High-frequency amplification assembly for a high-frequency generator, high-frequency generator, and plasma system

Abstract

To provide a high-frequency amplifying assembly with high stability and long service life.SOLUTION: A high-frequency amplifying assembly 10 for a high-frequency generator, particularly a high-frequency generator for operating a plasma generator, includes a signal generator 12 for generating a high-frequency signal, a first amplifying transistor 16 for amplifying the signal generated in the signal generator 12, an output terminal 20 for outputting the amplified signal to an external load 22, an input circuit network 14 disposed between the signal generator 12 and the first amplifying transistor 16 and supplying the high-frequency signal to the input of the first amplifying transistor 16, an output circuit network 18 disposed between the first amplifying transistor 16 and the external load 22 and applying a desired load impedance to the first amplifying transistor 16, and a voltage limiting assembly 30 disposed in the output terminal 20 and limiting the output voltage in the output terminal 20.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a high-frequency amplifier assembly for a high-frequency generator, a high-frequency generator having the same, and a plasma system having the high-frequency generator.

Background Art

[0002] High-frequency amplifier assemblies are generally known and are used in various applications. In particular, when used in the operation of a plasma generator, the requirements for the high-frequency amplifier assembly are particularly high.

[0003] This is because the amplifier transistor used in the high-frequency amplifier is easily damaged if not properly protected. There are various reasons for the damage of the amplifier transistor. In particular, when an excessively high voltage is applied to the terminals of the transistor or an excessively high current flows through the transistor, the amplifier transistor may be damaged.

[0004] When a high-frequency amplifier is used in a plasma generator, the generated plasma becomes a very unstable load, which has been a problem. As a result, generally, at least a part of the supplied power is reflected, and a large current flows through the amplifier transistor of the high-frequency amplifier assembly at least temporarily, and the amplifier transistor or the entire high-frequency amplifier assembly may be damaged.

[0005] Therefore, the lifespan of the high-frequency amplifier is generally not as expected.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Accordingly, an object of the present invention is to provide a high-frequency amplifier assembly that is particularly highly stable and has a long service life.

Means for Solving the Problem

[0007] To achieve the above object, the present invention proposes a high-frequency amplification assembly for a high-frequency generator, particularly for operating a plasma generator. The high-frequency amplification assembly includes a signal generator for generating a high-frequency signal, a first amplification transistor for amplifying the signal generated by the signal generator, an output terminal for outputting the amplified signal to an external load, an input network disposed between the signal generator and the first amplification transistor for supplying the high-frequency signal to the input of the first amplification transistor, an output network disposed between the first amplification transistor and the external load for providing a desired load impedance to the first amplification transistor, an electronic voltage-limiting assembly disposed at the output terminal for limiting the output voltage at the output terminal, and includes.

[0008] By providing a voltage-limiting assembly at the output terminal, the current flowing through the amplification transistor is also limited. This is achieved by the output network inverting the impedance of the external load and providing a desired load impedance to the first amplification transistor. As a result, when the output voltage is limited to a predetermined maximum value, the current flowing through the first amplification transistor is also limited to the maximum value. Since the voltage-limiting assembly is disposed at the output terminal, it is guaranteed that an excessively high current does not flow through the amplification transistor, and as a result, the amplification transistor is not destroyed.

[0009] The signal generator according to the present invention is for generating a high-frequency signal in the range of 100 kHz to 200 MHz. The high-frequency signal generated by the signal generator is supplied to the input of the amplification transistor by an input circuit network. The input circuit network can particularly include a transformer. Further, the input circuit network according to some embodiments of the present invention can include additional inductors and capacitors useful for impedance matching. The signal generated by the signal generator is amplified by a first amplification transistor, which can be configured particularly as a FET (Field Effect Transistor), preferably as a MOSFET (Metal Oxide Semiconductor FET). In particular, the first amplification transistor can be configured as an LDMOS (Laterally Diffused Metal-Oxide-Semiconductor) FET or a VDMOS (Vertically Diffused Metal-Oxide-Semiconductor) FET. The amplified signal is output to an external load via an output terminal. An output circuit network including particularly a transformer and optionally additional coils and / or capacitors is disposed between the amplification transistor and the external load. This output circuit network serves to provide a desired load impedance to the amplification transistor. Usually, the output circuit network is designed such that the high impedance of the external load is converted to a low impedance suitable for the amplification transistor.

[0010] The voltage limiting assembly arranged at the output terminal serves to prevent the output voltage at the output terminal from increasing to a value exceeding a predefined value, or at least to limit such increase to a value not exceeding a predefined value. Within the framework of the present invention, a number of different circuit variants can be used to realize the technical function of the voltage limiting assembly. For the purpose of deepening the understanding of the present invention, the present invention has been described in relation to one amplification transistor, however, in some embodiments of the present invention, two or more amplification transistors can be used. According to the present invention, in particular, two amplification transistors interconnected in a push-pull arrangement can be used. According to some embodiments of the present invention, the voltage limiting assembly arranged at the output terminal is not limited to being directly connected to the output terminal, and individual components may be arranged between the output terminal and the voltage limiting assembly, in which case the voltage limiting assembly may simply be indirectly connected to the output terminal (e.g., electrically, capacitively or inductively). In the framework of the present invention, it is simply important that the voltage limiting assembly arranged on the output side performs the voltage limiting function, as a result of which it contributes to the limitation of the current flowing through the amplification transistor.

[0011] Preferably, the voltage limiting assembly may comprise a load capable of reducing at least a part of the increased voltage at the output terminal. Thereby, the effective impedance of the voltage limiting assembly decreases, the load impedance of the amplification transistor increases, and the current flowing through the amplification transistor becomes smaller. The load can in particular be configured as an essentially capacitive load.

[0012] Preferably, the voltage limiting assembly may include a first rectifier diode and a first capacitor connected in series with the first rectifier diode. The rectifier diode is preferably a high-frequency silicon carbide diode having a very high breakdown voltage. The breakdown voltage can be particularly 500V or more, preferably 1kV or more. With such an arrangement, during the half-wave of the periodic output signal, a part of the temporarily increased voltage can be transmitted to the first capacitor, and as a result, the voltage at the output terminal can be timely and evenly reduced. Thereby, the current flowing through the amplification transistor also decreases. Therefore, the first capacitor is further charged during each cycle. When the capacitor has a relatively high capacitance, at least a temporary voltage increase can be compensated via the first capacitor.

[0013] Preferably, the voltage limiting assembly includes a first discharge assembly for discharging the first capacitor, and this first discharge assembly may be connected in parallel with the first capacitor. Thereby, the voltage limiting assembly has the advantage that it can compensate for voltage increases occurring over a long period of time. According to the present invention, the capacitance of the capacitor typically ranges from 100 pF to 1 nF. The selected capacitance range provides the advantage that, on the one hand, the first capacitor is charged during several periods, and on the other hand, the capacitance of the first capacitor is not overly high such that it significantly affects the pulse operation. By using the first discharge assembly, the first capacitor can be discharged when a predefined voltage is reached. The discharge assembly can be particularly composed of an ohmic resistor or a voltage-dependent resistor (e.g., a diode or a varistor).

[0014] Preferably, the capacitance of the first capacitor may be between 1 pF and 100 nF, particularly between 10 pF and 10 nF. By appropriately selecting the capacitance of the capacitor, the voltage limitation at the output terminal can be performed particularly efficiently.

[0015] Preferably, the first discharge assembly may include a first ohmic resistor for discharging the first capacitor. The first ohmic resistor is connected to the first capacitor on one hand and to the ground on the other hand. In this way, the first capacitor can be discharged through the first ohmic resistor. The resistor can particularly take values in the range of 5 to 100 k, preferably 10 to 50 k, and particularly preferably 25 k.

[0016] Preferably, the discharge assembly may include a first discharge diode for discharging the first capacitor. The discharge diode can preferably be an avalanche diode or a Zener diode. By using the discharge diode, the capacitor can be discharged particularly quickly. Also, by selecting the breakdown voltage of the discharge diode, the limit voltage at which the discharge assembly operates can be adjusted in a simple manner. The discharge diode is connected to the first capacitor on one hand and to the ground on the other hand.

[0017] Preferably, the first rectifier diode and the first discharge diode may be arranged such that the cathode of the first rectifier diode is connected to the cathode of the first discharge diode, or the anode of the first rectifier diode is connected to the anode of the first discharge diode.

[0018] Preferably, the discharge assembly may be composed of two or more diodes connected in series or in parallel. By using a plurality of diodes, the heat dissipation can be further improved. The diodes can particularly be configured as avalanche diodes or Zener diodes.

[0019] Preferably, the voltage limiting assembly may be connected to the ground.

[0020] Preferably, the voltage limiting assembly may include two sub - assemblies connected in parallel, The first sub - assembly includes the first rectifier diode, and A first parallel connection part that is connected in series to the first rectifying diode and includes a first capacitor and a first discharge assembly, wherein the cathode of the first rectifying diode is connected to the first parallel connection part, and The second sub-assembly a second rectifying diode, and a second parallel connection part that is connected in series to the second rectifying diode and includes a second capacitor and a second discharge assembly, wherein the anode of the second rectifying diode is connected to the second parallel connection part.

[0021] Here, the first discharge assembly and the first discharge assembly can be particularly composed of an ohmic resistor and / or a diode and / or a varistor arranged in parallel with their respective capacitors. Further, the first discharge assembly and / or the second discharge assembly can be composed of a combination of a discharge transistor and a drive diode. Possible arrangements of the discharge transistor and the drive diode will be described in detail below. Further, the first discharge assembly may include a first ohmic resistor and a first discharge diode arranged in parallel with the first capacitor. Here, the cathode of the first rectifying diode is connected to the cathode of the first discharge diode. Therefore, the second discharge assembly particularly includes a second ohmic resistor and a second discharge diode arranged in parallel with the second capacitor. Here, the anode of the discharge diode is connected to the anode of the rectifying diode. By using two rectifying diodes with the anode side of the first diode arranged at the output terminal and the cathode side of the second diode connected to the output terminal, an increased voltage can be compensated both during the positive half-wave and the negative half-wave of the output signal via the first and second capacitors. Thereby, the voltage at the output terminal can be particularly efficiently limited.

[0022] Preferably, the discharge assembly is composed of a varistor for discharging the first capacitor or may be composed only of a varistor for discharging the first capacitor.

[0023] Preferably, the discharge assembly may be composed of a first discharge diode for discharging the first capacitor and a drive diode for driving the first discharge diode. The combination of the discharge transistor and the drive diode can be used instead of the discharge diode or added to the discharge diode. The use of the discharge transistor has the advantages that it can dissipate very high power and has a higher reaction speed.

[0024] Preferably, the first discharge transistor may be configured as an npn bipolar transistor, the anode of the drive diode may be connected to the base of the npn bipolar transistor, and the cathode of the drive diode may be connected to the collector of the npn bipolar transistor. In this way, when a predetermined voltage in the drive diode is exceeded, the drive diode can be used to drive the npn bipolar transistor.

[0025] Preferably, a drive resistor arranged in parallel with the drive diode may be provided. Thereby, the discharge transistor can continuously discharge the first capacitor with a small current. Thereby, by replacing the first resistor arranged in parallel with the capacitor, the power loss can be received by the discharge transistor and its cooling body.

[0026] Preferably, the discharge assembly includes a first discharge transistor configured as an nMOS transistor, and the gate of the nMOS transistor may be driven via a resistor divider. Here, the resistor divider consists of two resistors, one resistor is arranged between the gate and the drain of the nMOS transistor, and the other resistor is arranged between the gate of the nMOS transistor and the ground connection.

[0027] Preferably, the first discharge transistor is disposed on a cooling element provided to dissipate heat generated in the discharge transistor. Since the first discharge transistor is disposed on the cooling element, the first discharge transistor can dissipate very high power. As a result, a more stable high-frequency amplification assembly can be provided as a whole.

[0028] Furthermore, within the framework of the present invention, a high-frequency generator, particularly for operating a plasma generator, is disclosed. The high-frequency generator comprises a high-frequency amplification assembly according to the present invention, a control and / or adjustment unit for controlling and / or adjusting a signal generated by a signal generator, and a direct voltage source for supplying a voltage to a first amplification transistor. and includes.

[0029] The high-power generator can be designed to generate an output power exceeding 100 W, preferably exceeding 1 kW.

[0030] In contrast to prior art high-frequency generators, the high-frequency generator according to the present invention provides greater robustness and a longer service life.

[0031] Finally, the present invention discloses a plasma system, The plasma system comprises a plasma generator for generating plasma, and a high-frequency generator according to the present invention for operating the plasma generator. and includes.

Brief Description of the Drawings

[0032] Hereinafter, the present invention will be described based on the following figures.

[0033]

Figure 1

Figure 2

Figure 3

Figure 4(a)(b)(c)

Figure 5

Figure 6(a)(b)

Figure 6(c)(d)

Figure 7

Figure 8(a)(b)(c)(d)

Figure 8(e)(f)(g)(h)

DETAILED DESCRIPTION OF THE INVENTION

[0034] Figure 1 shows a first embodiment of a prior art high-frequency amplification assembly 10. The high-frequency amplification assembly 10 includes a signal generator 12 for generating a high-frequency signal. The high-frequency signal can typically have a frequency in the range of 100 kHz to 200 MHz. The generated signal is provided to the input of an amplification transistor 16 via an input circuitry network 14. The input circuitry network 14 can include, for example, a transformer (not shown in Figure 1). Instead of or in addition to a transformer, the input circuitry network 14 can include coils, capacitors and / or resistors, which can be used for impedance matching. The amplification transistor 16 can be a bipolar transistor or a field effect transistor (FET) in particular. In particular, as shown in Figure 1, it is preferable to configure the amplification transistor 16 as a MOSFET. The latter can be arranged in a common source circuit in particular. In this case, the output of the input circuitry network 14 is connected to the gate terminal of the amplification transistor 16, while the drain terminal of the amplification transistor 16 is connected to the input of an output circuitry network 18. The output circuitry network 18 can include, for example, a transformer. Instead of or in addition to a transformer, the output circuitry network 18 can include coils and / or capacitors that are useful for impedance matching. The output circuitry network 18 reverses the impedance of an external load 22, for example, converting an impedance of 50 Ω to a considerably lower transistor impedance of 5 Ω, and the electrical length of the output circuitry network 18 between the drain and the output terminal 20 is approximately 1 / 4 of the RF period. The output circuitry network 18 connects the amplification transistor 16 to the output terminal 20 where the external load 22 is arranged. Further, the high-frequency amplification assembly 10 includes a first voltage source 24 for providing a gate bias voltage to the amplification transistor 16. In some high-frequency amplification assemblies 10, an additional stabilization circuit 26 can be provided that is arranged between the gate and the drain of the amplification transistor 16. The stabilization circuit 26 serves to suppress unwanted oscillations of the amplification transistor 16. As shown in Figure 1, the stabilization circuit 26 illustrated here includes a resistor and a capacitor.Finally, the high-frequency amplification assembly 10 shown in FIG. 1 includes a voltage source 28 for the amplification transistor 16.

[0035] FIG. 2 shows a second embodiment of a prior art high-frequency amplification assembly 10 in which two amplification transistors 16a, 16b are used. The two amplification transistors 16a, 16b are configured as MOSFETs, similar to the embodiment shown in FIG. 1. The amplification transistors 16a, 16b are connected to each other in a push-pull arrangement and are respectively arranged in a common-source circuit.

[0036] FIG. 3 illustrates a first exemplary embodiment of a high-frequency amplification assembly 10 according to the present invention. Compared with the prior art high-frequency amplification assembly 10, the high-frequency amplification assembly 10 according to the present invention includes a voltage limiting assembly 30 arranged at the output terminal 20 for limiting the output voltage at the output terminal 20. The voltage limiting assembly 30 is arranged in parallel with the external load 22. The voltage limiting assembly 30 at the output terminal 20 limits the impedance at the output of the output circuit network 18, thereby limiting the drain impedance of the amplification transistor 16 downward. Thereby, an excessively high drain current, which may lead to the destruction of the amplification transistor 16 or at least a shortening of its service life, is prevented from flowing through the amplification transistor 16.

[0037] FIGS. 4(a) to 4(c) show various embodiments of the voltage limiting assemblies 30a to 30c. According to the first exemplary embodiment, the voltage limiting assembly 30a includes a rectifying diode 32 and a capacitor 34 connected in series with the rectifying diode 32. With this arrangement, at least during the positive half-wave of the voltage applied to the output terminal 20, a part of the voltage applied to the capacitor 34 decreases and the capacitor 34 is charged. Thereby, the voltage at the output terminal 20 is at least partially limited, thereby avoiding or at least mitigating a sudden increase in the drain current of the amplification transistor 16.

[0038] Furthermore, in FIG. 4(b), a further voltage limiting assembly 30b is illustrated, which assembly includes a discharge assembly 36 arranged in parallel with capacitor 34 in addition to the components shown in FIG. 4(a). Typically, capacitor 34 is configured to be fully charged after a number of periods. Without a suitable discharge assembly, capacitor 34 can only limit the voltage at output terminal 20 for a short time. The additional discharge assembly 36 can discharge capacitor 34 periodically and, as a result, can permanently contribute to the voltage limitation at output terminal 20. As shown in conjunction with the following figures, discharge assembly 36 can include, in particular, an ohmic resistor or a voltage-dependent resistor (e.g., an avalanche diode or varistor). Since discharge assembly 36 can achieve a permanent voltage limitation that can contribute to a significant increase in the overall service life of amplifier transistor 16 and thus high-frequency amplification assembly 10, high-frequency amplification assembly 10 can be significantly improved.

[0039] In FIG. 4(c), another exemplary embodiment of the voltage limiting assembly 30c is illustrated. As shown in this figure, the voltage limiting assembly 30c can include a discharge assembly 36 consisting of an ohmic discharge resistor 38 and a discharge diode 40. Here, the discharge resistor 38 and the discharge diode 40 are arranged in parallel with each other and also in parallel with the capacitor 34. Further, the discharge diode 40 is arranged such that the cathode of the discharge diode 40 is connected to the cathode of the rectifier diode 32. The arrangement of the voltage limiting assembly 30c shown in FIG. 4(c) allows the capacitor 34 to be charged during the positive half-wave of the voltage at the output terminal 20 and enables this capacitor 34 to be discharged through the discharge resistor 38 and the discharge diode 40 so that the capacitor 34 can permanently contribute to the voltage limitation at the output terminal 20 during the positive half-wave of the voltage at the output terminal 20. Here, the combination of the discharge resistor 38 and the discharge diode 40 has the advantage that it can ensure rapid discharge through the discharge diode 40 when a particularly high voltage suddenly occurs at the output terminal, while it can also perform permanent discharge through the discharge resistor 38 even when there is no peak of a particularly high voltage at the output terminal 20. In this way, a particularly advantageous discharge process of the capacitor 34 is provided.

[0040] In FIG. 5, another exemplary embodiment of the voltage limiting assembly 30d is illustrated. Here, the voltage limiting assembly 30d includes a first sub-assembly including a first rectifying diode 32a, a first capacitor 34a, a first discharge resistor 38a connected in parallel to the first capacitor 34a, and a first discharge diode 40a connected in parallel to the latter. The second sub-assembly includes a second rectifying diode 32b, a second capacitor 23b, a second discharge resistor 38b disposed in parallel to the second capacitor 34b, and a second discharge diode 40b connected in parallel to the latter. The first sub-assembly serves to perform voltage limiting during the positive half-wave of the voltage at the output terminal 20. Thus, the second sub-assembly helps to provide a voltage limiting function during the negative half-wave of the voltage at the output terminal 20. The voltage limiting assembly 30d is particularly advantageous because it provides a particularly efficient voltage limiting function that can contribute to voltage limiting during the entire cycle time of the high-frequency output voltage.

[0041] In FIG. 6, the profiles of the drain current of the amplification transistor 16 (FIGS. 6(a), (c)) and the voltage of the output terminal 20 (FIGS. 6(b), (d)) are shown for the cases with (dashed line) and without (solid line) voltage limiting. In the simulated profiles, in addition to the voltage limiting assembly 30 which essentially corresponds to the voltage limiting assembly 30d shown in FIG. 5 (however, in contrast to the latter, the discharge resistors 38a, 38b are not included at all), a signal frequency f = 10 MHz and an output power P = 1500 watts were considered. Also, the first rectifying diode 32a and the second rectifying diode 32b were considered as ideal diodes (infinite breakdown voltage), and the breakdown voltages of the first discharge diode 40a and the second discharge diode 40b were considered as U_d = 500V in the simulation. Furthermore, the capacitances of the first capacitor 34a and the second capacitor 34b were set to C = 1.0 nF.

[0042] Figures 6(a) and 6(b) show the simulation results of the drain current of the amplification transistor 16 and the voltage of the output terminal 20 when operating with a 50 Ω load applied to the output. Here, the solid lines indicate the case without the voltage limiting assembly 30, and the dashed lines indicate the case with the above-described voltage limiting assembly 30. As can be seen from Figure 6(a), the current profiles are the same in both cases. Further, Figure 6(b) illustrates the profile of the voltage of the output terminal 20. Also in this figure, the solid line indicates the case without the voltage limiting assembly 30, and the dashed line indicates the case with the above-described voltage limiting assembly 30. As can also be seen from this figure, the voltage limiting assembly 30 does not change the profile of the voltage of the output terminal 20 when operating with a 50 Ω load.

[0043] Figures 6(c) and 6(d) show the profiles of the drain current of the amplification transistor 16 and the voltage of the output terminal 20 when the output impedance increases (operation at open output). Here, in Figure 6(c), it can be seen that when the voltage limiting assembly 30 is not used (solid line), the current profile reaches an amplitude approximately twice that of the cases shown in Figures 6(a) and 6(b) (operation at 50 Ω). By using the voltage limiting assembly 30, the drain current of the amplification transistor 16 is limited (dashed line). This extends the overall life of not only the amplification transistor 16 but also the high-frequency amplification assembly 10. Similarly, in Figure 6(d), it can be seen that when the voltage limiting assembly 30 is not used, the output voltage rises to a significantly higher peak value than that shown in Figures 6(a) and 6(b). By using the voltage limiting assembly 30, a significant limitation of the output voltage is achieved. This also makes it possible to limit the drain current of the amplification transistor 16.

[0044] FIG. 7 shows another embodiment of the present invention, where two high-frequency amplification assemblies 10a, 10b are used. Here, the first high-frequency amplification assembly 10a provides a first output signal at a first output terminal 20a, and the second high-frequency amplification assembly 10b provides a second output signal at a second output terminal 20b. Here, the output signal provided by the first high-frequency amplification assembly 10a is limited by a first sub-assembly consisting of a capacitor 34a, a discharge resistor 38a, and a discharge diode 40a in addition to a rectifier diode 32b, and is also limited by a second sub-assembly consisting of a rectifier diode 32c, a capacitor 34b, a discharge resistor 38b, and a discharge diode 40b. Here, the first sub-assembly serves as a voltage limiter during the positive half-wave of the output voltage, and the second sub-assembly serves as a voltage limiter during the negative half-wave of the output voltage. Similarly, the output voltage supplied by the second high-frequency amplification assembly 10b is limited by a sub-assembly consisting of a rectifier diode 32a, a capacitor 34a, a discharge resistor 38a, and a discharge diode 40a, and a sub-assembly consisting of a rectifier diode 32d, a capacitor 34b, a discharge resistor 38b, and a discharge diode 40b. The output powers of the individual high-frequency amplification assemblies 10a, 10b are coupled by a power coupler 42. The exemplary embodiment of the present invention shown in FIG. 7 provides the advantage that the number of electronic components required for voltage limiting is reduced even when a plurality of high-frequency amplification assemblies 10a, 10b are combined with each other or operate independently of each other. Therefore, each high-frequency amplification assembly 10a, 10b does not necessarily require separate capacitors 34a, 34b, separate discharge resistors 38a, 38b, and separate discharge diodes 40a, 40b. Instead, each of the aforementioned components can be used for voltage limiting of a plurality of high-frequency amplification assemblies. As shown in FIG. 7, additional components (e.g., a power coupler 42, etc.) can be arranged between the output terminals 20a, 20b and the external load 22. Therefore, within the framework of the present invention, it is not essential that the output terminals 20a, 20b or the voltage limiting assemblies 30 respectively arranged at the output terminals 20a, 20b are directly connected to the external load 22.

[0045] In FIG. 8, a further exemplary embodiment of the discharge assembly 36 of the high-frequency amplification assembly 10 according to the present invention is illustrated. In FIGS. 8(a) to (d), exemplary embodiments of the discharge assembly 36 that can be used for voltage limiting during the positive half-wave of the voltage at the output terminal 20 are shown. Further, in FIGS. 8(e) to (h), various exemplary embodiments of the discharge assembly 36 that can be used for voltage limiting at the output terminal 20 during the negative half-wave are illustrated. In FIGS. 8(a) to (h), the use of the discharge transistor 44 is illustrated. The discharge transistor 44 can be configured particularly as a bipolar transistor or a MOSFET. Further, in the exemplary embodiments shown in FIGS. 8(a) to (h), the use of a drive diode 46 for driving the discharge transistor 44 is proposed. When using a MOSFET, the threshold voltage is adjusted by a resistor divider.

[0046] For example, FIG. 8(a) shows a possible embodiment of a discharge assembly 36a using an npn bipolar transistor 44a and a drive diode 46a. The drive diode 46a can be configured as an avalanche diode in particular. As long as the voltage of the output terminal 20 is below a predefined threshold value, the discharge assembly 36a is not active. However, when the voltage of the output terminal 20 increases to a value higher than the predefined threshold value, the drive diode 46a breaks down and the discharge transistor 44a changes to a conductive state. As a result, the charged capacitor 34 can be discharged through the discharge transistor 44a. Note that it is also possible to use a varistor instead of the drive diode 46a (not shown in FIG. 8(a)). Using the discharge transistor 44a has the advantage that a very large amount of power can be released. For example, it is possible to release several hundred watts of power using a power transistor. Also, by providing a cooling device for the power transistor, the operation of the power transistor can be optimized. For example, by arranging the power transistor in a housing such as TO220, TO247, ISOTOP, etc. and cooling it, an appropriate amount of electric power can be consumed. The cooling of the power transistor can be performed, for example, passively (such as a heat sink) or actively (such as forced ventilation or cooling water).

[0047] Similar to the exemplary embodiment shown in FIG. 8(a), the discharge assemblies 36 shown in FIGS. 8(b) to 8(h) can be used for discharging the capacitor 34.

[0048] To explain the present invention, very specific exemplary embodiments of the present invention have been described with reference to the foregoing figures. However, it will be apparent to those skilled in the art that the specific exemplary embodiments are not intended to limit the scope of the present invention. Rather, they are merely useful for explaining the present invention.

Description of Reference Numerals

[0049] 10 High-frequency amplification assembly 10a First high-frequency amplification assembly 10b Second high-frequency amplification assembly 12 Signal generator 14 Input circuit network 16 Amplifying transistor 16a First amplifying transistor 16b Second amplifying transistor 18 Output circuit network 20 Output terminal 20a First output terminal 20b Second output terminal 22 External load 24 First voltage source 26 Stabilizing circuit 28 Second voltage source 30 Voltage limiting assembly 32 Rectifying diode 32a First rectifying diode 32b Second rectifying diode 32c Third rectifying diode 32d Fourth rectifying diode 34 Capacitor 34a First capacitor 34b Second capacitor 36 Discharging assembly 36a~36h First to eighth discharging assemblies 38 Discharging resistor 38a First discharging resistor 38b Second discharging resistor 40 Discharging diode 40a First discharging diode 40b Second discharging diode 42 Power coupler 42a Output terminal of the power coupler 44 Discharging transistor 44a, g npn bipolar transistor 44b, h nMOS transistor 44c, e pnp bipolar transistor 44d, f pMOS 46 Driving diode 48, 49 Resistor

Claims

1. A high-frequency amplification assembly for a high-frequency generator, A signal generator for generating a high-frequency signal, An amplification transistor for amplifying the signal generated by the signal generator, An output terminal for outputting the amplified signal to an external load, An input circuit disposed between the signal generator and the amplification transistor for supplying a high-frequency signal to the input of the amplification transistor, An output circuit disposed between the amplification transistor and the external load for giving a desired load impedance to the amplification transistor, A voltage limiting assembly disposed at the output terminal for limiting the output voltage at the output terminal, comprising The voltage limiting assembly includes a rectifying diode having an anode connected to the output terminal, a capacitor having a first terminal connected in series to the cathode of the rectifying diode and a second terminal connected to ground, and a discharge assembly connected to the first terminal of the capacitor for discharging the capacitor and disposed in parallel with the capacitor, The discharge assembly includes an ohmic resistor and a discharge diode disposed in parallel with the capacitor, The cathode of the discharge diode is connected in series to the cathode of the rectifying diode, and the anode of the discharge diode is connected to ground, The ohmic resistor has one terminal connected in series to the cathode of the rectifying diode and the other terminal connected to ground. A high-frequency amplification assembly.

2. A high-frequency amplification assembly for a high-frequency generator, A signal generator for generating a high-frequency signal, An amplification transistor for amplifying the signal generated by the signal generator, An output terminal for outputting the amplified signal to an external load, An input circuit disposed between the signal generator and the amplification transistor to supply a high-frequency signal to the input of the amplification transistor; An output circuit disposed between the amplification transistor and the external load to provide a desired load impedance to the amplification transistor; A voltage limiting assembly disposed at the output terminal to limit the output voltage at the output terminal; comprising; The voltage limiting assembly includes a rectifying diode having a cathode connected to the output terminal, a capacitor having one terminal connected in series to the anode of the rectifying diode and the other terminal connected to ground, and a discharge assembly connected to the one terminal of the capacitor for discharging the capacitor and disposed in parallel with the capacitor; The discharge assembly includes an ohmic resistor and a discharge diode disposed in parallel with the capacitor; The anode of the discharge diode is connected in series to the anode of the rectifying diode, and the cathode of the discharge diode is connected to ground; The ohmic resistor has one terminal connected in series to the anode of the rectifying diode and the other terminal connected to ground, a high-frequency amplification assembly.

3. The high-frequency amplification assembly according to claim 1 or 2, characterized in that the capacitor has a capacitance greater than 10 pF and less than 100 nF.

4. A high-frequency amplification assembly for a high-frequency generator, A signal generator for generating a high-frequency signal; An amplification transistor for amplifying the signal generated by the signal generator; An output terminal for outputting the amplified signal to an external load; An input circuit disposed between the signal generator and the amplification transistor to supply a high-frequency signal to the input of the amplification transistor; An output circuit disposed between the amplification transistor and the external load, and providing a desired load impedance to the amplification transistor; A voltage limiting assembly disposed at the output terminal and limiting the output voltage at the output terminal; comprising; wherein the voltage limiting assembly includes two sub-assemblies connected in parallel; The first sub-assembly includes: a first rectifying diode having an anode connected to the output terminal, a first capacitor having one terminal connected in series to the cathode of the first rectifying diode and the other terminal connected to ground, and a first discharging assembly connected to the one terminal of the first capacitor for discharging the first capacitor and disposed in parallel with the first capacitor; The first discharging assembly includes a first ohmic resistor and a first discharging diode disposed in parallel with the first capacitor; The cathode of the first discharging diode is connected in series to the cathode of the first rectifying diode, and the anode of the first discharging diode is connected to ground; One terminal of the first ohmic resistor is connected in series to the cathode of the first rectifying diode, and the other terminal is connected to ground; The second sub-assembly includes: a second rectifying diode having a cathode connected to the output terminal, a second capacitor having one terminal connected in series to the anode of the second rectifying diode and the other terminal connected to ground, and a second discharging assembly connected to the one terminal of the second capacitor for discharging the second capacitor and disposed in parallel with the second capacitor; The second discharging assembly includes a second ohmic resistor and a second discharging diode disposed in parallel with the second capacitor; The anode of the second discharging diode is connected in series to the anode of the second rectifying diode, and the cathode of the second discharging diode is connected to ground; The second ohmic resistor is a high-frequency amplification assembly in which one terminal is connected in series to the anode of the second rectifying diode and the other terminal is connected to ground. **Claim 5** A high-frequency amplification assembly according to any one of claims 1 to 4, A control and / or adjustment unit for controlling and / or adjusting a signal generated by a signal generator, A direct voltage source for supplying a voltage to the first amplification transistor, comprising a high-frequency generator. **Claim 6** A plasma generator for generating plasma, The high-frequency generator according to claim 5 for operating the plasma generator, comprising a plasma system.

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