Radar array phase shifter verification

Abstract

The present invention is entitled "Radar Array Phase Shifter Verification." An improved circuit configuration is disclosed for calibrating and / or verifying the operation of phase shifters in a phased array radar system. In one illustrative embodiment, a method includes: (i) programming a set of phase shifters to convert a radio frequency signal into a set of channel signals; (ii) separating a monitor signal from each channel signal while coupling the set of channel signals to a set of antenna feeds; and (iii) measuring a relative phase between each pair of monitor signals while employing the pair of monitor signals associated with adjacent channels.

Description

Technical Field

[0001] This disclosure generally relates to self-testing techniques for phased array radar systems, and more specifically to verifying the functionality of phase shifters in such systems. Background Technology

[0002] In search of safer and more convenient transportation options, many automakers are developing autonomous vehicles, which require a wide variety of sensors. Among the envisioned sensing technologies is a multi-input multi-output radar system, used to monitor the distance between the vehicle and any other vehicles or obstacles along its path. Such systems can employ beam steering technology to improve their measurement range and resolution.

[0003] On the transmitting side, phased arrays (i.e., by supplying transmit signals with different phase shifts to each of multiple antennas) are typically used for beam steering, with the beam direction determined by the difference between the phase shifts. When changing the phase difference to steering the beam, it is desirable that the signal amplitude remain the same. Device mismatch (even due to temperature and aging) can cause beam pattern distortion and even sidelobe formation. Such effects can cause line-of-sight shifts of obstacles or produce null values ​​that completely "hide" obstacles. Therefore, automotive radar safety standards or simply engineering design prudence may mandate the inclusion of some mechanism to calibrate and / or verify the proper operation of the phase shifters. Existing mechanisms for this purpose may unduly compromise the cost or reliability of automotive radar systems. Summary of the Invention

[0004] The aforementioned problems can be addressed, at least in part, by an improved circuit configuration for calibrating and / or verifying the operation of phase shifters in a phased array radar system.

[0005] According to one aspect of this application, a method is provided, characterized by comprising: programming a set of phase shifters to convert radio frequency signals into a set of channel signals; while coupling the set of channel signals to a set of antenna feed sections, separating a monitoring signal from each channel signal; and while employing pairs of monitoring signals associated with adjacent channels, measuring the relative phase between each pair of monitoring signals.

[0006] In one embodiment, the method is characterized by further comprising: acquiring sequential relative phase measurements within the range of phase settings of phase shifters associated with even channels while maintaining the phase settings of phase shifters associated with even channels; acquiring sequential relative phase measurements within the range of phase settings of phase shifters associated with odd channels while maintaining the phase settings of phase shifters associated with even channels; and providing an error notification if the difference between the sequential relative phase measurements fails to match a predetermined step size.

[0007] In one embodiment, the method is characterized by including determining a phase setting offset for each pair based on the relative phase measurement result, wherein the determination includes measuring the relative phase within the range of the phase setting difference between adjacent channels.

[0008] In one embodiment, the method is characterized in that the measurement includes: combining each pair of monitoring signals to form a combined signal; and measuring the power of each combined signal.

[0009] In one embodiment, the method is characterized by including: disabling an adjustable gain amplifier associated with odd-numbered channels while measuring the power of each combined signal; disabling an adjustable gain amplifier associated with even-numbered channels while measuring the power of each combined signal; and adjusting the gain of the adjustable gain amplifier based on the power measurement results to equalize the power of each channel signal in the set of channel signals.

[0010] According to another aspect, a radar system is provided, characterized by: a signal generator that provides a radio frequency signal; a set of programmable phase shifters that convert the radio frequency signal into a set of channel signals; a set of couplers that couple the set of channel signals to a set of antenna feeds, the couplers in the set providing monitoring signals; one or more power combiners, each power combiner combining a pair of monitoring signals to generate a combined signal; one or more power detectors, each power detector converting a corresponding combined signal into a power level signal; and a controller that uses at least one of the power level signals to determine the relative phase between at least one pair of channel signals in the set of channel signals.

[0011] In one embodiment, the radar system is characterized in that the controller uses at least one power level signal to determine the phase setting offset of each pair by the following steps: measuring the at least one power level signal within the range of the phase setting difference between adjacent channels; and identifying the maximum or minimum power level value corresponding to the phase setting offset.

[0012] In one embodiment, the radar system is characterized by a set of adjustable gain amplifiers that amplify the set of channel signals provided to the set of couplers, wherein the controller operates to: disable the adjustable gain amplifier associated with odd-numbered channels while measuring the power of each combined signal; disable the adjustable gain amplifier associated with even-numbered channels while measuring the power of each combined signal; and adjust the gain of the adjustable gain amplifiers to equalize the power of each channel signal in the set of channel signals.

[0013] According to another aspect, a radar system is provided, characterized by: a signal generator that provides a radio frequency signal; a set of programmable phase shifters that convert the radio frequency signal into a set of channel signals; a set of couplers that couple the set of channel signals to a set of antenna feeds, the couplers in the set providing monitoring signals; and one or more phase detectors, each phase detector determining the relative phase between a pair of monitoring signals of adjacent channels.

[0014] In one embodiment, the radar system is characterized by a controller that: acquires sequential relative phase measurements within the range of phase settings of phase shifters associated with even channels while maintaining the phase settings of phase shifters associated with even channels; acquires sequential relative phase measurements within the range of phase settings of phase shifters associated with odd channels while maintaining the phase settings of phase shifters associated with even channels; and provides an error notification if the difference between the sequential relative phase measurements fails to match a predetermined step size.

[0015] In one embodiment, the radar system is characterized in that the one or more phase detectors include: a pair of phase detectors that determine a first relative phase between a central channel and a first adjacent channel and a second relative phase between the central channel and a second adjacent channel, and the controller operates to calculate the difference between the first relative phase and the second relative phase. Attached Figure Description

[0016] Figure 1 A top view of an exemplary vehicle equipped with sensors.

[0017] Figure 2 Here is a block diagram of an illustrative driver assistance system.

[0018] Figure 3 This is a block diagram of an example radar transceiver chip.

[0019] Figure 4 This is a block diagram of an exemplary phase-shift transmitter array.

[0020] Figure 5 This is a schematic diagram of an exemplary phase detector.

[0021] Figure 6 This is a schematic diagram of an exemplary calibration circuit.

[0022] Figure 7 This is a schematic diagram of an exemplary verification circuit.

[0023] Figure 8 This is a schematic diagram of another example of an exemplary calibration circuit.

[0024] Figure 9A It is a graph of the output and phase of the inverting combiner.

[0025] Figure 9B It is a graph of the output and phase of the in-phase combiner.

[0026] Figure 10A This is a flowchart illustrating the verification method.

[0027] Figure 10B This is a flowchart illustrating an exemplary calibration method. Detailed Implementation

[0028] It should be understood that the following description and figures are provided for illustrative purposes and not for limiting this disclosure. Rather, they provide a basis for those skilled in the art to understand all modifications, equivalents, and alternatives that fall within the scope of the claims.

[0029] Figure 1 An exemplary vehicle 102 equipped with a radar antenna array is shown, comprising an antenna 104 for short-range sensing (e.g., for parking assistance), an antenna 106 for medium-range sensing (e.g., for monitoring parking & driving and overtaking events), and an antenna 108 for long-range sensing (e.g., for adaptive cruise control and collision warning), each of which may be positioned behind the front bumper. An antenna 110 for short-range sensing (e.g., for reversing assistance) and an antenna 112 for medium-range sensing (e.g., for rear collision warning) may be positioned behind the rear bumper. An antenna 114 for short-range sensing (e.g., for blind spot monitoring and side obstacle detection) may be positioned behind the vehicle's fenders. Each antenna array can perform multiple-input multiple-output (MIMO) radar sensing. For vehicles with driver assistance and autonomous driving functions, the type, number, and configuration of sensors in the sensor arrangement vary. Vehicles can employ sensor arrangements to detect and measure the distance / direction of objects in various detection zones, enabling the vehicle to navigate while avoiding other vehicles and obstacles.

[0030] Figure 2An electronic control unit (ECU) 202, coupled to various radar sensing front-ends 204 to 206, is shown as the center of a star-shaped topology. Of course, other topologies, including serial, parallel, and hierarchical (tree) topologies, are also suitable and are envisioned for use according to the principles disclosed herein. Each radar front-end includes a radio frequency (RF) transceiver coupled to some of the transmitting and receiving antennas 104 to 114 to transmit electromagnetic waves, receive reflections, and optionally perform processing to determine the spatial relationship between the vehicle and its surrounding environment. (Such processing may alternatively be performed by ECU 202.) To provide automatic parking assistance, ECU 202 may be further connected to a set of actuators, such as a turn signal actuator 208, a steering actuator 210, a brake actuator 212, and a throttle actuator 214. ECU 202 may be further coupled to a user interactive interface 216 to accept user input and provide displays of various measurements and system status.

[0031] Using interfaces, sensors, and actuators, ECU 202 can provide automatic parking, assisted parking, lane change assist, obstacle and blind spot detection, autonomous driving, and other desired features. In a vehicle, various sensor measurements are acquired by one or more electronic control units (ECUs), which can then use these measurements to determine the vehicle's state. The ECU can also act on the state and incoming information to actuate various signaling and control transducers to regulate and maintain the vehicle's operation. Operations provided by the ECU include various driver assistance features, including automatic parking, lane following, automatic braking, and autonomous driving.

[0032] To collect the necessary measurements, the ECU may employ a MIMO radar system. A radar system operates by emitting electromagnetic waves that travel outward from the transmitting antenna before reflecting back to the receiving antenna. A reflector can be any moderately reflective object in the path of the emitted electromagnetic waves. By measuring the travel time of the electromagnetic waves from the transmitting antenna to the reflector and back to the receiving antenna, the radar system can determine the distance to the reflector. If multiple transmitting or receiving antennas are used, or if multiple measurements are taken at different locations, the radar system can determine the orientation of the reflector and thus track its position relative to the vehicle. With more sophisticated processing, multiple reflectors can be tracked. At least some radar systems employ array processing to “scan” directional electromagnetic beams and construct an image of the area around the vehicle. Both pulse and continuous wave implementations of radar systems are possible, but frequency-modulated continuous wave radar systems are generally preferred for accuracy.

[0033] Figure 3A block diagram of an exemplary transceiver chip 300 for a radar system is shown. Chip 300 has an antenna feed section or termination coupled to an array of transmitting antennas 301 and receiving antennas 302. Adjustable gain amplifiers 303A to 303D drive the transmitting antenna 301 with an amplified signal from transmitter circuitry 304. Circuitry 304 uses a programmable chirp rate and range to generate a carrier signal within a programmable frequency band. The signal generator may employ a voltage-controlled oscillator with an appropriate frequency multiplier. A splitter and phase shifter derive transmit signals for multiple transmitters TX-1 to TX-4 to operate simultaneously and further provide a reference "local oscillator" signal to the receiver for down-conversion processing. In the illustrated example, transceiver chip 300 includes four transmitters (TX-1 to TX-4), each fixedly coupled to a corresponding transmitting antenna 301. In an alternative embodiment, multiple transmitting antennas may be selectively coupled to each transmitter.

[0034] Chip 300 further includes four receivers (RX-1 to RX-4), each selectively coupled to two receiver antennas in receiver antenna 302, thereby providing a reconfigurable MIMO system with eight receiver antennas, four of which can be used simultaneously to collect measurement results. Four analog-to-digital converters (ADCs) 306A to 306D sample and digitize the down-converted received signals from receivers RX-1 to RX-4, supplying the digitized signals to a digital signal processor (DSP) 308 for filtering and processing, or directly to a high-bandwidth interface 310 for off-chip processing of the digitized baseband signals. If used, DSP 308 generates image data that can be transmitted to the ECU via the high-bandwidth interface 310.

[0035] The control interface 312 enables the ECU or other host processor to configure the operation of the transceiver chip 300 (including the test and calibration peripheral circuitry 314 and the transmit signal generation circuitry 304).

[0036] Figure 4 Further details have been added to illustrate the phased array technology. The transmitted signal (for automotive radar, the envisioned frequency range is the W-band (75 GHz to 110 GHz)) is supplied to four programmable phase shifters 402A to 402D to provide a corresponding phase shift for the signal to each antenna. Adjustable gain amplifiers 303A to 303D amplify the phase-shifted signal to drive the transmitting antenna, but just before the drive signal is output from the chip, a set of couplers 404A to 404D separates a small portion of the signal power as a monitoring signal, enabling the calibration circuit 406 to monitor the performance of the transmitting circuit.

[0037] In at least some implementations, the calibration circuit monitors the relative amplitude and phase of the drive signal. Figure 5This is a block diagram of an exemplary phase detector 502 that can be used at the millimeter-wave frequencies envisioned herein. A quadrature coupler 504 converts the local oscillator (LO) signal into two quadrature signals (signals with the same frequency but 90 degrees out of phase). Quadrature couplers are known in the literature, and suitable examples include branch-line couplers, Lange couplers, and overlay couplers. A splitter 506 splits the RF input into two equal signals. A multiplier mixes each quadrature signal with one of the RF signals to produce a baseband voltage. The voltage obtained using the leading quadrature signal can be called the in-phase voltage VI, while the voltage obtained using the lagging quadrature signal can be called the quadrature phase voltage VQ. One or more ADCs 508 can digitize the voltage, and a processor, ASIC, or lookup table 510 can convert the digitized voltage into a detection phase θ using an equivalent form of performing an arctangent operation on the ratio of VQ to VI. det The detected phase represents the phase difference between the LO and RF inputs.

[0038] Figure 6 An exemplary calibration circuit using a naive method is shown, in which N drive signals are each supplied to the corresponding RF input of phase detectors 502A to 502N, and the LO input of the phase detectors receives buffered copies of the LO signals from the corresponding amplifiers 602A to 602N. (Although they impose large area requirements, amplifiers are typically needed to avoid inappropriate loading of the LO signal source.) The phase detectors (θ... i The phase angle measurement results represent the phase angle difference between the LO and RF inputs (where the offset represents the contributions of the coupler, amplifier, and any routing delay differences):

[0039] θ i,j =θ RFi –θ ref =θ PSi,j –θ LO –θ offset

[0040] Where θ PSi,j This refers to the j-th phase shift setting of the i-th phase shifter 402A to 402D, where i ranges from 1 to the number of phase shifters, and for each phase shifter, j ranges from 1 to the programmable number of phase shifts. The phase shift θ can be measured by comparing adjacent values ​​of j. i,j And confirm the difference from the expected step change Δθ s Matching is used to verify the operation of each phase shifter:

[0041] θ i,j –θ i,j+1 =Δθ s .

[0042] The verification can be repeated for each value of j, and when j reaches its maximum value (the number of available phase settings), a wrap-around operation will be performed.

[0043] Note that ensuring an appropriate inter-channel phase difference is also desirable. Distributing the LO signal to all phase detectors can cause problems, and the phase shift associated with the amplifier may be temperature-dependent. Therefore, along with the step change verification described above, it is desirable to perform inter-channel phase difference verification for one or more values ​​of j and k:

[0044] θ i,j –θ i+1,k =(j–k)Δθ s .

[0045] Inter-channel validation can be repeated for each value of i.

[0046] Figure 7 An exemplary verification circuit is shown, which uses an adjacent channel as a reference LO signal instead of the global LO signal. Three-port couplers 404A and 404D at the array edges are retained, but the couplers (404B and 404C) inside the array are replaced by four-port couplers 704B and 704C to supply monitoring signals to two (instead of one) phase detectors. In at least some embodiments, the four-port couplers include directional couplers cascaded with a power divider, while the three-port couplers can be implemented as standard directional couplers.

[0047] As previously described, the coupler separates a small portion of the RF signal power, outputting the majority of the signal to the corresponding transmit antenna. Amplifiers 602A to 602C amplify the monitoring signal to drive the LO inputs of phase detectors 502A to 502C. Each phase detector 502A to 502C compares the phase of the monitoring signal from the adjacent channel. (Because the channels are compared in pairs, the phase detectors used in this arrangement are more numerous than those in the adjacent channel.) Figure 6 (One less item is needed in the arrangement.)

[0048] Detected pairwise phase difference θ 12 θ 23 θ 34 yes

[0049] θ i(i+1),jk =θ RF(i+1),k –θ RFi,j –θ offset =θ PS(i+1),k –θ PSi,j –θ offset

[0050] As mentioned earlier, the difference between the measured phase shifts of adjacent values ​​of j or k and the expected step change Δθ can be confirmed by comparing them. s Matching is used to verify the operation of each phase shifter:

[0051] θ i(i+1),jk –θ i(i+1),(j+1)k =Δθ s

[0052] θ i(i+1),jk –θ i(i+1),j(k+1) =Δθ s

[0053] The verification can be repeated for each value of j or each value of k, and a wrap-around operation can be performed when j or k reaches its maximum value (the number of available phase settings).

[0054] For inter-channel phase difference verification, the difference between pairs of differences can be used (representing the phase settings of channels i, i+1, and i+2 as j, k, and l):

[0055] θ i(i+1),jk –θ (i+1)(i+2),kl =θ PSi,j +θ PS(i+2),l –2θ PS(i+1),k =(j+l–2k)Δθ s .

[0056] Inter-channel validation can be repeated for each value of i, and a wraparound operation can be performed when i+1 and i+2 exceed the maximum value (number of channels).

[0057] In-channel phase shift verification requires scanning the phase shift settings; therefore, it is preferable to perform this infrequently, preferably between regular transmissions, to maintain confidence consistent with the proper operation of the radar system. If it is anticipated that there may not be sufficient time to complete a full scan within the available time between regular transmissions, then the scan can be performed in stages, distributing it across multiple measurement cycles.

[0058] Conversely, inter-channel phase shift verification does not require changes to the phase shifter settings, so it can be performed during normal use. If desired, inter-channel verification can be performed on top of each transmission.

[0059] Because the phase shifter's operation is verified using measurement differences, the phase shift is eliminated, and there is no longer a need to determine the shift or calibrate its dependence on lifetime and process or temperature variations.

[0060] although Figure 7 The arrangement can be verified without explicit calibration, but it may still be necessary to calibrate the phase shifters and amplifiers for each channel to ensure accurate beam steering. Therefore, Figure 8 An illustrative calibration arrangement is shown. Figure 8 Couplers 404A, 704B, 704C, and 404D are not supplied as... Figure 7Instead of using a phase detector, the signal is supplied to power combiners 802A to 802C. Combiner 802A combines the monitoring signals from couplers 404A and 704B to provide a combined signal. Combiner 802B combines the signals from couplers 702B and 702C. Combiner 802C combines the signals from couplers 704C and 404D.

[0061] As discussed further below, combiners 802A to 802C can be in-phase or inverting power combiners. The combined signal output from each combiner is coupled to power detectors 804A to 804C. In at least some contemplated embodiments, the power detectors rectify the combined signal using diodes or other nonlinear elements. The power detectors generate voltages indicating the power output of the combiners. The outputs of detector 804A are labeled V12, the outputs of detector 804B are labeled V23, and the outputs of detector 804C are labeled V34. These voltages are digitized by ADCs 806A to 806C and provided to microcontroller unit (MCU) logic 808. In other contemplated embodiments, a single ADC is used in conjunction with a multiplexer to digitize the detector voltages.

[0062] like Figures 9A to 9B As shown, the detector output voltage V depends on the relative phase between the combined signals. The graphs all assume that each of the two signals is coupled to the combiner at a power level of -10 dBm and that there is no insertion loss. Figure 9A The output of the inverting combiner shown has a minimum value at zero degrees and monotonically increases to a maximum value at ±180° in each direction. Figure 9B The output of the non-inverting combiner shown has a maximum value at zero degrees and monotonically decreases to a minimum value at ±180 degrees. Examples of inverting combiners can include ring couplers, magic-t couplers, branch-line couplers, or blue-base couplers. These can also be configured as non-inverting couplers, or non-inverting couplers can be implemented as Wilkinson power converters.

[0063] The power detector does not need to have a large range to correctly detect the phase setting offset when the phase is 0. It only needs to be monotonic.

[0064] Let's express the input voltages of the power combiner as x1 = A1cos(ωt) and x2 = A2cos(ωt + θ). Regardless of insertion loss, the output voltage of the inverting power combiner is... And the output voltage of the in-phase combiner is If one or the other phase shifter associated with the input of the combiner is changed, the magnitude of y varies according to its relative phase angle θ. If A1 = A2, then y is zero, or it will reach its maximum value when the relative phase angle is zero.

[0065] Now for reference Figure 10A Discussion on use Figure 7 The method for verifying the circuit. In block 902, a controller (such as DSP 308) systematically changes the settings of phase shifters 402A to 402D relative to the feed. Figure 7 The phase detectors 502A to 502C in the radar system scan the phase of each of its adjacent channels. This allows the controller to verify that each adjustment to the phase setting produces a change in the phase detector output corresponding to the expected step change. If this verification fails, the process stops and alerts the ECU: a fault exists in the radar system. (The controller can send an error code to the ECU, set the measurement result to a value indicating an erroneous measurement, and / or set a field in the status register that is periodically read by the ECU.)

[0066] Otherwise, in block 904, normal operation begins with the first periodic transmit pulse in a series of periodic transmit pulses. The controller sets the phase shifter to the desired setting to redirect the beam from the phased-array transmitter in the desired direction and generate a pulse. When the pulse is generated, as discussed earlier, in block 906, the verification circuit measures the phase between relative channels and calculates the difference between the phases of adjacent relative channels, thereby verifying that this difference matches the expected difference. If this verification fails, the process may stop and issue an alert to the ECU: a fault exists in the radar system.

[0067] Otherwise, in box 908, the controller collects radar echo measurements, and repeats boxes 904 to 908 to collect a series of measurements. The echo measurements are processed according to existing practices to determine the direction and distance of the obstacle relative to the vehicle.

[0068] Now for reference Figure 10B Discussion on use Figure 8 The method describes a calibration circuit. In block 910, a controller (such as DSP 308) measures the output level of each channel. In one envisioned approach, the controller enables only one power amplifier 303A through 303D for each adjacent channel. For example, power amplifiers 303A and 303C can be enabled, while power amplifiers 303B and 303D are disabled. Subsequently, power amplifiers 303A and 303C can be disabled, while amplifiers 303B and 303D are enabled. The disabled power amplifiers do not provide an output signal.

[0069] Although only one power amplifier is enabled for each pair of adjacent channels, the controller measures the output of power detectors 804A to 804C. This process is repeated with another power amplifier enabled for each pair of adjacent channels, thus providing the controller with a power level measurement for each channel. Then, in block 912, the controller can equalize the power levels by adjusting the power amplifier settings (e.g., increasing the amplifier setting for the channel with the lowest power level and / or decreasing the amplifier setting for the channel with the highest power level). The controller performs a verification step, repeating the operations of blocks 910 and 912 until the power levels are equal.

[0070] Once the power levels are equalized, the controller performs phase calibration starting from block 914. The controller scans the phase shifter settings while keeping the phase shifter settings on adjacent channels constant. When the detected power level reaches a minimum (for inverting combiners) or a maximum (for in-phase combiners), the controller records the relative phase shifter settings (i.e., the phase setting offset) and specifies this phase setting offset as a relative phase angle θ = 0 in block 916, allowing the desired phase difference to be obtained by appropriately increasing or decreasing the relative phase shifter settings with respect to the phase setting offset. This process is performed for each pair of adjacent channels and can be verified for all phase shifter settings for each phase shifter.

[0071] Subsequently, during normal operation, as indicated by boxes 918 to 922, the controller sets the phase shifter to the desired setting to redirect the beam from the phased-array transmitter in the desired direction and generate a pulse. While the pulse is being generated, the verification circuit in box 920 measures the output levels of the power detectors and verifies that they match the power output levels expected by the desired phase shift (see [link to relevant documentation]). Figures 9A to 9B If this verification fails, the process may stop and send an alert to the ECU: there is a fault in the radar system.

[0072] Otherwise, in box 922, the controller collects radar echo measurements, and repeats boxes 918 to 922 to collect a series of measurements. The echo measurements are processed according to existing practices to determine the direction and distance of the obstacle relative to the vehicle.

[0073] Note that because a power detector is used instead of a down-conversion I / Q mixer to convert the RF signal to baseband / DC, therefore Figure 8 The implementation may require a much smaller silicon area. Both implementations avoid routing long lines to the calibration receiver, which could degrade fidelity when the calibration receiver intersects with the RF line carrying the TX signal. The coupled RF signal is immediately converted to DC, making it easier to route.

[0074] In summary, the disclosed method implementation includes: (i) programming a set of phase shifters to convert radio frequency signals into a set of channel signals; (ii) separating a monitoring signal from each channel signal while coupling the set of channel signals to a set of antenna feeds; and (iii) measuring the relative phase between each pair of monitoring signals while employing pairs of monitoring signals associated with adjacent channels.

[0075] The disclosed radar system implementation includes: a signal generator that provides a radio frequency (RF) signal; a set of programmable phase shifters that convert the RF signal into a set of channel signals; and a set of couplers that couple the channel signals to a set of antenna feeds, wherein the couplers in the set provide monitoring signals. The system also includes: one or more power combiners, each combining a pair of monitoring signals to generate a combined signal; and one or more power detectors, each converting a corresponding combined signal into a power level signal. A controller uses at least one of the power level signals to determine the relative phase between at least one pair of channel signals in the set of channel signals.

[0076] Another disclosed radar system implementation includes: a signal generator that provides a radio frequency (RF) signal; a set of programmable phase shifters that convert the RF signal into a set of channel signals; and a set of couplers that couple the channel signals to a set of antenna feeds, wherein the couplers in the set provide monitoring signals. One or more phase detectors are provided to each determine the relative phase between the monitoring signals of a pair of adjacent channels.

[0077] Each of the foregoing embodiments can be used individually or in combination, and can include one or more of the following features in any suitable combination: 1. Providing an error notification if one of the relative phase measurements fails to match the difference in the programmed phase shifts of a set of phase shifters. 2. Acquiring sequential relative phase measurements within the range of phase settings of phase shifters associated with even channels while maintaining the phase settings of phase shifters associated with even channels, and acquiring sequential relative phase measurements within the range of phase settings of phase shifters associated with odd channels while maintaining the phase settings of phase shifters associated with even channels; 3. Providing an error notification if the difference between sequential relative phase measurements fails to match a predetermined step size. 4. Determining the phase setting offset for each pair based on the relative phase measurements. 5. The determination includes measuring the relative phase within the range of phase setting differences between adjacent channels. 6. The measurement includes: combining each pair of monitoring signals to form a combined signal; and measuring the power of each combined signal. 7. While measuring the power of each combined signal, disable the adjustable gain amplifier associated with the odd-numbered channels; while measuring the power of each combined signal, disable the adjustable gain amplifier associated with the even-numbered channels; and based on the power measurement results, adjust the gain of the adjustable gain amplifier to equalize the power of each channel signal in the set of channel signals. 8. The controller uses at least one power level signal to determine the phase setting offset for each pair. 9. The controller determines the phase setting offset by: measuring at least one power level signal within the range of phase setting differences between adjacent channels; and identifying the maximum or minimum power level value corresponding to the phase setting offset. 10. One or more power combiners are inverting combiners, and the phase setting offset corresponds to the minimum power level. 11. One or more power combiners are non-inverting combiners, and the phase setting offset corresponds to the maximum power level. 12. A set of adjustable gain amplifiers amplifies a set of channel signals provided to a set of couplers. 13. Before determining the relative phase, the controller adjusts the gain of the adjustable gain amplifier to equalize the power of each channel signal in the set of channel signals. 14. Before equalizing the power, the controller disables the adjustable gain amplifier associated with the odd-numbered channels while measuring the power of each combined signal; and disables the adjustable gain amplifier associated with the even-numbered channels while measuring the power of each combined signal.15. A controller that: acquires sequential relative phase measurements within a range of phase settings of phase shifters associated with even channels while maintaining phase settings of phase shifters associated with odd channels; acquires sequential relative phase measurements within a range of phase settings of phase shifters associated with odd channels while maintaining phase settings of phase shifters associated with even channels; and provides an error notification if the difference between the sequential relative phase measurements fails to match a predetermined step size. 16. One or more phase detectors include a pair of phase detectors that determine a first relative phase between a center channel and a first adjacent channel and a second relative phase between the center channel and a second adjacent channel, the system further including a controller that calculates the difference between the first relative phase and the second relative phase. 17. If, based on the phase settings of the phase shifters associated with the center channel, the first adjacent channel, and the second adjacent channel, the difference fails to match an expected difference, the controller provides an error notification. 18. The expected difference is (j+l–2k)Δθ. s Where j, k, and l represent the phase settings of the first adjacent channel, the center channel, and the second adjacent channel, respectively, while Δθ s This represents a predetermined step change.

[0078] Once the foregoing disclosure is fully understood, many other modifications, equivalents, and alternatives will become apparent to those skilled in the art. For example, each of the disclosed circuit arrangements can be used for verification, calibration, or both. It is intended that the following claims be construed as including all such modifications, equivalents, and alternatives where applicable.

Claims

1. A self-test method, characterized by The method comprises: programming a set of phase shifters to convert a radio frequency signal into a set of channel signals; separating a monitor signal from each channel signal while coupling the set of channel signals to a set of antenna feeds; measuring a relative phase between each pair of monitor signals while employing pairs of the monitor signals associated with adjacent channels; wherein the self-test method further comprises: acquiring sequential relative phase measurements over a range of phase settings of phase shifters associated with even-numbered channels while maintaining phase settings of phase shifters associated with odd-numbered channels; acquiring sequential relative phase measurements over a range of phase settings of phase shifters associated with odd-numbered channels while maintaining phase settings of phase shifters associated with even-numbered channels; and providing an error notification if a difference between sequential relative phase measurements fails to match a predetermined step size.

2. The self-test method of claim 1, wherein comprises determining a phase setting offset for each pair based on the relative phase measurements, wherein the determining comprises measuring the relative phase over a range of phase setting differences of adjacent channels.

3. The self-test method of claim 1, wherein The measuring comprises: combining each pair of monitor signals to form a combined signal; and measuring a power of each combined signal.

4. The self-test method of claim 3, wherein comprises: disabling adjustable gain amplifiers associated with odd-numbered channels while measuring the power of each combined signal; disabling adjustable gain amplifiers associated with even-numbered channels while measuring the power of each combined signal; and adjusting a gain of the adjustable gain amplifiers based on the power measurements to equalize the power of each channel signal in the set of channel signals.

5. A radar system characterized by The radar system comprises: a signal generator providing a radio frequency signal; a set of programmable phase shifters converting the radio frequency signal into a set of channel signals; a set of couplers coupling the set of channel signals to a set of antenna feeds, the couplers in the set providing monitor signals; one or more power combiners, each power combiner combining a pair of monitor signals to produce a combined signal; one or more power detectors, each power detector converting a respective combined signal to a power level signal; and a controller using at least one of the power level signals to determine a relative phase between at least one pair of channel signals in the set of channel signals, wherein the controller uses the at least one power level signal to determine a phase setting offset for each pair by: measuring the at least one power level signal over a range of phase setting differences of adjacent channels; and identifying a power level maximum or minimum corresponding to the phase setting offset.

6. The radar system of claim 5, wherein: a set of adjustable gain amplifiers amplifying the set of channel signals provided to the set of couplers, wherein the controller operates to: disable adjustable gain amplifiers associated with odd-numbered channels while measuring the power of each combined signal; disable adjustable gain amplifiers associated with even-numbered channels while measuring the power of each combined signal; and adjust a gain of the adjustable gain amplifiers based on the power measurements to equalize the power of each channel signal in the set of channel signals. adjusting a gain of the adjustable gain amplifier to equalize power of each channel signal in the set of channel signals.

7. A radar system, characterized by The radar system comprises: a signal generator providing a radio frequency signal; a set of programmable phase shifters converting the radio frequency signal into a set of channel signals; a set of couplers coupling the set of channel signals to a set of antenna feeds, the couplers in the set providing monitor signals; and one or more phase detectors each determining a relative phase between monitor signals of a pair of adjacent channels, wherein the radar system further comprises a controller and the controller is configured to: acquire sequential relative phase measurements within a range of phase settings of the phase shifters associated with even-numbered channels while maintaining phase settings of the phase shifters associated with odd-numbered channels; acquire sequential relative phase measurements within a range of phase settings of the phase shifters associated with odd-numbered channels while maintaining phase settings of the phase shifters associated with even-numbered channels; and provide an error notification if a difference between sequential relative phase measurements fails to match a predetermined step size.

8. The radar system of claim 7, wherein The one or more phase detectors comprise a pair of phase detectors determining a first relative phase between a center channel and a first adjacent channel and a second relative phase between the center channel and a second adjacent channel, the controller operating to calculate a difference between the first relative phase and the second relative phase.

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