t32 of the next cycle T2 of the cycle T1 in which the average detection level is calculated. Is done.

  In the second period T2, the average detection level calculation unit 4 also detects the level detected by the level detection unit 2 during the stable period t11-Δt11 of the first interval period t11 of the first period T1 and the second period. The average value with the level detected by the level detector 2 during the stable period t12-Δt12 of the first interval period t12 of T2, and the level detector 2 during the stable period t21-Δt21 of the second interval period t21 of the first period T1. And the average value of the level detected by the level detector 2 during the stable period t22-Δt22 of the second interval period t22 of the second period T2, and the third interval period t31 of the first period T1. The level detected by the level detector 2 during the stable period t31-Δt31 and the level detected by the level detector 2 during the stable period t32-Δt32 of the third interval period t32 of the second period T2. Calculating an average value as the average detection level of the first interval period to third interval period, respectively. These average detection levels are stored in the next cycle target level storage unit 5 as target levels that the envelope waveform should take in the first to third interval periods of the cycle T3 next to the cycle T2 in which the average detection level is calculated.

  Similarly, in each cycle after the third cycle, an operation is performed to obtain an average value of the levels detected in the stable period of each interval period from the previous cycle to the current cycle. The average detected level is stored in the next cycle target level storage unit 5 as a target level that the envelope waveform should take in each interval period of the next cycle.

  The high-frequency power control unit 6 is a part that controls the high-frequency signal generation / amplification unit so that the level of the envelope waveform detected by the level detection unit 2 becomes the target level. A unit 602, an error level detection unit 604, a selection processing unit 605, and a control calculation unit 606.

  The output setting data input unit 602 is a part for inputting data (output setting data) necessary for defining the waveform of the envelope of the voltage waveform of the high frequency power output from the high frequency signal generating / amplifying unit 1 to the controller 601. The length of each interval period of the envelope waveform of the voltage waveform of the high-frequency power to be output, the voltage level in each interval period, the repetition frequency of the modulation waveform, and the like are input to the controller 601.

  The error level detector 604 detects a deviation (error) between the level detected by the level detector 2 in each interval period of each cycle of the envelope waveform and the set target level that the envelope waveform should take in the corresponding interval period. Part. The illustrated error level detection unit 604 includes the level of the envelope waveform in each interval period detected by the level detection unit 2 and the target in the corresponding interval period read from the set target level storage unit 3 or the next cycle target level storage unit 5. The level is compared, and an error signal indicating a deviation between the compared levels is output.

  The selection processing unit 605 is a part that performs an operation of selecting which of the error signal output from the error level detection unit 604 and the signal indicating the target level read from the target level storage unit 3 is used for control. Is given a control signal.

  The control calculation unit 606 is a part that calculates the size of the DDS level data and the level adjustment level data to be supplied to the high frequency signal generation unit 101 of the high frequency signal generation / amplification unit 1 and the D / A converter 104, respectively. The DDS level data and the level adjustment level data are calculated based on the control signal supplied from the unit 605, and the DDS level data and the level adjustment level data having the calculated sizes are respectively calculated as high frequency signals. This is given to the generator 101 and the D / A converter 104.

  In the embodiment shown in FIG. 1, the controller 601, the error level detection unit 604, the selection processing unit 605, and the control calculation unit 606 are configured by a microprocessor, and the output setting data input unit 602 is configured by a keyboard or the like. .

  The controller 601 controls the writing of data to the set target level storage unit 3 and the next cycle target level storage unit 5 and the reading of data from both storage units, the average detection level calculation unit 4, the error level detection unit 604, and The calculation operation of the control calculation unit 606 and the selection operation of the selection processing unit 605 are controlled.

  The set target level storage unit 3 may store the set target level itself, such as map data for interpolating the set target level with respect to the output data input from the output set data input unit 602. May be stored. For example, in order to obtain a set target level of the level of the high-frequency voltage output from the amplifier 102 with respect to the desired output (W) of the high-frequency power input from the output setting data input unit 602, You may make it memorize | store the map data which gives the relationship between setting target levels in the setting target level memory | storage part 3. FIG. In the present embodiment, it is assumed that the set target level itself is stored in the set target level storage unit 3.

  When the apparatus is activated, the controller 601 reads the set target level stored in the set target level storage unit 3 so that the envelope waveform is set at a level that should be taken in each interval period of the first cycle T1 after activation. The target level is acquired, and the acquired set target level is given to the selection processing unit 605.

  When the high-frequency power control unit 6 is activated, the controller 601 gives frequency data to the DDS 101 based on the frequency data given from the output setting data input unit 602. The controller 601 also operates each level change timing to change the level of the envelope waveform of the voltage waveform of the high frequency power in a step-like manner based on the data input from the output setting data input unit 602 by the operation of the built-in timer. Detecting the timing indicating the time when the set transition period has elapsed from each level change timing, generating a series of timing signals indicating the detected timing in time series, and synchronizing with these timing signals Control each part.

  During the transition period, after the envelope level of the voltage waveform of the high-frequency power is made equal to the target level by open loop control at each level change timing, the feedback control system can stably perform the feedback control. Set to be equal to the time required until. This transition period is actually the time required for the detected value of the voltage level detected by the level detection unit to become stable. When feedback control is performed at each level change timing, ringing and waveform dullness occur. This is a very short time compared to the transition period required to disappear. This transient period is set to an appropriate value in consideration of the programmable logic device used for control, the machine cycle of the microcomputer, the tracking characteristics of the control circuit, the actual behavior of the entire apparatus, and the like.

Here, an example of the operation of the high-frequency power control unit 6 will be specifically described with reference to the example shown in FIG.
When the high-frequency power is modulated with the step waveform shown in FIG. 5A, when the controller 601 detects the first level change timing ta1 of the first cycle T1, the first interval following the level change timing ta1. The set target level P11 of the envelope level of the voltage waveform of the high frequency power in the period t11 is read from the set target level storage unit 3, and the read set target level P11 is given to the selection processing unit 605. The controller 601 also instructs the selection processing unit 605 to input the read set target level P11 to the control calculation unit 606. At this time, the controller 601 instructs the control arithmetic unit 606 to supply the D / A converter 104 with level adjustment level data having a predetermined constant size, and also outputs a voltage waveform of the high-frequency power output from the amplifier 102. In order to set the envelope level to the set target level P11, the control calculation unit 606 is caused to calculate the level data level that needs to be given to the DDS 101.

  The control calculation unit 606 provides level adjustment level data having a certain magnitude corresponding to the set target level to the D / A converter 104 and also provides the DDS level data having the calculated magnitude to the DDS 101. As a result, the amplifier 102 instantaneously outputs high-frequency power in which the level of the envelope of the voltage waveform is equal to the set target level P11. Since this control is not based on feedback control but is performed by open loop control that only gives level data to the DDS 101 and the D / A converter 104, ringing or waveform dullness occurs at the level change timing ta1. Can be prevented. The above open loop control is continued from the level change timing t11 until the set transient period Δt11 elapses. For example, the level data to be given to the level adjusting unit during the open loop control is set to a level such that the level attenuation by the level adjusting unit 103 is 0 dB.

  When the controller 601 detects that the set transient period Δt11 has elapsed from the level change timing ta1 at which the first interval period t11 is started, the controller 601 uses the set target level P11 read from the set target level storage unit 3 as an error level. The difference between the set target level P11 and the envelope level of the voltage waveform of the high frequency power detected by the level detector 2 is given to the detector 604.

  The error level detection unit 604 inputs an error signal indicating the calculated deviation to the selection processing unit 605. At this time, the controller 601 gives a selection switching command to the selection processing unit 605 to switch the signal input from the selection processing unit 605 to the control calculation unit 606 from a signal giving the set target level P11 to an error signal indicating deviation, A calculation command is given to the control calculation unit 606, and is given to the level adjustment unit 103 so that the deviation between the set target level P11 and the envelope waveform level of the voltage waveform of the high frequency power detected by the level detection unit 2 becomes zero. Calculate the required level data size. The calculated value of the level data differs depending on the level data (level of the high frequency signal output from the DDS 101) given from the control calculation unit 606 to the high frequency signal DDS101.

  The control calculation unit 606 provides DDS level data having a preset size to the DDS 101 and also provides level adjustment level data having the calculated size to the D / A converter 104. The level data supplied from the control arithmetic unit 606 to the level adjusting unit 103 through the D / A converter 104 is an amplifier for setting the level of the high frequency signal (determined by the DDS level data) output from the DDS 101 to zero. This is data for setting the attenuation amount of the level adjusting unit 103 so as to adjust to a level that needs to be input to 102. As described above, by supplying level data to the DDS 101 and the level adjusting unit 103, high-frequency power having the envelope waveform level equal to the set target level P11 is output from the amplifier 102.

  As described above, in the stable period (period t11−Δt11) after the transition period Δt11 has elapsed from the level change timing ta1 of the first interval period t11 of the first cycle, the target level P11 and the level detection unit Control that keeps the envelope level of the voltage waveform of the high-frequency power output from the high-frequency signal generator / amplifier 1 at the set target level based on the deviation from the envelope level of the voltage waveform of the high-frequency power detected by 2 Is performed by feedback control. Therefore, the level of the envelope of the voltage waveform in the stable period (period t11−Δt11) after the lapse of the fixed period Δt11 corresponding to the transition period is accurately maintained at the target level P11. In this feedback control, level data given to the DDS 101 configured to receive serial data is set as a fixed value, and the level adjusting unit 103 is passed through a high-speed D / A converter 104 configured to receive parallel data. Since the level data for input level adjustment given to is changed as a variable value according to the deviation, it can be performed with high responsiveness.

  In the first cycle T1, the level detected by the level detector 2 in the respective stable periods of the first interval period t11 to the third interval period t31 is also the first interval of the next cycle (second cycle T2). The next cycle target level storage unit 5 stores the target level that the envelope waveform should take in the period t12 to the third interval period t32.

  Similarly, the level of the envelope of the voltage waveform of the high frequency power is set to the set target level P21 of the second interval period by open loop control from the start time tb1 of the second interval period t21 until the transition period Δt21 elapses. In the stable period t21-Δt21, control is performed to keep the envelope level of the voltage waveform of the high-frequency power at the set target level P21 by feedback control. In addition, control is performed by setting the envelope level of the voltage waveform of the high frequency power to the set target level P31 of the third interval period by open loop control from the start time tc1 of the third interval period t21 until the transition period Δt31 elapses. During the stable period t31-Δt31, control is performed to maintain the envelope level of the voltage waveform of the high-frequency power at the set target level P31 by feedback control.

  In the second cycle, the level of the envelope of the voltage waveform of the high frequency power is stored in the next cycle target level storage unit 5 until the transition period Δt12 elapses from the level change timing ta2 of the first interval period t12. Control to match the target level P12 is performed by open loop control, and the envelope level of the voltage waveform of the high frequency power is stored in the next cycle target level storage unit 5 during the stable period t12-Δt12 of the first interval period t12. Control to maintain the target level P12 is performed by feedback control. Further, the level of the envelope of the voltage waveform of the high frequency power matches the target level P22 stored in the next cycle target level storage unit 5 until the transition period Δt22 elapses from the level change timing tb2 of the second interval period t22. The target level P22 stored in the next cycle target level storage unit 5 is the level of the envelope of the voltage waveform of the high frequency power during the stable period t22-Δt22 of the second interval period t22. The control to maintain is performed by feedback control. Further, the level of the envelope of the voltage waveform of the high frequency power is stored in the target level P32 stored in the next cycle target level storage unit 5 until the transition period Δt32 elapses from the level change timing tc2 of the third interval period t32 (not shown). The target level stored in the next cycle target level storage unit 5 is the level of the envelope of the voltage waveform of the high-frequency power during the stable period t32-Δt32 of the third interval period t32. Control to maintain P32 is performed by feedback control.

  In the second cycle, the level detected by the level detector 2 in the first interval period t11 to the third interval period t31 of the first cycle and the first interval period of the second cycle are also detected. The average value with the level detected by the level detection unit 2 in the stable period of t12 to the third interval period t32 is calculated as the average detection level of the first to third interval periods, and these average detection levels are calculated in the next period (first cycle). (3rd cycle) is stored in the next cycle target level storage unit 5 as the target levels P31 to P33 to be taken by the envelope of the voltage waveform of the high frequency power in the first interval period to the third interval period, respectively.

  Similarly, in each cycle after the third cycle, the envelope level is stored in the next cycle target level storage unit in the transition period of each interval period of the envelope waveform of the voltage waveform of the high frequency power. Open loop control is performed to match the target level, and feedback control is performed to maintain the envelope level at the target level stored in the next cycle target level storage unit in the stable period of each interval period. When m = 2, the level detected in the stable period of the interval period corresponding to the previous period in each interval period and the level detected in the stable period of each interval period of the current period The average value is calculated as the average detection level, and the calculated average detection level of each interval period is stored in the next cycle target level storage unit 5 as the target level that the envelope should take in each interval period of the next cycle.

  The number of interval periods in which the average value is calculated (the number of periods in which the average value of the level of each interval period is calculated) m is set to an appropriate integer of 2 or more. The optimum value of m is determined by experimental data.

  As described above, in the present embodiment, when obtaining a high-frequency power having a voltage waveform modulated by a waveform indicating a step-like level change, each interval period of each cycle of the envelope waveform of the voltage waveform of the high-frequency power Level control during the transition period immediately after the start of the operation is performed not by feedback control but by open loop control, after the transition period of each interval period of each period of the envelope waveform of the voltage waveform of the high frequency power has elapsed Since the control that keeps the level detected by the level detection unit at the target level during the stable period of time is performed by feedback control, at any level change timing regardless of the speed of the level change and any period of the level change. Ringing and waveform dullness do not occur, and the envelope level in the stable period of each interval period is It is possible to obtain a high frequency power having a voltage waveform kept sure the target level.

  Further, in the present embodiment, the target level that the envelope waveform should take in each interval period of each cycle of the envelope waveform of the voltage waveform is set to m cycles from the m−1 previous cycle to the current cycle. Since the level detected by the level detector in the stable period of the corresponding interval period is averaged, the target level in each interval period is the stable level that is actually feedback controlled in the corresponding interval period of the most recent m cycles The level of the envelope of the voltage waveform of the high-frequency power that is output from the amplifier by performing open loop control until the time corresponding to the transient period elapses in each interval period, and feedback control There is almost no difference between the envelope level of the voltage waveform of the high frequency power output from the amplifier at the moment of switching to Flip can be so no. Therefore, according to the present embodiment, it is possible not only to prevent ringing and waveform dullness at each level change timing, but also when the control switches from open loop control to feedback control, regardless of the level change period. It is possible to obtain high-frequency power having a clean waveform by preventing voltage fluctuations from occurring.

  Furthermore, according to this embodiment, ringing and waveform dullness do not occur at each level change timing of the envelope waveform of the voltage waveform of the high-frequency power output from the amplifier 102, so that the excessive period can be shortened. The detection speed of the envelope of the high frequency voltage can be increased. For this reason, even when the level change of the waveform that modulates the high frequency power is high speed, the level control during the transition period from each level change timing and the level control during each interval period can be accurately performed. Even when the high-frequency power is modulated by the pulse waveform, step waveform, or the like, it can be handled without any problem.

  An example of the waveform of the envelope of the voltage waveform of the high-frequency power output from the high-frequency signal generating / amplifying unit 1 when the above control is performed is shown in an enlarged manner in FIGS. FIG. 6 is an enlarged view of the waveforms in the vicinity of the first half of the interval period t11 and interval period t21 in FIG. 5, and FIG. 7 shows the waveforms in the first half of the interval period t12 and interval period t22 in FIG. It is an enlarged view.

  In the first cycle T1, at the timing of each level change, first, open loop control is performed to set the level of the envelope waveform of the voltage waveform to a preset target level, and then the transition period has elapsed. Thus, the control signal supplied to the control calculation unit 606 is switched to the error signal, and the voltage level control is switched to the feedback control. In this switching, the waveform in the period of Δt11 and Δt21 in FIG. As shown, a slight level variation V may occur.

  On the other hand, in each interval period of each period after the second period, the average value of the stable levels detected in the stable period of the corresponding interval period of the latest maximum m periods is the target level. Therefore, in each period after the second period, the target level to be taken by the envelope of the voltage waveform in each interval period corresponds to each of the latest maximum m periods. It can be equal to the average value of the stable level detected in the stable period of the interval period. Therefore, the level of the envelope of the voltage waveform of the high frequency power output from the amplifier by the open loop control in the transition period of each interval period of each period after the second period, and the envelope of the envelope in the stable period of each interval period At the moment when the level control is switched from the open loop control to the feedback control, it is possible to make almost no difference from the envelope level of the voltage waveform of the high frequency power output from the amplifier. As can be seen in the waveform of the period and the waveform of Δt22, the voltage waveform in each period after the second period does not change when the control is switched from the open loop control to the feedback control. A clean waveform can be obtained.

  In the above description of operation, the first cycle when the high-frequency power output from the high-frequency signal generating / amplifying unit 1 is raised from zero is defined as the first cycle, and the voltage level in each interval period of the first cycle is changed. The target level is assumed to be a preset initial level. As described above, the target level in each interval period after the second period is detected in the stable period of each interval period in a plurality of periods before each period. In the case of adopting a configuration in which the average value of the measured levels is taken, after the high-frequency power is once output from the high-frequency signal generating / amplifying unit 1, the target level in each interval period is set halfway without interrupting the output of the high-frequency power. When changing, the initial cycle for generating high-frequency power with the target level changed (updated) in each interval period is changed. As the first period, it is necessary to set the target level to a target level is updated at each interval period of the cycle.

  As shown in FIG. 1, the high-frequency signal generator / amplifier 1 is provided with a high-frequency signal generator 101 and a level adjuster 103 so that level data given to the high-frequency signal generator 101 is a variable value. The configuration in which the open level control is performed with the level data to be given as a fixed value, the level data to be given to the high frequency signal generator 101 is a variable value, and the feedback control is performed with the level data to be given to the level adjustment unit 103 as a fixed value is a high frequency signal generator When only DDS 101 that forms level data is input as serial data can be obtained as DDS 101 that constitutes, and only when it is difficult to narrow down its output level to 0 dB as level adjustment unit 103 This is an advantageous configuration.

  If configured as shown in FIG. 1, the operation of raising the voltage level of the high-frequency power from zero at the level change timing and the operation of lowering the voltage level to zero can be realized without problems by the performance of the DDS. it can. Further, the level data is given to the level adjusting unit 103 through the high-speed D / A converter 104 to which the level data is inputted as parallel data, so that the feedback control in the stable period of each interval period is performed at a high speed. Thus, it is possible to accurately perform control for keeping the voltage level at the target level. In other words, taking advantage of each of the DDS and the level adjuster, open loop control performed during the transition period from each level change timing, and feedback control performed during the remaining period after the transition period of each interval period Both can be performed accurately.

The characteristics of the configuration of the high-frequency power supply device according to the embodiment shown in FIG. 1 are summarized as follows.
(A) The high-frequency signal generator / amplifier 1 includes a high-frequency signal generator 101, an amplifier 102 that amplifies a high-frequency signal generated by the high-frequency signal generator, and a level of a high-frequency signal that is supplied from the high-frequency signal generator 101 to the amplifier 102. Level adjustment unit 103 that adjusts the level according to the level data, and the envelope of the voltage waveform has a plurality of level change timings indicating a step-like level change in one cycle, and each level change timing and the next The high-frequency power modulated so as to exhibit a waveform in which the period between the level change timings is an interval period in which a constant level is maintained is output.
(B) A period until the set time elapses from the start of each interval period of each cycle of the waveform of the envelope waveform of the voltage waveform of the high frequency power output from the high frequency signal generating / amplifying unit 1 and the set time The remaining period after elapse of time is defined as a transition period and a stable period of each interval period, respectively.
(C) The high-frequency signal generator 101 is configured by a direct digital synthesizer (DDS) that outputs a high-frequency signal having a level indicated by level data given from the outside.
(D) The open loop control in each interval period of the first period of the envelope waveform of the voltage waveform of the high-frequency power is performed from the amplifier 102 until the set transient period elapses from the start of each interval period. This is performed by giving level data (variable value) to the DDS 101 so that the level of the envelope of the voltage waveform of the high frequency power to be output is equal to the corresponding set target level stored in the set target level storage unit 3. At this time, constant level data is given to the level adjuster 103.
(E) The feedback control in each interval period of the first period is a set target corresponding to the envelope level of the voltage waveform of the high frequency power detected by the level detection unit 2 during the stable period of each interval period. The level adjustment unit 103 is provided with level data so that the deviation from the level is zero.
(F) The average detection level calculation unit 4 first outputs high-frequency power from the high-frequency power supply apparatus with a set target level that is the level of the envelope waveform of the voltage waveform that should be taken in each interval period of each cycle. The first period is the first period, and each interval period of each period of the envelope waveform is divided into a transient period set immediately after the start and a stable period after the transient period has elapsed, In each cycle from the first cycle of the waveform to the (m-1) th cycle (m is a set value consisting of an integer of 2 or more), the correspondence of the respective cycles from the first cycle to the current cycle A level obtained by averaging the levels detected by the level detector 2 in the stable period of each interval period is calculated as an average detection level of each interval period, and in each period after the mth period of the envelope waveform , The average detection level of each interval period is the level obtained by averaging the m levels detected by the level detection unit 2 in the stable period of each interval period corresponding to each period from the previous cycle to the current cycle. Calculate as
(G) The average detection level calculated by the average detection level calculation unit 4 in each interval period of each cycle of the envelope waveform of the voltage waveform of the high-frequency power corresponds to the cycle next to the cycle in which the average detection level is calculated. In the interval period, the envelope is stored in the next cycle target level storage unit 5 as the target level to be taken.
(H) The open-loop control in each cycle after the second cycle of the envelope waveform of the voltage waveform of the high-frequency power is the voltage of the high-frequency power output from the amplifier 102 until the transition period of each interval period elapses. This is performed by giving level data to the DDS 101 so that the level of the waveform envelope is equal to the target level of the corresponding interval period stored in the next cycle target level storage unit 5.
(I) The feedback control performed in each interval period in each cycle after the second cycle of the envelope waveform of the voltage waveform of the high-frequency power is the level detected by the level detection unit 2 in the stable period of each interval period. The level adjustment unit 103 is provided with level data (variable value) so that the deviation from the target level of the corresponding interval period stored in the periodic target level storage unit 5 becomes zero. At this time, level data fixed to a constant value is given to the DDS 101.

[Second Embodiment]
FIG. 2 is a block diagram showing a configuration of a high-frequency power supply device according to the second embodiment of the present invention. In the present embodiment, level data (fixed value) is supplied from the controller 601 to the high-frequency signal generator (DDS) 101, and level data (variable value) is supplied only from the control calculation unit 606 to the level adjustment unit 103.

  In the embodiment shown in FIG. 2, the open loop control performed during the period from the start of each interval period of each cycle until the set transient period elapses, and the feedback control performed during the stable period of each interval period of each cycle. Both are performed by making the level data given to the level adjusting unit 103 a variable value. The other points are the same as in the embodiment shown in FIG. The configuration of the embodiment shown in FIG. 2 is advantageous when the level adjusting unit 103 having a characteristic that can narrow down the output level to zero level without any problem can be used. When configured as in the present embodiment, the open loop control performed between each level change timing and the set transition period elapses, and the remaining stable period after the transition period elapses from each level change timing. Both feedback control to be performed can be performed with high responsiveness.

The characteristics of the configuration of the high-frequency power supply device according to the embodiment shown in FIG. 2 are summarized as follows.
(A) The high-frequency signal generator / amplifier 1 includes a high-frequency signal generator 101, an amplifier 102 that amplifies a high-frequency signal generated by the high-frequency signal generator, and a level of a high-frequency signal that is supplied from the high-frequency signal generator 101 to the amplifier 102. Level adjustment unit 103 that adjusts the level according to the level data, and the envelope of the voltage waveform has a plurality of level change timings indicating a step-like level change in one cycle, and each level change timing and the next The high-frequency power modulated so as to exhibit a waveform in which the period between the level change timings is an interval period in which a constant level is maintained is output.
(B) A period until the set time elapses from the start of each interval period of each cycle of the waveform of the envelope waveform of the voltage waveform of the high frequency power output from the high frequency signal generating / amplifying unit 1 and the set time The remaining period after elapse of time is defined as a transition period and a stable period of each interval period, respectively.
(C) The open loop control performed in each interval period of the first cycle of the envelope waveform of the voltage waveform of the high-frequency power is performed by the amplifier 102 from the start of each interval period until the set transient period elapses. The level adjustment unit 103 is provided with level data so that the level of the envelope of the voltage waveform of the high-frequency power output from the level adjustment unit 103 is equal to the set target level of the corresponding interval period stored in the set target level storage unit 3.
(D) The feedback control performed in each interval period of the first cycle is a setting corresponding to the envelope level of the voltage waveform of the high-frequency power detected by the level detection unit 2 during the stable period of each interval period. The level adjustment unit 103 is provided with level data so that the deviation from the target level is zero.
(E) The average detection level calculation unit 4 first outputs high-frequency power from the high-frequency power supply apparatus with high-frequency power having the voltage waveform envelope waveform set to the level to be taken in each interval period of each cycle. The first period is the first period, and each interval period of each period of the envelope waveform is divided into a transient period set immediately after the start and a stable period after the transient period has elapsed, In each cycle from the first cycle of the waveform to the (m-1) th cycle (m is a set value consisting of an integer of 2 or more), the correspondence of the respective cycles from the first cycle to the current cycle A level obtained by averaging the levels detected by the level detector 2 in the stable period of each interval period is calculated as an average detection level of each interval period, and in each period after the mth period of the envelope waveform , The average detection level of each interval period is the level obtained by averaging the m levels detected by the level detection unit 2 in the stable period of each interval period corresponding to each period from the previous cycle to the current cycle. Calculate as
(F) The average detection level calculated by the average detection level calculation unit 4 in each interval period of each cycle of the envelope waveform of the voltage waveform of the high-frequency power corresponds to the cycle next to the cycle in which the average detection level is calculated. In the interval period, the envelope is stored in the next cycle target level storage unit 5 as the target level to be taken.
(G) The open loop control in each cycle after the second cycle of the envelope waveform of the voltage waveform of the high frequency power is performed from the amplifier 102 until the set transient period elapses from the start of each interval period. This is performed by giving level data to the level adjustment unit so that the level of the envelope of the voltage waveform of the high frequency power to be output is equal to the target level of the corresponding interval period stored in the next cycle target level storage unit 5.
(H) The feedback control in each interval period of each cycle after the second cycle of the envelope waveform of the voltage waveform of the high frequency power is performed by the high frequency power detected by the level detector 2 during the stable period of each interval period. This is performed by giving level data to the level adjusting unit 103 so that the deviation between the envelope level of the voltage waveform and the target level of the corresponding interval period stored in the next cycle target level storage unit 5 becomes zero.

[Third Embodiment]
FIG. 3 is a block diagram showing a configuration of a high-frequency power supply device according to the third embodiment of the present invention. In the present embodiment, the level adjusting unit 103 provided in the embodiment of FIGS. 1 and 2 is omitted, and the output of the high frequency signal generator (DDS) 101 is directly input to the amplifier 102.

  In this example, the level data that provides the high-frequency signal generator 101 with both the open loop control performed until the transition period of each interval period of each cycle elapses and the feedback control performed during the stable period of each interval period. As a variable value. The other points are the same as in the embodiment shown in FIG.

  When configured as shown in FIG. 3, the level adjusting unit 103 used in the embodiment of FIGS. 1 and 2 can be omitted, and thus the configuration of the apparatus can be simplified. The configuration of the embodiment shown in FIG. 3 is advantageous when a high-speed DDS 101 that can input level data as serial data (that can adjust the output level at high speed) can be obtained. It is a simple configuration.

The characteristics of the configuration of the high-frequency power supply device according to the embodiment shown in FIG. 3 are summarized as follows.
(A) A high-frequency signal generator / amplifier 1 includes a high-frequency signal generator 101 configured by a direct digital synthesizer (DDS) that outputs a high-frequency signal having a level indicated by level data given from the outside, and a high-frequency signal And an amplifier 102 for amplifying the output of the generator 101. The envelope of the voltage waveform has a plurality of level change timings indicating stepped level changes in one cycle, and each level change timing and the next The high-frequency power modulated so as to exhibit a waveform in which the period between the level change timings is an interval period in which a constant level is maintained is output.
(B) A period until the set time elapses from the start of each interval period of each cycle of the waveform of the envelope waveform of the voltage waveform of the high frequency power output from the high frequency signal generating / amplifying unit 1 and the set time The remaining period after elapse of time is defined as a transition period and a stable period of each interval period, respectively.
(C) The open-loop control in each interval period of the first cycle is performed by the envelope of the voltage waveform of the high-frequency power output from the amplifier 102 from the start of each interval period until the set transient period elapses. This is performed by giving level data to the DDS so that the level is equal to the corresponding set target level stored in the set target level storage unit 3.
(D) The feedback control performed in each interval period in the first period of the envelope waveform of the voltage waveform of the high frequency power is the voltage waveform of the high frequency power detected by the level detection unit 2 during the stable period of each interval period. This is performed by giving level data to the DDS 101 so that the deviation between the envelope level and the corresponding set target level becomes zero.
(E) The average detection level calculation unit 4 first outputs high-frequency power from the high-frequency power supply device with the set target level being the level that the envelope waveform of the voltage waveform should take in each interval period of each cycle. The first cycle of the waveform is the first cycle, and each interval period of each cycle of the envelope waveform is divided into a transient period set immediately after the start and a stable period after the transient period has elapsed, In each cycle from the first cycle of the line waveform to the (m-1) th cycle (m is a set value made up of an integer of 2 or more), the respective cycles from the first cycle to the current cycle The level obtained by averaging the levels detected by the level detector 2 in the corresponding stable period of each interval period is calculated as the average detection level of each interval period, and is calculated for each period after the mth period of the envelope waveform. In other words, the level obtained by averaging the m levels detected by the level detector 2 in the stable period of each interval period corresponding to each period from the m-1 previous cycle to the current cycle is the average of the interval periods. Calculate as the detection level.
(F) The average detection level calculated by the average detection level calculation unit 4 in each interval period of each cycle of the envelope waveform of the voltage waveform of the high-frequency power corresponds to the cycle next to the cycle in which the average detection level is calculated. In the interval period, the envelope is stored in the next cycle target level storage unit 5 as the target level to be taken.
(G) The open loop control in each interval period of each period after the second period of the envelope waveform of the voltage waveform of the high-frequency power is performed from the start of each interval period until the set transient period elapses. The level data is supplied to the DDS 101 so that the envelope level of the voltage waveform of the high-frequency power output from the amplifier 102 is equal to the target level of the corresponding interval period stored in the next cycle target level storage unit 5. .
(H) The feedback control in each interval period of each cycle after the second cycle of the envelope waveform of the voltage waveform of the high frequency power is performed by the high frequency power detected by the level detector 2 during the stable period of each interval period. This is performed by giving level data to the DDS 101 so that the deviation between the level of the envelope of the voltage waveform and the target level of the corresponding interval period stored in the next cycle target level storage unit 3B is zero.

  In each of the above embodiments, a plurality of level change timings indicating step-like level changes are provided in one cycle, and the interval period from each level change timing to the next level change timing is a period for holding the level. The high-frequency signal generating / amplifying unit 1 is controlled so as to obtain a high-frequency power modulated with this modulation waveform using the step waveform as a modulation waveform. It is not limited, and there are a plurality of level change timings indicating stepwise level changes in one cycle, and the interval period between each level change timing and the next level change timing continues to hold the level The present invention can be widely applied to the case where high-frequency power is modulated with a modulation waveform that exhibits a waveform.

  For example, as shown in FIG. 8, the present invention can also be applied to the case where high-frequency power is modulated by a pulse waveform.

1 High Frequency Signal Generation / Amplification Unit 101 High Frequency Signal Generation Unit (DDS)
DESCRIPTION OF SYMBOLS 102 Amplifier 103 Level adjustment part 104 D / A converter 2 Level detection part 201 Demultiplexer 202 Filter 203 Detector 204 Level detector 205 A / D converter 3 Setting target level memory | storage part 4 Average detection level calculation part 5th period Target level storage unit 6 High frequency power control unit 601 Controller 602 Output setting data input unit 604 Error level detection unit 605 Selection processing unit 606 Control calculation unit

Claims (6)

An envelope waveform of a voltage waveform (hereinafter referred to as an envelope waveform) has a plurality of level change timings indicating step-like level changes in one cycle, and a period between adjacent level change timings is a constant level. A method of controlling a high frequency power supply device that outputs high frequency power modulated so as to exhibit a step waveform that is an interval period for holding
A level detector for detecting the level of the envelope waveform is provided,
The set value of the level to be taken in each interval period that the envelope waveform of the voltage waveform of the high frequency power output from the high frequency power supply device has during one cycle is stored in the set target level storage unit as the set target level for each interval period. Let me know
Dividing each interval period of each cycle of the envelope waveform into a transient period set immediately after its start and a stable period after the transient period has passed,
The first cycle of the envelope waveform when the high-frequency power is first output from the high-frequency power supply device with the envelope waveform of the voltage waveform having the level to be taken in each interval period of each cycle as the set target level is the first. In each cycle from the first cycle of the envelope waveform to the m-1st cycle (m is a set value consisting of an integer of 2 or more), the first cycle to the current A level obtained by averaging the levels detected by the level detection unit in the stable period of each interval period corresponding to each period up to the period is calculated as an average detection level of each interval period, and the mth period of the envelope waveform In each subsequent period, m number of levels detected by the level detection unit in the stable period of each interval period corresponding to each period from the m-1 previous cycle to the current cycle. The average level of the bell is calculated as the average detection level of each interval period, and the average detection level of each calculated interval period is an envelope waveform in the interval period corresponding to the next cycle of the period in which the average detection level is calculated. Is stored in the next cycle target level storage unit as a target level to be taken,
In each interval period of the first period of the envelope waveform, the level detected by the level detection unit until the transition period elapses, the corresponding setting target stored in the setting target level storage unit After performing control equal to the level by open loop control, during the stable period, feedback control is performed to maintain the level detected by the level detection unit at the corresponding set target level stored in the set target level storage unit By
In each interval period of each cycle after the second cycle of the envelope waveform, the level detected by the level detection unit until the transition period elapses is stored in the next cycle target level storage unit After performing control equal to the target level to be performed by open loop control, during the stable period, control to maintain the level detected by the level detection unit at the corresponding target level stored in the next cycle target level storage unit What to do with feedback control,
A method for controlling a high-frequency power supply device. A voltage waveform envelope waveform (hereinafter referred to as an envelope waveform) has a plurality of level change timings indicating step-like level changes in one cycle, and a period between adjacent level change timings is a constant level. A high-frequency signal generator / amplifier comprising a high-frequency signal generator and an amplifier for amplifying a high-frequency signal generated by the high-frequency signal generator for high-frequency power modulated so as to exhibit a step waveform having an interval period for holding A high-frequency power supply that outputs from the unit,
A level detector for detecting the level of the envelope waveform;
A set target level storage unit that stores, as a set target level for each interval period, a level to be taken in each interval period that the envelope waveform of the voltage waveform of the high-frequency power output from the high-frequency power supply device has during one cycle;
The first cycle of the envelope waveform when the high-frequency power is first output from the high-frequency power supply device with the envelope waveform of the voltage waveform having the level to be taken in each interval period of each cycle as the set target level is the first. And the interval period of each period of the envelope waveform is divided into a transient period set immediately after its start and a stable period after the transition period has elapsed, and the first waveform of the envelope waveform In each cycle from the cycle to the (m-1) -th cycle (m is a set value consisting of an integer of 2 or more), each interval period corresponding to each cycle from the first cycle to the current cycle A level obtained by averaging the levels detected by the level detection unit in a stable period is calculated as an average detection level in each interval period, and in each period after the m-th period of the envelope waveform The level obtained by averaging the m levels detected by the level detection unit in the stable period of each interval period corresponding to each period from the m-1 previous cycle to the current cycle is calculated as the average detection level of each interval period. An average detection level calculation unit,
The average detection level of each interval period calculated by the average detection level calculation unit in each period of the envelope waveform should be the envelope waveform in each interval period of the period following the period in which the average detection level was calculated. A next cycle target level storage unit for storing the target level;
A high-frequency power control unit that controls the high-frequency signal generation / amplification unit so that the level detected by the level detection unit becomes a target level;
Comprising
The high frequency power control unit stores the level detected by the level detection unit in the set target level storage unit until the transition period elapses in each interval period of the first cycle of the envelope waveform. After performing control to equalize the corresponding set target level by open loop control, the level detected by the level detection unit during the stable period is set to the corresponding set target level stored in the set target level storage unit. The control to maintain is performed by feedback control, and in each interval period of each period after the second period following the first period, the level detected by the level detection unit until the transition period elapses. Open control to equalize the target level of the corresponding interval period stored in the next cycle target level storage unit After performing the loop control, the control for maintaining the level detected by the level detection unit at the corresponding target level stored in the next cycle target level storage unit is performed by the feedback control during the stable period of each interval period. The high frequency power supply device is configured as described above. A voltage waveform envelope waveform (hereinafter referred to as an envelope waveform) has a plurality of level change timings indicating step-like level changes in one cycle, and a period between adjacent level change timings is a constant level. A high-frequency signal generator / amplifier comprising a high-frequency signal generator and an amplifier for amplifying a high-frequency signal generated by the high-frequency signal generator for high-frequency power modulated so as to exhibit a step waveform having an interval period for holding A high-frequency power supply that outputs from the unit,
A level detector for detecting the level of the envelope waveform;
A set target level storage unit that stores, as a set target level for each interval period, a level to be taken in each interval period that the envelope waveform of the voltage waveform of the high-frequency power output from the high-frequency power supply device has during one cycle;
The first cycle of the envelope waveform when the high-frequency power is first output from the high-frequency power supply device with the envelope waveform of the voltage waveform having the level to be taken in each interval period of each cycle as the set target level is the first. And the interval period of each period of the envelope waveform is divided into a transient period set immediately after its start and a stable period after the transition period has elapsed, and the first waveform of the envelope waveform In each cycle from the cycle to the (m-1) -th cycle (m is a set value consisting of an integer of 2 or more), each interval period corresponding to each cycle from the first cycle to the current cycle A level obtained by averaging the levels detected by the level detection unit in a stable period is calculated as an average detection level in each interval period, and in each period after the m-th period of the envelope waveform The level obtained by averaging the m levels detected by the level detection unit in the stable period of each interval period corresponding to each period from the m-1 previous cycle to the current cycle is calculated as the average detection level of each interval period. An average detection level calculation unit,
The average detection level of each interval period calculated by the average detection level calculation unit in each cycle of the envelope waveform is taken as the envelope waveform in each interval period following the cycle in which the average detection level is calculated. A next cycle target level storage unit for storing the target level as a power level;
A high-frequency power control unit that controls the high-frequency signal generation / amplification unit so that the level detected by the level detection unit becomes a target level;
Comprising
The high-frequency signal generation / amplification unit is configured to have a function of adjusting a voltage level of high-frequency power output from the amplifier according to given level data,
The high frequency power control unit stores the level detected by the level detection unit in the set target level storage unit until the transition period elapses in each interval period of the first cycle of the envelope waveform. By providing the high-frequency signal generation / amplification unit with level data necessary to output the high-frequency power equal to the corresponding set target level from the high-frequency signal generation / amplification unit, the level of the envelope waveform is After performing control equal to the set target level by open loop control, during the stable period, the high frequency is set so that the deviation between the level detected by the level detection unit and the set target level of the corresponding interval period becomes zero. Feedback is provided to control the level of the envelope waveform at the set target level by providing level data to the signal generator / amplifier. In each interval period of each period after the second period following the first period, the envelope waveform level is set to the next period target until the transition period elapses. An open loop control is performed to make the level of the envelope waveform equal to the target level by providing the high-frequency signal generating / amplifying unit with level data necessary to equalize the corresponding target level stored in the level storage unit. After the control, the high-frequency signal is generated so that the deviation between the level detected by the level detection unit and the corresponding target level stored in the next cycle target level storage unit is zero during the stable period. -It is configured to perform control for giving level data to the amplifying unit and maintaining the level of the envelope waveform at the target level by feedback control. That it is,
A high frequency power supply device characterized by. The high-frequency signal generation / amplification unit includes a level adjustment unit that adjusts a level of a high-frequency signal given from the high-frequency signal generator to the amplifier according to level data,
The high-frequency signal generator is configured by a direct digital synthesizer (DDS) that outputs a high-frequency signal having a level indicated by level data given from outside,
The high frequency power control unit includes:
Until the transition period of each interval period of the first cycle elapses, the level of the envelope of the voltage waveform of the high-frequency power output from the amplifier is stored in the corresponding set target level storage unit. Performing open loop control in the first period by providing level data to the DDS to be equal to the level;
During the stable period of each interval period of the first cycle, level data is sent to the level adjustment unit so that the deviation between the level detected by the level detection unit and the set target level of the corresponding interval period becomes zero. To perform feedback control in each interval period of the first cycle,
Until the transition period of each interval period of each period after the second period elapses, the level of the envelope of the voltage waveform of the high frequency power output from the amplifier is stored in the next period target level storage unit. Performing open loop control in each interval period of each period after the second period by providing level data to the DDS so as to be equal to the target level of the corresponding interval period,
Deviation between the level detected by the level detection unit during the stable period of each interval period of each cycle after the second cycle and the target level of the corresponding interval period stored in the next cycle target level storage unit Feedback control in each interval period of each period after the second period by giving level data to the level adjusting unit so as to make zero
The high frequency power supply device according to claim 3, which is configured as described above. The high-frequency signal generation / amplification unit includes a level adjustment unit that adjusts a level of a high-frequency signal given from the high-frequency signal generator to the amplifier according to level data,
The high frequency power control unit includes:
Until the transition period of each interval period of the first cycle elapses, the level of the envelope of the voltage waveform of the high-frequency power output from the amplifier is the corresponding interval period stored in the set target level storage unit Performing an open loop control in each interval period of the first cycle by giving level data to the level adjuster so as to be equal to the set target level of
By providing level data to the level adjustment unit so that the deviation between the level detected by the level detection unit and the corresponding set target level is zero during the stable period of each interval period of the first cycle. Performing feedback control in each interval period of the first period;
Until the transition period of each interval period of each period after the second period elapses, the level of the envelope of the voltage waveform of the high frequency power output from the amplifier is stored in the next period target level storage unit. Performing open loop control in each interval period of each period after the second period by providing level data to the level adjuster so as to be equal to the target level of the corresponding interval period,
Deviation between the level detected by the level detection unit during the stable period of each interval period of each cycle after the second cycle and the target level of the corresponding interval period stored in the next cycle target level storage unit Feedback control in each interval period of each period after the second period by giving level data to the level adjusting unit so as to make zero
The high frequency power supply device according to claim 3, which is configured as described above. The high-frequency signal generator is configured by a direct digital synthesizer (DDS) that outputs a high-frequency signal having a level indicated by level data given from outside,
The high frequency power control unit includes:
The level of the envelope of the voltage waveform of the high-frequency power output from the amplifier until the transition period of each interval period of the first period elapses in the corresponding interval period stored in the set target level storage unit Open loop control of each interval period in the first cycle by giving level data to the DDS so as to be equal to the set target level,
By providing level data to the DDS so that the deviation between the level detected by the level detector and the set target level of the corresponding interval period is zero during the stable period of each interval period of the first cycle Performing feedback control in each interval period of the first period;
Until the transition period of each interval period of each period after the second period elapses, the level of the envelope of the voltage waveform of the high frequency power output from the amplifier is stored in the next period target level storage unit. Performing open loop control in each period after the second period by providing level data to the DDS to be equal to the target level of the corresponding interval period being
Deviation between the level detected by the level detection unit and the target level of the corresponding interval period stored in the next cycle target level storage unit during the stable period of each interval period of each cycle after the second cycle Feedback control in each period after the second period is performed by giving level data to the DDS so as to make zero
The high frequency power supply device according to claim 3, which is configured as described above.

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