Active interference compensation circuit for an electronic device and method for operating the same

Abstract

The invention relates to an active interference compensation circuit (35) for an electronic device and a method (60) for operating an active interference compensation circuit (35) for an electronic circuit. The active interference compensation circuit (35) comprises an amplification circuit (36). The amplification circuit (36) includes a push-pull output stage (12) with at least two transistors (14A, 14B) coupled together, wherein an output node (16) is coupled between the transistors (14A, 14B). The output node (16) is coupled to an output (20) of the amplification circuit (36). A bias voltage for the transistors (14A, 14B) of the push-pull output stage (12) is provided using a rubber diode (37), so that the transistors (14A, 14B) of the push-pull output stage (12) are biased.

Description

[0001] The invention relates to an active interference compensation circuit for an electronic device and a method for operating an active interference compensation circuit for an electronic circuit.

[0002] In modern power electronics devices, high-power switching devices, such as transistors, are used to control the provided power parameters. Due to the switching frequencies and gate current profiles used to control the transistors, the generation of electromagnetic interference (EMI) is unavoidable. To attenuate this EMI, passive EMI filter circuits, such as common-mode chokes, are used according to current technology. However, passive filter circuits have their own limitations because the size of the required circuits represents a significant bottleneck. Consequently, these EMI filter circuits require considerable installation space in the respective electronic devices, such as converters. Furthermore, these filters are quite heavy.Additionally, the capacitors in such filter circuits, used to reduce EMI noise, are subject to safety restrictions. Therefore, a significant number of disadvantages and limitations must be considered. Particularly in high-voltage applications, the passive components of the filter circuits are cascaded to achieve better performance, consequently resulting in even larger and bulkier EMI filter circuits that cannot be easily integrated into the respective electronic devices, such as power converters.

[0003] As one approach to circumvent at least some of these disadvantages, active EMI filter circuits (AEFs) have already been proposed. To attenuate EMI noise, AEF circuits, similar to sound suppression techniques, inject an inverse signal with respect to the noise signal segments into the power converter circuit. The AEFs comprise a detection circuit, an amplification circuit, and an injection circuit, thus forming an active interference compensation circuit.

[0004] Amplification circuits comprise two complementary switching devices. Alternatively, amplification circuits can also refer to inverting operational amplifiers. However, to date, such amplification circuits are known exclusively for low-power applications, such as compensating common-mode or differential-mode noise sections of current signals with signal amplitudes in the milliampere range. In these devices, amplification circuits are controlled by transistors such that each transistor individually drives the output current for half the period of the underlying wave signal. However, the concepts and arrangements for active low-power amplification circuits cannot be readily transferred to high-power applications because crossover distortion is introduced when switching occurs between the individual switching devices to drive the load.Crossover distortion leads to an undesirable low output signal quality, e.g. by causing artificially distorted signal sections with dead zone plateaus, thereby reducing the performance of the entire underlying electronic circuit.

[0005] Accordingly, there is a need for an EMI filter mechanism applicable to high-power applications, such as current signals with signal amplitudes within the A-signal range (a factor of 1000 higher than in known devices), which is less susceptible to negative effects that impair signal quality and the efficiency of the underlying electronic circuit.

[0006] The technical problem to be solved can be seen as overcoming or at least reducing the disadvantages according to the state of the art by providing an active interference compensation circuit that enables a reduction in crossover distortion and thereby provides high signal quality and high operational efficiency of the underlying electronic device.

[0007] The problem is solved by the subject matter of the independent claims. Preferred embodiments are specified in the dependent claims and the following description, each of which, individually or in combination, may represent aspects of the disclosure.

[0008] According to one aspect, an active interference compensation circuit is provided for an electronic device. The active interference compensation circuit comprises an amplification circuit. The amplification circuit includes a push-pull output stage with at least two transistors coupled together, with an output node coupled between the transistors. The output node is coupled to an output of the amplification circuit. A bias voltage for the transistors of the push-pull output stage is provided using a rubber diode, such that the transistors of the push-pull output stage are biased.

[0009] The invention is based on the finding that by biasing the transistors of the push-pull output stage, the crossover distortion of the output signal provided by the amplification circuit can be reduced. This is achieved because the rubber diode establishes a predetermined voltage difference between the reference nodes used to control both transistors of the underlying push-pull output stage. This modifies each individual transistor so that it remains in the conducting state for more than half of the underlying period of the electrical waveform. In other words, due to the rubber diode, the transistors are controlled cooperatively, so that they never completely switch off together.This allows at least a reduction, or, assuming well-designed layouts and control routines, even the elimination, of crossover distortion, thus reducing or avoiding a dead zone within the output signal. In other words, the transistors are controlled so that they are never simultaneously in the off state, which allows the signal plateaus related to crossover distortion to be avoided (or reduced). In effect, the output signal exhibits an improved signal profile. This enables improved compensation signals, allowing a higher proportion of the noise signal components to be compensated, regardless of whether the noise is common-mode or differential-mode.After suppressing the noise signal components, an improved signal-to-noise ratio is achieved, which in turn enables the processing of the underlying signals with increased accuracy. Because the accuracy of the signal processing is improved, less power loss occurs, thus improving the overall operating efficiency of the underlying electronic device for which the noise signal components are suppressed by the active noise compensation circuit.

[0010] According to another aspect, a method for operating an active interference compensation circuit for an electronic circuit is provided. The method comprises at least the following steps: - A preferably variable bias voltage for transistors of a push-pull output stage of an amplification circuit of the active interference compensation circuit is provided based on a rubber diode. - The transistors of the push-pull output stage are operated based on the bias voltage, so that an input signal provided to the amplification circuit is amplified by the push-pull output stage to produce an output signal. - The output signal is provided by the active interference compensation circuit.

[0011] The advantages described with regard to the active interference compensation circuit are also easily achieved based on the method for operating an active interference compensation circuit.

[0012] The active noise compensation circuit can be considered a circuit for generating an output signal with a desired signal profile. The output signal's profile is such that it represents an inverted version of a noise signal detected by a detection circuit within the active noise compensation circuit. This detected signal is then used as the input signal for the circuit's amplification stage. The active noise compensation circuit is specifically designed to amplify specific signal segments so that the inverted signal matches the input signal, given that both signals are electrically inverted by 180°. An injection circuit within the active noise compensation circuit can be used to inject the output signal to compensate for the noise signal segments.

[0013] The electronic device can be considered to be at least one inverter, on-board charger, DC / DC converter, AC / AC converter, or DC / AC converter. The electronic device can be specifically designed for use in a vehicle, particularly an electric vehicle. In this respect, the signals used to control electric motors in electric vehicles often include current signals with current amplitudes greater than 1 A, typically up to several hundred A. Therefore, the control signals for operating the underlying electric motors differ significantly from those used in known low-power applications where AEFs have been employed previously.In other words, the active noise compensation circuit can be used for electronic devices with signals having signal amplitudes that are 1000 times greater than the signal amplitudes of signals for which AEFs have previously been used. This difference in signal amplitude illustrates why known approaches for AEFs cannot simply be applied to the high-power applications of interest for the present invention.

[0014] The noise signal used as an input signal for the amplification circuit of the active interference compensation circuit is preferably detected with regard to the electronic circuit to which the active interference compensation circuit is coupled.

[0015] The push-pull output stage represents an amplifier topology in which a pair of active devices, in this case transistors, are controlled to supply current to the output node. Unlike prior art approaches where the transistors were controlled to alternately provide the output signal, the active interference compensation circuit is designed so that the transistors are controlled to work together to provide the output signal. This reduces (or eliminates) crossover distortion. In particular, by biasing the transistors so that they are controlled to supply and output current for more than half of the underlying electronic waveform, the respective dead zone normally caused by alternate control is avoided.

[0016] The rubber diode can also be considered a bias servo and, according to some conventions, can also be referred to as a VBE (voltage-bass-to-emitter) or VGS (voltage-gate-to-source) multiplier. The specific topology may depend on the transistors of the push-pull output stage.

[0017] Generally, prior art approaches involved establishing a bias voltage between the reference nodes of the push-pull output stage. This bias voltage can be achieved, for example, by means of series-connected diodes forming a diode network. However, these topologies result in complex and bulky electronic circuits. In contrast, a rubber diode is much more compact. The rubber diode comprises at least one additional switching device, preferably a transistor, and at least two electrical resistors. Therefore, the required installation space and the complexity of the underlying active interference compensation circuit are greatly reduced compared to prior art approaches using diode networks. Consequently, the performance of the active interference compensation circuit with a rubber diode is improved compared to prior art approaches.

[0018] Preferably, the reference nodes, between which the bias voltage for the transistors of the push-pull output stage is generated by the rubber diodes, are individually coupled to the gate electrodes of the respective transistors. Using this topology, the control of the transistors of the push-pull output stage is directly influenced based on the rubber diode that generates the bias voltage.

[0019] Optionally, the transistors of the push-pull output stage can be either metal oxide field-effect transistors or bipolar transistors.

[0020] Preferably, a first transistor of the push-pull output stage is formed by an NMOS transistor (n-type metal-oxide-semiconductor transistor), such as an NPN transistor, while the second transistor is formed by a PMOS transistor (p-type metal-oxide-semiconductor transistor), such as a PNP transistor.

[0021] According to some embodiments, the rubber diode contains at least one transistor that is controlled, at least indirectly, by a control device such that the bias voltage provided to the transistors of the push-pull output stage is variable. In other words, the properties of the rubber diode can be changed so that the bias voltage established between the reference nodes with respect to the transistors of the push-pull output stage is modifiable during use. A bias voltage can be modified, for example, based on a control signal. This makes it possible to change the electronic properties of the rubber diode during use, which affects the bias voltage established between the reference nodes for the transistors of the push-pull output stage.With regard to known approaches to generating bias voltages based on networks of series-connected diodes, the ability of the rubber diode to modify the bias voltage amplitude during use provides an additional degree of freedom, allowing the characteristics of the active interference compensation circuit to be adapted.

[0022] With variable bias, low crossover distortion is achieved because the bias can be adjusted, thus minimizing crossover distortion. This allows EMI noise segments of a signal underlying the external electronic device for which the noise is detected to be compensated more efficiently and with improved accuracy.

[0023] Preferably, the control device is configured to vary the gate bias of the at least one transistor of the rubber diode depending on an input reference signal received by the control device. In particular, the gate bias is varied so that the bias voltage supplied to the transistors of the push-pull output stage between the reference nodes is varied. Precise adjustment of the inverted compensation signal is possible with respect to the gate bias.

[0024] In some embodiments, the transistors of the push-pull output stage are biased such that each transistor is continuously conducting for more than half of an input cycle. The input cycle represents one electrical period of a wave used as an input signal. In some embodiments, the input signal can be provided to a control device that controls the transistors of the push-pull output stage, at least indirectly. While prior art approaches focus on topologies in which the transistors of the push-pull stage alternately provide the output signal for less than half of the input cycle, causing crossover distortion, the plateaus in the output signal related to crossover distortion are compensated by the present topology.The topology of the active interference compensation circuit allows the transistors of the push-pull output stage to be used for more than half of the input cycle, specifically for more than 180° of the electrical period. As a result, the plateaus related to crossover distortion within the output signal are reduced or eliminated.

[0025] Preferably, the transistors of the push-pull output stage are biased so that at least two transistors are continuously conducting, thus providing a drain current to the output node. Consequently, the plateaus of the output signal, which represent configurations where no drain current is provided, can be efficiently avoided. This is achieved by selectively controlling the transistors by applying suitable bias voltages between the reference nodes used to control the transistors of the push-pull output stage. Although this configuration may result in higher power consumption, the improved compensation of noise signal segments within the underlying signals of the electronic devices for which the active noise compensation circuit is configured outweighs this disadvantage.The improved compensation of noise signal segments enables better signal quality, resulting in reduced power losses. This also allows for the reduction of additional filter devices, such as passive filters like common-mode chokes, in size and functionality. Consequently, installation space and weight can be saved, leading to overall improved performance of the entire electronic circuit.

[0026] Preferably, the rubber diode and the transistors of the push-pull output stage are coupled to a single cooling device. For improved noise compensation, the cooling concept can be modified to require only a single cooling device. This further reduces the required installation space and the complexity of the underlying circuit. Consequently, the manufacturing costs for the entire electronic circuit are reduced, and its operating efficiency is improved. In particular, the elimination of separate cooling devices is made possible by the lower power dissipation achieved through the arrangement of the active noise compensation circuit. The elimination of multiple series-connected diodes and resistors results in less thermal heating, thus simplifying the cooling concept.

[0027] According to some embodiments, the active interference compensation circuit further comprises at least one detection circuit and one injection circuit. The amplification circuit is coupled between the detection circuit and the injection circuit. The detection circuit is configured to detect a noise-affected EMI signal with respect to an external component and to provide the noise-affected EMI signal to the amplification circuit, preferably to a control device thereof. The amplification circuit is configured to provide an injection signal to the injection circuit in order to compensate for the noise of the EMI signal.

[0028] The external component can be, for example, an electronic device. Consequently, noise-affected signal segments of the external component can be compensated for by an inverted compensation signal provided by the active noise compensation circuit. After injecting the inverted signal, the signal quality of the external component is significantly improved.

[0029] The active interference compensation circuit can preferably be used according to feedback and feedforward topologies. Consequently, the variety of active interference compensation circuits is increased.

[0030] Preferably, the amplification circuit is configured to provide the injection signal such that the difference between the maximum signal amplitude and the minimum signal amplitude is 1.0 A or greater, preferably 2.0 A or greater, preferably 5.0 A or greater, preferably 10.0 A or greater, preferably 12.0 A or greater, preferably 14.0 A or greater, and preferably up to 100.0 A. While prior art approaches relate to AEFs that can be used to generate injection signals with signal amplitudes in the mA range, the active interference compensation circuit presented here is usable for signal amplitudes within the A range, and in particular even with signal amplitudes of more than 10 A.

[0031] Optionally, the amplification circuit is configured to provide the injection signal in such a way that the injection signal exhibits only negligible crossover distortion between the partial signals provided by the individual transistors of the push-pull output stage. Therefore, the crossover distortion is essentially compensated, providing clean and desirable signal profiles that do not include artificial signal sections that degrade signal quality. Consequently, the compensation of noise signal sections is improved.

[0032] According to some embodiments, the amplification circuit is configured to provide the injection signal such that the noise of the EMI signal with a frequency-dependent signal amplitude greater than 500 mA, preferably greater than 1.0 A, preferably greater than 2.0 A, preferably greater than 5.0 A, preferably greater than 10.0 A, preferably greater than 15.0 A, preferably greater than 20.0 A, and preferably up to 100.0 A, is compensated. Accordingly, high-amplitude signal segments can also be compensated by adapted inverted signal segments generated and provided by the active noise compensation circuit.

[0033] Optionally, the active interference compensation circuit is configured to provide an output signal to compensate for noise in the EMI signal, ensuring that the resulting signal is compatible with safety-certified high-voltage potential-bridging coupling devices, such as capacitors and / or magnetic cores. Many applications related to electronic circuits and electric vehicles must comply with EMI noise regulations. In other words, electromagnetic compatibility must be achieved by sufficiently reducing and suppressing noise components so that the resulting noise levels remain below specified frequency-dependent thresholds. This active interference compensation circuit enables compliance with these thresholds by adequately reducing the noise components of the electromagnetic signals in the relevant electronic circuits.Consequently, unlike prior art approaches where these limitations have so far only been met for the mA regime, electromagnetic compatibility can even be achieved within the A regime if AEFs are taken into account.

[0034] Preferably, the active interference compensation circuit is applicable for suppressing EMI noise signal sections of electromagnetic signals with HV amplitudes, such as 200 V or greater, preferably 400 V or greater, more preferably 600 V or greater, more preferably 800 V or greater, more preferably 1000 V or less.

[0035] All features and embodiments disclosed with respect to any aspect of the present disclosure are combinable alone or in (partial) combination with any of the remaining aspects of the present disclosure, including any of its preferred embodiments, provided that the resulting combination of features is meaningful to a person skilled in the art.

[0036] The aforementioned aspects and further advantages of the claimed subject matter are more readily apparent, as they become more understandable when viewed in conjunction with the accompanying drawings and the detailed description below. The drawings show: - Fig. 1A and Fig. 1B Schematic drawings of an amplifier using resistive biasing and a corresponding signal profile according to the state of the art, - Fig. 2 a schematic drawing of another amplifier using diodes, according to the prior art, - Fig. 3 a schematic drawing of an active disturbance compensation circuit according to one embodiment, - Fig. 4 a pictorial representation of a signal profile provided by the active interference compensation circuit according to an embodiment and - Fig. 5A and Fig. 5B Block diagrams of active disturbance compensation circuits according to embodiments, - Fig. 6 a flowchart of a method for operating an active disturbance compensation circuit according to an embodiment.

[0037] Fig. 1A and Fig. Figure 1B shows schematic drawings of an amplifier 10 using resistive biasing and a respective signal profile 30 according to the state of the art.

[0038] The amplifier 10 includes a push-pull output stage 12.

[0039] The push-pull output stage 12 comprises several transistors 14. A first transistor 14A is connected in series with a second transistor 14B. In this configuration, the first transistor 14A (M2) comprises an NMOS transistor. In contrast, the second transistor 14B (M1) comprises a PMOS transistor. An output node 16 of the push-pull output stage 12 is located between the two transistors 14A and 14B. The source electrode of the first transistor 14A is coupled to the output node 16 of the push-pull output stage 12. Furthermore, the source electrode of the second transistor 14B is also coupled to the output node 16.

[0040] Amplifier 10 receives an input voltage VIN at an input node 18. The output node 16 of the push-pull output stage 12 is coupled to an output 20 of amplifier 10, at which an output voltage VOUT is provided. In other words, using the push-pull output stage 12, the input voltage VIN is amplified so that the output voltage VOUT is provided with a signal profile dependent on the input voltage VIN.

[0041] A supply voltage VDD is provided at a supply node 22 and via a resistor RD of the drain electrode of the first transistor 14A (M2).

[0042] The supply voltage VDD is provided with respect to the negative supply voltage VSS, which is applied to the negative supply node 24 and via a resistor RS to the drain electrode of the second transistor 14B (M1).

[0043] The gate electrode of the first transistor 14A is coupled to a first reference node 26A. The gate electrode of the second transistor 14B is coupled to a second reference node 26B. The first reference node 26A is also coupled via resistor R4 to the supply node 22, where the supply voltage VDD is provided. Additionally, the second reference node 26B is also coupled via resistor R1 to the negative supply node 24, where the negative supply voltage VSS is applied.

[0044] Between the two reference nodes 26A, 26B, at least two resistors R2, R3 are arranged in series, forming a resistor network 28.

[0045] In addition, the reference nodes 26A, 26B are coupled to the input node 18, where the input voltage VIN is provided, via the respective capacitors C1, C2, which are arranged in parallel to each other.

[0046] This configuration results in a push-pull output stage 12, which can provide the output voltage VOUT with an exemplary signal profile 30, as shown in Fig. Figure 1B shows that signal profile 30 has an amplitude (y-axis) over time (x-axis). Because transistors 14A and 14B of the push-pull output stage 12 alternately drive the output voltage, crossover distortion occurs, which can be seen as crossover-distortion-induced plateau-like signal sections 32 within signal profile 30. As a consequence of the plateau-like signal sections 32 of signal profile 30, the output voltage VOUT cannot be provided in such a way that it represents a sufficiently optimized inverted signal profile with respect to the input voltage VIN. In other words, if the output voltage VOUT is injected to compensate for the EMI noise signal sections, the compensation effect is insufficient to eliminate all noise-related effects. Consequently, non-negligible noise signal sections remain, reducing the overall signal quality.

[0047] Moreover, the in Fig. The configuration of the push-pull output stage 12 shown in Figure 1A requires no modifications during use because the values ​​of all resistors and capacitors cannot be varied. Therefore, the drive behavior of the push-pull output stage 12 remains constant and depends solely on the input voltage VIN.

[0048] Fig. Figure 2 shows a schematic drawing of another amplifier using diodes according to the prior art. Considering the above regarding Fig. In section 1A, the discussed configuration of amplifier 10 only addresses the differences regarding the... Fig. The configuration shown in section 2 is explained.

[0049] Instead of a resistor network 28 between the reference nodes 26A, 26B, a diode network 34 is provided according to this configuration of the amplifier 10, consisting of the series-connected diodes D1, D1. Consequently, a bias differential is created between the reference nodes 26A, 26B. This biases the gate electrodes of the respective transistors 14A, 14B of the push-pull output stage 12. This biasing effect reduces the plateau-like signal sections 32 of the respective signal profile 30 of the output voltage VOUT. However, the non-negligible plateau-like signal sections 32 still remain, so that a compensating effect for EMI noise signal sections is still insufficient.Because the diodes of the diode network 34 cannot be varied during use, the compensation effect cannot be adjusted to the specific requirements during use. In other words, the application scenarios in which the compensation effect of compensating for signal sections related to EMI noise is sufficient by adjusting the diodes in the network are limited. Fig. The use of the 2 shown configurations is very rare.

[0050] To improve the performance of the compensation mechanism, it shows Fig. 3 a schematic drawing of an active disturbance compensation circuit 35 according to one embodiment.

[0051] The active interference compensation circuit 35 comprises an amplification circuit 36 ​​with a push-pull output stage 12. The push-pull output stage 12 includes a first NMOS transistor 14A (M2) connected in series with a second PMOS transistor 14B (M1). The output node 16 of the push-pull output stage 12 is located between the two transistors 14A and 14B. The output stage 16 is coupled to the output 20 of the active interference compensation circuit 35.

[0052] The supply voltage VDD is provided at supply node 22 and at the drain electrode of the first transistor 14A. Optionally, a resistor could be placed between the first transistor 14A and supply node 22.

[0053] Furthermore, the negative supply voltage VSS is applied to the negative supply node 24 and to the drain electrode of the second transistor 14B. Optionally, a resistor RS could be placed between the negative supply node 24 and the drain electrode of the second transistor 14B.

[0054] A rubber diode 37 of the push-pull output stage 12 is arranged between the reference nodes 26A, 26B, which are individually coupled to the gate electrodes of the transistors 14A, 14B of the push-pull output stage 12.

[0055] The rubber diode 37 comprises two resistors 38 (R4, R5) connected in series between the reference nodes 26A, 26B with a middle node 39 arranged between both resistors 38.

[0056] Furthermore, the rubber diode 37 includes an additional transistor 40, which, according to this embodiment, is an NMOS transistor. Alternatively, the additional transistor 40 could, of course, also be a PMOS transistor. The gate electrode of transistor 40 of the rubber diode 37 is coupled between resistors 38 at the central node 39. The drain and source electrodes of transistor 40 are correspondingly coupled to reference nodes 26A and 26B.

[0057] In addition, according to this embodiment, a controlled voltage source 41 is used to provide the input voltage VIN of the amplification circuit 36 ​​of the active interference compensation circuit 35. The controlled voltage source 41 is controlled by a control device 42.

[0058] The control device 42 is configured to modify a gate bias using the controlled voltage source 41 based on a control signal provided to it. With respect to the rubber diode 37, the bias voltage for biasing the gate electrodes of transistors 14A, 14B, which exists between the reference nodes 26A, 26B, can therefore be modified during the use of the active noise compensation circuit 35. As a result, transistors 14A, 14B of the push-pull output stage 12 are operated to provide the respective output voltage VOUT for more than half of the period underlying the input signal. Accordingly, a modified output voltage VOUT with respect to a reference signal that can be provided to the control device 42 is achievable, so that the controlled voltage source 41 can be controlled according to the requirements.

[0059] Because the power dissipation is reduced according to the active interference compensation circuit 35, the rubber diode 37 and the transistors 14A, 14B of the push-pull output stage 12 can be thermally coupled to a single cooling device 43. Accordingly, the cooling concept is simplified compared to prior art approaches, which require separate cooling devices. It is mentioned that the in Fig. 3 the connections shown with regard to the cooling device 43 are electrically insulating but thermally conductive.

[0060] Based on the configuration of the active interference compensation circuit 35, an output voltage VOUT with the exemplary signal profile 44 is achieved, as shown in the graphical representation according to Fig. The signal profile 44 is shown with an amplitude (y-axis) versus time (x-axis). In particular, the signal profile 44 is shown without the plateau-like signal sections 32 (compare Fig. 1B). This proves that the takeover distortion effect is efficiently compensated. As a result, the effects related to EMI noise can be compensated with improved accuracy, thus achieving improved signal quality.

[0061] The Fig. 5A and Fig. Figure 5B shows block diagrams of active disturbance compensation circuits 35 according to embodiments.

[0062] The active interference compensation circuit 35 is particularly useful in combination with an external device that is affected by EMI noise, here referred to as the EMI victim 46.

[0063] The active interference compensation circuit 35 can be used according to a feedback configuration 45. In this case, a detection circuit 47 of the active interference compensation circuit 35 is used to detect the EMI noise signal sections of a signal at the EMI victim 46. The detected EMI noise-related detection signal is fed into the active interference compensation circuit 35, in particular into the amplification circuit 36 ​​with the push-pull output stage 12. The detected noise signal can, for example, be provided to the control device 42. The amplification circuit 36 ​​provides an inverted output voltage VOUT with a signal profile 44 that can be used to compensate for the noise signal sections. Alternatively, the amplification circuit 36 ​​can also provide an inverted output current COUT with a signal profile 44 that can be used to compensate for the noise signal sections.Downstream of the push-pull output stage 12, an injection circuit 48 of the active noise compensation circuit 35 is used to inject the respective generated output voltage VOUT (COUT). This results in a compensation effect with respect to the EMI noise signal sections, so that a clean (noise-compensated) signal can be provided to the downstream external EMI source 49.

[0064] The active noise compensation circuit 35 can also be used according to a forward feedback configuration 50, in which the propagation direction of the signal is opposite to that of the feedback configuration 45. Unlike in the feedback configuration 45, the detection circuit 47 of the active noise compensation circuit 35 is used to detect the EMI interference signal segments with respect to the external EMI source 49. The active noise compensation circuit 35 then uses the amplification circuit 36 ​​with the push-pull output stage 12 to generate a corresponding output voltage VOUT (or a corresponding output current COUT), which is injected downstream using the injection circuit 48 to provide a clean (noise-compensated) signal to the EMI victim 46 according to this configuration.

[0065] Fig.Figure 6 shows a flowchart of a method 60 for operating an active disturbance compensation circuit 35 according to one embodiment. Optional steps are shown using dashed lines.

[0066] Method 60 can include the optional step S1, in which EMI noise signal segments within an underlying signal of an external electronic device to which the active interference compensation circuit 35 is coupled are detected. The detection circuit 47 of the active interference compensation circuit 35 can, for example, be used in this respect to detect frequency-dependent noise signal segments.

[0067] The frequency-dependent noise signal sections are then provided to the control device 42.

[0068] Based on the detected frequency-dependent noise signal segments, the transistors 14A, 14B of the push-pull output stage 12 of the amplification circuit 36 ​​of the active noise compensation circuit 35 are biased in a subsequent step S2 of the procedure 60 based on the rubber diode 37. This is achieved by establishing a bias voltage between the reference nodes 26A, 26B, which are individually coupled to the gate electrodes of the transistors 14A, 14B of the push-pull output stage 12.

[0069] Step S2 can optionally be further developed by using an optional step S3. In this respect, the bias voltage established between the reference nodes 26A and 26B is varied during operation by using the rubber diode 37. In particular, the bias voltage can be varied based on a control mechanism implemented by the control device 42. The control device 42 can, for example, modify a gate bias voltage provided by the controlled voltage source 41. The control device 42 can, for example, output a corresponding control signal to the controlled voltage source 41, thus changing the operating parameters of the controlled voltage source 41.The modified gate bias affects the bias established between the reference nodes 26A, 26B of the push-pull output stage 12, so that the biasing procedure with respect to the transistors 14A, 14B can be adapted according to the respective requirements.

[0070] In the subsequent step S4 of the procedure 60, the transistors 14A, 14B of the push-pull output stage 12 are operated based on the bias voltage established between the reference nodes 26A, 26B, so that an input signal provided to the amplification circuit 36 ​​is amplified by the push-pull output stage 12 to generate an output signal. With regard to the bias mechanism provided for the transistors 14A, 14B, the transistors 14A, 14B are continuously conducting for more than half of an input cycle, i.e., for more than 180° of the underlying electrical period. As a result, plateau-like signal sections related to crossover distortion are avoided within the output signal.

[0071] Procedure 60 also includes the subsequent step S5, in which the output signal from the active noise compensation circuit 35 is output. Consequently, the output signal obtained by the push-pull output stage 12 can be used for further procedures.

[0072] According to the subsequent optional step S6, the output signal of the active interference compensation circuit 35 is injected into an underlying signal whose EMI interference segments were detected in optional step S1. In this respect, the injection circuit 48 of the active interference compensation circuit 35 can be used. Because the output signal includes signal segments that are inverted with respect to the EMI interference signal segments, the amplitude of the EMI interference signal segments is consequently reduced or even completely compensated, so that their resulting amplitude is negligible. As a result, the EMI interference is largely reduced or suppressed, providing a signal with a high signal-to-noise ratio.

[0073] Essentially, a noise reduction circuit is provided that can be used to compensate for noise signal segments with amplitudes within the A-mode range. Accordingly, high-power signals can be cleaned of the effects of EMI noise, thus enabling high signal quality to be achieved. As a result, the requirements for additional noise reduction devices, such as passive devices like common-mode chokes, are reduced. Therefore, the required installation space and weight can be reduced. Because the rubber diode 37 enables a very compact design for the active noise compensation circuit 35, the rubber diode 37, in particular its transistor 40, and the transistors 14A and 14B of the push-pull output stage 12 can be coupled to a single cooling device 43. Therefore, the complexity of the active noise compensation circuit 35 is further reduced.With regard to the noise suppression effect, the power losses can be reduced, thus improving the operating efficiency of electronic circuits in which the active interference compensation circuit 35 is applied.

Claims

[1] Active interference compensation circuit (35) for an electronic device, wherein the active interference compensation circuit (35) comprises an amplification circuit (36), the amplification circuit (36) comprising a push-pull output stage (12) with at least two transistors (14A, 14B) coupled together, wherein an output node (16) is coupled between the transistors (14A, 14B), the output node (16) being coupled to an output (20) of the amplification circuit (36), and wherein a bias voltage is provided for the transistors (14A, 14B) of the push-pull output stage (12) using a rubber diode (37), such that the transistors (14A, 14B) of the push-pull output stage (12) are biased. [2] Active interference compensation circuit (35) according to claim 1, wherein the rubber diode (37) contains at least one transistor (40) which is controlled by a control device (42) so that the bias voltage provided for the transistors (14A, 14B) of the push-pull output stage (12) is variable. [3] Active interference compensation circuit (35) according to claim 2, wherein the control device (42) is configured to vary a gate bias of the at least one transistor (40) of the rubber diode (37) depending on an input reference signal received by the control device (42), so that the bias supplied to the transistors (14A, 14B) of the push-pull output stage (12) is varied. [4] Active interference compensation circuit (35) according to one of the preceding claims, wherein the transistors (14A, 14B) of the push-pull output stage (12) are biased based on the bias voltage such that each transistor (14A, 14B) is continuously conducting for more than half of an input cycle. [5] Active interference compensation circuit (35) according to one of the preceding claims, wherein the transistors (14A, 14B) of the push-pull output stage (12) are metal oxide field-effect transistors or bipolar transistors. [6] Active interference compensation circuit (35) according to one of the preceding claims, wherein the rubber diode (37) and the transistors (14A, 14B) of the push-pull output stage (12) are coupled to a single cooling device (43). [7] Active interference compensation circuit (35) according to one of the preceding claims, further comprising at least one detection circuit (47) and one injection circuit (48), wherein the amplification circuit (36) is coupled between the detection circuit (47) and the injection circuit (48), wherein the detection circuit (47) is configured to detect a noise-affected electromagnetic interference signal with respect to an external component and to provide the noise-affected electromagnetic interference signal to the amplification circuit (36), and wherein the amplification circuit (36) is configured to provide an injection signal to the injection circuit (48) to compensate for the noise of the electromagnetic interference signal. [8] Active interference compensation circuit (35) according to claim 7, wherein the amplification circuit (36) is configured to provide the injection signal such that the difference between the maximum signal amplitude and the minimum signal amplitude is 1.0 A or greater, preferably 2.0 A or greater, preferably 5.0 A or greater, preferably 10.0 A or greater, preferably 12.0 A or greater, preferably 14.0 A or greater. [9] Active interference compensation circuit (35) according to claim 7 or 8, wherein the amplification circuit (36) is configured to provide the injection signal such that the injection signal has only a negligible crossover distortion between the partial signals provided by the individual transistors (14A, 14B) of the push-pull output stage (12). [10] Active interference compensation circuit (35) according to one of claims 7 to 9, wherein the amplification circuit (36) is configured to provide the injection signal so that the noise of the electromagnetic interference signal is compensated with a frequency-dependent signal amplitude of greater than 500 mA, preferably greater than 1.0 A, preferably greater than 2.0 A, preferably greater than 5.0 A, preferably greater than 10.0 A, preferably greater than 15.0 A, preferably greater than 20.0 A. [11] Method (60) for operating an active interference compensation circuit (35) for an electronic circuit, wherein the method (60) comprises at least the following steps: - Providing a variable bias voltage for the transistors (14A, 14B) of a push-pull output stage (12) of an amplification circuit (36) of the active interference compensation circuit (35) based on a rubber diode (37), - Operating the transistors (14A, 14B) of the push-pull output stage (12) based on the bias voltage, so that an input signal provided to the amplification circuit (36) is amplified by the push-pull output stage (12) to generate an output signal, and - Output of the output signal from the active interference compensation circuit (35).

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