Radar transmitter phase step and phase difference check

Abstract

A method includes techniques for identifying a phase step size of one transmitter while making a phase difference measurement between two transmitters in a multi-transmitter radar apparatus. The method includes setting a first phase of a first transmitter in the multi-transmitter device to a fixed phase value and setting a second phase of a second transmitter in the multi-transmitter device to an initial phase value; changing the second phase of the second transmitter from the initial phase value to a final phase value and performing a sample measurement at each change to obtain a plurality of intermediate frequency (IF) samples; and transforming the plurality of IF samples into complex samples. The method then includes determining one or more phase steps for the second transmitter based on the complex samples.

Description

Technical Field

[0001] The invention relates to a method, a device and a circuit for checking the phase step and phase difference of a radar transmitter. Background Art

[0002] Radar is used to detect objects and provide information about the detected objects for a wide variety of applications. For example, vehicles may employ radar systems to implement driver assistance features and autonomous driving capabilities. In order to quickly and accurately detect nearby objects, next-generation radar systems, such as frequency modulated continuous wave (FMCW) radars, are employed. These radar systems sometimes utilize transceivers with multiple transmitters to implement radar beam steering techniques. In some cases, these techniques dynamically adapt the radar transmission beam pattern by modifying the phase of each transmitter in real time without changing the physical configuration of the transmitting antenna. In general, the performance and accuracy of beam steering techniques depend on the ability to control the phase shifters to set the phase of each transmitter. Deviations in the programmed phase applied at any transmitter will likely reduce the performance and accuracy of the radar system. To this end, many radar systems include built-in self-test (BIST) components to monitor and ensure the accuracy and control of their transmitters and corresponding phase shifters. Summary of the invention

[0003] Various example embodiments are directed to radar transmitter BIST techniques.

[0004] In a first embodiment, a method includes setting a first phase of a first transmitter in a multi-transmitter arrangement to a fixed phase value and setting a second phase of a second transmitter in the multi-transmitter arrangement to an initial phase value. The method also includes varying the second phase of the second transmitter from the initial phase value to a final phase value and performing sample measurements at each variation to obtain a plurality of intermediate frequency (IF) samples. The method also includes transforming the plurality of IF samples into complex samples and determining one or more phase steps of the second transmitter based on the complex samples.

[0005] In some aspects of the first embodiment, the method includes performing the sample measurement relative to the first phase at each change. In some aspects of the first embodiment, performing the sample measurement relative to the first phase at each change to obtain the plurality of IF samples includes mixing a signal from the first transmitter with a signal from the second transmitter and performing an analog-to-digital conversion to obtain the plurality of IF samples.

[0006] In some aspects of the first embodiment, the method includes determining a phase difference between the first transmitter and the second transmitter based on the complex samples.

[0007] In some aspects of the first embodiment, transforming the plurality of IF samples into complex samples comprises applying a Hilbert transform to the plurality of IF samples. In some aspects of the first embodiment, determining one or more phase steps for the second transmitter comprises calculating an arc tangent of a resulting product of the Hilbert transform to identify a phase corresponding to each of the plurality of IF samples. In some aspects of the first embodiment, determining the one or more phase steps for the second transmitter comprises calculating a relative difference between each identified phase corresponding to each of the plurality of IF samples. In some aspects of the first embodiment, the relative difference is based on a number of sample measurements performed.

[0008] In some aspects of the first embodiment, changing the second phase of the second transmitter from an initial phase value to a final phase value includes increasing the phase by a fixed amount between each change. In some aspects of the first embodiment, the fixed amount is in a range of 1° to approximately 90°.

[0009] In some aspects of the first embodiment, the method is performed during a built-in self-test (BIST) time slot in a radar cycle.

[0010] In a second embodiment, an apparatus includes: a first transmitter including a first phase rotator, and a second transmitter including a second phase rotator. The apparatus also includes a mixer that combines outputs from the first transmitter and the second transmitter. The apparatus also includes a processor that sets a first phase of the first transmitter to a fixed phase value and sets a second phase of the second transmitter to an initial phase value; varies the second phase of the second transmitter from the initial phase value to a final phase value and performs sample measurements at each variation to obtain a plurality of intermediate frequency (IF) samples; and transforms the plurality of IF samples into complex samples and determines one or more phase steps of the second transmitter based on the complex samples.

[0011] In some aspects of the second embodiment, the processor is configured to perform the sample measurement relative to the first phase at each change.

[0012] In some aspects of the second embodiment, the processor is configured to determine a phase difference between the first transmitter and the second transmitter based on the complex samples.

[0013] In some aspects of the second embodiment, transforming the plurality of IF samples into complex samples comprises applying a Hilbert transform to the plurality of IF samples. In some aspects of the second embodiment, determining one or more phase steps of the second transmitter comprises calculating an inverse tangent of a resulting product of the Hilbert transform to identify a phase corresponding to each of the plurality of IF samples.

[0014] In some aspects of the second embodiment, determining the one or more phase steps of the second transmitter includes calculating a relative difference between each identified phase corresponding to each of the plurality of IF samples.

[0015] In a third embodiment, a built-in safety test (BIST) circuit for a multi-transmitter device includes a BIST circuit for: setting a first phase of a first transmitter in the multi-transmitter device to a fixed phase value, and setting a second phase of a second transmitter in the multi-transmitter device to an initial phase value; changing the second phase of the second transmitter from the initial phase value to a final phase value in an incremental manner, and performing sample measurement at each increment to obtain a plurality of intermediate frequency (IF) samples; and transforming the plurality of IF samples into complex samples, and determining one or more phase steps of the second transmitter based on the complex samples.

[0016] In some aspects of the third embodiment, the BIST circuit is further configured to determine a phase difference between the first transmitter and the second transmitter based on the complex samples.

[0017] In some aspects of the third embodiment, transforming the plurality of IF samples into complex samples includes applying a Hilbert transform to the plurality of IF samples, and determining one or more phase steps for the second transmitter includes calculating an inverse tangent of a resulting product of the Hilbert transform to identify a phase corresponding to each of the plurality of IF samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By referring to the accompanying drawings, the present disclosure can be better understood and its numerous features and advantages made apparent to those skilled in the art. The use of the same reference numerals in different drawings indicates similar or identical items.

[0019] Figure 1 is a diagram depicting an example depiction of transmit components and BIST circuits in a multi-transmitter radar apparatus and corresponding radar cycles in accordance with various embodiments.

[0020] Figure 2 is a diagram depicting a process flow through a BIST circuit component, according to various embodiments.

[0021] Figure 3 is shown embedded in, for example, Figure 1 2 is a diagram of an example of an output of a mixer between two transmitters in a multi-transmitter radar apparatus such as the multi-transmitter radar apparatus shown in .

[0022] Figure 4is a flow chart of a method for identifying a phase step of a transmitter and a phase difference measurement between two transmitters of a multi-transmitter radar device according to various embodiments.

[0023] Figure 5 is a flow chart of a method for identifying a phase step of a transmitter and a phase difference measurement between two transmitters of a multi-transmitter radar device according to various embodiments. DETAILED DESCRIPTION

[0024] In some radar systems, a radar cycle signal sequence (or simply a radar cycle) includes multiple time slots, including a radar chirp sequence time slot and a BIST time slot. During the radar chirp sequence time slot, the radar system sends a radar chirp sequence to obtain radar information (e.g., position and velocity) of nearby objects based on the reflections of the received radar chirp sequence. During the BIST time slot, the BIST controller of the radar system performs tests to monitor the radar system components and ensure that these components operate according to a set of specified criteria, thereby ensuring that the radar system provides accurate and up-to-date information. For example, the BIST controller performs a set of transmit (TX) tests to see if the phase difference between the transmitters of the radar system is within a specified range and whether the phase step adopted by each transmitter is accurate (e.g., each phase step matches the specified phase step value or is within the range of the specified phase step value). However, during the time period when the BIST controller performs these TX tests, the transmitter cannot send the radar chirp sequence. The period of time during which the transmitter cannot be used to transmit the radar chirp sequence is called the "blind time" because the radar system cannot detect objects during this period (i.e., the system is "blind"). Generally, it is desirable to reduce the duration of transmitter testing in order to reduce the "blind time". In addition, longer test times result in increased power consumption.

[0025] Conventional techniques test phase difference and phase step size (ie, perform TX testing) by repeating several sets of phase difference measurements to identify the phase step size for each transmitter. Repeating these measurements multiple times results in longer test times. Figure 1-5 A TXBIST technique is described for reducing the time required to test phase difference and phase step of transmit components in a radar system, which in turn reduces the total time required for each TX test and thus improves the performance and efficiency of the radar system. For example, in some cases, the disclosed phase difference and phase step test technique provides up to 85% test duration reduction compared to conventional techniques.

[0026] For illustration, the technology described herein relates to a BIST controller that performs phase step and phase difference measurements on multiple transmitters in a set of measurements by utilizing mixers between transmitters embedded in a multi-transmitter radar device. In some embodiments, the BIST controller sets the first phase of the first transmitter to a fixed phase value and sets the second phase of the second transmitter to an initial phase value. The BIST controller increases the second phase of the second transmitter from the initial phase value to the final phase value in an incremental manner, and performs sample measurements relative to the fixed phase value of the first transmitter at each incremental increase to obtain a plurality of intermediate frequency (IF) samples. In some embodiments, the plurality of IF samples are provided as discrete sine waves at the mixer output. In some embodiments, the BIST controller applies a Hilbert transform to the IF samples to transform the IF samples into complex samples, and then identifies the phase of each sample by applying an inverse tangent (Atan) function. Then, the BIST controller calculates the relative difference between the phases of the samples from a single set of measurements to identify the phase step of the second transmitter and obtain the phase difference between the two transmitters. Thus, the phase difference between the two transmitters and the phase step of the second transmitter are derived from the same set of measurements. This reduces the total time required to perform BIST measurements. Thus, the duration of the BIST time slot is reduced, thereby reducing the "blind time" of the radar system. In other words, the disclosed technique measures the phase difference between the two transmitters and the phase step size of one of the transmitters from a single set of measurements, whereas conventional techniques only perform phase difference measurements during the same set of measurements and require additional measurements to obtain the phase step size of either of the two transmitters.

[0027] In some embodiments, the BIST controller (eg Figure 1 and 2 The BIST controller 140 in the embodiment of the present invention may be implemented as hardware, software, firmware, or any combination thereof. For example, in various embodiments, the BIST controller is implemented as software executed on a digital processor (e.g., on a digital signal processor (DSP)), is hardwired (e.g., as a circuit or circuit arrangement) to perform the various techniques described herein (e.g., Figure 2 , 4 One of the hardware or a combination thereof of the techniques described in and 5).

[0028] Figure 1An example depiction of the transmitting components in a multi-transmitter radar device 110 and a corresponding radar cycle 100 according to some embodiments is shown. The radar cycle 100 includes a plurality of time slots. In some embodiments, the multi-transmitter radar device 110 (or simply the radar device 110) includes a plurality of transmitters 112-1, 112-2, a transmit (TX) BIST module 130, an analog / digital converter (ADC) 142, and a BIST controller 140. In some embodiments, the TX BIST module 130, the ADC 142, and the BIST controller 140 are collectively referred to as a "BIST circuit". The radar device 110 includes components for calibrating the phase shifters 114-1, 114-2 (also referred to as phase rotators) in the transmitters, performing phase alignment, and checking phase shifter drift to ensure that the phase shifters perform correctly. In some embodiments, the multi-transmitter radar device 110 is implemented in a radar system of a vehicle and is used to support driver assistance or autonomous driving features. The number of transmitters in the multi-transmitter radar device 110 is a matter of design choice and can be extended to other numbers (e.g., more than two).

[0029] The radar cycle 100 includes a plurality of time slots 102, 104, 106, 108 during which different radar functions are performed. For example, the radar cycle 100 includes a recalibration time slot 102, a radar chirp sequence time slot 104, a BIST time slot 106, and a radar front end (RFE) idle / reconfiguration time slot 108. For example, during the recalibration time slot 102, the radar device 110 can recalibrate the radar transmission components (e.g., phase shifters) of the radar device 110 based on the test results acquired during the previous BIST time slot 106. During the chirp sequence time slot 104, the radar device 110 transmits a radar chirp sequence via one or more of its transmitters (e.g., such as transmitters 112, 114). The radar device 110 then performs radar measurements based on the received reflections of the transmitted radar chirp sequence. During the BIST time slot 106, the radar device 110 performs tests to ensure that all key radar system components (e.g., transmitters, receivers, ADCs, etc.) function and operate according to a set of predetermined criteria (e.g., within a set of timing thresholds or phase correlation thresholds). For example, during the BIST time slot 106, the radar device 110 checks to see if the phase difference between the phase shifters 114-1, 114-2 in the transmitters 112-1, 112-2 is within a defined range, and checks to see if the phase step size of each of the phase shifters 114-1, 114-2 in the transmitters 112-1, 112-2 is within a specific threshold or within the range of such values. During the RFE idle / reconfiguration time slot 108, the radar device 110 may, for example, be in an idle mode to save power, or may perform system reconfiguration.

[0030] In some cases, it is advantageous for the radar device 110 to minimize the duration of the BIST time slot 106 relative to the chirp sequence time slot 104. For example, any time spent by the transmitter in the test phase takes up time that can be used to acquire radar measurement data when the transmitter can transmit radar signals. In other words, although the transmitter is operable and transmits during the BIST time slot 106, the test run during the BIST time slot 106 is not used to perform radar data acquisition. In some cases, the time when the radar device 110 cannot perform functions directly related to radar data acquisition is called "blind time". Many radar systems are designed to minimize the duration spent in "blind time" because any increase in the duration of "blind time" may affect the quality and relevance of radar data in rapidly changing scenes. For example, a longer "blind time" may cause recently acquired radar data to become outdated, thereby negatively affecting applications that rely on the latest data, such as autonomous driving or driver assistance applications.

[0031] Each of the transmitters 112-1, 112-2 includes a respective phase shifter 114-1, 114-2, a respective gain (G) amplifier 116-1, 116-2, and a respective power amplifier (PA) 118-1, 118-2. Each of the transmitters 112-1, 112-2 is coupled to a respective output 150, 160, which may correspond to one or more antenna components for transmitting signals from the radar device 110. The phase shifter 114-1 in the transmitter 112-1 receives an input signal from a local oscillator (LO) 170 and converts the input signal into a complex (I / Q) radio frequency (RF) signal including a first signal component 172-1 (also referred to as a sine component) and a second signal component 172-2 (also referred to as a cosine component). The first signal component 172-1 is represented as sin(Φ1(t)+Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t)) / (Φ1(t) init_TX1 ), where Ф1(t) is the phase step at time t, and Ф init_TX1 is the initial phase of the first transmitter 112-1. The second signal component 172-2 is represented by cos(Φ1(t)+Φ init_TX1 ), where Ф1(t) is the phase step at time t, and Ф init_TX1is the initial phase of the first transmitter 112-1. In some embodiments, the phase shifter 114-1 receives a feedback signal from a BIST controller (BIST CTRL) 140. For example, in some embodiments, the feedback signal from the BIST controller 140 is sent via a direct digital synthesizer (not shown), which provides the feedback signal to the phase shifter 114-1 as an intermediate frequency (IF) signal. This IF feedback signal fed back from the BIST controller 140 to the phase shifter 114-1 is used to program or calibrate the phase parameters of the phase shifter 114-1. Based on these input signals, the phase shifter 114-1 generates an output signal, which is fed to the gain amplifier 116-1 and the power amplifier 118-1 before being transmitted from the first transmitter 112-1.

[0032] Similarly, the phase shifter 114-2 in the transmitter 112-2 receives the input signal from the LO 170 and converts the input signal into a complex (I / Q) radio frequency (RF) signal including a first signal component 174-1 and a second signal component 174-2. The first signal component 174-1 is represented as sin(Φ2(t)+Φ init_TX2 ), where Ф2(t) is the phase step at time t, and Ф init_TX2 is the initial phase of the second transmitter 112-2. The second signal component 174-2 is represented by cos(Φ2(t)+Φ init_TX2 ), where Ф2(t) is the phase step at time t, and Ф init_TX2 is the initial phase of the second transmitter 112-2. In some embodiments, the phase shifter 114-2 receives a feedback signal from the BIST controller 140. For example, in some embodiments, the feedback signal from the BIST controller 140 is sent via a direct digital synthesizer (not shown), which provides the feedback signal as an IF signal to the phase shifter 114-2. This IF feedback signal fed back from the BIST controller 140 to the phase shifter 114-2 is used to program or calibrate the phase parameters of the phase shifter 114-2. Based on these input signals, the phase shifter 114-2 generates an output signal, which is fed to the gain amplifier 116-2 and the power amplifier 118-2 before being transmitted from the second transmitter 112-2.

[0033] The mixer 132 in the TX BIST module 130 is connected to the outputs of both transmitters 112-1, 112-2. The output of the mixer 132 is coupled to a variable gain amplifier (VGA) 134, which in turn is connected to a low pass filter (LPF) 136. The ADC 142 is connected to the output of the LPF 136 and converts the mixed analog signal to a digital signal and outputs the digitized signal to the BIST controller 140. In some embodiments, the BIST controller 140 is any digital signal processing device, such as a microcontroller or a digital processor, that is programmed to perform the operations described herein.

[0034] The two transmitters 112-1, 112-2 each provide a corresponding output signal with a phase shift (or phase rotation). In some cases, the output of each of the transmitters 112-1, 112-2 is affected by one or more factors that may cause a phase error in the transmitter output. In some embodiments, one or more factors that may cause a phase error in the phase shifter of the transmitter include phase shifter gain imbalance, phase shifter phase imbalance, and phase shifter LO to RF leakage. In order to calibrate the phase shifters 114-1, 114-2 to reduce these effects, the BIST controller 140 of the radar device 110 performs calibration based on the transmitter output. Based on the calibration performed by the BIST controller 140, the BIST controller 140 feeds back a signal to the phase shifters 114-1, 114-2 in the corresponding transmitters 112-1, 112-2. The signal fed back to the phase shifter includes a compensation value, which is used to adjust or modify the input of the phase shifter 114-1, 114-2 to compensate for any detected phase difference or phase step imbalance.

[0035] In some embodiments, the BIST controller 140 performs tests to ensure that the phase shifters 114-1, 114-2 of the two transmitters 112-1, 112-2 operate within an allowable error tolerance of each other to ensure the accuracy of the signal transmitted from the radar device 110. For example, these tests include measuring the phase difference between the two phase shifters 114-1, 114-2 of the two transmitters 112-1, 112-2 to confirm that the phase difference is within a defined range. As another example, these tests include measuring the phase step size of each of the two phase shifters 114-1, 114-2 of the two transmitters 112-1, 112-2 to confirm that the phase step size adopted by each phase shifter is accurate. According to some embodiments, BIST controller 140 performs phase difference measurement on multiple transmitters 112 - 1 , 112 - 2 and phase step measurement on one of the transmitters in a single set of measurements by utilizing mixer 132 between transmitters 112 - 1 , 112 - 2 embedded in radar device 110 .

[0036] In some embodiments, the BIST controller 140 sets the phase of the phase shifter 114-1 of the first transmitter 112-1 to a fixed phase value and sets the phase of the phase shifter 114-2 of the second transmitter 112-2 to an initial phase value. The BIST controller 140 increases the second phase of the phase shifter 114-2 of the second transmitter 112-2 from the initial phase value to the final phase value in an incremental manner and performs sample measurements relative to the fixed phase value of the phase shifter 114-1 of the first transmitter 112-1 at each incremental increase to obtain a plurality of IF samples. In some embodiments, the plurality of IF samples are provided as discrete sine waves at the output of the mixer 132. In some embodiments, the BIST controller 140 applies a Hilbert transform to the IF samples to transform the IF samples into complex samples and then identifies the phase of each sample by applying an inverse tangent (Atan) function. Next, the BIST controller 140 calculates the relative difference between the phases of the samples to obtain the phase step of the phase shifter 114-2 of the second transmitter 112-2, and identifies the phase difference between the phase shifters 114-1, 114-2 of the two transmitters 112-1, 112-2. Thus, the phase difference between the two transmitters 112-1, 112-2 and the phase step of the second transmitter 112-2 are derived from the same set of measurements. This reduces the total time required to perform the BIST measurements. Therefore, the duration of the BIST time slot 106 is reduced, thereby reducing the "blind time" of the radar system compared to conventional techniques.

[0037] Figure 2 A diagram depicting the process flow through the BIST circuit component 200 according to some embodiments is shown. In some embodiments, Figure 2 The BIST circuit component 200 depicted in FIG. Figure 1 1 and includes components in the TX BIST module 130 and the BIST controller 140 as well as the ADC 142. The following explanation of the process flow describes a phase step measurement applied to the second transmitter 112-2, but a similar process flow is also applied to the first transmitter 112-1 to identify the phase step measurement of the first transmitter 112-1.

[0038] Signal 202 corresponds to the output of the first transmitter 112-1 and has a fixed phase. That is, the phase of the phase shifter 114-1 of the first transmitter 112-1 is set to a fixed phase value. Signal 204 corresponds to the output of the second transmitter 112-2 and is initially set to an initial phase value. For example, in some embodiments, the initial phase value is 0°. The phase of the phase shifter 114-2 of the second transmitter 112-2 sweeps a specific phase range incrementally, with a specific phase step Δθ between each increment. For example, the phase of the second transmitter 112-2 changes from an initial phase value of 0° to 360°. In some embodiments, this includes incrementing the phase of the second transmitter 112-2 from 0° to 360° based on a fixed phase step ranging from 1° to 90°. For example, if the fixed phase step is 90°, the phase of the second transmitter 112-2 increases from 0° to 90° to 180° to 270° to 360°. Thus, the phase of the first transmitter 112-1 is fixed to provide a fixed phase value in the signal 202, and the phase of the second transmitter 112-2 is swept through a phase range with a fixed phase step size to provide a series of different phase values ​​in the signal 204. For each different phase in the signal 204, the BIST circuit 200 captures a sample at the mixer 132 output 206 to produce an IF waveform of real samples. Figure 3 An example of samples captured at the output 206 of the mixer 132 is shown in FIG.

[0039] Figure 3 An example of a diagram 300 is shown, where line 302 represents the output of a mixer (e.g., Figure 1 and 2 In the diagram 300, the x-axis 306 is in degrees and the y-axis 304 represents the value of the measured samples. In some embodiments, the value of the measured samples indicates the measured phase difference between the two transmitters.

[0040] In this example, the phase of a first transmitter (e.g., transmitter 112-1) is fixed at 0 degrees, and the phase of a second transmitter (transmitter 112-2) is varied from 0 degrees in a first sample 312 to 360 degrees in a final sample 316 in increments of 22.5 degrees. For example, after capturing the first sample 312 when both the phase of the first transmitter and the phase of the second transmitter are set to 0 degrees, the phase of the second transmitter is increased to 22.5 degrees. Then, a second sample 314 is captured when the phase of the first transmitter is at 0 degrees and the phase of the second transmitter is at 22.5 degrees. This process of increasing the phase of the second transmitter by 22.5 degrees (while keeping the phase of the first transmitter fixed at 0 degrees) and taking measurements at each increment continues until the entire range (360 degrees in this case) is covered. In this manner, the mixer provides a sampled IF waveform at its output.

[0041] Return to reference Figure 2 , the output 206 of the mixer 132 is sent to the VGA 134. The output 208 of the VGA 134 is input to the LPF 136. The output 210 of the LPF is input to the ADC 142 to digitize the signal of the sample. The output 212 of the ADC 142 includes a plurality of real samples, which are sent to the BIST controller 140. The output 212 of the ADC 142 is input to the Hilbert transform block 242 at the first stage in the BIST controller 140. The Hilbert transform block 242 transforms the plurality of real samples in the signal output 212 from the ADC 142 into a plurality of complex samples and outputs the complex samples in the output 214. The complex samples in the output 214 of the Hilbert transform block 242 are input to the Atan block 244, which performs the Atan function on the input complex samples to generate the phase of each sample (e.g., θ1, θ2, θ3, ..., θN, where N is the number of samples taken). Next, the output 216 of the Atan block 224 is input to the difference block 246, which calculates the relative difference (Δθ / dn) between the phases of the samples to identify the phase step of the second transmitter 112-2 in the output 218. Thus, the BIST controller 140 is able to measure the phase difference between the phase shifter 114-1 of the first transmitter 112-1 and the phase shifter 114-2 of the second transmitter 112-2 and identify the phase step of the phase shifter 114-2 of the second transmitter 112-2 in the same set of measurements.

[0042] In various embodiments, Figure 2 Any of the various elements of, including components of the BIST controller 140 (e.g., Hilbert transform block 242, Atan block 244, difference block 246), are implemented as one of software executing on a processor, hardware (e.g., circuits) hardwired to perform the various operations described herein, or a combination thereof.

[0043] Figure 4 A flowchart 400 is shown describing a method of performing a phase difference measurement between two transmitters and a phase step measurement of one of the two transmitters according to some embodiments. In some embodiments, the BIST controller 140 performs the method described in the flowchart 400 in conjunction with other components of a multi-transmitter radar device such as the radar device 110 (e.g., in conjunction with the TX BIST module 130 and the two transmitters 112-1, 112-2).

[0044] At 402, the method includes the BIST controller 140 setting one transmitter (e.g., the first transmitter 112-1) to a fixed phase value. In some embodiments, this includes setting the phase of the phase shifter 114-1 in the first transmitter 112-1 to a fixed value. For example, the fixed phase value is any phase value ranging from 0° to 360°.

[0045] At 404, the method includes the BIST controller 140 setting the second transmitter (eg, the second transmitter 112-2) to an initial phase value. In some embodiments, this includes setting the phase of the phase shifter 114-2 in the second transmitter 112-2 to an initial phase value ranging from 0° to 360°.

[0046] At 406, the method includes incrementing the phase of the second transmitter and performing sample measurements relative to the fixed value of the first transmitter at each increment. In some embodiments, this includes the BIST controller 140 incrementing (or in other embodiments, decrementing) the phase of the phase shifter 114-2 in the second transmitter 112-2 by a phase step size Δθ and performing measurements relative to the fixed phase value of the first transmitter 112-1 at each increment (e.g., via the mixer 132) to generate a measured sample quasi-IF waveform. In some embodiments, the measured sample quasi-IF waveform is fed to an ADC (e.g., ADC 142) to generate a digital signal of the measured samples.

[0047] At 408, the method includes the BIST controller 140 transforming the digitized samples into complex samples. In some embodiments, this includes applying a Hilbert transform (e.g., via the Hilbert transform block 242) to a digital signal of the measured samples output from the ADC 142. After transforming the digitized samples into complex samples, the BIST controller 140 applies an inverse tangent (Atan) function to the complex samples (e.g., via the Atan block 244) to generate a signal including a measured phase of the samples. In some embodiments, the measured phase indicates a phase difference between the first transmitter 112-1 and the second transmitter 112-2.

[0048] At 410 , the BIST controller 140 determines a phase step size for the second transmitter based on the complex samples. In some embodiments, this includes the difference block 246 in the BIST controller 140 identifying a phase step size for the second transmitter based on calculating relative differences between the phases of the samples output from the Atan block 244 .

[0049] In some embodiments, the phase of the second transmitter 112 - 2 is fixed, and the phase of the first transmitter 112 - 1 is varied to measure a phase step of the first transmitter 112 - 1 but not the second transmitter 112 - 2 .

[0050] Therefore, by executing the method shown in flowchart 400, the BIST controller is able to identify the phase difference between two transmitters (e.g., transmitter 112-1 and transmitter 112-2) and the phase step of one of the two transmitters (e.g., transmitter 112-2) from the same set of measurements. This reduces the global measurement time required to perform BIST measurements in a BIST time slot (e.g., BIST time slot 106), thereby allowing the radar system to save up to 85% of the transmit phase step measurement time compared to conventional techniques.

[0051] Figure 5 A flowchart 500 is shown describing a method of performing a phase difference measurement between two transmitters and a phase step measurement of one of the two transmitters according to some embodiments. In some embodiments, the BIST controller 140 performs the method described in the flowchart 500 in conjunction with other components of a multi-transmitter radar device such as the radar device 110 (e.g., in conjunction with the TX BIST module 130 and the two transmitters 112-1, 112-2).

[0052] At 502, the method includes the BIST controller 140 setting the first transmitter TX1 (e.g., either transmitter 112-1 or 112-2) to a fixed phase value. In some embodiments, this includes any of the following: setting the phase of the phase shifter 114-1 in the first transmitter 112-1 to a fixed value; or setting the phase of the phase shifter 114-2 in the second transmitter 112-2 to a fixed value. For example, the fixed phase value is any phase value ranging from 0° to 360°.

[0053] At 504, the method includes the BIST controller 140 setting the second transmitter TX2 (e.g., the other of the transmitters 112-1 or 112-2) to an initial phase value. In some embodiments, this includes setting the phase of the other of the phase shifter 114-1 in the first transmitter 112-1 or the phase shifter 114-2 in the second transmitter 112-2 to an initial phase value ranging from 0° to 360°.

[0054] At 506, an ADC (e.g., ADC 142) measures the phase difference of the two transmitters TX1 and TX2. For example, a mixer (e.g., mixer 132) receives outputs from both transmitters TX1 and TX2 and produces an output that is input to the ADC (e.g., via other components such as a VGA). The BIST controller 140 stores the measured phase difference as a sample, then increments the phase of the second transmitter TX2 504 by a phase step (Δθ) in loop 508 and repeats the ADC measurement at 506. The BIST controller 140 continues this process of incrementing the phase of the second transmitter TX2 until a final phase value of the second transmitter TX2 is reached. For example, in one embodiment, this includes performing ADC measurements 506 by incrementally adjusting the phase value of the second transmitter TX2 as follows: 0°, 45°, 90°, 135°, 180°, 225°, 270°, 315°, and 360°. Thus, the phase step (Δθ) in this example is 45°. In other embodiments, the phase step size (Δθ) may be any other value ranging from 2° to 60°. Once the entire phase range (eg, 0° to 360°) is covered and a sample measured IF-like waveform is generated, the method proceeds to block 510 .

[0055] At 510, the BIST controller 140 applies a Hilbert transform (e.g., via the Hilbert transform block 242) to the IF-like sample measurements to obtain a frequency domain spectrum. By applying the Hilbert transform, the BIST controller 140 forces the negative portion of the spectrum (e.g., corresponding to having Figure 3 In addition, the Hilbert transform applies an inverse Fourier transform to obtain complex samples of the original IF sine wave.

[0056] At 512 , the BIST controller 140 applies the Atan function (eg, via the Atan block 244 ) to identify the phase of each sample. Next, at 514 , the BIST controller calculates the relative difference between the phases of the samples to generate a phase step at 516 .

[0057] Therefore, by implementing the method according to flowchart 500, the BIST controller 140 is able to identify the phase step of TX2 in addition to measuring the phase difference between the two transmitters TX1 and TX2. For example, conventional techniques require additional steps of incrementing the phase step of the first transmitter TX1 to measure the phase step of the second transmitter TX2. This results in a significant increase in the time for testing the same components tested in the methods described in flowcharts 400 and 500. For example, for a safety test of 8 steps (i.e., a phase step of 45°), according to the embodiments described herein, the amount of time to measure the phase difference between the two transmitters and the phase step of one of the transmitters is in the range of about 16 μs. The amount of time to measure these same parameters according to conventional techniques is in the range of about 128 μs. In this way, for a step size of 45°, the technology disclosed herein reduces the test time by about 6 to 8 times.

[0058] In some embodiments, certain aspects of the techniques described above may be implemented by one or more processors of a processing system that executes software. The software includes one or more sets of executable instructions stored or otherwise tangibly embodied on a non-transitory computer-readable storage medium. The software may include instructions and certain data that manipulate the one or more processors to perform one or more aspects of the techniques described above when executed by one or more processors. A non-transitory computer-readable storage medium may include, for example, a magnetic or optical disk storage device, a solid-state storage device such as a flash memory, a cache, a random access memory (RAM) or other non-volatile memory device or multiple devices, etc. The executable instructions stored on a non-transitory computer-readable storage medium may be in the form of source code, assembly language code, object code, or in the form of other instruction formats that can be interpreted or otherwise executed by one or more processors.

[0059] Computer-readable storage media may include any storage media or combination of storage media that can be accessed by a computer system during use to provide instructions and / or data to the computer system. Such storage media may include, but are not limited to, optical media (e.g., compact discs (CDs), digital versatile discs (DVDs), Blu-ray discs), magnetic media (e.g., floppy disks, magnetic tapes, or magnetic hard drives), volatile memory (e.g., random access memory (RAM) or cache memory), non-volatile memory (e.g., read-only memory (ROM) or flash memory), or micro-electromechanical system (MEMS)-based storage media. Computer-readable storage media may be embedded in a computing system (e.g., system RAM or ROM), fixedly attached to a computing system (e.g., a magnetic hard drive), removably attached to a computing system (e.g., an optical disc or flash memory based on a universal serial bus (USB)), or coupled to a computer system via a wired or wireless network (e.g., a network accessible storage device (NAS)).

[0060] It should be noted that not all of the activities or elements described above in the general description are required, a portion of a particular activity or device may not be required, and one or more additional activities may be performed or include one or more additional elements in addition to those described. In addition, the order in which the activities are listed is not necessarily the order in which the activities are performed. In addition, the concepts have been described with reference to specific embodiments. However, it will be appreciated by those skilled in the art that various modifications and changes may be made without departing from the scope of the present disclosure as set forth in the following claims. Therefore, the present specification and drawings should be viewed in an illustrative rather than a restrictive sense, and it is expected that all such modifications are included within the scope of the present disclosure.

[0061] Benefits, other advantages, and solutions to problems have been described above with respect to specific embodiments. However, these benefits, advantages, solutions to problems, and any features that may make any benefit, advantage, or solution occur or become more significant should not be understood as important, necessary, or essential features of any or all claims. In addition, the specific embodiments disclosed above are merely illustrative, as the disclosed subject matter may be modified and practiced in different but equivalent ways that are obvious to those skilled in the art who benefit from the teachings herein. It is not intended to limit the details of construction or design shown herein, except as described in the appended claims. Therefore, it is apparent that the specific embodiments disclosed above may be changed or modified, and all such changes are deemed to be within the scope of the disclosed subject matter. Therefore, the protection sought herein is as set forth in the appended claims.

Claims

1. A method, characterized in that include: setting a first phase of a first transmitter in a multi-transmitter arrangement to a fixed phase value and setting a second phase of a second transmitter in the multi-transmitter arrangement to an initial phase value; varying the second phase of the second transmitter from the initial phase value to a final phase value and performing sample measurements at each variation to obtain a plurality of intermediate frequency (IF) samples; as well as The plurality of IF samples are transformed into complex samples and one or more phase steps of the second transmitter are determined based on the complex samples.

2. The method according to claim 1, characterized in that Also included is performing the sample measurement relative to the first phase at each change.

3. The method according to claim 2, characterized in that Performing the sample measurements relative to the first phase at each change to obtain the plurality of IF samples includes mixing a signal from the first transmitter with a signal from the second transmitter and performing an analog-to-digital conversion to obtain the plurality of IF samples.

4. The method according to any one of claims 1 to 3, characterized in that Transforming the plurality of IF samples into complex samples includes applying a Hilbert transform to the plurality of IF samples.

5. The method according to claim 4, characterized in that Determining the one or more phase steps of the second transmitter includes calculating an inverse tangent of a resulting product of the Hilbert transform to identify a phase corresponding to each of the plurality of IF samples.

6. A device, characterized in that: include: a first transmitter comprising a first phase rotator; a second transmitter comprising a second phase rotator; a mixer that combines outputs from the first transmitter and the second transmitter; as well as A processor for: setting a first phase of the first transmitter to a fixed phase value and setting a second phase of the second transmitter to an initial phase value; varying the second phase of the second transmitter from the initial phase value to a final phase value and performing sample measurements at each variation to obtain a plurality of intermediate frequency (IF) samples; as well as The plurality of IF samples are transformed into complex samples, and one or more phase steps of the second transmitter are determined based on the complex samples.

7. The device according to claim 6, characterized in that The processor is configured to perform the sample measurement relative to the first phase at each change.

8. The device according to claim 6, characterized in that Transforming the plurality of IF samples into complex samples includes applying a Hilbert transform to the plurality of IF samples.

9. The device according to claim 8, characterized in that Determining the one or more phase steps of the second transmitter includes calculating an inverse tangent of a resulting product of the Hilbert transform to identify a phase corresponding to each of the plurality of IF samples.

10. A built-in safety test (BIST) circuit for a multi-transmitter device, characterized in that: The BIST circuit is used to: Setting a first phase of a first transmitter in the multi-transmitter arrangement to a fixed phase value, and setting a second phase of a second transmitter in the multi-transmitter arrangement to an initial phase value; Incrementally varying the second phase of the second transmitter from the initial phase value to a final phase value and performing sample measurements at each increment to obtain a plurality of intermediate frequency (IF) samples; and The plurality of IF samples are transformed into complex samples, and one or more phase steps of the second transmitter are determined based on the complex samples.

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