METHOD FOR DETERMINING PHASE INFORMATION RELATED TO AN RF TRANSMITTING CHANNEL AND RADAR MMIC DEVICE

Abstract

Method for determining phase information with respect to an RF transmit channel, wherein the method comprises the following: Generating a frequency-modulated RF signal, wherein the frequency-modulated RF signal includes a frequency ramp, coupling a first representation of the frequency-modulated RF signal into the RF transmit channel to generate a first frequency-modulated RF output signal, and coupling a second representation of the frequency-modulated RF signal into a test phase shifter. A set of measurement samples is generated during the frequency ramp, wherein the set of measurement samples is based on setting, during the frequency ramp, a phase shift provided by the test phase shifter, to each phase shift value of a predetermined set of phase shift values ​​and the phase shifting of the second representation of the frequency-modulated RF signal according to the respective phase shift value to generate a frequency-modulated RF test signal, generating a down-converted signal based on mixing a first representation of the first frequency-modulated RF output signal with the frequency-modulated RF test signal, sampling the down-converted signal to generate a respective measurement sample of a set of measurement samples for each phase shift value of the set of phase shift values.and calculating the phase information in relation to the RF transmit channel based on the set of measurement samples.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of determining phase information related to an RF transmit channel, and more particularly to determining phase information of a transmit channel of a radar MMIC device. BACKGROUND

[0002] Radar sensors that utilize at least one radar MMIC (Monolithic Microwave Integrated Circuit) device are used in many cars and other vehicles today to assist the driver or provide autonomous driving. Such applications require a high level of safety, as a failure of the radar MMIC or operation outside the specified operating range of the radar MMIC can lead to unreliable operation or failure of the assistance system. Typically, several safety objectives of a radar MMIC are defined toward specific transmit signal parameters. These parameters are typically monitored by the radar MMIC to achieve the required level of safety.

[0003] Typically, the phase and amplitude alignment between all transmit or TX channels involved in a radar measurement must be within a certain range to ensure operation as defined in the device specification. Typically, only a few degrees of phase imbalance are permitted for the phases of the transmit channels.

[0004] In view of the above, there is a need for a concept to provide improved determination of phase information for a transmit channel of a radar MMIC. SUMMARY

[0005] According to one example, a method for determining phase information related to an RF transmit channel includes generating a frequency-modulated RF signal, wherein the frequency-modulated RF signal includes a frequency ramp, coupling a first representation of the frequency-modulated RF signal into the RF transmit channel to generate a first frequency-modulated RF output signal, and coupling a second representation of the frequency-modulated RF signal into a test phase shifter. A set of measurement samples is generated during the frequency ramp, wherein the set of measurement samples is based on setting, during the frequency ramp, a phase shift provided by the test phase shifter to each phase shift value of a predetermined set of phase shift values ​​and phase-shifting the second representation of the frequency-modulated RF signal according to the respective phase shift value.to generate a frequency-modulated RF test signal, generating a down-converted signal based on mixing a first representation of the first frequency-modulated RF output signal with the frequency-modulated RF test signal, sampling the down-converted signal to generate a respective measurement sample of a set of measurement samples for each phase shift value of the set of phase shift values, and calculating the phase information related to the RF transmit channel based on the set of measurement samples.

[0006] According to another example, a radar MMIC device includes a local oscillator for generating a frequency-modulated RF signal including a frequency ramp, an RF transmit channel, a test phase shifter, and a first coupler configured to couple a first representation of the frequency-modulated RF signal into the RF transmit channel and a second representation of the frequency-modulated RF signal into the test phase shifter. The RF transmit channel is configured to generate a first frequency-modulated RF output signal based on the frequency-modulated RF signal, and the test phase shifter is configured to phase-shift the second representation of the frequency-modulated RF signal according to a phase shift applied to the test phase shifter and generate a frequency-modulated RF test signal. A second coupler is coupled to the RF transmit channel to generate a first representation of the frequency-modulated RF output signal.A mixer is coupled to the test phase shifter and the second coupler to receive the first representation of the frequency-modulated RF output signal and the frequency-modulated RF test signal, the mixer further configured to generate a down-converted signal based on mixing the first representation of the frequency-modulated RF output signal with the frequency-modulated RF test signal. A controller is configured to adjust the phase shift applied to the test phase shifter during the frequency ramp to each phase shift value of a predetermined set of phase shift values. A sampler is provided to sample the down-converted signal to generate a respective measurement sample of a set of measurement samples for each phase shift value of the set of phase shift values.A processor calculates phase information related to the transmit channel based on the set of measurement samples.

[0007] Those skilled in the art will recognize additional features and advantages upon reading the following detailed description and upon viewing the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present disclosure is illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like reference numerals 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 illustrated examples may be combined, provided they are not mutually exclusive. Fig. 1 illustrates a circuit diagram according to an example. Fig. 2A to Fig. 2C illustrate generating a set of measurement samples according to an example. Fig. 3 illustrates an estimation of a phase error according to an example. Fig. Figure 4 illustrates another example of generating a set of measurement samples. Fig. 5 illustrates a flowchart according to an example. DETAILED DESCRIPTION

[0009] The examples described herein provide a new concept for determining phase information for calibration and monitoring routines. This new concept allows for reducing the power spectral density generated during the determination of phase information and, in some examples, further allows for determining the phase information during field operation of the radar MMIC device based on frequency-modulated continuous wave (FMCW) signals.

[0010] Existing solutions use continuous-wave signals from the phase-locked loop (PLL) with a constant frequency to determine the phase information of a transmit channel. In contrast, the use of an FMCW signal to determine phase information achieves a significant reduction in the average spectral power density emitted by the MMIC device during operation, as the frequency of the signal used to determine the phase information is no longer concentrated at one frequency but is distributed across a frequency band. This makes it possible to remain within the emission requirements of standards bodies such as ETSI (European Telecommunications Standards Institute) without requiring a reduction in transmit power.

[0011] Additionally, the same type of signals, i.e., FMCW signals, are used for specified field operation (i.e., determining a range, speed, or direction of arrival) and monitoring or calibration. Accordingly, monitoring and calibration are performed under realistic conditions, increasing the level of safety. Furthermore, the measurement is performed during only one frequency ramp, enabling rapid determination of phase information suitable for field operation.

[0012] The determination of the phase information can be performed periodically during field operation, for example between respective FMCW ramps (chirps) or between a frame of FMCW ramps.

[0013] In other examples, the same FMCW signal transmitted during a frequency ramp to detect a range, speed, or angle of arrival of objects can be used for monitoring and calibration.

[0014] The determination of phase information as proposed herein allows the required components to be integrated into a semiconductor chip (e.g., an MMIC chip), and the concept can therefore be implemented as an on-chip measurement (all required steps are performed in a semiconductor chip).

[0015] With reference to Fig. 1, a radar device 10 is shown as including a plurality of transmission channels 12-1 to 12-4 for generating transmission signals. The radar device 10 may be an MMIC semiconductor chip, and further functionalities, such as reception channels, that may be implemented in the radar device 10 are shown in Fig. 1 has been omitted for clarity. Each input of a respective transmit channel is coupled to a local oscillator (LO) 18 via a first coupler 14 and a second coupler 16. The first coupler 14 and the second coupler 16 are implemented as splitters, which may be formed by passive components. Each transmit channel includes a phase shifter 20 (hereinafter referred to as transmit phase shifter 20), a power amplifier 22, and a coupler 24. Each of the transmit channels 12-1 to 12-4 may include other components that are not shown for simplicity. The local oscillator 18 is configured to generate a frequency-modulated radio frequency signal 25 (frequency-modulated RF signal 25) that includes a frequency ramp. In examples, the frequency modulated RF signal 25 is a frequency modulated continuous wave (FMCW) signal that includes a linear frequency ramp with a start frequency and a stop frequency.The frequency ramp can be an ascending ramp, so that the frequency increases over time, or a descending ramp, so that the frequency decreases over time.

[0016] The frequency-modulated RF signal 25 is split by the first coupler 14 into a first representation of the frequency-modulated RF signal (referred to herein as the transmit path signal 26) and a second representation of the frequency-modulated RF signal (referred to herein as the test path signal 28). The transmit path signal 26 and the test path signal 28 are replicas of the frequency-modulated RF signal with a reduced power level compared to the LO signal. The test path signal 28 is transmitted to the test circuitry 30, which is described in more detail below. The transmit path signal 26 is coupled to an input of the second coupler 16. The second splitter 16 splits the transmit path signal 26 into four representations, which are transmitted via outputs of the second splitter 16 to the transmit channels 12-1 through 12-4, respectively.Transmit channels 12-1 to 12-4 can be controlled to be enabled or disabled for processing, for example, by enabling or disabling power amplifier 22. During radar processing operation, for example, all or a set of transmit channels 12-1 to 12-4 can be enabled. During monitoring or calibration operation, described below, only one of the plurality of transmit channels can be enabled.

[0017] The activated transmit channel processes the received transmit path signal 26 by applying a respective phase shift via the transmit phase shifter 20 and amplifying the phase-shifted transmit path signal 26 to generate a frequency-modulated RF output signal 32. The frequency-modulated RF output signal 32 is transmitted to an input of the coupler 24, which couples a first representation 34 of the frequency-modulated RF output signal 32 to an input of a combiner 36. A second representation 38 of the frequency-modulated RF output signal 32 may be transmitted to an antenna port associated with the respective transmit channel. The second representation may be a major portion of the frequency-modulated RF output signal 32, i.e., the signal power of the second representation 38 may be higher than the signal power of the first representation 34.

[0018] Combiner 36 may include an input associated with each of the transmit channels 12-1 through 12-4, which is coupled to the coupler 24 of the respective transmit channel. Combiner 36 couples the first representation 34 of the frequency-modulated RF output signal 32 to a first input of a mixer 38 (also referred to herein as test mixer 38) of test circuitry 30.

[0019] The test circuitry 30 further includes a phase shifter 40 (also referred to herein as test phase shifter 40). In some examples, the test phase shifter 40 may include a passive phase shifter that increases the accuracy of the phase shift. An input of the test phase shifter 40 is coupled to an output of the coupler 14 to receive the test path signal 28. The test phase shifter 40 applies a phase shift to the test path signal 28 to generate a frequency-modulated RF test signal 29 having a phase shift according to a phase shift value applied to the test phase shifter 40 by a controller 50. An output of the test phase shifter 40 is coupled to a second input of the test mixer 38 to transmit the frequency-modulated RF test signal 29 to the test mixer 38.The test mixer 38 mixes the two signals (also referred to herein as downconverting) and provides a downconverted signal 42 at an output, which may be amplified by an optional amplifier 44. The amplified downconverted signal 42 is provided to an analog-to-digital converter 46 to generate a set of measurement samples, as described in more detail below.

[0020] The set of measurement samples is provided to a processor 48 configured to calculate phase information related to the respective transmit channel. The controller 50 is configured to set a phase shift applied to the test phase shifter 40 during the frequency ramp to each phase shift value of a predetermined set of phase shift values, as described in more detail. The controller 50 further controls the sampling of the measurement samples such that at least one measurement sample is generated for each phase shift value of the set of phase shift values. The controller 50 and the processor 48 may be implemented as hardware circuitry, software, firmware, or any combination thereof.Processor 48 may include, for example, a Goertzel filter or an FFT circuit and a programmable arithmetic logic unit or a digital processor capable of performing data processing or executing programming steps. In some examples, controller 50 may use all or part of the same components or be implemented as a single unit. For example, controller 50 may use processor 48 to perform control operations.

[0021] With reference to Fig. 2A to Fig. 2C describes the setting of the phase shift and the sampling of the measurement samples during the frequency ramp in more detail. Fig. Figure 2A shows the frequency of the frequency-modulated RF signal 25 as a function of time during a frequency ramp. Fig. 2A shows the frequency of the frequency-modulated RF signal 25 increasing linearly during the frequency ramp from a start frequency to a stop frequency. In other examples, the frequency may decrease linearly. While the examples shown herein use a linear frequency ramp, other examples may deviate from a linear ramp characteristic. For example, the start frequency and stop frequency may be within a dedicated radar band, for example, between 76 GHz and 81 GHz.

[0022] Fig. 2B shows the phase shift applied by the test phase shifter 40 to generate the frequency-modulated RF test signal 29. During the frequency ramp of the frequency-modulated RF test signal 28 (which corresponds to the frequency ramp of the frequency-modulated RF signal 25), each phase shift value of a set of 100 phase shift values ​​is applied to the test phase shifter 40 to provide the corresponding phase shift for the frequency-modulated RF test signal 29. In other words, the frequency-modulated RF test signal 29 can be considered to be divided into a sequence of time intervals. During a respective time interval of the sequence of time intervals, the frequency-modulated RF test signal 29 contains a phase shift according to a phase shift value of the set of 100 phase shift values ​​associated with that time interval. In the example of Fig. 2B, the phase shift value is a sequence of eight phase shift values ​​that increase in equidistant steps from 0 to 7π / 4. While Fig. While Figure 2B shows eight phase shift values ​​applied during the frequency ramp, note that in other examples, different numbers of phase shift values ​​may be applied. The number of phase shift values ​​may be N, and the phase shift values ​​may increase from 0 to 2π(N-1) / N. Fig. Figure 2B shows the time intervals during which the respective phase shifts are applied to have an equal duration. However, in other examples, the duration may not be equal.

[0023] As previously described, the frequency-modulated RF test signal 29 is mixed with the first representation 34 of the frequency-modulated RF output signal 32 to generate the down-converted signal 42.

[0024] The frequency modulated RF test signal 29 can be described by SPMLO(t)=A1⋅cos(2πf0t+πkt2+φIQM), where sPMLO is the frequency-modulated RF test signal 29, t is the time in the interval [0, T], where T is the duration of the frequency ramp, k is the slope of the frequency ramp, f0 is the starting frequency of the frequency ramp, and A1 is a constant amplitude. φ IQM is the phase shift in radians applied by the test phase shifter 40 and can be defined by φIQM=2πnN where N is the number of phase shift values ​​in the set of phase shift values ​​and n = 0, 1, ..., N-1 is an index defined by a sequence of integers.

[0025] The first representation 36 of the frequency modulated RF output signal 34 can be described by sTX(t)=A2⋅cos(2πf0(t−τ)+πk(t−τ)2+φTX) where S TX(t) is the first representation 36 of the frequency-modulated RF output signal 34, φ TX is the configured phase shift applied by the phase shifter 20 in the respective transmit channel, and T is the difference in arrival time (also referred to herein as RF delay time) between the signals s PMLO (t) and s TX (t) at the test mixer 40. As in Fig. As shown in Figure 1, T results from the signal delay caused by additional circuit components of the transmit channel.

[0026] After mixing, the down-converted signal 42 is obtained as mixout(t)=A1 A2cos{2πkt2−2πkτt+4πf0t+φTX+πkt2−2πf0τ+2πnN}2+A1 A2cos{2πk τt−φTX−πkτ2+2πf0τ+2πnN}2 where mixout(t) is the downconverted signal 42.

[0027] Considering that in the first summand of mixout(t) the term 4πf0t corresponds to a frequency of 2f0 which is in the range of tens (several tens) or hundreds (several hundreds) GHz, and the other time-dependent terms 2πkτt and 2πkt 2 modify this frequency only slightly, the first summand can be neglected due to the low-pass filter characteristics of the circuits after the test mixer 38 (e.g. amplifier 44), and the down-converted signal 42 at the input of the analog-to-digital converter 46 can be represented by s(t)=A1⋅A22⋅cos(2πkτt+2πf0τ−πkτ2+2πnN−φTX).

[0028] Note that the difference in arrival time T introduces an oscillation in the down-converted signal 42 with frequency kτ. Note further that for τ = 0 (no difference in arrival time), the down-converted signal 42 would be a DC value that matches the DC value obtained when using a continuous wave signal without frequency modulation (k = 0). The phase term of this function is given by φ = 2πf0τ - πkτ 2 - φ TX Assuming that a sample of the down-converted signal 42 is time-aligned with the adjustment of the phase shifts every nTs, where Ts is the sampling interval and n is the previously introduced index variable, the sampled down-converted signal s[n] can be represented as a set of measured values ​​of s[n]=s(nTs)=A1⋅A22⋅cos(2πn(kτTs+1N)+2πf0τ−φTX) be considered.

[0029] It should be noted that the term πkτ 2was approximated as zero, since T is in the picosecond range. Timing may, in examples, involve a time interval between two consecutive phase shift adjustments corresponding to a time interval between two consecutive samplings of measurement samples, which allows for a reduction in processing and implementation effort.

[0030] Fig. Figure 2C shows an example of a set of measurement samples 102 taken with a sampling time T s Accordingly, the set of measured values ​​S[n] contains N discrete measurement points representing a sampled period of a cosine wave as a function of the index variable n. Fig. Figure 2C shows the sampled value in volts of eight measurement samples s1..s7 versus time, and for illustrative purposes the corresponding cosine function s(t) is shown as described above.

[0031] The frequency of the first order harmonic function is defined by 2πn(kτTs+1N). Compared to a continuous wave signal, the use of a frequency modulated signal introduces an additional frequency component 2πkτT s which can be considered as an error frequency. The phase term of this first-order harmonic function is obtained as 2πf0τ - φ TXIt should be noted that all information for determining amplitude and phase parameters can be derived from the first-order harmonic bin value (bin with frequency index 1 from a set of frequency indices m = 0, 1, ... M-1, with M = N) of the Fourier transform result (coefficient of the first-order harmonic Fourier transform) by a fast Fourier transform (FFT) or a single-point digital Fourier transform (e.g., using a Goertzel filter). The result can be used to calibrate and / or monitor safety-relevant transmission parameters within the radar device 10.

[0032] The first-order harmonic bin value is a complex value and can be written as z1 = Re(z1) + Im(z1), where Re is the real part of the complex-valued first-order harmonic bin value and Im is the imaginary part of the complex-valued first-order harmonic bin value.

[0033] Assuming that πkτ 2 is small, the phase term 2πf0τ - φ TX For example, it can be derived by determining or estimating the inverse tangent of (Im(z1) / Re(z1)) or arctan2(Im(z1),Relm(z1)). The inverse tangent or arctan2 can be estimated, for example, using a Cordic implementation or using a processor capable of calculating or estimating the inverse tangent function.

[0034] It should be noted that the phase term 2πf0τ - φ TX the phase φ TX of the transmission channel to be determined and a factor 2πf0τ caused by the difference in arrival times T, which is the same for all transmission channels. By determining the above phase term between two or more transmission channels, the relative phase information between the channels can be determined, enabling calibration and monitoring of the transmission channels relative to each other.

[0035] Furthermore, it should be noted that due to discrete sampling, a phase error may be introduced, considering that a frequency-modulated RF signal, rather than a fixed-frequency signal, is used as the test signal. The phase error can be estimated by the integral of the error frequency, introduced above over the full harmonic deviation. Since s[n] represents a digital signal, the integral can be replaced by a sum, and the analytical phase error can be estimated. e=1N⋅∑n=0N−12πkτnTs=πkτTs(N−1)

[0036] The introduced error, and therefore any post-processing error correction, depends on the slope k of the ramp, the sampling interval Ts, and the number N of phase shifts in the sequence of phase shifts. All of these parameters can be determined or are known, and the phase error can be calculated and corrected based on these parameters. The RF delay time T can be estimated from the zero-order harmonic bin (DC mean). Considering the following values: k = 1 MHz / µs, T s = 3 µs, N = 8 and τ = 250 ps, ​​which are typical values ​​for a radar application, the expected error is calculated as e = 0.945°.

[0037] The test circuitry 30 of the radar device 10 estimates the deviation from the true phase value φ TX based on applying a Fourier transform to s[n].

[0038] This subsequently leads to a dependence on the phase term φ = 2πf0t - πkτ2 - φ TX , which effectively results in a sinusoidal fluctuation around e. It can be shown that the actual error can be approximated by eFT=2πkTsτ cos(2φ+π4)+πkτTs(N−1).

[0039] The phase error e FT depends on the phase term φ = 2πf0t - πkτ 2 - φ TX and therefore effectively from the phase φ TX which is to be determined.

[0040] Fig. 3 is a graph 200 showing the above estimates of the phase errors as a function of the phase term φ. A curve 202 shows the phase error e=1N⋅∑n=0N−12πkτnTs=πkτTs(N−1), which was calculated as e = 0.945° and is independent of the phase term φ. A curve 202 shows the phase error introduced by the digital Fourier transform (DFT), and a curve 204 shows the above-described estimate of the phase error introduced by the DFT. eFT=2πkTsτ cos(2φ+π4)+πkτTs(N−1). It should be noted that curves 202 and 204 have an average value of πkτT s (N - 1).

[0041] It can be observed that curve 204 is almost identical to curve 202, showing that the introduced phase error can be accurately corrected using the approximation outlined above.

[0042] It should also be noted that a delayed start of sampling may introduce a further phase error, which may be significant with respect to Fig. 4 is described.

[0043] Fig. 4 shows the sampling of the down-converted signal with a delay time T D .

[0044] This leads to replacing the frequency f0 by the effective frequency f0 + kT D . It should be noted that Fig. 4 shows a decreasing ramp with a negative gradient K. s[n]=s(nTs)=A1⋅A22⋅cos(2πn(kτTs+1N)+2πkτTD+2πf0τ−φTX)

[0045] It can be observed from the above equation that an additional term 2πkτT D by the delay time T D which can also be calculated and corrected.

[0046] A basic flowchart example of a process using the proposed concept will now be presented in terms of Fig.5. The method begins with generating a frequency-modulated RF signal, wherein the frequency-modulated RF signal includes a frequency ramp, S10. A first representation of the frequency-modulated RF signal is coupled into the RF transmit channel to generate a first frequency-modulated RF output signal, S20. A second representation of the frequency-modulated RF signal is coupled into a test phase shifter, S30. A set of measurement samples is generated during the frequency ramp, wherein the set of measurement samples is generated based on substeps S40-1 to S40-3.Substep S40-1 includes setting, during the frequency ramp, a phase shift provided by the test phase shifter to each phase shift value of a predetermined set of phase shift values ​​and phase shifting the second representation of the frequency-modulated RF signal according to the respective phase shift value to generate a frequency-modulated RF test signal. Substep S40-2 includes generating a down-converted signal based on mixing a first representation of the first frequency-modulated RF output signal with the frequency-modulated RF test signal. Substep S40-3 includes sampling the down-converted signal to generate a respective measurement sample of a set of measurement samples for each phase shift value of the set of phase shift values.Finally, in step S50, the phase information related to the RF transmit channel is calculated based on the set of measurement samples.

[0047] In addition to the examples described above, the following examples are disclosed herein.

[0048] Example 1 is a method for determining phase information related to an RF transmit channel, the method comprising: Generating a frequency-modulated RF signal, wherein the frequency-modulated RF signal includes a frequency ramp, coupling a first representation of the frequency-modulated RF signal into the RF transmit channel to generate a first frequency-modulated RF output signal, coupling a second representation of the frequency-modulated RF signal into a test phase shifter, Generating a set of measurement samples during the frequency ramp, wherein the set of measurement samples is generated based on: Setting, during the frequency ramp, a phase shift provided by the test phase shifter to each phase shift value of a predetermined set of phase shift values ​​and phase shifting the second representation of the frequency-modulated RF signal according to the respective phase shift value to generate a frequency-modulated RF test signal, Generating a down-converted signal based on mixing a first representation of the first frequency-modulated RF output signal with the frequency-modulated RF test signal, Sampling the down-converted signal to generate a respective measurement sample of a set of measurement samples for each phase shift value of the set of phase shift values, and Calculate the phase information related to the RF transmit channel based on the set of measurement samples.

[0049] Example 2 is the method of Example 1, wherein the sampling of the down-converted signal is timed to coincide with the setting of a phase shift.

[0050] Example 3 is the method of Example 2, wherein a time interval between two consecutive adjustments of the phase shift corresponds to a time interval between two consecutive samplings of measurement samples.

[0051] Example 4 is the method of any one of Examples 1 to 3, wherein calculating the phase information comprises generating first-order harmonic information with respect to a first-order harmonic included in the set of measured values.

[0052] Example 5 is the method of Example 4, wherein generating first-order harmonic information comprises a Fourier transform of the set of measured values, and wherein the first-order harmonic information corresponds to a coefficient of the first-order harmonic Fourier transform.

[0053] Example 6 is the method of Example 4 or 5, wherein the first-order harmonic information includes an imaginary part and a real part, and determining the phase information is based on using the imaginary part and the real part.

[0054] Example 7 is the method of Example 6, the method further comprising: estimating a phase error correction value and determining the phase information based on the phase error correction value.

[0055] Example 8 is the method of Example 7, wherein the phase error correction value is estimated as a function of a slope of the frequency ramp.

[0056] Example 9 is the method of any one of examples 7 or 8, wherein the phase error correction value is estimated as a function of a sampling rate used in sampling the down-converted signal.

[0057] Example 10 is the method of any one of Examples 7 to 9, wherein the phase error correction value is estimated as a function of an RF delay time corresponding to a difference in arrival time between the first frequency-modulated RF output signal and the frequency-modulated RF test signal.

[0058] Example 11 is the method of any one of Examples 7 to 10, wherein the phase error correction value is estimated as a function of the number of phase shift values ​​in the set of phase shift values.

[0059] Example 12 is the method of any one of Examples 7 to 11, wherein the phase error correction value is estimated as a function of a time difference between a start of the frequency ramp and a start of sampling of the down-converted signal.

[0060] Example 13 is the method of any one of Examples 1 to 12, wherein a time at which the phase shift is changed from a previously applied phase shift value to a currently applied phase shift value is offset from a time at which the down-converted signal is sampled to generate the respective measurement sample corresponding to the currently applied phase shift value.

[0061] Example 14 is the method of any one of Examples 1 to 13, further comprising storing the phase information related to the transmit channel in a memory and adjusting a phase shift of a phase shifter in the transmit channel based on the stored phase information.

[0062] Example 15 is the method of any one of Examples 1 to 14, further comprising determining whether the phase information exceeds a predetermined criterion, and if the phase information exceeds a predetermined criterion, generating monitoring alert information.

[0063] Example 16 is the method of any one of Examples 1 to 15, further comprising coupling a second representation of the first frequency-modulated RF output signal into an antenna for transmission, receiving a reflection signal of the second representation of the first frequency-modulated RF signal from an object, and processing the reflection signal to determine at least one of a distance or a speed of the object or a direction of arrival.

[0064] Example 17 is the method of any one of Examples 1 to 16, wherein the down-converted signal is low-pass filtered prior to sampling.

[0065] Example 18 is a radar MMIC device comprising: a local oscillator for generating a frequency-modulated RF signal including a frequency ramp, an RF transmission channel, a test phase shifter, a first coupler configured to couple a first representation of the frequency-modulated RF signal into the RF transmit channel and a second representation of the frequency-modulated RF signal into the test phase shifter, wherein the RF transmit channel is configured to generate a first frequency-modulated RF output signal based on the frequency-modulated RF signal, and wherein the test phase shifter is configured to phase-shift the second representation of the frequency-modulated RF signal according to a phase shift applied to the test phase shifter and generate a frequency-modulated RF test signal, a second coupler coupled into the RF transmit channel to generate a first representation of the frequency-modulated RF output signal, a mixer coupled to the test phase shifter and the second coupler for receiving the first representation of the frequency-modulated RF output signal and the frequency-modulated RF test signal, the mixer further configured to generate a down-converted signal based on mixing the first representation of the frequency-modulated RF output signal with the frequency-modulated RF test signal, a control for setting the phase shift applied to the test phase shifter during the frequency ramp to each phase shift value of a predetermined set of phase shift values, a sampler for sampling the down-converted signal to generate a respective measurement sample of a set of measurement samples for each phase shift value of the set of phase shift values, and a processor for calculating phase information relating to the transmit channel based on the set of measurement samples.

[0066] Example 19 is the radar MMIC device of Example 18, wherein the controller is configured to time the adjustment of a phase shift with the sampling of the down-converted signal.

[0067] Example 20 is the radar MMIC device method of example 18 or 19, wherein the processor is configured to calculate the phase information based on generating first-order harmonic information related to a first-order harmonic included in the set of measurements.

[0068] Example 21 is the radar MMIC device of Example 20, wherein the first harmonic information includes an imaginary part and a real part, and wherein the processor is configured to calculate the phase information based on the imaginary part and the real part.

[0069] Example 22 is the radar MMIC device of any one of examples 18 to 21, wherein the processor is configured to estimate a phase error correction value and calculate the phase information based on the phase error correction value.

[0070] Example 23 is the radar MMIC device of any one of Examples 18 to 22, wherein the controller is further configured to determine whether the calculated phase information exceeds a predetermined criterion, and if the phase information exceeds a predetermined criterion, generate monitoring alert information.

[0071] Although specific examples have been illustrated and described herein, those skilled in the art will recognize that a variety of alternative and / or equivalent implementations may be substituted for the specific examples shown and described without departing from 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 be limited only by the claims and their equivalents.

[0072] It should be noted that the methods and devices, including their preferred embodiments, as outlined in the present document may be used alone or in combination with the other methods and devices disclosed in this document. Additionally, the features outlined in the context of one device are also applicable to a corresponding method, and vice versa. Furthermore, all aspects of the methods and devices outlined in the present document may be combined in any desired manner. In particular, the features of the claims may be combined with one another in any desired manner.

[0073] It should be noted that the description and drawings merely illustrate the principles of the proposed methods and systems. Those skilled in the art will be able to implement various arrangements that, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and embodiments outlined herein are primarily intended to be expressly provided for illustrative purposes only to assist the reader in understanding the principles of the proposed methods and systems. Furthermore, all statements herein that provide principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to include their equivalents.

Claims

[1] A method for determining phase information relating to an RF transmission channel, the method comprising: Generating a frequency-modulated RF signal, wherein the frequency-modulated RF signal includes a frequency ramp, coupling a first representation of the frequency-modulated RF signal into the RF transmit channel to generate a first frequency-modulated RF output signal, coupling a second representation of the frequency-modulated RF signal into a test phase shifter, Generating a set of measurement samples during the frequency ramp, wherein the set of measurement samples is generated based on: Setting, during the frequency ramp, a phase shift provided by the test phase shifter to each phase shift value of a predetermined set of phase shift values ​​and phase shifting the second representation of the frequency-modulated RF signal according to the respective phase shift value to generate a frequency-modulated RF test signal, Generating a down-converted signal based on mixing a first representation of the first frequency-modulated RF output signal with the frequency-modulated RF test signal, Sampling the down-converted signal to generate a respective measurement sample of a set of measurement samples for each phase shift value of the set of phase shift values, and calculating the phase information related to the RF transmit channel based on the set of measurement samples. [2] The method of claim 1, wherein the sampling of the down-converted signal is timed to adjust a phase shift. [3] A method according to claim 2, wherein a time interval between two consecutive adjustments of the phase shift corresponds to a time interval between two consecutive samplings of measurement samples. [4] A method according to any one of claims 1 to 3, wherein calculating the phase information comprises generating first order harmonic information with respect to a first order harmonic included in the set of measured values. [5] The method of claim 4, wherein generating first-order harmonic information comprises a Fourier transform of the set of measured values, and wherein the first-order harmonic information corresponds to a coefficient of the first-order harmonic Fourier transform. [6] A method according to claim 4 or 5, wherein the first-order harmonic information includes an imaginary part and a real part, and determining the phase information is based on the use of the imaginary part and the real part. [7] The method of claim 6, wherein the method further comprises: Estimating a phase error correction value and determining the phase information based on the phase error correction value. [8] A method according to claim 7, wherein the phase error correction value is estimated as a function of a slope of the frequency ramp. [9] A method according to any one of claims 7 or 8, wherein the phase error correction value is estimated in dependence on a sampling rate used in sampling the down-converted signal. [10] A method according to any one of claims 7 to 9, wherein the phase error correction value is estimated as a function of an RF delay time corresponding to a time difference between the first frequency-modulated RF output signal and the frequency-modulated RF test signal. [11] A method according to any one of claims 7 to 10, wherein the phase error correction value is estimated as a function of the number of phase shift values ​​in the set of phase shift values. [12] A method according to any one of claims 7 to 11, wherein the phase error correction value is estimated as a function of a time difference between a start of the frequency ramp and a start of sampling of the down-converted signal. [13] A method according to any one of claims 1 to 12, wherein a time at which the phase shift is changed from a previously applied phase shift value to a currently applied phase shift value is offset from a time at which the down-converted signal is sampled to generate the respective measurement sample corresponding to the currently applied phase shift value. [14] The method of any one of claims 1 to 13, further comprising storing the phase information relating to the transmission channel in a memory and adjusting a phase shift of a phase shifter in the transmission channel based on the stored phase information. [15] The method of any one of claims 1 to 14, further comprising determining whether the phase information exceeds a predetermined criterion, and if the phase information exceeds a predetermined criterion, generating monitoring warning information. [16] The method of any one of claims 1 to 15, further comprising coupling a second representation of the first frequency modulated RF output signal into an antenna for transmission, receiving a reflection signal of the second representation of the first frequency modulated RF signal from an object, and processing the reflection signal to determine at least one of a distance or a speed of the object or a direction of arrival. [17] A method according to any one of claims 1 to 16, wherein the down-converted signal is low-pass filtered before sampling. [18] Radar MMIC device comprising: a local oscillator for generating a frequency-modulated RF signal including a frequency ramp, an RF transmission channel, a test phase shifter, a first coupler configured to couple a first representation of the frequency-modulated RF signal into the RF transmit channel and a second representation of the frequency-modulated RF signal into the test phase shifter, wherein the RF transmit channel is configured to generate a first frequency-modulated RF output signal based on the frequency-modulated RF signal, and wherein the test phase shifter is configured to phase-shift the second representation of the frequency-modulated RF signal according to a phase shift applied to the test phase shifter and generate a frequency-modulated RF test signal, a second coupler coupled to the RF transmit channel to generate a first representation of the frequency-modulated RF output signal, a mixer coupled to the test phase shifter and the second coupler to receive the first representation of the frequency-modulated RF output signal and the frequency-modulated RF test signal, the mixer further configured to generate a down-converted signal based on mixing the first representation of the frequency-modulated RF output signal with the frequency-modulated RF test signal, a control for setting the phase shift applied to the test phase shifter during the frequency ramp to each phase shift value of a predetermined set of phase shift values, a sampler for sampling the down-converted signal to generate, for each phase shift value of the set of phase shift values, a respective measurement sample of a set of measurement samples, and a processor for calculating phase information relating to the transmit channel based on the set of measurement samples. [19] The radar MMIC device of claim 18, wherein the controller is configured to time the setting of a phase shift with the sampling of the down-converted signal. [20] The radar MMIC device method according to claim 18 or 19, wherein the processor is configured to calculate the phase information based on generating first-order harmonic information related to a first-order harmonic included in the set of measured values. [21] The radar MMIC device of claim 20, wherein the first harmonic information includes an imaginary part and a real part, and wherein the processor is configured to calculate the phase information based on the imaginary part and the real part. [22] The radar MMIC device according to any one of claims 18 to 21, wherein the processor is configured to estimate a phase error correction value and calculate the phase information based on the phase error correction value. [23] The radar MMIC device of any one of claims 18 to 22, wherein the controller is further configured to determine whether the calculated phase information exceeds a predetermined criterion and, if the phase information exceeds a predetermined criterion, generate monitoring warning information.

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