Radiofrequency apparatus, radiofrequency system, radar system and method for monitoring a radiofrequency apparatus

Abstract

The invention relates to a method for monitoring the transmission paths for the distribution of a frequency signal for synchronizing a plurality of cascaded radiofrequency apparatuses. To this end, a frequency signal is supplied to a phase comparison device via two different paths, wherein one path comprises at least a portion of the signal path for the transfer of the frequency signal to further radiofrequency apparatuses.

Description

[0001] Description

[0002] title

[0003] Radio frequency device, radio frequency system, radar system and method for monitoring a radio frequency device

[0004] Technical area

[0005] The present invention relates to a high-frequency device and a method for monitoring such a high-frequency device. The present invention further relates to a radar system having such a high-frequency device.

[0006] background

[0007] Modern radar systems, such as those used for environment detection in motor vehicles, typically utilize multiple transmit and receive channels. Cascading multiple transceivers is particularly suitable for this purpose. In addition to digital signals, a high-frequency signal can also be exchanged as a reference signal. In this context, a stable phase relationship between the reference signals at all transceivers is essential for reliable angle estimation by the radar system.

[0008] The document DE 10 2018 117 688 A1, for example, describes a radar method in which a high-frequency signal is transmitted from the transmission path of a first channel to a second transmission unit.

[0009] Disclosure of the invention

[0010] The present invention provides a high-frequency device, a high-frequency system, a radar system, and a method for monitoring a high-frequency device having the features of the independent claims. Further advantageous embodiments are the subject of the dependent claims.

[0011] Accordingly, it is provided:

[0012] A high-frequency device comprising a local oscillator, an output terminal, an input terminal, a phase comparison device, and a monitoring device. The local oscillator is configured to generate a local frequency signal. This can be, for example, a signal, in particular a signal, with a predetermined frequency or a predetermined frequency characteristic. The output terminal is configured to provide the local frequency signal generated by the local oscillator. In particular, the output terminal can provide the local frequency signal for forwarding to another high-frequency device. The input terminal is configured to receive an externally provided reference frequency signal.In particular, the reference frequency signal provided at the input terminal can be the frequency signal that is passed from the output terminal to the input terminal, for example, via a suitable coupling element. The phase comparison device is designed to determine a phase difference between the local frequency signal from the local oscillator and the reference frequency signal at the input terminal. The monitoring device is designed to detect a malfunction in the high-frequency device. This can, in particular, be a malfunction in the transmission of the local frequency signal generated by the local oscillator. The malfunction can be detected in particular using the determined phase difference, i.e. the phase difference between the local frequency signal from the local oscillator and the frequency signal at the input terminal.

[0013] Furthermore, it is planned:

[0014] A radio-frequency system comprising a first transceiver and at least one second transceiver, as well as a coupling element. The transceivers each comprise a radio-frequency device according to the invention. The coupling element is designed to couple the input terminals and the output terminals of the first transceiver and the second transceiver to one another. In this way, for example, a frequency signal can be provided from an output terminal, in particular the output terminal of the first transceiver, to the two input terminals of the first transceiver and the second transceiver. If multiple second transceivers are provided, the frequency signal can also be provided from the output terminal of the first transceiver to all input terminals in the second transceiver.Furthermore, a local oscillator signal of the second or further transceiver can also be passed to the input terminal of the first transceiver through the coupling element.

[0015] Furthermore, it is planned:

[0016] A radar system with a high-frequency system according to the invention. The first transceiver and the second transceiver are each designed to output radar signals and receive and process radar echoes from the transmitted radar signals.

[0017] Finally, it is planned:

[0018] Method for monitoring a high-frequency device. The method comprises a step for generating a local frequency signal. The local frequency signal can be generated, in particular, by means of a local oscillator. The method further comprises a step for providing the local frequency signal at an output terminal of the high-frequency device. The method further comprises a step for receiving a reference frequency signal. The reference frequency signal can be received, in particular, at an input terminal of the high-frequency device. The method further comprises a step for determining a phase difference between the local frequency signal and the reference frequency signal. Finally, the method comprises a step for detecting a malfunction, in particular a malfunction in a transmission of the local frequency signal.The malfunction can be detected in particular using the determined phase difference between the local frequency signal and the reference frequency signal.

[0019] Advantages of the invention

[0020] The present invention is based on the realization that in high-frequency systems with multiple cascaded transceiver units, the signals emitted by the individual transceiver units should be coordinated with one another. For this purpose, a primary high-frequency unit can generate a local frequency signal, which can also be provided to one or more additional (secondary) high-frequency units. For this purpose, the individual high-frequency units can be provided with outputs for providing a local frequency signal and inputs for receiving a frequency signal from another high-frequency unit. Correct operation requires correct, reliable transmission of the frequency signals.

[0021] The present invention provides for monitoring the provision and distribution of frequency signals. In particular, the inventive concept can be used to check the transmission paths for distributing the frequency signals as well as the functionality of the local oscillator used. The proposed concept according to the present invention can be implemented with minimal hardware and software effort.

[0022] In particular, the required modifications can be implemented in conventional high-frequency devices such that the individual high-frequency devices can be used both as primary devices, which generate and provide a local frequency signal, and as secondary devices, which receive and use a reference frequency signal from a primary device. Thus, it is possible to use identical high-frequency devices for all high-frequency devices in a cascaded high-frequency system with multiple high-frequency devices. The monitoring according to the invention makes it possible, on the one hand, to detect a defect, such as a sudden partial degradation. For example, a change in the electrical phase can be detected due to a change in a solder joint or the like.Detecting such a defect can prevent faulty operating states and undefined system behavior. In particular, active circuit components in high-frequency devices, which are at risk from faulty transmission of a local frequency signal, can also be protected. This allows the functional safety of the entire system to be monitored and protected.

[0023] Furthermore, the inventive monitoring of the frequency signal transmission also allows changes due to temperature fluctuations or aging, and the associated variation in the phase reference, to be detected and, if necessary, corrected. For example, it is possible to perform recalibration during operation based on the inventive monitoring.

[0024] According to one embodiment, the input terminal is designed to receive the local frequency signal provided at the output terminal as a reference frequency signal. In particular, an external coupling device can be provided between the output terminal and the input terminal, via which the reference signal is provided from the output terminal to the input terminal.

[0025] According to one embodiment, the monitoring device is designed to store an initial phase difference between the local frequency signal from the local oscillator and the frequency signal at the input terminal. A suitable storage element can be provided for this purpose if necessary. In this case, the monitoring device can be designed to detect a malfunction if the phase difference between the local frequency signal from the local oscillator and the frequency signal at the input terminal deviates from the stored initial phase difference by more than a predetermined threshold value. In particular, when considering the deviation between the initial phase difference and the currently determined phase difference, the consideration can be based on the absolute value, i.e., without a sign.

[0026] According to one embodiment, the high-frequency device comprises a first frequency multiplier and a second frequency multiplier. The first frequency multiplier is configured to multiply a frequency of the local frequency signal by a predetermined factor. The second frequency multiplier is configured to multiply a frequency of the reference frequency signal by the predetermined factor. In other words, the frequency of the local frequency signal and the reference frequency signal are multiplied by the same factor. In this case, the phase comparison device can be configured to determine the phase difference using the signals with the multiplied frequency.

[0027] According to one embodiment, a receive path and a first mixer are provided in the radio-frequency device. The receive path is designed to receive an external radio-frequency signal. The receive path further comprises a coupling element. This coupling element is designed to couple a radio-frequency signal into the receive path. The radio-frequency signal coupled into the receive path is generated using the reference signal received at the input terminal. The first mixer is designed to mix a signal in the receive path and the local frequency signal generated by the local oscillator. The resulting signal can be provided by the mixer to the phase comparison device. The coupling element in the receive path and the mixer can be components of a circuit arrangement for an internal self-test (built-in self-test, BIST).

[0028] According to one embodiment, a transmission path is provided in the radio-frequency device. This transmission path can be designed to output a radio-frequency signal. Furthermore, the transmission path is designed to generate the radio-frequency signal using the reference signal received at the input terminal. A further coupling element can be provided in the transmission path. This further coupling element is designed to extract the radio-frequency signal to be output and to provide the extracted radio-frequency signal to the coupling element of the reception path. The further coupling element for extracting the radio-frequency signal from the transmission path can also be part of a BIST circuit arrangement. Such an embodiment is particularly possible if the source for the radio-frequency signal in the transmission path and in the reception path can be independently selected between the local oscillator signal and the reference signal.

[0029] According to one embodiment, the high-frequency device comprises a test device. This test device can, in particular, be an internal circuit for a self-test (BIST). The test device comprises a test signal generator and a second mixer. The test signal generator is designed to generate a test signal. The second mixer is designed to mix the test signal with the high-frequency signal to be coupled in before coupling it into the receive path. In this case, the phase difference between the local frequency signal and the reference frequency signal can be determined in the frequency range of the test signal.

[0030] According to one embodiment, the coupling device comprises a ring coupler, a hybrid coupler, or a network with multiple Wilkinson power dividers. Such coupling devices between individual radio-frequency devices can provide a frequency signal from a local oscillator, which is provided at an output terminal of a primary radio-frequency device, to one or more further secondary radio-frequency devices. Furthermore, at least said coupling devices are also capable of simultaneously providing the frequency signal to the input terminal of the primary radio-frequency device. In particular, said coupling devices also enable the provision of a frequency signal from the output terminal of a secondary radio-frequency device to the input terminal of a secondary radio-frequency device.According to one embodiment, the second transceiver is configured to perform signal generation and processing using the local radio-frequency signal of the first transceiver received at the input terminal of the second transceiver. In other words, the signal generation and processing in the second transceiver are not based on a locally generated frequency signal, but rather on an externally provided frequency signal. This allows multiple transceivers to be synchronized with each other.

[0031] The above embodiments and further developments can be combined with one another as desired, where appropriate. Further embodiments, further developments, and implementations of the invention also include combinations of features of the invention not explicitly mentioned above or described below with respect to the exemplary embodiments. In particular, those skilled in the art will also add individual aspects as improvements or additions to the respective basic forms of the invention.

[0032] Short description of the drawings

[0033] Further features and advantages of the invention are explained below with reference to the figures.

[0034] Fig. 1 : a schematic representation of a high frequency system with a

[0035] High frequency device according to an embodiment;

[0036] Fig. 2: a schematic representation of a phase comparison device according to an embodiment;

[0037] Fig. 3a-3d: schematic representations of embodiments for coupling devices as they can be used in high-frequency systems of the embodiments;

[0038] Fig. 4: a schematic representation of a radio-frequency system with multiple radio-frequency devices according to one embodiment; Fig. 5: a schematic representation of a radio-frequency system with multiple radio-frequency devices according to another embodiment;

[0039] Fig. 6: a flow chart of a method for operating a

[0040] High-frequency device according to one embodiment; and

[0041] Fig. 7 is a schematic diagram of a conventional high frequency system.

[0042] Description of embodiments

[0043] Figure 7 shows a schematic representation of a conventional radio-frequency system with two cascaded radio-frequency devices 100, 200. For example, the two radio-frequency devices 100, 200 can be transceivers for a radar system. Each of these transceivers can include one or more transmit paths 140 for transmitting radar signals and one or more receive paths 130 for receiving radar echoes. A local oscillator 110 can be provided in a primary radio-frequency device 100. This local oscillator 110 can provide a frequency signal for the transmit paths 140 and the receive paths 130.

[0044] Furthermore, the frequency signal of the local oscillator 110 can be provided at an output terminal 121. The frequency signal provided at the output terminal 121 can be provided via a suitable connection to an input terminal 222 of a secondary radio-frequency device 200. Thus, the secondary radio-frequency device 200 can use the frequency signal from the primary radio-frequency device 100 as a reference frequency signal for the transmit paths 240 and the receive paths 230.

[0045] Figure 1 shows a schematic representation of a radio-frequency system with a plurality of radio-frequency devices 1, 2 according to an embodiment of the present invention. The radio-frequency devices 1, 2 of this radio-frequency system can also be, for example, transceivers, in particular transceivers of a radar system. In particular, the individual radio-frequency devices 1, 2 can be, for example, integrated circuits or assemblies in which the components described below are integrated, for example, in a microchip. The individual radio-frequency devices 1, 2 can here be arranged, for example, on a common carrier substrate, for example a common printed circuit board.

[0046] The high-frequency devices 1, 2 of the high-frequency system differ from a conventional high-frequency device in particular in that the high-frequency devices 1, 2 according to the invention provide a means of monitoring the generation and transmission of the frequency signal, in particular the local frequency signal. This allows errors, such as an interruption in the signal routing or the like, to be detected. Furthermore, changes in the phase response due to temperature fluctuations or aging effects, for example, can also be detected and corrected if necessary.

[0047] The individual high-frequency devices 1, 2 in a high-frequency system can, in principle, all be constructed identically. Thus, the same components can be used for the high-frequency devices, referred to below as primary high-frequency device 1 or secondary high-frequency device 2. A primary high-frequency device 1 is a high-frequency device that generates a local frequency signal using a local oscillator 10. This locally generated frequency signal can also be provided to other secondary high-frequency devices 2, so that all high-frequency devices 1, 2 can be operated based on the same frequency signal. The signals from the local oscillators 10 of the secondary high-frequency devices 2 are not used for operational purposes.

[0048] Although only one secondary high-frequency device 2 is described in the example described here, the present invention is not limited to such an embodiment. Rather, two or more secondary high-frequency devices 2 may also be provided.

[0049] The individual high-frequency devices 1, 2 are connected to one another via a coupling device 3. This coupling device 3 makes it possible to provide the frequency signal of the local oscillator 11 provided at the output terminal 21 to the input terminals 22 of the primary high-frequency device 1 and the secondary high-frequency device 2. Furthermore, the coupling device 3 can also provide a frequency signal provided at the output terminal 21 by the secondary high-frequency device 2 during the test operation described below to the input terminal of the secondary high-frequency device 2 and, if appropriate, to the input terminal 22 of the primary high-frequency device 1. Possible embodiments of this coupling device 3 are described in more detail below.

[0050] Since, as already explained above, the structure of the primary high-frequency device 1 and the secondary high-frequency device 2 can be the same, only the structure of a high-frequency device will be explained in more detail below using the example of the primary high-frequency device 1.

[0051] The high-frequency device 1 comprises the previously described local oscillator 10, at least one transmission path 41 and optionally one or more additional transmission paths 42. Furthermore, the high-frequency device 1 comprises at least one reception path 31 and optionally one or more additional reception paths 32. A memory and a signal processing device 60 are provided for processing.

[0052] The frequency signal generated by the local oscillator 10 can be provided directly in the primary radio-frequency device 1 to the transmission paths 41, 42 and the reception paths 31, 32. Alternatively, in a secondary radio-frequency device 2, the reference frequency signal can be provided from the input terminal 22 to the transmission paths 41, 42 and the reception paths 31, 32. A switching element 53, for example, can be provided to select the respective frequency signal depending on whether the device is operating as the primary or secondary radio-frequency device 1, 2.

[0053] Optionally, the frequency of the frequency signal from the local oscillator 10 can be increased using a frequency multiplier 51. Any suitable known circuit concepts are possible for this purpose. Similarly, the reference frequency signal from the input terminal 22 can also be increased using another frequency multiplier 52. In this case, the two frequency multipliers 51, 52 each use the same factor to increase the frequency signals.

[0054] In the embodiment shown in Figure 1, the frequency signal from the local oscillator 10—possibly after frequency multiplication—and a frequency signal provided at the input terminal 22—possibly after the same frequency multiplication—are fed to a phase comparison device 70. The frequency signal present at the input terminal 22 can be a frequency signal that originates via the coupling device 3 from the output terminal 21 and thus from the local oscillator 10. Suitable amplifiers can optionally be provided at the output terminal 21 and the input terminal 22.

[0055] The phase comparison device 70 determines a phase difference between the local frequency signal from the local oscillator 10 and the frequency signal at the input terminal 22. Using this determined phase difference, a monitoring device 80 can then detect a possible malfunction. For this purpose, for example, the currently determined phase difference can be compared with a previously determined reference value. If the current phase difference deviates from the reference value (in terms of absolute value) by more than a predetermined threshold, this can be interpreted as an indication of a possible malfunction. If the currently determined phase difference deviates by less than the predetermined threshold, this phase difference can be tolerated, and no malfunction is detected.As a reference value for evaluating the phase difference, an initial phase difference can be determined and stored, for example, during commissioning or initialization. A suitable memory can be provided for this purpose.

[0056] A malfunction can be, for example, a disturbance, such as an interruption in the signal flow for transmitting the local frequency signal. However, other disturbances or errors, such as a sudden degradation, e.g., a change in the phase response due to a defective solder joint or the like, can also be detected. For example, it can be determined whether an error or the like exists in the signal flow from the local oscillator 10 via the output terminal 21, the coupling device 3, the input terminal 22 to the phase comparison device 70.

[0057] Since a similar check can also be performed in the secondary high-frequency devices 2 using the local oscillator provided therein, the complete signal flow path for the propagation of the frequency signal can be checked in this way.

[0058] In addition to checking for malfunctions such as faults, especially interruptions, it is also possible to detect changes in the phase response. Such changes in the phase response can occur, for example, due to temperature fluctuations or aging effects. This allows the change in the phase difference, for example, relative to an initially stored phase difference, to be determined. This deviation can be used, for example, for recalibration during operation.

[0059] In one embodiment, PLLs implemented in the radio-frequency devices 1, 2 can also be used to monitor the phase difference. These can be set to an equal integer multiple of a signal at a common reference input to provide phase references for implemented phase-detection mixers.

[0060] Figure 2 shows a schematic representation of a schematic structure for a phase comparison device 70 according to one embodiment. In the embodiment shown here, for example, the signal from the local oscillator 10 (optionally after frequency multiplication) and the signal from the input terminal 22 (also optionally after the same frequency multiplication) can be fed to the input side of a mixer 71. The resulting output signal of the mixer 71 can then be fed to a frequency filter 72 and, if necessary, to an amplifier 73. For further digital processing, the resulting signal can be digitized using a suitable analog-to-digital converter 74. The digital output signal obtained therefrom can then be fed to the monitoring device 80 for further evaluation.

[0061] As will be explained in more detail below, further alternative embodiments for determining the phase difference are also possible.

[0062] Figure 3a shows a schematic representation of a coupling device 3 according to one embodiment. The output terminals 21 of the respective high-frequency device 1, 2 can be connected on the left-hand side. As already explained, arrangements with more than two high-frequency devices 1, 2, in particular several secondary high-frequency devices 2, are also possible in principle. In this case, the output terminals 21 of all high-frequency devices in 1, 2 can be connected to the coupling device 3. Analogously, the input terminals 22 of all high-frequency devices 1, 2 can be connected to corresponding terminals (shown on the right) of the coupling device 3.

[0063] Figure 3b shows a schematic representation of a coupling device 3 according to one embodiment. In the embodiment shown here, a ring coupler can be provided in the coupling device 3, for example.

[0064] Figure 3c shows a schematic representation of a coupling device 3 according to another embodiment. In the embodiment shown here, a hybrid coupler can be provided in the coupling device 3, for example. Figure 3d shows a schematic representation of a coupling device 3 according to yet another embodiment. In the embodiment shown here, a network with Wilkinson power dividers can be provided in the coupling device 3, for example.

[0065] Figure 4 shows a schematic representation of a high-frequency device 1 according to another embodiment. Since, as previously explained, primary high-frequency devices 1 and secondary high-frequency devices 2 in a high-frequency system are generally identical, only one high-frequency device in the form of the primary high-frequency device 1 will be described for the following embodiments. These explanations apply analogously to the secondary high-frequency devices 2.

[0066] The high-frequency device 1 according to Figure 4 comprises a test signal generator 90. This test signal generator 90 is part of an integrated test circuit (BIST). The signal of this test signal generator 90 can be coupled into a receive path 31 via a coupling element 35. The (digital) output signal of the receive path 30 can be evaluated by a digital signal processing device 60. In this way, a test of the receive path 30 can be performed.

[0067] To test the signal path for providing the frequency signal from the local oscillator 10, for example, the signal from the input terminal 22 (possibly after frequency multiplication) can be combined with the test signal from the test signal generator 90 by means of a mixer 91. In this way, the frequency signal from the input terminal 22 is fed into the signal path of the corresponding reception path 31.

[0068] Furthermore, the signal from the local oscillator 10 (after corresponding frequency multiplication) can be fed to a mixer 36 in the receive path 31. The output signal of the mixer 36 can be fed to a digital signal processor 60 after appropriate further processing, for example, filtering by a filter 37, amplification by an amplifier 38, and analog-to-digital conversion in the A / D converter 39. In this case, a unit 70 in the signal processor 60 can determine the phase difference between the frequency signal from the local oscillator 10 and the frequency signal at the input terminal 22. This phase difference can be evaluated, as already explained above, to detect a malfunction or to perform recalibration if necessary.

[0069] To select or distribute the local frequency signal from the local oscillator 10 and the frequency signal from the input terminal 22, a switching element 53 can be provided in the high-frequency device 1, which can supply a corresponding frequency signal (from the local oscillator 10 or the input terminal 22) to the receive path 31, in particular to the mixer 36, as well as to the transmit path 41. Furthermore, a switching element 54 can be provided, which can supply a corresponding frequency signal (from the input terminal 22 or from the local oscillator 10) to the mixer 91 in the self-test path.

[0070] Figure 5 shows a schematic representation of a high-frequency device 1 according to a further embodiment. In the embodiment according to Figure 5, the frequency signal from the local oscillator 10 or the input terminal 22 can be supplied to at least one transmission path 41 by means of the switching element 54. To test the signal path for distributing the frequency signal between the individual high-frequency devices 1, 2, the frequency signal from the input terminal 22 can be supplied to at least one transmission path 41. The output signal of the transmission path 41 can be coupled out by means of a further coupling element 45, and the coupled-out signal can be mixed with the test signal from the test signal generator 90 by means of the mixer 91, analogous to the previously described embodiment.

[0071] If the frequency signal from the local oscillator 10 is fed to the mixer 36 in the reception path 31, a phase difference between the frequency signal of the local oscillator 10 and the frequency signal at the input terminal 22 can also be determined in this case, analogously to the previously described embodiment.

[0072] Figure 6 shows a flowchart underlying a method for monitoring a high-frequency device 1, 2 according to one embodiment. The method can, in principle, comprise any steps as previously described for implementing a check of the signal path for transmitting the frequency signal in connection with the high-frequency system, and in particular the high-frequency devices 1, 2. Analogously, the previously described high-frequency devices 1, 2 can also comprise any components that may be required to implement the method described below.

[0073] In a step S1, a local frequency signal is generated. The local frequency signal can be generated, in particular, by means of a local oscillator 10.

[0074] In a step S2, the local frequency signal is provided at an output terminal 21 of the high-frequency device 1, 2.

[0075] In step S3, a reference frequency signal is received at an input terminal 22 of the high-frequency device 1, 2. The received reference frequency signal can in particular be the frequency signal which is forwarded from the output terminal 21 to the input terminal 22 by means of a coupling device 3.

[0076] In step S4, a phase difference between the local frequency signal and the reference frequency signal is determined.

[0077] Finally, in step S5, a malfunction is detected during transmission of the local frequency signal. The malfunction can be detected, in particular, using the determined phase difference between the local frequency signal and the reference frequency signal. In addition to detecting a malfunction, the phase difference can also be used to perform a recalibration during operation of the high-frequency device 1, 2. This can be done, in particular, if variations in the

[0078] Phase response of the propagation paths.

[0079] In summary, the present invention relates to monitoring the transmission paths for the distribution of a frequency signal for the synchronization of several cascaded radio frequency devices. For this purpose, a

[0080] Frequency signal is fed to a phase comparison device via two different paths, wherein one path comprises at least part of the signal path for transmitting the frequency signal to further high-frequency devices.

Claims

Claims 1. A high-frequency device (1, 2), comprising: a local oscillator (10) configured to generate a local frequency signal; an output terminal (21) configured to provide the local frequency signal generated by the local oscillator (10); an input terminal (22) configured to receive an externally provided reference frequency signal; a phase comparison device (70) configured to determine a phase difference between the local frequency signal from the local oscillator (10) and the reference frequency signal at the input terminal (22); a monitoring device (80) configured to detect a malfunction in a transmission of the local frequency signal generated by the local oscillator (10) using the determined phase difference between the local frequency signal from the local oscillator (10) and the frequency signal at the input terminal (22).

2. High-frequency device (1, 2) according to claim 1, wherein the input terminal (22) is designed to receive the local frequency signal provided at the output terminal (21) as a reference frequency signal via an external coupling device (3).

3. High-frequency device (1, 2) according to claim 1 or 2, wherein the monitoring device (80) is designed to store an initial phase difference between the local frequency signal from the local oscillator (10) and the frequency signal at the input terminal (22) and to detect a malfunction if the phase difference between the local frequency signal from the local oscillator (10) and the frequency signal at the input terminal (22) deviates from the stored initial phase difference by more than a predetermined threshold value.

4. High-frequency device (1, 2) according to one of claims 1 to 3, comprising a first frequency multiplier (51) designed to multiply a frequency of the local frequency signal by a predetermined factor, and a second frequency multiplier (52) designed to multiply a frequency of the reference frequency signal by the predetermined factor, wherein the phase comparison device (70) determines the phase difference using the signals with the multiplied frequency 5. High-frequency device (1, 2) according to one of claims 1 to 4, with a reception path (31) which is designed to receive an external high-frequency signal, wherein the reception path (31) comprises a coupling element (35) which is designed to couple a high-frequency signal into the reception path (31) which has been generated using the reference signal received at the input terminal (22), and a mixer (36) which is designed to mix an input signal in the reception path (31) and the local frequency signal generated by the local oscillator (10) and to provide it to the phase comparison device (70).

6. High-frequency device (1, 2) according to claim 5, comprising a transmission path (41) which is designed to output a high-frequency signal, wherein the transmission path (41) is designed to generate the high-frequency signal using the reference signal received at the input terminal (22), and wherein the transmission path (41) comprises a further coupling element (45) which is designed to decouple the high-frequency signal to be output and the to provide the coupled high-frequency signal to the coupling element (35) of the receiving path (31).

7. High-frequency device (1, 2) according to claim 6, with a test device, wherein the test device comprises a test signal generator (90) and a further mixer (91), wherein the test signal generator (90) is designed to generate a test signal, and wherein the further mixer (91) is designed to mix the test signal with the high-frequency signal to be coupled in before coupling it into the reception path (31).

8. A radio-frequency system comprising a first transceiver; a second transceiver; and a coupling device (3), wherein the first transceiver and the second transceiver each comprise a radio-frequency device (1, 2) according to one of claims 1 to 7, and the coupling device (3) is designed to couple the input terminals (22) and the output terminals (21) of the first transceiver and the second transceiver to one another.

9. High-frequency system according to claim 8, wherein the coupling device (3) is a ring coupler, a hybrid coupler, or a network with several Wi I kinson - Leistu ngsteil ern u mhalbt.

10. A radio frequency system according to claim 8 or 9, wherein the second transceiver is configured to perform signal generation and processing using the local radio frequency signal of the first transceiver received at the input terminal (22) of the second transceiver.

11. A radar system comprising a high-frequency system according to any one of claims 8 to 10, wherein the first transceiver and the second transceiver are each configured to output radar signals and to receive and process radar echoes on the transmitted radar signals.

12. Method for monitoring a high-frequency device (1, 2), comprising the steps: Generating (S1) a local frequency signal by means of a local oscillator (10); Providing (S2) the local frequency signal at an output terminal of the high-frequency device (1, 2); Receiving (S3) a reference frequency signal at an input terminal (21) of the high-frequency device (1, 2); Determining (S4) a phase difference between the local frequency signal and the reference frequency signal; and Detecting (S5) a malfunction in a transmission of the local frequency signal using the determined phase difference between the local frequency signal and the reference frequency signal.

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