METHOD FOR DETERMINING PHASE INFORMATION AND RF DEVICE

Abstract

Examples relating to the determination of phase information that specifies a phase error of a phase shifter are described and disclosed herein.

Description

TECHNICAL AREA

[0001] The present disclosure relates to the determination of phase information indicating a phase error of a phase shifter. BACKGROUND

[0002] High-frequency (HF) circuits in the MHz to THz range are used in many applications today. For example, HF circuits are used to transmit data according to modern communication protocols or to generate and transmit radar signals for object detection. In radar applications, angle-resolved object detection may require the transmission of MIMO (Multiple In Multiple Out) signals of different phases via multiple antennas. The phase setting for each transmission path can be changed using a phase shifter, which is capable of shifting the phase of the transmitted signals. In each of the above applications, it is desirable to set the phase with high precision when transmitting the HF signals to avoid unwanted and detrimental effects.In radar applications, for example, an inaccurate phase setting of a transmission channel can lead to additional spectral components, which can significantly reduce the accuracy of angle detection.

[0003] German patent application DE 10 2018 130 556 A1 describes a method for a radar system. The method comprises generating a frequency-modulated RF oscillator signal and feeding the RF oscillator signal to a first transmit channel and a second transmit channel. The method further comprises generating a first RF transmit signal in the first transmit channel based on the RF oscillator signal, transmitting the first RF transmit signal via a first transmit antenna, receiving a first RF radar signal via a receive antenna, and converting the first RF radar signal into a baseband signal, thereby obtaining a first baseband signal that has a first signal component with a first frequency and a first phase, wherein the first signal component can be attributed to direct crosstalk from the first transmit antenna. This procedure is repeated for the second transmit channel. SUMMARY

[0004] According to one aspect, a method for determining phase information indicating a phase error of a phase shifter in a transmit path of an RF device comprises controlling a phase shifter of the transmit path to apply a phase shift according to a target phase value of a set of target phase values ​​in order to produce an RF transmit signal corresponding to the target phase value, transmitting the RF transmit signal via the transmit path, and receiving a plurality of RF receive signals in a plurality of receive paths, each of the plurality of RF receive signals being assigned to a respective receive path and exhibiting crosstalk of the respective RF transmit signal into the respective receive path.The method further comprises down-converting the plurality of RF receive signals to generate a plurality of down-converted receive signals, and processing in each receive path of the plurality of receive paths of the respective down-converted receive signal associated with the respective receive path to generate a measurement value for each receive path that corresponds to the target phase value applied by the phase shifter.

[0005] The method further comprises generating a plurality of sets of measured values, wherein each set of the plurality of sets of measured values ​​is assigned to a respective receive path of the plurality of receive paths, wherein the plurality of sets of measured values ​​is generated by repeating the control of the phase shifter, the transmission of the RF transmit signal, the step-down conversion, and the processing in each receive path in order to generate, for each target phase value of the set of target phase values ​​in each respective receive path, a corresponding measured value of a respective set of measured values. The phase information is determined based on processing of the plurality of sets of measured values.

[0006] According to another aspect, an RF device comprises a transmit path configured to send an RF transmit signal over the transmit path, a phase shifter located in the transmit path and configured to apply a phase shift to the RF transmit signal according to a target phase value from a set of target phase values, and a plurality of receive paths configured to receive a plurality of RF receive signals, each exhibiting crosstalk from the respective RF transmit signal into the respective receive path. A plurality of mixers is located in the plurality of receive paths to step down the plurality of RF receive signals into a plurality of down-converted receive signals. A controller is configured to control the phase shifter to apply each target phase value from the set of target phase values.The RF device further comprises a measurement circuit to generate a plurality of sets of measurements based on the plurality of down-converted received signals, wherein each set of the plurality of sets of measurements is assigned to a respective receive path of the plurality of receive paths, and each measurement within a set of measurements is assigned to a respective target phase value applied by the phase shifter. The RF device further comprises a processor configured to process the plurality of sets of measurements and to determine phase information indicating a phase error of the phase shifter based on the plurality of sets of measurements.

[0007] The expert will recognize additional features and advantages upon reading the following detailed description and upon examining the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure is illustrated by way of example and without limitation in the figures of the accompanying drawings, in which the same reference symbols refer to similar or identical elements. The elements of the drawings are not necessarily to scale relative to one another. The features of the various examples shown may be combined, provided they are not mutually exclusive. Fig. Figure 1A represents a first example of an RF device and crosstalk from one transmit path to several receive paths of the RF device. Fig. Figure 1B represents a second example of an RF device and crosstalk from one transmit path to multiple receive paths of the RF device. Fig. 1C represents a third example of an RF device and crosstalk from one transmit path to multiple receive paths of the RF device. Fig. 2A, Fig. 2B and Fig. Section 2C shows examples of measured values ​​and fitted curves for different reception paths. Fig. 3A, Fig. 3B and Fig. 3C shows examples of sets of measurement phase values ​​and fitted curves for different reception paths. Fig. 4A, Fig. 4B and Fig. 4C shows examples of sets of measurement phase step values ​​and expected target phase step values ​​for different receive paths. Fig. 5A to Fig. Figure 5D shows further examples of sets of measurement phase step values ​​for different receive paths. Fig. 6A to Fig. Figure 6D shows examples of sets of measurement phase step values ​​after applying a sliding window processing and sets of first derivative values ​​of fitted curves for the in Fig. 5A to Fig. 5D shown measurement phase step values. Fig. Figure 7 shows an example of the distribution of measurement phase step values ​​for the measurement phase step values ​​of Fig. 5A and an example of the distribution of measurement phase step values ​​after outlier removal processing. Fig. Figure 8 shows an example of a set of combined and averaged measurement phase step values ​​after combining and averaging several sets of measurement phase step values. DETAILED DESCRIPTION

[0009] The examples described herein provide a novel concept for determining phase information that specifies a phase error of the phase shifter. This concept is based on using crosstalk information from a transmit path to multiple receive paths to determine the phase error of the phase settings by the phase shifter in the transmit path. The receive paths used to determine the phase error are also intended for use during field operation of the RF device for precise measurements, such as receiving radar signals reflected from radar targets to determine the range and velocity of those targets.

[0010] Since this concept utilizes existing receive paths, it can be implemented in existing RF equipment without hardware modifications and may only require additional processing or software capabilities and / or minor reconfigurations within the multiple receive paths, which can be performed quickly. The concept can be used to achieve phase shifter calibration over one or more calibration time intervals.

[0011] Calibration time intervals can be planned before the intended operation of the RF device, for example after switching on the RF device or between operating phases of the RF device, for example after sending a frame of radar chirps.

[0012] In addition to calibration, the concept can also be used to monitor the phase shifter, either additionally or alternatively.

[0013] In one example, phase errors can be determined for each of a set of predetermined target phase steps. A target phase step is a difference between a pair of target phases (e.g., a pair of nearest target phases) applied by the phase shifter.

[0014] The concept can be used in any configuration or situation, e.g., in situations where no antennas are connected, in situations where antennas are connected, or in situations where a nearby object reflects crosstalk back to the receiving paths.

[0015] The present concept achieves a very high phase measurement accuracy, which can improve upon existing concepts using a dedicated built-in measurement circuit by a factor of 4 to 5. This is achieved with regard to the use of multiple receive paths, which are also configured to receive RF signals during regular operation and which receive crosstalk with different phase delays.

[0016] With reference to Fig. In Figure 1a, a first example of an RF device 10A is described according to the concept. The RF device 10A has a transmit path 12 and a plurality of receive paths 14-1, 14-2, and 14-3. The transmit path 12 includes a transmit channel 13, which is implemented in a semiconductor chip. The transmit channel 13 may include a phase shifter 16. The phase shifter 16 is coupled to a local oscillator (LO) 11 for receiving an LO signal (here also referred to as the first representation of the LO signal). The phase shifter 16 is configured to apply a phase shift to the LO signal received from the local oscillator according to a target phase value input into the phase shifter 16 by a controller 33 to produce a phase-shifted signal. The phase shifter 16 can include any type of phase shifter, for example analog phase shifters or digital phase shifters.For example, the phase shifter 16 in an example may include an IQ modulator capable of shifting a phase by adjusting the amplitudes of the I-path and the Q-path. The phase shifter 16 may include one or more resistive, capacitive, or inductive elements. It may also include delay lines and switching elements. The phase shifter 16 is coupled to a power amplifier 18 to amplify the phase-shifted signal to generate a transmit signal. The transmit path 12 may also include a terminal 15 for sending the transmit signal outside the semiconductor chip.

[0017] Each of the plurality of receive paths 14-1, 14-2, and 14-3 has a respective receive channel 20 implemented on a semiconductor chip. Each respective receive channel 20 includes a mixer 22, which is coupled upstream to a respective terminal 23 for step-down conversion of received signals received by the respective terminal 23. In some examples, a low-noise amplifier may be placed between the mixer 22 and the respective terminal 23. In one example, the receive channel 20 may be implemented as an IQ receiver, and the mixer 22 may be implemented as an IQ mixer. Each respective mixer 22 is coupled to the local oscillator 11 for receiving the respective LO signal (hereafter also referred to as the respective representation of the LO signal), which is used to step down the respective received signal.Each mixer 22 is further coupled downstream to an optional analog baseband circuit 24 for processing the down-converted signal. The analog baseband circuit 24 can, for example, include an amplifier and / or an analog filter. The analog baseband circuit 24 is coupled downstream to an analog-to-digital converter (ADC) 26, which generates digital measurements based on the received down-converted signal. The ADC 26 is coupled downstream to an optional digital baseband circuit 28 for providing digital processing operations for each respective receive channel 20. The digital baseband circuit 28 can, for example, include a digital filter, up- or down-sampling circuits, etc. The ADC 26 and the optional digital baseband circuit 28 can form a measurement circuit 29 that generates measurements based on the down-converted signal.

[0018] Each respective measuring circuit 29 is coupled to a processor 30 for processing the measured values ​​received from each respective receive path, as will be described later.

[0019] According to some examples, the transmit channel 13 and each respective receive channel 20 can be implemented in a single semiconductor chip. In some examples, the transmit channel 13 and the receive channels 20 can be implemented in different semiconductor chips, for example, in semiconductor chips of a cascaded radar system. In some examples, the RF device 10A can include more than one transmit path 12.

[0020] According to some examples, the RF device 10A is a radar device configured to transmit and receive radar signals during a radar operating mode to detect the distances, velocities, or angular positions of objects. The radar operation can, for example, use frequency-modulated continuous wave (FMCW) radar signals. Accordingly, the local oscillator 11 is configured to generate FMCW signals during the radar operating mode.

[0021] As outlined above, the RF device 10A is configured to determine phase error information during a second operating mode. This phase error information relates to phase errors introduced by the phase shifter 16. The phase error information can be determined using only the RF device 10A, without any additional hardware components or circuitry. Determining the phase error information may involve reconfiguration, such as dynamic modifications or dynamic switching of certain elements compared to the intended field operation of the RF device 10A. For example, filters in the respective analog baseband circuit 24 and / or digital baseband circuit 28 may be dynamically modified to bypass or eliminate high-pass filtering of the down-converted signal during the second operating mode.At one end of the second operating mode (after completion of calibration and / or monitoring), the high-pass filter can be reactivated or switched back to the receive path.

[0022] Determining the phase error information is based on using crosstalk from the transmit path to the majority of receive paths 14-1, 14-2, and 14-3. While crosstalk is typically an unwanted signal segment during radar operation (e.g., in the radar operating mode), the presented concept uses the crosstalk signals during the second operating mode to determine the phase error information.

[0023] Crosstalk can occur within different sections of the transmit path 12 and the receive paths 14-1, 14-2 and 14-3. Fig. Figure 1A shows the RF device 10A without transmit and receive antennas. In this situation, the crosstalk 34 results mainly from crosstalk coupling between terminal 15 and the respective terminal 23 of each receive path.

[0024] Fig. Figure 1B shows an RF device 10B, in which the in Fig. The RF device 10A shown in Figure 1A is connected to antennas. Accordingly, the transmit path 12 further comprises a transmit antenna 17 and an antenna path 19, which is coupled between the transmit antenna 17 and the terminal 15. Furthermore, each of the plurality of receive paths 14-1, 14-2, and 14-3 comprises a receive antenna 31 and an antenna path 32, which is coupled between the respective receive antenna 31 and the respective terminal 23 for transmitting the respective received signals from the receive antenna to the respective terminal 23. In this example, in addition to the crosstalk 34, crosstalk 36, resulting from the coupling of the transmit antenna 17 with each respective receive antenna 31, is included in the crosstalk signal.

[0025] The transmitting antenna 17 can be a waveguide antenna, a patch antenna, or other types of RF antennas in some examples. The antenna path 19 can, for example, include one or more wireless sections and / or one or more wired sections. In some examples, the antenna path 19 can include at least one waveguide, stripline, substrate-integrated waveguide, etc. In some examples, the antenna path 19 can include one or more wireless sections. In some examples, the antenna path 19 can include elements such as a coupler, coupling device, etc., for coupling from one section to another. Typically, crosstalk signals can originate from outside the semiconductor chips, since good RF isolation is typically provided between transmit and receive channels within the semiconductor chip.However, the present concept is not limited to such situations.

[0026] It should be noted that the concept does not depend on specific crosstalk between specific sections. In fact, crosstalk from multiple crosstalk paths can add up to increase the strength of the crosstalk signal, which can be advantageous. Accordingly, in some examples, each of the crosstalk signals may exhibit crosstalk originating from multiple crosstalk paths. Therefore, the following considerations apply to all situations of crosstalk being introduced into the respective receive paths 14-1, 14-2, and 14-3.

[0027] The concept can also be used for signals that are reflected from a fixed near distance to the receiving paths 14-1, 14-2, 14-3. Fig. Figure 1C shows an example in which, in addition to crosstalk 34 and 36, indirect signals 38, resulting from reflection of the transmitted signals from a nearby object 40, are reflected back to the receiving paths 14-1, 14-2, and 14-3. To use the concept described above in such a situation, the distance of the nearby object 40 to the receiving paths 14-1, 14-2, and 14-3 must be fixed. The nearby object 40 could, for example, be a metal wall positioned at a fixed distance. Fig. Figure 1C shows an RF device 10C similar to the one in Fig. Figure 1B shows an RF device 10B, which is placed in front of object 40 at a fixed distance to reflect the transmitted signal back to the respective receiving paths. The above description can be applied similarly to such situations.

[0028] As an example, the local oscillator 11 is controlled in the second operating mode to generate a continuous wave signal with a fixed RF frequency. For example, the RF frequency can be selected to be between 20 and 100 GHz.

[0029] If the RF system includes more than one transmit channel 13, the other transmit channels are controlled so that they do not transmit during the measurement described above, thus introducing crosstalk resulting from only one transmit channel into receive paths 14-1, 14-2, and 14-3. After the phase information for transmit channel 13 has been determined, each of the other transmit channels can then be activated sequentially to determine the phase information for the respective other transmit channels.

[0030] To determine the phase error information, the controller 33 is configured to control the phase shifter 16 to sequentially apply target phase values ​​from a set of target phase values. It should be noted that in some examples, the controller 33 may be fully or partially implemented in the processor 30, for example, using software executed by the processor 30 to generate the set of target phase values.

[0031] Transmit channel 20 generates a corresponding RF transmit signal according to the applied target phase value. This transmit signal is sent via transmit path 12. In each of the receive paths 14-1, 14-2, and 14-3, the respective RF receive signal, which includes the crosstalk from RF transmit path 12 into the respective RF receive path, is received by the respective mixer 22 and down-converted. The down-converted signal is processed by the analog baseband circuit 24 and converted into a digital measurement value using the analog-to-digital converter 26.

[0032] In one example, the measured value represents the DC value of the down-converted signal. In radar operation, DC portions of the down-converted signal are typically filtered out using a high-pass filter in the analog baseband circuit and / or digital baseband circuit. In the second mode, however, the respective receive path is reconfigured so that the high-pass filter is bypassed or no low-frequency filtering is applied, thus allowing the DC value of the down-converted signal to be measured.

[0033] For each of the target phase values ​​applied by the phase shifter 16, a corresponding measurement is generated in each of the plurality of receive paths 14-1, 14-2, 14-3. Accordingly, a plurality of sets of measurements is generated, with each set being assigned to one of the receive paths 14-1, 14-2, 14-3. Each measurement in a set of measurements is assigned to a target phase setting of the set of target phase settings. By way of example, the set of target phase values ​​comprises regularly spaced target phase values ​​between 0 and 360°, which are defined by φ=nN360° can be determined where N is an integer and n is an integer ranging from 0 to N-1.

[0034] The majority of sets of measured values ​​are then processed by processor 30 to determine the phase information.

[0035] According to one example, the processor 30 can arrange the set of measurements in a sequence such that the target phase corresponding to a measurement value increases continuously if the target phase values ​​were not applied in an increasing sequence.

[0036] Fig. 2A to Fig. 2C shows an illustrative example of a plurality of sets of measurements for twelve target phase values ​​for receive paths 14-1, 14-2 and 14-3. Fig. 2A corresponds to receive path 14-1, Fig. 2B corresponds to receive path 14-2 and Fig. 2C corresponds to receive path 14-3. The measured values ​​(DC values) are shown as points in the respective Fig. 2A to Fig. 2C shown.

[0037] For continuous wave signals, the DC value of the step-down signal can be determined for each measurement by M(n)=A sin(360°nN+ϕerr(n)+ϕ)+B are described where A is the amplitude of the respective sinusoidal curve corresponding to the DC values, B is a DC offset of the respective sinusoidal curve corresponding to the DC values, φr(n) is the phase error introduced by the phase shifter when applying the target phase value of 360°n / N, and φ is the phase introduced by the crosstalk signal with respect to the LO signal received at mixer 22. It should be noted that the phase φ introduced by the crosstalk is different for each receive path because the lengths of the crosstalk paths are different.For a receive path, however, the phase φ can be assumed to be constant for all measurements, since the crosstalk scenario and the length of the crosstalk paths typically do not change within a measurement period (which can range from hundreds of microseconds to milliseconds), a period that can be considered sufficiently fulfilled for applications including automotive applications. It should be noted that in the absence of a phase error introduced by the phase shifter 16, the measurements are expected to lie precisely on a sine wave (assuming no measurement errors).

[0038] For each set of measured values ​​M(n), a fitted sine curve can be determined using processor 30 to determine fitted values ​​for the parameters A, B, and φ. Values ​​for the parameters A and / or B and / or φ, or information representing values ​​for the parameters A and / or B and / or φ, may also be referred to herein as information specifying the parameters A and / or B and / or φ. The fitted sine curve can be obtained, for example, by minimizing an error function. E(n)=|M(n)−A sin(360°nN+ϕ)+B|2 for the parameters A, B and φ.

[0039] In some examples, the values ​​for the parameters A, B and φ can be determined using the processor 30 by Fourier transforming the set of measured values ​​M(n), where the 0th order frequency component (DC component) gives the offset B, provides the magnitude of the third order frequency component A and provides the phase of the third order frequency component φ.

[0040] Fig. 2A to Fig. 2C shows illustrative examples of fitted sine curves 202A, 202B and 202C that correspond to the respective set of measured values.

[0041] After the fitted sine curve and / or the values ​​for parameters A and B have been determined, the processor 30 can derive a plurality of sets of measurement phase values ​​from the plurality of sets of measured values ​​M(n) by using the inverse sine function (arcsin) to φ(n)=arcsin(M(n)−BA) to obtain, and apply to each respective measured value M(n) to calculate.

[0042] Fig. 3A to Fig. Figure 3C shows an illustrative example of the plurality of sets of measurement phase values ​​(shown as points) and corresponding curves fitted to each set of measurement phase values. It can be noted that the fitted curves have the same slope but different offsets with respect to the various cross-coupling paths for each receive path.

[0043] From a plurality of sets of measurement phase values, a plurality of sets of measurement phase step values ​​can be calculated by determining respective pairs of measurement phase values ​​within each set of measurement phase values ​​and calculating the difference between the respective measurement phase values ​​of each pair. For example, the processor determines 30 pairs of adjacent measurement phase values ​​φ(n) and φ(n + 1) and uses the following equation to determine a respective measurement phase step value φstep(n): φstep(n)=φ(n)−φ(n+1)=arcsin(M(n)−BA)−arcsin(M(n+1)−BA)

[0044] As understood herein, a neighboring measurement phase value of a given measurement phase value is the measurement phase value of a measured value that corresponds to a target phase value that is closest to the target phase value of the respective measurement phase value among all target phase values. A phase step value assigned to a target phase value (e.g., index n) therefore represents the phase difference between the measurement phase value assigned to the target phase value (e.g., index n) and a phase value assigned to the neighboring target phase value (e.g., index n+1).

[0045] Fig. 4A to Fig. Figure 4C shows an illustrative example of a plurality of sets of measurement phase step values ​​determined using Equation 1. Additionally, they show... Fig. 4A to Fig. 4C the expected target phase step value, which is the difference between a pair of target phase values, for example, between two consecutive target phase values, which in this case is 360° / 12 = 30°. Assuming that no phase errors are introduced by the phase shifter 16 and that there are no measurement errors or other processing errors, each phase step value of each set of phase step values ​​determined using Equation 1 would be calculated to be exactly the target phase step value.

[0046] If the phase shifter 16 introduces a phase error, each set of measurement phase step values ​​follows the phase step error curve of the phase shifter 16, provided no measurement errors are present. If measurement errors or other processing errors are present, the measurement phase step values ​​fluctuate around the phase error curve of the phase shifter 16.

[0047] The fluctuation (deviation between the measured phase step values ​​and the expected phase step error curve) can, in some examples, depend on the target phase values ​​associated with the measured phase step value. In particular, it has been observed that in a region where the fitted sine curve has a maximum, the accuracy of the measurement decreases because a small deviation of the measured value due to measurement errors leads to a deviation of the determined phase value. This can also be seen from Equation 1, as it requires subtracting a first arcsine value from a second arcsine value. When the absolute value of the derivative of an arcsine function approaches infinity at 90° and 270° (extrema of the sine curve), any measurement error of a measured value near the extrema of the sine curve fitting the set of measured values ​​significantly affects the result of Equation 1.Furthermore, the influence of measurement errors or processing errors on the result becomes stronger if both measured values ​​of equation 1 are close to the extremum of the respective sinusoidal fitting curve.

[0048] Fig. 5A to Fig. Figure 5D shows a plurality of sets of measurement phase step values ​​resulting from actual measurements in four receive paths RX1, RX2, RX3, and RX4 with a target phase step value of 360 / 256 = 1.40625°. Furthermore, it should be noted that the measurement was performed with a calibrated phase shifter, so no errors are introduced by the phase shifter, and the measurement phase step values ​​are expected to be the target phase step value. It should be noted that when measuring Fig. 5A to Fig. In 5D, the target phase applied by the phase shifter 16 is rotated twice in succession from 0 to 360° in steps of 1.40625° (target phase step value). Each of Fig. 5A to Fig. 5D therefore shows a set of 512 measurement phase step values ​​and measurement number i and measurement number 256 + i correspond to the same target phase applied by the phase shifter 16.

[0049] Fig. Figure 5A shows the set of measurement phase step values ​​corresponding to the receive path RX1. As shown in Figure 5A, the following information is available: Fig. As can be seen in 5A, the measurement phase step values ​​show increased fluctuations in the ranges between measurement numbers 10 to 40, 135 to 165, 265 to 295, and 395 to 425. Similar behavior can be observed in Fig. 5B to Fig. 5D can be observed, but in different areas.

[0050] Fig. 6A to Fig. The upper diagram in each of the 6D diagrams shows the majority of sets of measurement phase step values ​​after a moving average processing of 5 points. The lower diagram in each of the 6D diagrams shows the majority of sets of measurement phase step values ​​after a moving average processing of 5 points. Fig. 6A to Fig. Figure 6D shows the absolute value of the derivative of the fitted sine curve that fits the respective set of measurements. As can be seen, the increased fluctuation in the measurement phase step value corresponds to zero in the derivative of the respective fitting curve. In other words, the increased fluctuations appear in regions where the respective fitting curve of the measurements is close to an extremum.

[0051] However, due to the fact that the extrema of the fitted sine curves are located at different target phase values ​​for the majority of receive paths, a combination of the sets of measurement phase step values ​​can provide an accurate measurement of the measurement phase step value for all target phase values, as explained in more detail below.

[0052] According to one example, the majority of sets of measurement phase step values ​​are processed by combining one or more of the sets of measurement phase step values ​​using weighting factors. According to one example, a weighting factor w j (n) for each n, which specifies the target phase value (running from 1 to N), and each j, which specifies a respective reception path. According to an example, a weighted sum can be determined using the weighting factor w j (n) according to φstep(n)=∑j=1Jwj(n)φstepj(n)∑j=1Jwj(n) calculated where J is the number of receive paths used for the calculation, j is the index of each receive path, and φ stepj (n) is the respective measurement phase step value.

[0053] According to some examples, the weighting factor w j (n) based on the fitted sine curve M fittingby using slope information (first derivative) of the sine curve at the respective target phase value φ(n). A value of the derivative of the fitted curve can be considered here as an example of a fitted derivative value. According to an example, the weighting factor w j (n) as the absolute value of the first derivative at the respective target phase value wj(n)=|d Mfittingdφ|φ=φ(n)|, the square of the first derivative wj(n)=(d Mfittingdφ|φ=φ(n))2 or polynomials of degree 1, 2 or higher with the first derivative as a variable.

[0054] In some examples, the slope information may include a value assigned to a range of slopes. For example, for a first range around an extremum of the fitted sine curves, an equal value for the weighting factor w may be used. j(n) are assigned, while for areas outside the extremum one or more other values ​​for the weighting factor w are assigned. j (n) can be assigned.

[0055] According to some examples, the weighting factor w j (n) are determined based on statistical information for each set of measurement phase step values. According to some examples, the statistical information may be distribution information that provides a measure of the distribution of the measurement phase step values ​​within the respective set of measurement phase step values.

[0056] According to some examples, the weighting factor w j (n) can be determined based on the distance of each measurement phase step value from a median or mean value. In some examples, the weighting factor w can be j(n) will be set to zero if a given measurement phase step value lies outside specific limits, for example outside the 20th and 80th percentiles of the set of measurement phase step values.

[0057] According to some examples, the weighting factor w is based on j (n) on a size of the down-converted signal, which can be determined, for example, by the amplitude A of the matching curve for each receive path. In some examples, the weighting factor w j (n) are based on a DC offset of the down-converted signal, which can be determined, for example, by the offset B of the matching curve for each receive path.

[0058] According to some examples, the weighting factor can be based on a combination of statistical information and / or amplitude and / or a measurement DC offset. According to one example, the weighting factor can be determined according to w j (n) = A j σ j or w j(n) = B j σ j or wj(n)=AjσjBj be determined, where σ j the standard deviation of the respective set of measurement phase step values ​​corresponding to the receive path j, A j . the amplitude of the matching curve that corresponds to the receiving path j, and B j The measurement DC offset of the matching curve is that which corresponds to the receive path j, as described above.

[0059] According to some examples, combining the sets of measurement phase step values ​​involves removing outliers before averaging the measurement phase step values.

[0060] Fig. Figure 7A shows a distribution of the measurement phase step values ​​of the set corresponding to receive path RX1. It can be observed that the average calculated phase step value is 1.4995° and the standard deviation of the set of measurement phase step values ​​is determined to be 0.57611. Fig. Figure 7B shows a distribution of the same set of calculated measurement phase step values ​​with a preselection in which outliers outside the 20th and 80th percentiles are removed before processing. The average calculated phase step value is reduced to 1.4293°, which is much closer to the expected value of 1.4062°. Furthermore, the standard deviation is reduced to 0.10404, indicating the improvement achieved by removing outliers.

[0061] Fig. Figure 8 shows a set of measurement phase step values, which includes initial measurement phase step values ​​generated using weighting factors derived from wj(n)=|d Mfittingdφ|φ=φ(n)| determined and averaged over 30 measurements.

[0062] The phase step error of the phase shifter 16 can be determined for each target phase value by comparing the respective measurement phase step value with the target phase value (e.g., by subtracting the respective measurement phase step value from the target phase value). In this way, a phase step error curve of the phase shifter 16 can be generated for the different target phase values.

[0063] It should be noted that the phase error in the measurements was approximately zero, as the phase shifter 16 used in the measurements was pre-calibrated. Fig.Figure 8 shows that the phase step values ​​are determined with an accuracy of + / - 0.3°, being very close to the expected target phase step value (dashed line). This demonstrates the high accuracy of the concept for determining the actual phase step error applied by the phase shifter when the target phase value is changed from a first value to a second value, or by a corresponding error of the actual phase step introduced by the phase shifter.

[0064] In addition to the examples above, the following examples are disclosed herein. According to one example, a method for determining phase information indicating a phase error of a phase shifter in a transmit path of an RF device comprises a series of operations for measuring and calculating the phase information. The method begins by controlling a phase shifter of the transmit path to apply a phase shift according to a target phase value from a set of target phase values, which may be related to a predetermined range of phase values, in order to produce an RF transmit signal corresponding to the target phase value. This RF transmit signal is then transmitted via the transmit path.

[0065] The RF transmit signal is received as crosstalk in a plurality of receive paths, with each receive path receiving a corresponding RF receive signal that exhibits crosstalk of the respective RF transmit signal into the respective receive path. Crosstalk can refer to a direct transfer of energy from the transmit path to a given receive path or a transfer of energy from the transmit path to a given receive path via a near-reflecting object. The plurality of RF receive signals are then down-converted to generate a plurality of down-converted receive signals. Down-conversion can refer to the process of converting a high-frequency signal into a low-frequency signal.

[0066] In each receive path, the respective down-converted received signal is processed to generate a measurement value that corresponds to the target phase value applied by the phase shifter. This processing can include various signal processing techniques, such as filtering or amplification.

[0067] Multiple sets of measurements are generated by repeating the phase shifter control, RF transmit signal transmission, step-down conversion, and processing for each receive path. Each set of measurements is assigned to a specific receive path and is generated for each target phase value within that set of target phase values.

[0068] The phase information is then determined based on processing the majority of sets of measurements. This processing can involve various algorithms and techniques, such as curve fitting, Fourier transform, or interpolation, to extract the phase information from the measurements.

[0069] In one implementation, the RF transmit signal is a continuous-wave RF signal with a fixed frequency and / or the set of target phase values ​​includes every phase value φ n = 360° n N , where N is a number equal to or greater than 4 and n is a number from 1 to N.

[0070] In another implementation, determining the phase information involves processing the plurality of sets of measured values ​​to calculate a plurality of sets of measurement phase values.

[0071] In another implementation, determining the phase information involves: processing each set of measurements to determine initial information specifying an amplitude, A, and an offset, B, of a respective sinusoidal curve corresponding to that set of measurements; and processing that set of measurements to generate the plurality of sets of measurement phase values. Processing each set of measurements might, for example, involve applying a function arcsin((M(m) - B) / A) to each measurement M.

[0072] In another implementation, processing each set of measurements to determine the initial information includes at least one of the following steps: Fourier transforming the set of measurements to determine the initial information, or fitting a sinusoidal curve to determine the initial information.

[0073] In another implementation, determining the phase information involves: processing the plurality of sets of measurement phase values ​​to generate a plurality of sets of measurement phase step values. Each respective set of phase step values ​​is calculated by determining pairs of respective measurement phase values ​​within a respective set of measurement phase values ​​and calculating a difference between the respective measurement phase values ​​of each pair, and combining two or more of the sets of measurement phase step values ​​to generate a set of initial phase step values.

[0074] In another implementation, combining two or more of the sets of measurement phase step values ​​involves determining a respective weighting factor for each measurement phase step value of the plurality of sets of measurement phase step values ​​and combining the plurality of sets of measurement phase step values ​​using the respective weighting factor for each measurement phase step value to determine the set of first phase step values.

[0075] In another implementation, determining a given weighting factor involves at least one of the following: determining amplitude information, determining slope information for each measurement phase value, or determining distribution information. The amplitude information specifies the amplitude of each respective RF received signal. The slope information specifies the difference between a given measurement phase value and an adjacent measurement phase value, or it specifies the derivative of a curve that fits a given set of measurement phase values. The distribution information can specify a measure of the distribution with respect to a given set of measurement phase step values. The respective weighting factor is determined based on at least one of the amplitude information, the slope information, or the distribution information.

[0076] In another implementation, combining two or more of the sets of measurement phase step values ​​to generate a set of first phase step values ​​involves processing the plurality of sets of measurement phase step values ​​to determine whether the measurement phase step value is an outlier or not, and if one or more outliers are identified, removing one or more measurement phase step values ​​corresponding to the one or more identified outliers from the respective set of measurement phase step values.

[0077] In another implementation, processing the multiple sets of measurement phase step values ​​to determine whether a measurement phase step value is an outlier involves processing the multiple sets of measurement phase step values ​​by applying a statistical function to each set of measurement phase step values ​​to generate statistical information, and using the statistical information to determine for each measurement phase step value whether the respective measurement phase step value is an outlier or not. The statistical information can include, for example, percentile information, such as 20th-80th percentile information.

[0078] Another implementation involves comparing the initial phase step values ​​with a target phase step value to determine the phase information, where the target phase step value is a difference between a pair of target phase values.

[0079] Another implementation includes at least one of the following operations: determining calibration information based on the phase information or using the calibration information during operation of the RF device.

[0080] According to another example, an RF device comprises a transmit path configured to send an RF transmit signal over the transmit path, a phase shifter located in the transmit path and configured to apply a phase shift to the RF transmit signal according to a target phase value from a set of target phase values, and a plurality of receive paths configured to receive a plurality of RF receive signals, including crosstalk of the respective RF transmit signal into the respective receive path. A plurality of mixers is located in the plurality of receive paths to down-convert the plurality of RF receive signals into a plurality of down-converted receive signals.A controller is configured to control the phase shifter to apply each target phase value of the set of target phase values ​​to a measurement circuit to generate a plurality of sets of measurements based on the plurality of down-converted receive signals, with each set of the plurality of sets of measurements corresponding to a respective receive path of the plurality of receive paths, and each measurement within a set of measurements corresponding to a respective target phase value applied by the phase shifter. The RF device further includes a processor configured to process the plurality of sets of measurements and to determine phase information indicating a phase error of the phase shifter based on the plurality of sets of measurements.

[0081] In one implementation of the RF device, the transmit path is configured to generate the RF transmit signal as a continuous-wave RF signal at a fixed frequency, and / or the control is configured to control the phase shifter to apply any target phase value φ(n) = 360° n / N, where N is a number equal to or greater than 4 and n is a number from 1 to N.

[0082] In another implementation, the measuring circuit is configured to determine a respective DC value of the down-converted received signal as a respective measured value for each receive path of the plurality of receive paths.

[0083] In another implementation, the processor is configured to process the plurality of sets of measured values ​​in order to calculate a plurality of sets of measurement phase values.

[0084] In another implementation, the processor is configured to process each set of measurements to determine initial information specifying an amplitude, A, and an offset, B, of a respective sinusoidal curve corresponding to that set of measurements. The processor is further configured to process the set of measurements to generate the plurality of sets of measurement phase values. Processing the set of measurements might, in one example, involve applying a function arcsin((M(m) - B) / A) to each respective measurement M(m).

[0085] In another implementation, the processor is configured to process each set of measurements to determine the initial information by at least one of the following processing operations: Fourier transforming the set of measurements to determine the initial information, or fitting a sinusoidal curve to determine the initial information.

[0086] In another implementation, the processor is configured to process multiple sets of measurement phase values ​​to generate a respective set of measurement phase step values ​​for each receive path. The processor is configured to generate each set of phase step values ​​based on determining pairs of respective measurement phase values ​​and calculating the difference between each pair. It then combines two or more sets of measurement phase step values ​​to generate a set of initial phase step values.

[0087] In another implementation, the processor is configured to combine two or more of the sets of measurement phase step values ​​by determining a respective weighting factor for each measurement phase step value of the plurality of sets of measurement phase step values ​​and combining the plurality of sets of measurement phase step values ​​using the respective weighting factor for each measurement phase step value to determine the first phase step value.

[0088] In another implementation of the RF according to the second aspect, the processor is configured to determine at least one of the following pieces of information: amplitude information, slope information, or distribution information. The amplitude information can specify the amplitude of each respective RF receive signal; the slope information specifies, for each measurement phase value, the difference between a given measurement phase value and an adjacent measurement phase value, or it can specify a derivative of a curve that fits a given set of measurement phase values; and the distribution information can specify a measure of the distribution with respect to a given set of measurement phase step values. The processor is further configured to determine the weighting factor based on at least one of the amplitude, slope, or distribution information.

[0089] In another implementation, the processor is configured to: process the plurality of sets of measurement phase step values ​​to determine whether the measurement phase step value is an outlier or not, and if one or more outliers are identified, remove one or more measurement phase step values ​​corresponding to the one or more identified outliers from the respective set of measurement phase step values.

[0090] In another implementation, the processor is configured to: process the plurality of sets of measurement phase step values ​​by applying a statistical function to each set of measurement phase step values ​​to generate statistical information, and apply the statistical information to determine for each measurement phase step value whether the respective measurement phase step value is an outlier.

[0091] In another implementation, the RF device is further configured to determine calibration information based on the phase information and to use the calibration information during operation of the RF device, and / or to monitor the phase information during operation of the RF device.

[0092] Although specific examples have been illustrated and described here, the person skilled in the art will recognize that a multitude of alternative and / or equivalent implementations can replace the specific examples shown and described without altering the scope of the present invention. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this invention is limited only by the claims and their equivalents.

[0093] In another implementation of the procedure according to the second aspect, the processor is configured to process each set of measurements in order to determine the initial information by at least one of the following processing operations: Fourier transforming the set of measurements to determine the initial information, or fitting a sinusoidal curve to determine the initial information.

[0094] It should be noted that the methods and devices, including their preferred embodiments, as set forth in this document, can be used alone or in combination with the other methods and devices disclosed herein. Furthermore, the features set forth in connection with a device are also applicable to a corresponding method and vice versa. Moreover, all aspects of the methods and devices set forth in this document can be combined as desired. In particular, the features of the claims can be combined with one another in any way desired.

[0095] It should be noted that the description and drawings merely illustrate the principles of the proposed methods and systems. A person skilled in the art will be able to implement various arrangements which, although not explicitly described or shown here, embody the principles of the invention and are included in its meaning and scope. Furthermore, all examples and embodiments presented in this document are expressly intended primarily for illustrative purposes only, to assist the reader in understanding the principles of the proposed methods and systems. Moreover, all statements herein that provide principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to include equivalents thereof.

Claims

[1] Method for determining phase information indicating a phase error of a phase shifter in a transmit path of an RF device, wherein the method comprises: Controlling a phase shifter of the transmit path to apply a phase shift according to a target phase value from a set of target phase values ​​in order to generate an RF transmit signal corresponding to the target phase value; transmitting the RF transmit signal via the transmit path. Receiving a plurality of RF receive signals in a plurality of receive paths, wherein each of the plurality of RF receive signals is assigned to a respective receive path and exhibits crosstalk of the respective RF transmit signal into the respective receive path, Down-converting the majority of RF received signals to generate a majority of down-converted received signals, in each receive path of the plurality of receive paths, processing the respective down-converted receive signal that is assigned to the respective receive path in order to generate a measurement value for each receive path that is assigned to the target phase value that is applied by the phase shifter, Generating a plurality of sets of measured values, wherein each set of the plurality of sets of measured values ​​is assigned to a respective receive path of the plurality of receive paths, wherein the plurality of sets of measured values ​​is generated by repeating the control of the phase shifter, the transmission of the RF transmit signal, the step-down conversion and the processing in each receive path in order to generate, for each target phase value of the set of target phase values ​​in each respective receive path, a corresponding measured value of a respective set of measured values, and Determining phase information based on processing the majority of sets of measured values. [2] Method according to claim 1, wherein the RF transmit signal is a continuous-wave RF signal with a fixed frequency and / or the set of target phase values ​​is each phase value φ(n)=360°nN includes, where N is a number equal to or greater than 4 and n is a number from 1 to N. [3] Method according to any of the preceding claims, wherein the processing in each receive path comprises the plurality of receive paths: Determine for each receive path of the plurality of receive paths a respective DC value of the down-converted received signal as a respective measured value that is assigned to the respective target phase value applied by the phase shifter. [4] Method according to any of the preceding claims, wherein the determination of the phase information comprises: Processing the plurality of sets of measured values ​​to calculate a plurality of sets of measurement phase values, wherein each set of measurement phase values ​​is assigned to one of the plurality of receive paths, and wherein each measurement phase value within a respective set of measurement phase values ​​is assigned to a corresponding measured value and indicates a measured phase value of the crosstalk into the respective receive path. [5] The method of claim 4, wherein the determination of the phase information comprises: Processing each set of measurements to determine initial information specifying an amplitude, A, and an offset, B, of a respective sinusoidal curve that corresponds to the respective set of measurements, and Processing each set of measured values ​​to generate the majority of sets of measurement phase values. [6] Method according to claim 5, wherein the processing of each set of measured values ​​to determine the first information comprises at least one of the following operations: Fourier transforming the set of measured values ​​to determine the initial information, or Fitting a sinusoidal curve to determine the initial information. [7] Method according to any one of claims 4 to 6, wherein the determination of the phase information comprises: Processing the plurality of sets of measurement phase values ​​to generate a plurality of sets of measurement phase step values, wherein each respective set of phase step values ​​is calculated by determining pairs of respective measurement phase values ​​within a respective set of measurement phase values ​​and calculating a difference between the respective measurement phase values ​​of each pair. Combining two or more of the sets of measurement phase step values ​​to generate a set of first phase step values. [8] Method according to claim 7, wherein the combination comprises two or more of the sets of measurement phase step values: Determining a respective weighting factor for each measurement phase step value of the plurality of sets of measurement phase step values, Combining the plurality of sets of measurement phase step values ​​using the respective weighting factor for each measurement phase step value to determine the set of first phase step values. [9] The method of claim 8, wherein determining a respective weighting factor comprises at least one of: Determining amplitude information that specifies the amplitude of each respective RF received signal, Determining slope information, wherein the slope information provides information about a difference between a given measurement phase value and an adjacent measurement phase value, or provides a derivative of a curve that fits a given set of measurement phase values, and determining the given weighting factor based on the slope information. Determining distribution information that provides a measure of the distribution with respect to a given set of measurement phase step values, and determining the weighting factor based on the distribution information, and Determining the respective weighting factor based on at least one of the amplitude information, the slope information, or the distribution information. [10] Method according to claim 7, comprising combining two or more of the sets of measurement phase step values ​​to generate a set of first phase step values: Processing the majority of sets of measurement phase step values ​​to determine whether the measurement phase step value is an outlier or not, and If one or more outliers are identified, remove one or more measurement phase step values ​​corresponding to the one or more identified outliers from the respective set of measurement phase step values. [11] Method according to claim 10, comprising processing the plurality of sets of measurement phase step values ​​to determine whether the measurement phase step value is an outlier or not: Processing the plurality of sets of measurement phase step values ​​by applying a statistical function to each set of measurement phase step values ​​to generate statistical information, and Using the statistical information to determine for each measurement phase step value whether the respective measurement phase step value is an outlier or not. [12] Method according to any one of claims 5 to 11, further comprising comparing the first phase step values ​​with a target phase step value to determine the phase information, wherein the target phase step value is a difference between a pair of target phase values. [13] A method according to any of the preceding claims, further comprising at least one of the following processes: Determining calibration information based on the phase information and using the calibration information during operation of the RF device, or Monitoring phase information during operation of the RF device. [14] RF device which features: a transmit path that is configured to send an RF transmit signal over the transmit path, a phase shifter that is placed in the transmit path and configured to apply a phase shift to the RF transmit signal according to a target phase value from a set of target phase values, a plurality of receive paths configured to receive a plurality of RF receive signals, exhibiting crosstalk of the respective RF transmit signal into the respective receive path, a plurality of mixers arranged in the plurality of receive paths to down-convert the plurality of RF receive signals into a plurality of down-converted receive signals, a controller configured to control the phase shifter to apply each target phase value from the set of target phase values, a measuring circuit to generate a plurality of sets of measured values ​​based on the plurality of down-converted received signals, wherein each set of the plurality of sets of measured values ​​is assigned to a respective receive path of the plurality of receive paths, and each measured value within a set of measured values ​​is assigned to a respective target phase value applied by the phase shifter, and a processor configured to process the plurality of sets of measurements and to determine phase information that specifies a phase error of the phase shifter based on the plurality of sets of measurements. [15] RF device according to claim 14, wherein the transmit path is configured to generate the RF transmit signal as a continuous-wave RF signal with a fixed frequency, and / or wherein the control is configured to control the phase shifter to achieve any target phase value φ(n)=360°nN to apply, where N is a number equal to or greater than 4 and n is a number from 1 to N. [16] RF device according to claim 14 or 15, wherein the measuring circuit is configured to determine a respective DC value of the down-converted received signal as a respective measured value for each receive path of the plurality of receive paths. [17] RF device according to one of the preceding claims, wherein the processor is configured to process the plurality of sets of measured values ​​in order to calculate a plurality of sets of measurement phase values, wherein each set of measurement phase values ​​is assigned to one of the plurality of receive paths and wherein each measurement phase value indicates a measured transmit phase value corresponding to the respective measured value. [18] RF device according to claim 17, wherein the processor is configured to process each set of measured values ​​to determine initial information specifying an amplitude, A, and an offset, B, of a respective sinusoidal curve corresponding to the respective set of measured values, and wherein the processor is further configured to process the set of measured values ​​to generate the plurality of sets of measurement phase values. [19] RF device according to claim 18, wherein the processor is configured to process each set of measured values ​​in order to determine the first information by at least one of the following processing operations: Fourier transforming the set of measured values ​​to determine the initial information, or Fitting a sinusoidal curve to determine the initial information. [20] RF device according to any one of claims 17 to 19, wherein the processor is configured to process the plurality of sets of measurement phase values ​​in order to generate for each receive path a respective set of measurement phase step values ​​of a plurality of sets of measurement phase step values, wherein the processor is configured to generate a respective set of phase step values ​​based on determining pairs of respective measurement phase values ​​and calculating a difference between the respective measurement phase values ​​of each pair, and wherein the processor is configured to combine two or more of the sets of measurement phase step values ​​to generate a set of first phase step values. [21] RF device according to claim 20, wherein the processor is configured to combine two or more of the sets of measurement phase step values ​​by determining a respective weighting factor for each measurement phase step value of the plurality of sets of measurement phase step values, and combining the plurality of sets of measurement phase step values ​​using the respective weighting factor for each measurement phase step value to determine the first phase step value. [22] RF device according to claim 21, wherein the processor is configured to determine at least one of the following information: Amplitude information specifying the amplitude of each respective RF received signal, Slope information for each measurement phase value, wherein the slope information specifies a difference between a given measurement phase value and an adjacent measurement phase value, or specifies a derivative of a curve that fits a given set of measurement phase values. Distribution information that provides a measure of the distribution with respect to a given set of measurement phase step values, and wherein the processor is further configured to determine the weighting factor based on at least one of the amplitude information, the slope information or the distribution information. [23] RF device according to claim 20, wherein the processor is configured to: to process the majority of sets of measurement phase step values ​​to determine whether the measurement phase step value is an outlier or not, and If one or more outliers are identified, remove one or more measurement phase step values ​​corresponding to the one or more identified outliers from the respective set of measurement phase step values. [24] RF device according to claim 23, wherein the processor is configured to: to process the majority of sets of measurement phase step values ​​by applying a statistical function to each set of measurement phase step values ​​in order to generate statistical information, and to apply the statistical information to determine for each measurement phase step value whether the respective measurement phase step value is an outlier. [25] RF device according to any one of claims 14 to 24, further configured to determine calibration information based on the phase information and to use the calibration information during operation of the RF device, and / or to monitor the phase information during operation of the RF device.

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