RF SYSTEM FOR A HIGH-FREQUENCY LAMP

Description

[0001] The invention relates to a signal coupling device according to the preamble of claim 1 and to a method for operating an RF signal coupling device according to the preamble of claim 13.

[0002] An RF system of the type discussed here is known, for example, from WO 2009 / 068618 A2. It is used in particular for the efficient operation of high-frequency devices such as high-frequency lamps at high frequencies, particularly in the ISM band at 2.45 GHz. The operation of RF devices, in particular RF lamps, RF spark plugs, or similar RF plasma applications, requires good high-frequency matching of the lamp. The lamp's matching is frequency-dependent and a measure of what proportion of the RF signal generated by an oscillator can be absorbed by the lamp to operate it. The greater the matching of the RF device to the frequency of an applied RF signal, the lower the proportion of a signal reflected by the lamp. The matching of the RF device thus contributes significantly to the overall efficiency of the RF system.Deviations of the operating frequency from the optimally matched frequency in an RF system on the order of a few tens of MHz can lead to a reduction in efficiency of more than 50%, particularly in high-frequency energy-saving lamps. The adaptation of the RF device to an applied RF signal depends on several factors. These include, in particular, manufacturing tolerances, temperature behavior, and aging-related changes in the RF device's electronics. Furthermore, the position and usually also the amount of adaptation change after the RF device is ignited, as can be seen from [the original text]. Fig. 1 becomes clear. Fig. 1a shows a schematic representation of the operating frequency f 0 of the RF signal supplied to the RF device before ignition and Fig. 1b shows the same signal after the RF device has been triggered. It is clear that the operating frequency f 0 ' has shifted after the RF device has been triggered, so that it no longer corresponds to the optimal operating frequency of the RF device. In this case, the tuning of the RF device is no longer optimal, and reflections of an RF signal supplied to the RF device occur, which, as mentioned, can significantly reduce the efficiency of the RF device.

[0003] In particular, American patent application US 5 688 357 A describes methods of operation for modifying inductively coupled RF plasma reactors of the type used in semiconductor processing which use a wound antenna for coupling RF energy into the plasma reactor chamber.

[0004] Control circuits designed for dynamic adjustment of an RF device are known from the state of the art. These utilize variable capacitors known, for example, from amplifier development and MHz plasma technology. Variable capacitors connected to stepper motors are used to achieve impedance transformation. This solution enables analog adjustment of the RF device, but requires the use of a microcontroller to control the control and make the individual settings. This increases the dynamic adjustment time and also makes the circuit relatively complex and cost-intensive.

[0005] Furthermore, at higher frequencies, for example in the mobile communications sector, it is known to provide switching networks that enable matching circuits with discrete states for dynamic antenna tuning by switching various inductive and capacitive elements on or off. This solution allows for discrete matching values ​​for a wide range of load impedances. The achievable discrete stages and compensable load deviations depend on the number of switching states and the elements of the matching circuits. This solution also requires the use of a microcontroller, which in turn makes the entire system complex and relatively expensive.

[0006] In this context, US 2002 / 0 79845 A1 discloses, among other things, a high-performance oscillator circuit with a resonance pole configuration of reduced complexity, parallel RF power FET transistors with soft gate switching, a circuit for continuously variable frequency tuning, a directional coupler with six terminals, an RF source with impedance switching and an RF source with controlled frequency-load characteristics.

[0007] The object of the present invention is therefore to provide an RF system comprising an RF device and an RF signal coupling device, which realizes the adaptation of the RF device to an optimal operating frequency in a simple, cost-effective and efficient manner.

[0008] A key aspect of the present invention is therefore that optimal adaptation of the RF device is ensured at the time of ignition and during operation. This is achieved by a control circuit that dynamically regulates the frequency of the control signal to the frequency of the optimal adaptation of the RF device. Such a control circuit can be referred to as an ALL circuit (amplitude locked loop circuit). The RF signal coupling device thus enables analog and dynamic control of the frequency position of an RF signal to adapt an RF device, in particular an energy-saving lamp, both at the time of ignition and during operation of the energy-saving lamp. In contrast to the previously known solutions of the prior art, the present invention preferably does not require a microcontroller, but rather only a few logic gates that form a logic unit necessary for controlling the circuit elements.This greatly simplifies the entire RF system and can, if required, be implemented on a single semiconductor IC.

[0009] The essential basic idea of ​​the present invention is that a voltage signal proportional to the degree of adaptation of the RF device is generated, or corresponding means are provided for this purpose. The voltage signal proportional to the degree of adaptation of the RF device is generated on the basis of the RF signal generated by the oscillator and a signal reflected by the RF device. The voltage signal proportional to the degree of adaptation of the RF device is then further processed in a preferably microprocessor-free device, in particular using at least one logic gate, such that a control signal for adjusting the output frequency of the oscillator can be output within a very short time.

[0010] The RF signal coupling device according to the invention provides analog control of the operating frequency to the frequency with the best adaptation of the RF device. This ensures that the RF plasma is reliably ignited at an optimal frequency. Furthermore, it ensures that the lamp operates at an optimal frequency. Furthermore, it ensures that deviations between the operating frequency and the optimal frequency, which may be due, for example, to manufacturing tolerances, temperature behavior, or aging-related changes in the electronics, are taken into account during ignition and operation. By omitting a microcontroller, a preferred RF system according to the present invention achieves faster control of the operating frequency, since the control time is now essentially a function of gate delays.Furthermore, the entire circuit arrangement of the RF signal coupling device becomes more compact, as only individual logic gates are required. The circuit arrangement can also be implemented on a single semiconductor IC if necessary. A semiconductor IC provides a compact and cost-effective solution for mass production. A further advantage offered by the present invention is the significantly less complex development, as the hardware is leaner and no software is required. Furthermore, since no software is required, software bugs cannot occur, making the RF system as a whole less susceptible to interference.

[0011] Particularly preferred is an RF system in which the means for generating a voltage signal proportional to the degree of adaptation of the RF device comprise at least one decoupling device for decoupling a portion of the RF signal generated by the oscillator and at least one further decoupling device for decoupling a portion of the signal reflected by the RF device. Furthermore, a voltage detection device for detecting and outputting a voltage signal of the decoupled portion of the RF signal generated by the oscillator and at least one further voltage detection device for detecting and outputting a voltage signal of the decoupled portion of the signal reflected by the RF device are preferably provided.To generate the actual voltage signal proportional to the degree of adaptation of the RF device, a device, in particular at least one operational amplifier, is preferably provided which generates the voltage signal proportional to the degree of adaptation of the RF device on the basis of the voltage signal of the decoupled portion of the signal reflected by the RF device and the voltage signal of the decoupled portion of the RF signal generated by the oscillator.

[0012] Alternatively, the means for generating a voltage signal proportional to the degree of adaptation of the RF device can comprise a circulator configured to extract a portion of the RF signal generated by the oscillator and a portion of the signal reflected by the RF device, and optionally detects and outputs corresponding voltage signals of the extracted portions. The circulator preferably comprises at least one device, in particular at least one operational amplifier or at least one amplifier circuit, which generates a voltage signal proportional to the voltage level of the RF device based on the voltage signals of the extracted portions.

[0013] In a further preferred RF system, the preferably microprocessor-free device for generating a control signal for adjusting the output frequency of the oscillator comprises a logic unit with at least one, preferably two logic gates, which outputs a control signal for adjusting the output frequency of the oscillator based on at least one, preferably three conditions. Furthermore, the logic unit can be connected to a shift register, wherein the shift register is provided for receiving an output signal of the logic unit. Furthermore, the preferably microprocessor-free device can also comprise a clock device for clocking the output signal of the logic unit. In this way, an artificial digital signal can be generated or clocked. The logic unit is preferably connected to the oscillator via a loop filter for generating an analog output voltage for controlling the oscillator.The analog output frequency is generated in particular by smoothing the digital output signal of the logic unit by the loop filter. Alternatively, instead of the loop filter, a charge pump arrangement can be provided to generate an analog output voltage for regulating the frequency of the oscillator. As a further alternative, both the loop filter and the charge pump arrangement can be omitted and, instead, the preferably microprocessor-free device and, in particular, the logic unit can be designed to generate an analog output voltage for regulating the frequency of the oscillator. Preferably, the RF system also has a reset circuit designed to set the oscillator to a predefined state.The reset circuit therefore makes it possible to set a predefined state of the oscillator, in particular a predefined operating frequency.

[0014] To achieve the above-described object, a signal coupling device for use in an RF system according to one of claims 1 to 12 is proposed.

[0015] Finally, to achieve the above-mentioned object, a method for operating an RF signal coupling device is also proposed. The method comprises the step of generating an RF signal for operating the RF device by means of an oscillator. It is characterized in that a voltage signal proportional to the degree of adaptation of the RF device is generated on the basis of the RF signal generated by the oscillator and a signal reflected from the RF device. Furthermore, the method is characterized by generating a control signal for adjusting the output frequency of the oscillator based on the voltage signal proportional to the degree of adaptation of the RF device.

[0016] A preferred method is one in which a first condition is generated based on the voltage signal proportional to the degree of adaptation of the RF device before generating a control signal for adjusting the output frequency of the oscillator. In particular, the first condition is obtained by deriving the voltage signal proportional to the degree of adaptation of the RF device. Preferably, a second condition is also generated based on the voltage signal proportional to the degree of adaptation of the RF device before generating a control signal for adjusting the output frequency of the oscillator. This second condition is preferably obtained by comparing the voltage signal proportional to the degree of adaptation of the RF device with a predefined voltage value.The method according to the invention preferably also comprises the step of supplying the first and the second condition and in particular a third condition to one or more logic gates and generating a control signal for adjusting the output frequency of the oscillator on the basis of a truth table based on the logic gate(s).

[0017] With regard to the advantages of the method according to the invention, reference is made to the advantages of the RF signal coupling device according to the invention explained above.

[0018] The invention is explained in more detail below with reference to the drawings. They show: Fig. 1a shows a schematic diagram of the operating frequency before the ignition of the RF device; Fig. 1b shows a schematic diagram of the operating frequency after the ignition of the RF device; Fig. 2 shows a schematic circuit diagram of an embodiment of an RF system according to the invention; Fig. 3 shows a schematic circuit diagram of an embodiment of a preferably microprocessor-free device for generating a control signal for adjusting the output frequency of the oscillator; Fig. 4 shows a schematic representation of an embodiment of a logic unit according to the invention; Fig. 5 shows a truth table implemented by the logic unit; Fig. 6 shows a schematic representation of an embodiment of a clock generator device; Fig. 7 shows a schematic representation of an embodiment of a loop filter, and Fig. 8 shows a schematic representation of an embodiment of a reset circuit.

[0019] Fig. 2 shows a schematic representation of an embodiment of an RF system 1 according to the invention. The RF system 1 comprises an RF signal coupling device 3 and an RF device 5, which can be an RF lamp, an RF spark plug, or a similar RF plasma application. The invention is described below purely by way of example with reference to an RF lamp, using the reference numeral 5.

[0020] The RF signal coupling device 3 serves to operate the RF lamp 5 and generates an RF signal with an operating frequency for the ignition and operation of the RF lamp 5 by means of an oscillator 7. Fig. 2 In the embodiment of the RF system 1 according to the invention shown, an amplifier 9 and an attenuator 11 are connected to the oscillator 7, by means of which the output signal of the oscillator 7 can be increased or reduced before it is increased to the operating power via a further amplifier 13. The amplifiers 9 and 13 as well as the attenuator 11 are optional and can either be omitted or replaced by other suitable elements. Arrangement in other combinations between the RF lamp 5 and the oscillator 7 is also conceivable.

[0021] The RF signal coupling device 3 also has means, designated by reference numeral 15, for generating a voltage signal proportional to the degree of adaptation of the RF device. According to the Fig. 2 In the embodiment of the invention shown, these means 15 comprise two decoupling devices 17 and 19, wherein the decoupling device 17 serves to decouple a portion a of the RF signal generated by the oscillator 7, while the decoupling device 19 serves to decouple a portion b of the signal reflected by the RF lamp 5. It is understood that a signal b is only reflected by the RF lamp 5 if the lamp is not optimally matched to the frequency of the RF signal generated by the oscillator 7. The decoupling device 17 therefore serves to decouple power flowing towards the RF lamp 5, while the decoupling device 19 serves to decouple power flowing away from the RF lamp 5, i.e. reflected power.

[0022] The means with the reference number 15 also have a voltage detection device 21 (detector), which serves to detect and output a voltage signal of the decoupled portion a of the RF signal generated by the oscillator 13. Furthermore, a voltage detection device 23 (detector) is provided, which serves to detect and output a voltage signal of the decoupled portion of the signal b reflected by the RF lamp 5. According to the present embodiment of the invention, the two voltage signals generated by the voltage detection devices 21 and 23 are fed to a common operational amplifier 25, which, based on the output voltages of the voltage detection devices 21 and 23, generates a voltage U prop proportional to the lamp adjustment.

[0023] As an alternative to the embodiment of the means designated by reference numeral 15 for generating a voltage signal U prop that is proportional to the degree of adaptation of the RF lamp, a circulator can be used instead of the decoupling devices 17 and 19, which circulator couples the two signals, i.e. the RF signal of the oscillator 7 and the reflected signal of the RF lamp 5, from the connection between the RF lamp 5 and the oscillator 7. In this case, the operational amplifier 25 can either be omitted or it can be replaced by an amplifier circuit. In a further embodiment of the means 15 for generating a voltage signal that is proportional to the degree of adaptation of the RF lamp, it can also be provided to provide only one decoupling device 17 or 19, which can each serve to couple out both the portion of the RF signal generated by the oscillator 7 and the RF signal portion reflected by the lamp 5.

[0024] The only decisive factor is that a device is provided that generates a voltage signal proportional to the degree of matching of the RF device from the RF signal of oscillator 7 and the signal reflected by lamp 5. This means that the generated voltage signal, which is proportional to the degree of matching of the RF device, is a measure of how much of the RF signal from oscillator 7, which is fed to RF lamp 5, is reflected by RF lamp 5 and, consequently, how high the mismatch of the RF lamp is.

[0025] In a subsequent step, according to the invention, the voltage U prop proportional to the lamp adjustment is fed to a preferably microprocessor-free device 27 for generating a control signal for adjusting the output frequency of the oscillator 7. The preferably microprocessor-free device 27 comprises Fig. 2 The embodiment shown comprises an amplitude discriminator 29, a loop filter 31, and a reset circuit 33. Based on the voltage U prop proportional to the degree of adaptation of the RF lamp 5, the amplitude discriminator 29 generates a digital or clocked output voltage UD , which in turn is fed to a filter device, in particular the loop filter 31, which smooths the clocked signal UD such that a substantially analog output signal UA is generated, which is fed to the oscillator 7 as a control voltage. The control voltage UA supplied to the oscillator 7 is therefore a measure of whether the frequency of the oscillator 7 should be increased, decreased, or remain the same.

[0026] Fig. 3 shows an exemplary embodiment of the Fig. 2 The amplitude discriminator 29 has an input 35 to which the voltage U prop proportional to the degree of adaptation of the HF lamp 5 is supplied. In the present exemplary embodiment, a total of three conditions K1, K2, and K3 are generated in the amplitude discriminator 29. The first condition K1 is generated on the basis of the voltage signal U prop proportional to the degree of adaptation of the HF lamp 5 by comparing it with a predefined voltage value. For this purpose, the amplitude discriminator 29 has a comparator 39 to which the voltage signal U prop and a fixed voltage value generated by a voltage value generation device 41 are supplied on the one hand. The voltage value generation device 41 is preferably implemented by a voltage divider.The comparator 39 compares the current value of the voltage U prop with the fixed voltage value of the voltage value generating device 41. The resulting output signal of the comparator 39 corresponds to the first condition K1.

[0027] At the same time, in the amplitude discriminator 29, the voltage signal U prop is fed to a differentiator unit 43 with an integrated inverted comparator, which derives the voltage signal U prop. The output signal of the differentiator unit 43 thus provides information about the tendency of the lamp adjustment, i.e., whether it is decreasing or increasing, and corresponds to the second condition K2.

[0028] The first condition K1 and the second condition K2 are fed to a logic unit 45. The logic unit 45 is connected to a shift register, in particular to a 2-bit shift register 47, which can be implemented, for example, by two D flip-flops, and receives a third condition K3 from them. The shift register 47 can, as in the Fig. 3 shown, be connected to a clock generator 49 in order to artificially digitize or clock the analog process within the amplitude discriminator 29.

[0029] A possible realization of the logic unit 45 of the amplitude discriminator 29 is shown in the schematic embodiment according to Fig. 4 The logic unit 45 comprises three inputs 51, 53 and 55, wherein the first condition K1 is supplied to the logic unit 45 via the input 51, the second condition K2 via the second input 53 and the third condition K3 via the third input 55. The logic unit 45 further comprises a Fig. 3 output 57 connected to the shift register 47 shown.

[0030] In the exemplary embodiment according to Fig. 4 The logic unit 45 comprises two logic gates 59 and 61 and an inverter 63. The logic gate 61 is, for example, an XOR gate, while the logic gate 49 is an AND gate. In the inverter 63, the signal supplied from the XOR gate 61 is inverted. If the output signal Y is present at the output 57 of the logic unit 45, the following applies to the Fig. 4 shown arrangement as follows: Y = K1 • K2 ⊕ K3 ¯

[0031] The logic unit 45, which has the above-mentioned relationship, can be Fig. 5 From the truth table shown in Fig. 5 It follows that in this embodiment, the output frequency of the oscillator 7 is only increased (Y=1) when the voltage U prop proportional to the lamp adjustment from the operational amplifier 25 exceeds a value determined by the voltage value generating device 41 and at the same time the condition K2 generated by the differentiator unit 43 with integrated inverting comparator is present (K2="1"), while the n-1 bit from the shift register 47 corresponds to a "0" or the condition K2 generated by the differentiator unit 43 with integrated inverting comparator is not present (K2="0"), while the N-1 bit from the shift register 47 corresponds to a "1".

[0032] The clock generator 49 is advantageous because it can prevent incorrect decisions due to the transient response of the individual logic gates. A possible implementation of the clock generator 49 is shown in the Fig. 6 shown. Purely by way of example, the clock generator device 49 comprises three inverters 65, 67, and 69, two resistors 71 and 73, and a capacitor 75 to produce a signal at the output terminal 77 with a fixed frequency f. For a resistance value R for the resistors 71 and 73 and a capacitance value C for the capacitor 75, the following frequency results: f = 0,558 / RC .

[0033] In Fig. 7 is an exemplary embodiment of the Fig. 2 shown loop filter 31, which receives a clocked output voltage UD from the amplitude discriminator 29. The loop filter 31 generates an analog voltage for controlling the output frequency of the oscillator 7 from the digital control signals of the logic unit 45 running via the shift register 47. In the embodiment according to Fig. 7 the loop filter 31 comprises a series resistor 79 and at least one shunt capacitor 81 and at least one shunt resistor 83, which are located between the input terminal 85 connected to the shift register 47 and the output terminal 87 of the loop filter 31 connected to the oscillator 7.

[0034] To increase the output frequency of oscillator 7, output 57 of logic unit 45 is set to "1." This signal charges shunt capacitor 81 in loop filter 31 via series resistor 79 with a time constant τ charge , which corresponds to the product of the resistance of series resistor 79 and the capacitance of shunt capacitor 81. The value "0" at output 57 of logic unit 45 causes the charge on shunt capacitor 81 to be discharged via the parallel connection of shunt resistor 83 and resistor 79. The corresponding time constant τ discharge corresponds to the product of the capacitance of shunt capacitor 81 and the resulting resistance of the parallel connection of the two resistors 79 and 83.

[0035] Fig. 8 shows a possible embodiment of the Fig. 2 shown reset circuit 33. In this embodiment, the reset circuit 33 comprises a comparator 89 for comparing the voltage across the shunt capacitor 81 in the loop filter 31 with a reference voltage U comparison, wherein the reference voltage U comparison can be generated, for example, by an external voltage divider 91. This allows the lower limit frequency of the regulation to be set. If the voltage across the shunt capacitor 81 in the loop filter 31 falls below the voltage value U comparison, a voltage is generated via a monostable switch 93, which charges the shunt capacitor 81 in the loop filter 31. This allows the output frequency of the oscillator 7 to be set to an upper limit frequency of the regulation. The reset circuit 33 and the resulting reset process can be activated both when the RF lamp 5 is switched on and during operation, as needed.

[0036] In summary, it can be said that the Fig. 2 The RF system 1 shown is merely an embodiment which can be modified with respect to some elements. In particular, the output coupling devices can be replaced by a circulator. The voltage detection devices 21 and 23 can be any suitable detectors. Furthermore, it is possible to Fig. 8 The reset circuit 33 shown or its function can be integrated into the logic unit 45. Alternatively, it is possible to replace the reset circuit 33 with gates, in particular comparators and / or simple sample-and-hold circuits.

[0037] The loop filter 31 according to Fig. 7can also be replaced by charge pumps, i.e., charge pump circuits modeled on a phase-locked loop (PLL) circuit. The circuit can be designed to "maintain" an optimal operating frequency. In this case, the circuit is somewhat more complex and larger and requires a new logic unit as well as negative voltages. It is also conceivable to integrate the loop filter 31, or at least its function, into the logic unit 45. An analog output voltage is then generated directly in the logic unit 45, making the use of a clock generator unnecessary. It is also conceivable to expand the logic unit 45. In particular, further conditions can be considered that can implement additional functions without the use of a microprocessor. Additional logic gates may then be necessary for this.Furthermore, the shift register 47 can also be modified and, in particular, supplemented, for example, by using astable flip-flops. In particular, additional elements can be provided that make the clock generator or clock generator device 49 superfluous.

[0038] The use of amplifiers 9 and 12, as well as attenuator 11, is also optional. For example, the use of an amplifier with variable gain for more precise power adjustment is also conceivable. Likewise, the attenuator can be variable, or a corresponding additional variable attenuator can be provided. In particular, the order of amplification and attenuation is also optional.

[0039] Overall, the present invention implements an RF system and, in particular, an advantageous RF signal coupling device for use in an RF system for coupling an RF signal into an RF device, in particular into an RF lamp, with as little loss as possible. The RF signal coupling device is preferably designed without a microprocessor and instead uses logic gates that eliminate the need for a microprocessor. In this way, the RF system implements fast analog control of the output frequency of an RF signal coupling device, e.g., for energy-saving lamps. The RF signal coupling device according to the invention enables ignition and efficient operation of an RF lamp at the operating frequency that best matches the RF lamp.The advantageous analog control can also compensate for frequency shifts caused by manufacturing tolerances, operational temperature behavior, or aging-related changes in the electronics. The implemented logic unit consists of individual logic gates and thus enables advantageous integration of the circuit into a single semiconductor IC. This creates the conditions for cost-effective implementation of the RF signal coupling device and thus the entire RF system in mass production.

Claims

1. High-frequency signal injection device (3), adapted to operate a high-frequency device (5) comprising: - an oscillator (7) for generating a high-frequency signal which is supplied to the high-frequency device (5) for its operation - means (15) adapted to generate a voltage signal (Uprop) proportional to the degree of adaptation of the high-frequency device (5) on the basis of the high-frequency signal generated by the oscillator (7) and supplied to the high-frequency device and a signal reflected from the high-frequency device; and - a device (27) for generating a regulating signal (UA) for adjusting the output frequency of the oscillator (7) based on the voltage signal (Up-rop) wherein the device (27) comprises an amplitude discriminator (29) and a filter device (31), characterized in that the amplitude discriminator (29) creates a digital output voltage (UD), based on the voltage signal (Uprop), that is supplied to the filter device (31), which smoothes the digital output voltage (UD) such that a, in principle analogue, output signal with a output voltage (UA) is created, which is supplied to the oscillator (7) as regulation voltage.

2. High-frequency signal injection device (3) according to claim 1, wherein the amplitude discriminator (29) comprises a comparator (39) a voltage value generating device (41), a differentiating unit (43) and a logic unit (45), wherein the logic unit (45) is connected to the oscillator (7) over the filter device (31) for the creation of the analogue output voltage UD for the regulation of the oscillator (7), and wherein the voltage value generating device (41) creates a fixed voltage value; and the comparator (39) compares the voltage signal (Uprop), proportional to the degree of adaptation of the high-frequency device (5), and the fixed voltage and creates a first condition (K1).

3. High-frequency signal injection device (3) according to claim 2, wherein the differentiating unit (43) creates a second condition (K2), based on the voltage signal (Uprop), proportional to the degree of adaptation of the high-frequency device (5), and the logic unit (45) creates an output (57), based on the first condition (K1) and the second condition(K2).

4. High-frequency signal injection device (3) according to claim 3, wherein the amplitude discriminator (29) creates an output voltage (UD) for the filter device (31) based on the output (57) of the logic unit (45); and the filter device (31) is configured to smooth the output voltage (UD), to provide the analogue output voltage (UA) for the oscillator (7) as a regulating signal for the adjustment of the output frequency.

5. High-frequency signal injection device (3) according to claim 4, wherein the amplitude discriminator (29) further comprises a shift register (47) for receiving the output (57) from the logic unit (45).

6. High-frequency signal injection device (3) according to claim 5, wherein the amplitude discriminator (29) further comprises a clock device (49) for clocking the output (57) from the logic unit (45) into the shift register (47).

7. High-frequency signal injection device (3) according to claim 5, wherein the filter device (31) generates, based on the output (57) from the logic unit (45), the control signal (UA) for adjusting an output frequency of the high-frequency signal generated by the oscillator (7).

8. High-frequency signal injection device (3) according to claim 7, wherein the filter device (31) comprises a phase-locked loop circuit (PPL circuit) for controlling the output frequency of the high-frequency signal generated by the oscillator (7).

9. High-frequency signal injection device (3) according to one of the claims 1 to 8, wherein the means (15) for generating the voltage signal (Uprop) proportional to the degree of adaptation of the high-frequency device (5) comprise at least one decoupling device (17, 19) for decoupling a portion of the high-frequency signal generated by the oscillator (7) and for decoupling a portion of the signal reflected by the high-frequency device (5)10. High-frequency signal injection device (3) according to one of the claims 1 to 8, wherein the means (15) for generating the voltage signal (Uprop) proportional to the degree of adaptation of the high-frequency device (5) comprise a circulator adapted to decouple a portion of the high-frequency signal generated by the oscillator (7) and a portion of the signal reflected by the high-frequency device (5)11. High-frequency signal injection device (3) according to one of the claims 1 to 8, further comprising a reset-circuit (33), adapted to transfer the oscillator (7) into a predefined state.

12. High-frequency signal injection device (3) according to one of the claims 1 to 9, wherein the high-frequency device (5) comprises one of a high-frequency lamp, a high-frequency spark plug or a high-frequency plasma device.

13. Method for operating a high frequency signal injection device (3) according to claim 1, comprising: - generating a fixed voltage value by means of a voltage value generating device (41) of the amplitude discriminator (29); - generating a first condition (K1) by supplying the voltage signal (Uprop) proportional to the degree of adaptation of the high-frequency device (5) and the fixed voltage value to a comparator (39) of the amplitude discriminator (29), and comparing the voltage signal (Uprop) proportional to the degree of adaptation of the high-frequency device (5) and the fixed voltage value in the comparator (39); - creating a second condition (K2) in the amplitude discriminator (29), based on the voltage signal (Uprop) proportional to the degree of adaptation of the high-frequency device (5); - supplying the first (K1) and second (K2) conditions to a logic unit (45) of the amplitude discriminator (29); and creating a output voltage (UD), based on the output (57) of the logic unit (45).

14. Method for operating a high frequency signal injection device (3) according to claim 13, wherein generating the second condition (K2) comprises deriving the voltage signal (Uprop) proportional to the matching degree of the high-frequency device (5).