MIMO radar system with dual-mode output power amplification

Abstract

The present disclosure relates to a MIMO radar system with dual-mode output power amplification. An automotive radar system is disclosed that is capable of switching between one or more high-power modes and one or more increased channel modes. The radar system includes: a plurality of transmit antennas; an integrated circuit including a transmit chain that generates a positive transmit signal and a negative transmit signal that together form a differential transmit signal; and a coupling interface. The coupling interface configurably couples the differential transmit signal to two transmit antennas of the plurality of transmit antennas to selectively drive the two transmit antennas in a differential mode or in a power combining mode that combines power from the positive transmit signal and the negative transmit signal to drive a first transmit antenna of the plurality of transmit antennas while isolating a second transmit antenna of the two transmit antennas.

Description

Technical Field

[0001] The present patent application generally relates to frequency modulated continuous wave radar systems. In particular, the present patent application relates to frequency modulated continuous wave radar systems having a multiple-input multiple-output (MIMO) architecture, in which the number of transmitting elements is increased with minimal area and power penalties. Background Art

[0002] In their quest for safer and more convenient transportation options, many automakers are developing self-driving cars, which require a significant number and variety of sensors, typically including arrays of acoustic and / or electromagnetic sensors, to monitor the distance between the car and any nearby people, pets, vehicles, or obstacles. However, many of these arrays cannot provide the required level of resolution without incurring excessive power and / or range losses. Therefore, there is room for improvement in this area. Summary of the Invention

[0003] According to one aspect of the present application, the present invention provides a method, characterized in that the method includes: generating a positive transmit signal and a negative transmit signal that together form a differential transmit signal; setting a transmit antenna coupling interface to a first configuration, the first configuration using the differential transmit signal to drive a first transmit antenna and drive a second transmit antenna; and switching the transmit antenna coupling interface to a second configuration, the second configuration combining power from the positive transmit signal and the negative transmit signal to drive the first transmit antenna while isolating the second transmit antenna.

[0004] In one embodiment the method is characterized in that the method further comprises switching the transmit antenna coupling interface to a third configuration which combines power from the positive transmit signal and the negative transmit signal to drive the second transmit antenna while isolating the first transmit antenna.

[0005] In one embodiment, the method is characterized in that the transmit antenna coupling interface includes: a 90-degree hybrid coupler having a first output port coupled to the first transmit antenna and a second output port coupled to the second transmit antenna, and having a first input port coupled to receive a positive transmit signal; and a configurable phase shifter coupling a negative transmit signal to the second input port of the 90-degree hybrid coupler, wherein in a first configuration, the configurable phase shifter is set to zero degrees, and in a second configuration, the configurable phase shifter is set to negative 90 degrees.

[0006] In one embodiment, the method is characterized in that the transmit antenna coupling interface includes: an output transformer having a primary coupled between a positive transmit signal and a negative transmit signal and having a secondary selectively coupled between a first transmit antenna and a second transmit antenna; a switch arrangement that connects a terminal of the secondary to the second transmit antenna in a first configuration and to ground in a second configuration; and a second switch arrangement that connects an opposite terminal of the secondary of the output transformer to the first transmit antenna in the first configuration and to ground in a third configuration.

[0007] In one embodiment, the method is characterized in that the transmit antenna coupling interface further comprises: an input transformer having a primary and a secondary; and a power amplifier having an input port and an output port, wherein the primary of the input transformer is coupled between the positive transmit signal and the negative transmit signal, the secondary of the input transformer is coupled to the input port of the power amplifier, and the output port of the power amplifier is connected to the primary of the output transformer.

[0008] According to another aspect, the present invention provides an automotive radar system, characterized in that the automotive radar system includes: a plurality of transmit antennas; an integrated circuit, the integrated circuit including a transmit chain, the transmit chain generating a positive transmit signal and a negative transmit signal that together form a differential transmit signal; and a coupling interface, the coupling interface configurably coupling the differential transmit signal to two transmit antennas of the plurality of transmit antennas to selectively drive the two transmit antennas in a differential mode or in a power combining mode, the power combining mode combining power from the positive transmit signal and the negative transmit signal to drive a first transmit antenna of the plurality of transmit antennas while isolating a second transmit antenna of the two transmit antennas.

[0009] In one embodiment, the automotive radar system features a coupling interface that further configurably couples the differential transmit signal to two transmit antennas to selectively drive the two transmit antennas in a second power combining mode that combines power from the positive transmit signal and the negative transmit signal to drive the second transmit antenna while isolating the first transmit antenna.

[0010] In one embodiment, the automotive radar system is characterized in that the coupling interface includes: a 90-degree hybrid coupler having a first output port coupled to a first transmit antenna and a second output port coupled to a second transmit antenna, and having a first input port coupled to receive a positive transmit signal; and a configurable phase shifter that couples a negative transmit signal to the second input port of the 90-degree hybrid coupler, wherein the configurable phase shifter is alternately set to zero degrees corresponding to a differential mode or to 90 degrees corresponding to a power combining mode.

[0011] In one embodiment, the automotive radar system is characterized in that the coupling interface includes: an output transformer having a primary coupled between a positive transmit signal and a negative transmit signal, and having a secondary selectively coupled between a first transmit antenna and a second transmit antenna; and a switch arrangement that connects a terminal of the secondary to the second transmit antenna in a first configuration corresponding to a differential mode, and connects the terminal to ground in a second configuration corresponding to a power combining mode.

[0012] In one embodiment, the automotive radar system is characterized in that the coupling interface further comprises: a second switch arrangement that connects the opposite terminal of the secondary of the output transformer to the first transmitting antenna in the first configuration and connects the opposite terminal of the secondary of the output transformer to ground in the third configuration.

[0013] In one embodiment, the automotive radar system is characterized in that the coupling interface further includes: an input transformer having a primary and a secondary; and a power amplifier having an input port and an output port, wherein the primary of the input transformer is coupled between the positive transmit signal and the negative transmit signal, the secondary of the input transformer is coupled to the input port of the power amplifier, and the output port of the power amplifier is connected to the primary of the output transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A vehicle equipped with a radar sensor according to an example of the present disclosure is shown;

[0015] Figure 2 is a block diagram of a driver assistance system according to an example of the present disclosure;

[0016] Figure 3 A radar system according to an example of the present disclosure is shown;

[0017] Figure 4 A radar system according to an example of the present disclosure is shown;

[0018] Figure 5 A circuit for an automotive radar system according to an example of the present disclosure is shown;

[0019] Figure 6A According to the examples of the present disclosure Figure 5 A graph of the output of the circuit;

[0020] Figure 6B According to the examples of the present disclosure Figure 5 a second graph of the output of the circuit;

[0021] Figure 7A circuit for an automotive radar system according to an example of the present disclosure is shown;

[0022] Figure 8A According to the examples of the present disclosure Figure 7 A graph of the output of the circuit;

[0023] Figure 8B According to the examples of the present disclosure Figure 7 another graph of the output of the circuit;

[0024] Figure 8C According to the examples of the present disclosure Figure 7 A graph of the output of the circuit;

[0025] Figure 9A shows an idealized version of an output transformer according to an example of the present disclosure;

[0026] Figure 9B An example according to the present disclosure is shown. Figure 7 On-chip implementation of the circuit;

[0027] Figure 10A According to the examples of the present disclosure Figure 7 a graph of the input impedance of the circuit in; and

[0028] Figure 10B According to the examples of the present disclosure Figure 7 Another graph of the input impedance of the circuit.

[0029] The accompanying drawings and the following detailed description do not limit the present disclosure, but rather provide a basis for understanding all modifications, equivalents, and alternatives that fall within the scope of the appended claims. Specific configurations, parameter values, and examples are illustrative rather than restrictive. DETAILED DESCRIPTION

[0030] Figure 1An exemplary vehicle 100 is shown equipped with a radar antenna array 115, which includes an antenna 104 for short-range sensing (e.g., for parking assistance), an antenna 106 for medium-range sensing (e.g., for monitoring stop & go and overtaking events), and an antenna 108 for long-range sensing (e.g., for adaptive cruise control and collision warning), each of which can be placed behind the front bumper cover. Antenna 110 for short-range sensing (e.g., for backup assistance) and antenna 112 for medium-range sensing (e.g., for rear collision warning) can be placed behind the rear bumper cover. Antenna 114 for short-range sensing (e.g., for blind spot monitoring and side obstacle detection) can be placed behind the vehicle's fender. Each antenna and each group of antennas can be grouped into one or more arrays. Each array can be controlled by a radar array controller (205). Each group of antennas can perform multiple-input multiple-output (MIMO) radar sensing. The type, number, and configuration of sensors in the sensor arrangement vary for vehicles with driver assistance and autonomous driving capabilities. The vehicle may employ a sensor arrangement to detect and measure the distance / direction to objects in various detection zones to enable the vehicle to navigate while avoiding other vehicles and obstacles.

[0031] Figure 2 1 is a block diagram of a driver assistance system (control network) 200 for a vehicle (e.g., 100). The control network 200 includes an electronic control unit (ECU) 202 at the center of a star topology coupled to various ultrasonic sensors 204 and a radar array controller 205. Other topologies, including serial, parallel, and hierarchical (tree) topologies, are also suitable and are contemplated for use according to the principles disclosed herein. The radar array controller 205 is coupled to the transmit and receive antennas in the radar antenna array 115 to transmit electromagnetic waves, receive reflections, and determine the spatial relationship between the vehicle and its surroundings. The radar array controller 205 is coupled to a carrier signal generator. In at least one example, the radar array controller 205 controls the timing and sequence of activation of the multiple carrier signal generators.

[0032] To provide automatic parking assistance, ECU 202 may be further connected to a set of actuators, such as turn signal actuator 208, steering actuator 210, brake actuator 212, and throttle actuator 214. ECU 202 may be further coupled to a user interactive interface 216 to accept user input and provide a display of various measurements and system status.

[0033] Using interfaces, sensors, and actuators, ECU 202 can provide automated parking, assisted parking, lane change assistance, obstacle and blind spot detection, automated driving, and other desired features. In an automobile, various sensor measurements are collected by one or more ECUs 202 and can be used by the ECUs 202 to determine the state of the automobile. ECU 202 can further act on the state and incoming information to activate various signaling and control transducers to regulate and maintain the operation of the automobile. Among the operations provided by ECU 202 are various driver assistance functions, including automated parking, lane following, automatic braking, and self-driving.

[0034] To collect the necessary measurements, ECU 202 may employ a MIMO radar system. A radar system operates by transmitting an electromagnetic wave that travels outward from a transmitting antenna before reflecting toward a receiving antenna. A reflector can be any moderately reflective object in the path of the transmitted electromagnetic wave. By measuring the travel time of the electromagnetic wave from the transmitting antenna to the reflector and back to the receiving antenna, the radar system can determine the distance to the reflector and its speed relative to the vehicle. If multiple transmitting or receiving antennas are used, or if multiple measurements are taken at different locations, the radar system can determine the direction of the reflector and therefore track its position relative to the vehicle. Using more complex processing, multiple reflectors can be tracked. At least some radar systems employ array processing to "scan" a directional electromagnetic beam and construct an image of the vehicle's surroundings. Both pulsed and continuous wave implementations of the radar system are possible.

[0035] Figure 3 An exemplary radar system 300 is shown having a MIMO configuration in which J transmitters are commonly coupled to M transmit antennas 301 to transmit a transmit signal 307. M possible signals 307 can be differently reflected from one or more targets 305 to be received as receive signals 309 via N receive antennas 302 coupled to P receivers. Each receiver can extract the amplitude and phase, or travel delay, associated with each of the M transmit signals 307, enabling the system to obtain N*M measurements (although only J*P of the measurements are available simultaneously). The processing requirements associated with each receiver extracting the J measurements can be reduced through the use of time division multiplexing and / or orthogonal coding. Available antennas are systematically multiplexed to available transmitters and receivers to collect a complete set of measurements for radar imaging.

[0036] Figure 4A radar system 400 (e.g., 300) according to an example of the present disclosure is shown in block diagram form. In at least one example, radar system 400 is implemented as an integrated circuit in a packaged chip (such as a front-end chip). Radar system 400 includes a carrier signal generator 404, a transmit filter 420, an amplifier 412, and a transmit antenna 301, which can transmit a signal 307 based on the output of carrier signal generator 404. Radar system 400 also includes a receiver antenna 302, a low-noise amplifier 413, and a mixer 407. Mixer 407 mixes the signal detected by antenna 302 with the signal from carrier signal generator 404. Low-noise amplifier 413 is used to amplify signal 309 detected by antenna 302. Radar system 400 also includes a wideband filter 415, an analog-to-digital converter 417, and a processor 419 (e.g., 202, 205). Processor 419 and low-noise amplifier 413 can be coupled for bidirectional communication, as shown. The transmitted signal 307 is reflected by the target, and the reflected signal 309 is received by the receiving antenna 302 .

[0037] In an example of the present disclosure, a carrier signal generator 404 is coupled to the radar array controller 205. The carrier signal generator 404 includes a chirp generator to generate a frequency modulated continuous wave (FMCW) signal. The chip rate of the carrier signal generator 404 can be controlled by the radar array controller 205. In at least one example, the carrier signal generator 404 can be disabled by the radar array controller 205 to provide an unmodulated carrier signal. The carrier signal generator 404 can be implemented as a local oscillator (LO) signal generator, as a fractional-number phase-locked loop (PLL) with a ΣΔ controller, or as a direct digital synthesis generator.

[0038] The carrier signal generator 404 is connected to the transmit antenna 301 through the transmit filter 420 and the amplifier 412. The carrier signal generator 404 is connected to the receive antenna 302 through the mixer 407 and the low noise amplifier 413. The carrier signal generator 404 generates a signal (e.g., a chirp signal). The amplifier 412 receives the signal from the carrier signal generator 404 and transmits the transmit signal 307 corresponding to the signal from the carrier signal generator 404 using the transmit antenna 301.

[0039] In digital beamforming radars, spatial resolution is determined by the number of antennas in the radar array. Silicon area and power considerations limit the number of transmit chains allowed on a single chip. According to examples of the present disclosure, the number of transmit elements in the array is doubled by connecting two antennas to a single transmit chain. In at least one example, a MIMO+ array can be implemented while incurring minimal area and / or power penalties.

[0040] In one or more examples of the present disclosure, a radar system includes a hybrid coupler configuration in which two single-ended amplifiers are driven differentially, while one of the branches includes a 0 / -90 phase shifter. The output of the hybrid coupler configuration can be connected to two antennas using the hybrid coupler. When operating as a balanced amplifier, the coupled ports of the hybrid coupler can be switched (terminated) to perform power summing in a single antenna.

[0041] Figure 5 A circuit 500 for an automotive radar system (e.g., 300, 400) according to an example of the present disclosure is shown. The circuit 500 corresponds to a hybrid coupler arrangement. The circuit 500 includes multiple antennas 505, including a first transmit antenna 507 and a second transmit antenna 509. In at least one example of the present disclosure, at least some portions of the circuit 500 reside on an integrated circuit 511. The integrated circuit 511 includes a transmit chain 513 (corresponding to an input port INP and an input port INN). The transmit chain 513 generates a positive transmit signal 515 and a negative transmit signal 517 that together form a differential transmit signal 519. In at least one example, the circuit 500 includes a coupling interface 521 that includes a hybrid coupler 523 and first and second switches S1 and S2. Switch S1 can be switched from an open position, in which S1 is not coupled to the second antenna 509, to a closed position, in which S1 is coupled to the second antenna 509, such as by contacting a pin (antenna port) 525 of the second antenna 509. The switch S2 can be switched from an open position, in which S2 is not coupled to the ground 527, to a closed position, in which S2 is coupled to the ground 527, such as by being connected to a pin 529 connected to the ground 527. In some examples, an impedance or resistance (e.g., 531) is interposed between the pin 529 and the ground 527. The circuit 500 also includes a phase shifter 532. In at least one example, the phase shifter 532 couples the negative transmit signal 517 to the hybrid coupler 523.

[0042] According to one or more examples of the present disclosure, the circuit 500 is switchable between a first configuration and a second configuration. In the first configuration of the circuit 500, the switch S1 is closed and the switch S2 is open. In the first configuration of the circuit 500, the circuit 500 operates in a differential mode, in which a differential transmit signal 519 is transmitted to the first transmit antenna 507 and the second transmit antenna 509.

[0043] In the second configuration of the circuit 500, the switch S1 is open and the switch S2 is closed. In the second configuration of the circuit 500, the circuit 500 operates in a power combining mode in which the power from the positive transmit signal 515 and the negative transmit signal 517 drives the first transmit 507 while the second transmit antenna 509 is isolated. According to one or more examples of the present disclosure, the circuit 500 can be switched (such as by a user or triggered by environmental conditions) between a first configuration in which more transmit antennas provide greater angular resolution (at shorter distances) and a second configuration in which fewer (half) transmit antennas provide readings at greater distances, but at lower resolution (compared to the first configuration).

[0044] In at least one example of the present disclosure, the hybrid coupler 523 is a 90-degree hybrid coupler having a first output port 533 and a second output port 535. The first output port 533 is coupled to the first transmit antenna 507, and the second output port is alternately and switchably connected to the second antenna 509 or the ground 527, depending on whether the switch S1 is closed and the switch S2 is open, or alternatively, the switch S1 is open and the switch S2 is closed.

[0045] The hybrid coupler 523 includes a first input port 537 and a second input port 539. In at least one example of the present disclosure, the first input port 537 is coupled to receive the positive transmit signal 515. In at least one example, the second input port 539 of the hybrid coupler 523 receives the negative transmit signal 517 via the phase shifter 532. In some examples, the phase shifter 532 can be configured to shift the negative transmit signal 517 by zero degrees in a first configuration and to positively shift the negative transmit signal 517 by 90 (ninety) degrees in a second configuration. In some examples, the phase shifter 532 can be configured to shift the negative transmit signal 517 by zero degrees in a first configuration and to negatively shift the negative transmit signal 517 by 90 (ninety) degrees in a second configuration.

[0046] In some examples, the phase shifter 532 can be configured to negatively shift the negative transmit signal 517 by 90 (ninety) degrees in a first configuration, to shift the negative transmit signal 517 by zero degrees in a second configuration, and to positively shift the negative transmit signal 517 by 90 (ninety) degrees in a third configuration.

[0047] In at least one example of the present disclosure, the circuit 500 further includes a first power amplifier PA1 that amplifies the positive transmit signal 515 at the first input port 537 of the 90-degree hybrid coupler 523. In some examples, the circuit 500 further includes a second power amplifier PA2 that amplifies the negative transmit signal 517 at the second input port 539 of the 90-degree hybrid coupler 523.

[0048] In at least one example, circuit 500 enables simultaneous transmission from two antennas without affecting the area of ​​the integrated chip on which circuit 500 resides because switches S1 , S2 are significantly smaller than a power combining structure.

[0049] Figure 6A 6 is a graph 600 of the output of the circuit (500) according to an example of the present disclosure. Graph 600 corresponds to an operating configuration of the circuit (500) in which the phase shifter (532) is set to 0 (zero), the switch S1 is closed, and the switch S2 is open. Because the phase shifter (532) does not rotate the negative transmit signal 517, the transmit signal 606 from the first antenna (507) is ninety degrees out of phase with the transmit signal 608 from the second antenna (509). The amplitude (power) of the transmit signal 606 from the first antenna (507) is substantially equal to the amplitude (power) of the transmit signal 608 from the second antenna (509). The transmit signal 606 of the first antenna (507) may be shifted according to the setting of the phase shifter (532). Since the coupler (523) is symmetrical, if the signals received at the input port (537) and the input port (539) are differential, the signals output from the output port (533) and the output port (535) are also differential and have equal amplitudes.

[0050] Figure 6B 6 is another graph 650 of the output of the circuit (500) according to an example of the present disclosure. Graph 650 corresponds to an operating configuration of the circuit (500) in which the phase shifter (532) is set to 90 (ninety) degrees, the switch S1 is open, and the switch S2 is closed. Although the amplitude (power) of the second antenna (509) is almost 0 (zero), because the switch S2 is open, the amplitude (power) of the transmitted signal 606 from the first antenna (507) is approximately 412.5 mV, which is significantly greater than when the circuit (500) is in the configuration corresponding to Figure 6A The operating configuration is such that the first antenna (507) receives a negative transmit signal (517) and the second antenna (509) receives a positive transmit signal (515). Due to the signal cancellation at the coupler port (539) caused by the phase shift performed by the phase shifter (532), the amplitude at the antenna port (525) and the output port (535) is zero. When the 50 ohm terminals (529, 531, 527) are connected, the switch S1 enables the antenna 509 to be disconnected to avoid additional loading that would cause an impedance mismatch; the coupler (523) needs to "see" the 50 ohm terminals (529, 531, 527).

[0051] In one or more examples of the present disclosure, the radar circuit has a differential configuration in which a fully differential amplifier is a transformer coupled to two antennas. The two ports of the transformer's secondary coil can be shorted to ground by a switch to perform power summing in a single antenna.

[0052] Figure 7 A circuit 700 for an automotive radar system (e.g., 300, 400) according to an example of the present disclosure is shown. The circuit 700 includes multiple antennas 705, including a first transmit antenna 707 and a second transmit antenna 709. In at least one example of the present disclosure, at least some portions of the circuit 700 reside on an integrated circuit 711. The integrated circuit 711 includes a transmit chain 713 (corresponding to an input port INP and an input port INN). The transmit chain 713 generates a positive transmit signal 715 and a negative transmit signal 717 that together form a differential transmit signal 719. In at least one example, the circuit 700 includes a coupling interface 721 that includes a switch arrangement 722 that includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The switch S1 is switchable from an open position, in which S1 is not coupled to the second antenna 709, to a closed position, in which S1 is coupled to the second antenna 709, such as by contacting a pin 725 of the second antenna 709. Switch S2 is switchable from an open position, in which S2 is not coupled to ground 727, to a closed position, in which S2 is coupled to ground 727, such as by being connected to pin 729, which is connected to ground 727. In some examples, an impedance or resistance (not shown) is interposed between pin 729 and ground 727.

[0053] Switch S3 can be switched from an open position, in which S3 is not coupled to first antenna 707, to a closed position, in which S3 is coupled to first antenna 707, such as by contacting pin 730 of first antenna 707. Switch S4 can be switched from an open position, in which S4 is not coupled to ground 727, to a closed position, in which S4 is coupled to ground 727, such as by connecting to pin 731 connected to ground 727. In some examples, an impedance or resistance (not shown) is interposed between pin 731 and ground 727.

[0054] According to one or more examples of the present disclosure, circuit 700 is capable of switching between a first configuration, a second configuration, and a third configuration using a switch arrangement. In at least one example, switch arrangement 722 includes switch S1, switch S2, switch S3, and switch S4. In the first configuration of circuit 700, switch S1 is closed and switch S2 is open, and switch S3 is closed and switch S4 is open. In the first configuration of circuit 700, circuit 700 operates in a differential mode, in which a differential transmit signal 719 is transmitted to first transmit antenna 707 and second transmit antenna 709. In the second configuration of circuit 700, switch S1 is open and switch S2 is closed, and switch S3 is closed and switch S4 is open. In the second configuration of circuit 700, circuit 700 operates in a (first) power combining mode, in which power from positive transmit signal 715 and negative transmit signal 717 drives first transmit antenna 707, while second transmit antenna 709 is isolated. In a third configuration of circuit 700, switch S1 is closed and switch S2 is open, and switch S3 is open and switch S4 is closed. In the third configuration of circuit 700, in this third configuration, circuit 700 operates in a second power combining mode, with power from positive transmit signal 715 and negative transmit signal 717 driving second transmit antenna 709, while first transmit antenna 707 is isolated. According to one or more examples of the present disclosure, circuit 700 can switch from differential mode (such as by a user switch or triggered by an environmental condition) to the first power combining mode or the second power combining mode. In at least one example, circuit 700 can switch from the first power combining mode (such as by a user switch or triggered by an environmental condition) to the differential mode or the second power combining mode. In at least one other example, circuit 700 can switch from the second power combining mode (such as by a user switch or triggered by an environmental condition) to the differential mode or the first power combining mode.

[0055] According to one or more examples of the present disclosure, the circuit 700 can be switched between a first configuration, a second configuration, and a third configuration. In the first and third configurations of the circuit 700, fewer transmit antennas 705 provide readings at a greater distance, while in the second configuration, more transmit antennas 705 provide greater angular resolution at a shorter distance.

[0056] In at least one example of the present disclosure, circuit 700 further includes a power amplifier PA3 that amplifies differential signal 719. In one or more examples, coupling interface 721 of circuit 700 includes an output transformer 733 having a primary 735 coupled between positive transmit signal 715 and negative transmit signal 717, and having a secondary 737 selectively coupled between first transmit antenna 707 and second transmit antenna 709.

[0057] In at least one example of the present disclosure, in a first configuration of the circuit 700, the switch arrangement 722 connects a terminal of the secondary 737 to the antenna 709, connects an opposite terminal of the secondary 737 of the output transformer 733 to the first transmit antenna 707, and connects the opposite terminal of the secondary 737 of the output transformer to the ground 727 in a third configuration.

[0058] According to one or more examples, the coupling interface 721 of the circuit 700 includes an input transformer 739 having a primary 741 and a secondary 743. In at least one example, the power amplifier PA3 receives an input signal 745 from the input transformer 739, amplifies the input signal 745, and outputs an amplified signal 747 to the output transformer 733. In some examples, the primary 741 of the input transformer 739 is coupled between the positive transmit signal 715 and the negative transmit signal 717, the secondary 743 of the input transformer 739 is coupled to the input 745 of the power amplifier PA3, and the output signal 747 of the power amplifier PA3 is connected to the primary 735 of the output transformer 733.

[0059] In at least one example of the present disclosure, when both S1 and S4 are open and both S2 and S3 are closed, the output transformer 733 acts as a balun and the power from the two PAs is combined in the first antenna 707. In at least one example of the present disclosure, when both S1 and S4 are closed and both S2 and S3 are open, the output transformer 733 acts as a balun and the power from the two PAs is combined in the second antenna 709.

[0060] In at least one example, circuit 700 enables simultaneous transmission from two antennas without affecting the area of ​​the integrated chip on which circuit 700 resides because switches S1 , S2 , S3 , S4 are significantly smaller than a power combining structure.

[0061] Figure 8A 800 is a graph of the output of the circuit (700) according to an example of the present disclosure. Graph 800 corresponds to an operating configuration of the circuit (700) in which switches S1 and S3 are closed and switches S2 and S4 are open. The transmit signal 808 from the first antenna (707) is 180 degrees out of phase with the transmit signal 810 from the second antenna (709). The amplitude (power) of the transmit signal 808 from the first antenna (707) is substantially equal to the amplitude (power) of the transmit signal 810 from the second antenna (709).

[0062] Figure 8Bis another graph 820 of the output of the circuit (700) according to an example of the present disclosure. Graph 820 corresponds to an operating configuration of the circuit (700) in which switch S1 is open, switch S2 is closed, switch S3 is open, and switch S4 is closed. Although the amplitude (power) of the transmit signal 810 of the second antenna (709) is almost 0 (zero), because switch S1 is open (e.g., not connected to pin (725)), the amplitude (power) of the transmit signal 808 from the first antenna (707) is approximately greater than when both the first antenna (707) and the second antenna receive the differential signal 719 and transmit the differential signal (e.g., when the circuit (700) is in a state corresponding to Figure 8A ) when configuring the operation.

[0063] Figure 8C is another graph 830 of the output of the circuit (700) according to an example of the present disclosure. Graph 830 corresponds to an operating configuration of the circuit (700) in which switch S1 is closed, switch S2 is open, switch S3 is closed, and switch S4 is open. Although the amplitude (power) of the transmit signal 808 of the first antenna (707) is almost 0 (zero), because switch S3 is open (e.g., not connected to pin (730)), the amplitude (power) of the transmit signal 810 from the first antenna (707) is substantially greater than when both the first antenna (707) and the second antenna receive the differential signal 719 simultaneously (e.g., when the circuit (700) is in a state corresponding to Figure 8A ) when configuring the operation.

[0064] Figure 9A Shown Figure 7 An idealized version 900 of the output transformer (733) is shown, where V1 corresponds to the output signal 747 from PA3 to the primary 735 of the output transformer (733), and V2 corresponds to the voltage across the opposite ends of the secondary 737 delivered to the first antenna (707), the second antenna (709), and the switch arrangement (722). I1 corresponds to the current flowing through the primary 735, and I2 corresponds to the current flowing through the secondary. L1 corresponds to the self-inductance of the primary (735), L2 corresponds to the self-inductance of the secondary (737), and k is the transformer coupling coefficient.

[0065] When switching from differential antenna mode to single-ended mode, the ideal transformer 900 with a 1:n input / output ratio presents a different load impedance (Z L), in the differential antenna mode, both the first antenna (707) and the second antenna (709) receive the differential signal (719), and in the single-ended mode, only the first antenna (707) or the second antenna (709) receives the differential signal (719). Theoretically, the load impedance (Z) when the first antenna (707) and the second antenna (709) receive the differential signal (719) is L ) is larger (e.g., 50 ohms) than the load impedance in the case where only the first antenna (707) or the second antenna (709) receives the differential signal (719). However, as described below with reference to Figure 9B As explained, these problems associated with the ideal transformer 900 are overcome according to one or more examples of the present disclosure.

[0066] Figure 9B An on-chip implementation 950 of a circuit (700) according to an example of the present disclosure is shown. The on-chip transformer implementation 950 has limited self-inductance (L1, L2) and non-ideal coupling between components, which can be used for matching. In implementing the circuit (700), design parameters such as the size of the circuit (700), L1, L2, and k can be selected to match both the single-ended impedance (e.g., 50Ω) and the differential impedance (100Ω) to the desired optimal load (Z) of the antenna (707, 709). L ) are matched, and the switch arrangement (722) has relatively small variation in the operating bandwidth of the circuit (700). In some examples, no additional matching components are required. In some examples, additional matching components such as fixed capacitors can be used to enhance performance, such as, for example, by widening the bandwidth. In some examples, one or more fixed components such as shunt capacitors (not shown) can be added to further enhance flexibility.

[0067] Figure 10A 1 is a graph 1000 of the input impedance of the transformer primary of the circuit (700) versus the operating frequency observed over the operating frequency range of 60 (sixty) GHz to 100 (one hundred) GHz. Line 1002 indicates the impedance of the transformer primary for a load impedance (Z) of 100 ohms when only the first antenna 707 or the second antenna 709 is coupled to the output transformer (733). L ), operating frequency and input impedance (Z in ), line 1004 indicates the relationship between the real part of the first antenna 707 and the second antenna 709 when only the first antenna 707 or the second antenna 709 is coupled to the output transformer (733), for a load impedance of 50 ohms (Z L ), operating frequency and input impedance (Z in )’s real part.

[0068] Figure 10B10 is a second graph 1010 of the input impedance of the transformer primary of the circuit (700) versus the operating frequency, observed over the operating frequency range of 60 (sixty) GHz to 100 (one hundred) GHz. Line 1006 indicates the impedance of the transformer primary to the operating frequency for a load impedance (Z) of 100 ohms when only the first antenna 707 or the second antenna 709 is coupled to the output transformer (733). L ), operating frequency and input impedance (Z in ), line 1008 indicates that when only the first antenna 707 or the second antenna 709 is coupled to the output transformer (733), for a load impedance of 50 ohms (Z L ), operating frequency and input impedance (Z in )’s imaginary part.

[0069] The various aspects and / or components of the examples may be used alone or in any combination. The examples set forth in this disclosure are exemplary and illustrative. The scope of the invention of the present disclosure is set forth in the following claims.

Claims

1. A method, characterized in that The method comprises: generating a positive transmit signal and a negative transmit signal that together form a differential transmit signal; setting the transmit antenna coupling interface to a first configuration, the first configuration driving the first transmit antenna and driving the second transmit antenna using the differential transmit signal; and Switching the transmit antenna coupling interface to a second configuration that combines power from the positive transmit signal and the negative transmit signal to drive the first transmit antenna while disconnecting and isolating the second transmit antenna from the transmit antenna coupling interface.

2. The method according to claim 1, characterized in that The method also includes switching the transmit antenna coupling interface to a third configuration that combines power from the positive transmit signal and the negative transmit signal to drive the second transmit antenna while isolating the first transmit antenna.

3. The method according to claim 1, characterized in that The transmitting antenna coupling interface includes: a 90-degree hybrid coupler having a first output port coupled to the first transmit antenna and a second output port coupled to the second transmit antenna, and having a first input port coupled to receive the positive transmit signal; and a configurable phase shifter that couples the negative transmit signal to the second input port of the 90-degree hybrid coupler, Wherein in the first configuration, the configurable phase shifter is set to zero degrees, and in the second configuration, the configurable phase shifter is set to negative 90 degrees.

4. The method according to claim 1, wherein The transmitting antenna coupling interface includes: an output transformer having a primary coupled between the positive transmit signal and the negative transmit signal, and having a secondary selectively coupled between the first transmit antenna and the second transmit antenna; a switch arrangement connecting a terminal of the secondary to the second transmitting antenna in the first configuration and connecting the terminal to ground in the second configuration; and A second switch arrangement connects opposite terminals of the secondary of the output transformer to the first transmit antenna in the first configuration and connects the opposite terminals of the secondary of the output transformer to ground in a third configuration.

5. The method according to claim 4, characterized in that The transmitting antenna coupling interface also includes: an input transformer having a primary and a secondary; and a power amplifier having an input port and an output port, The primary of the input transformer is coupled between the positive transmission signal and the negative transmission signal, the secondary of the input transformer is coupled to the input port of the power amplifier, and the output port of the power amplifier is connected to the primary of the output transformer.

6. An automotive radar system, characterized in that: The automotive radar system comprises: multiple transmit antennas; an integrated circuit comprising a transmit chain that generates a positive transmit signal and a negative transmit signal that together form a differential transmit signal; and a coupling interface that configurably couples the differential transmit signal to two transmit antennas of the plurality of transmit antennas to selectively drive the two transmit antennas in a differential mode or in a power combining mode that combines power from the positive transmit signal and the negative transmit signal to drive a first transmit antenna of the plurality of transmit antennas while disconnecting and isolating a second transmit antenna of the two transmit antennas from the coupling interface.

7. The automotive radar system according to claim 6, characterized in that The coupling interface further configurably couples the differential transmit signal to the two transmit antennas to selectively drive the two transmit antennas in a second power combining mode that combines power from the positive transmit signal and the negative transmit signal to drive the second transmit antenna while isolating the first transmit antenna.

8. The automotive radar system according to claim 6, characterized in that The coupling interface includes: a 90-degree hybrid coupler having a first output port coupled to the first transmit antenna and a second output port coupled to the second transmit antenna, and having a first input port coupled to receive the positive transmit signal; and a configurable phase shifter that couples the negative transmit signal to the second input port of the 90-degree hybrid coupler, The configurable phase shifter is alternately set to zero degrees corresponding to the differential mode or to 90 degrees corresponding to the power combining mode.

9. The automotive radar system according to claim 6, characterized in that The coupling interface includes: an output transformer having a primary coupled between the positive transmit signal and the negative transmit signal, and having a secondary selectively coupled between the first transmit antenna and the second transmit antenna; and A switch arrangement connects a terminal of the secondary to the second transmit antenna in a first configuration corresponding to the differential mode and connects the terminal to ground in a second configuration corresponding to the power combining mode.

10. The automotive radar system according to claim 9, characterized in that The coupling interface further includes: A second switch arrangement connects opposite terminals of the secondary of the output transformer to the first transmit antenna in the first configuration and connects the opposite terminals of the secondary of the output transformer to ground in a third configuration.

11. The automotive radar system according to claim 10, characterized in that The coupling interface further includes: an input transformer having a primary and a secondary; and a power amplifier having an input port and an output port, The primary of the input transformer is coupled between the positive transmission signal and the negative transmission signal, the secondary of the input transformer is coupled to the input port of the power amplifier, and the output port of the power amplifier is connected to the primary of the output transformer.

Images