Phase-adjustable injection locking

Abstract

Various aspects of the present disclosure relate to injection locking and related devices. As may be implemented according to one or more embodiments, a device includes a plurality of injection locking circuits configured to receive an injection signal, each injection locking circuit including a mixer and a lock detection circuit. In each of the injection locking circuits, the lock detection circuit detects a lock state relationship between the injection signal and a signal output from the injection locking circuit. In response to the lock state relationship indicating an unlock condition, the phase / amplitude of the injection signal is adjusted. In response to the lock state relationship indicating a lock condition, the transmission of an FM continuous wave (FMCW) linear frequency modulation signal is facilitated.

Description

Technical Field

[0001] Aspects of the various embodiments relate to injection locking, which can be facilitated by phase tuning of the injected signal. Background Art

[0002] Various circuit systems can utilize injection locking. For example, an injection-locked amplifier can be used to lock onto an injected signal to generate various outputs, such as those used in radar transceivers. This approach can be useful in the automotive industry, where radar-based signals are used in a variety of applications. Such systems can utilize several (differential) amplifier stages tuned to the operating frequency.

[0003] While injection locking is useful, it can be complex to implement and consumes significant power when performing the locking function. Additionally, the locking range can be limited, the amplitude can be excessive, and the phase can vary with the signal. These and other issues challenge the efficiency of injection locking implementations for a variety of applications. Summary of the Invention

[0004] Various example embodiments address various issues, such as those set forth above, and / or other issues that may become apparent from the following disclosure regarding injection locking and achieving injection locking using phase adjustment methods.

[0005] In certain example embodiments, aspects of the present disclosure relate to using feedback and / or feedforward loops to adjust the phase of an output signal generated using an injection signal. For example, such methods can be performed by using a feedback circuit to determine a phase difference between the injection signal and an amplified version of the output signal, and adjusting the phase of the output signal based on any such determined difference.

[0006] In a more specific example embodiment, a device includes a plurality of injection-locked circuits configured to receive an injection signal, each injection-locked circuit including a mixer and a lock detection circuit. In each of the injection-locked circuits, the lock detection circuit detects a lock state relationship between the injection signal and an output signal from the injection-locked circuit. In response to the lock state relationship indicating an unlocked condition, the phase of the output signal is adjusted. In response to the lock state relationship indicating a locked condition, transmission of an FM continuous wave (FMCW) chirp signal is facilitated.

[0007] In another specific example embodiment, a method is performed as follows. A plurality of injection-locked circuits are driven with associated injection signals, wherein each of the plurality of injection-locked circuits includes a mixer and a lock detection circuit to adjust the phase of an output signal. In each of the plurality of injection-locked circuits, a lock state relationship between the injection signal and an output signal from the injection-locked circuit is detected using the lock detection circuit. In response to the lock state relationship indicating an unlocked condition, the phase of the output signal is adjusted. In response to the lock state relationship indicating a locked condition, an FM continuous wave (FMCW) chirp signal is output.

[0008] In another specific example embodiment, a device includes an antenna, an oscillator, an amplifier, an injection-locked circuit, and a feedback circuit. The oscillator is configured and arranged to generate an oscillating FM continuous wave (FMCW) radar injection signal, the injection signal used to generate an output signal. The injection-locked circuit is configured to adjust the phase of the output signal based on a tuning voltage to provide a phase-adjusted FMCW output signal to the amplifier. The amplifier is configured and arranged to output an amplified version of the phase-adjusted FMCW output signal to the antenna for transmission. The feedback circuit is configured and arranged to supply the tuning voltage by comparing the phase of the output signal with the phase of the injection signal and, in response to the comparison indicating a corresponding phase difference, setting the tuning voltage to cause the injection-locked circuit to adjust the phase of the output signal.

[0009] The above discussion / summary is not intended to describe each embodiment or every implementation of the present disclosure. The following figures and detailed description also illustrate various embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Various example embodiments may be more fully understood upon consideration of the following detailed description taken in conjunction with the accompanying drawings, in which:

[0011] Figure 1A An injection locking device according to the present disclosure is shown.

[0012] Figure 1B Shows that it can be Figure 1A an embodiment of an injection locking circuit system including an RMS circuit system implemented in conjunction with a device;

[0013] Figure 1C Shows that it can be Figure 1A Another embodiment of the injection locking circuit system implemented together with the device;

[0014] Figure 2 An injection-locked device with feed-forward circuitry according to the present disclosure is shown; and

[0015] Figure 3 A radar device according to the present disclosure is shown.

[0016] Although the various embodiments discussed herein are susceptible to modifications and alternative forms, aspects of the various embodiments have been illustrated by way of example in the drawings and will be described in detail. However, it should be understood that the present invention is not intended to limit the present disclosure to the specific embodiments described. On the contrary, the present invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure, including those defined in the claims. Furthermore, the term "example" as used throughout this application is illustrative only and not limiting. DETAILED DESCRIPTION

[0017] It is believed that various aspects of the present invention are applicable to various different types of devices, systems, and methods involving phase locking. In certain embodiments, various aspects of the present disclosure have proven beneficial when used in the context of signal generation and amplification, such as in automotive signaling applications, including radar-based applications. In some embodiments, the phase of an amplified FMCW radar chirp output signal is compared to the phase of an injection signal used to generate the chirp. The phase of the output signal is modified in response to the comparison indicating a phase difference. Although not necessarily so limited, various aspects may be understood through the following discussion of non-limiting examples using exemplary scenarios.

[0018] In the following description, various specific details are set forth to describe the specific examples presented herein. However, it will be apparent to those skilled in the art that one or more other examples and / or variations of these examples may be practiced without all of the specific details given below. In other cases, well-known features are not described in detail to avoid obscuring the description of the examples herein. For ease of illustration, the same reference numerals may be used in different figures to refer to the same elements or other instances of the same elements. Similarly, although various aspects and features may be described in different figures in some cases, it will be understood that features of one figure or embodiment may be combined with features of another figure or embodiment, even if the combination is not explicitly shown or is not explicitly described as a combination.

[0019] Various embodiments relate to using feedback to lock the phase of an output signal relative to an injected signal on which the output signal is based. For example, by using a varactor diode with a tunable input voltage Vtune utilized in an injection locking stage to tune the oscillation frequency. The feedback loop detects the phase deviation between the signals and corrects it to achieve phase lock. This method can be implemented using a mixer that provides a zero output once phase lock is achieved. This can involve applying a 90-degree phase shift between the output signal and the injected signal, or applying an opposite -45-degree offset to the injected signal and a +45-degree offset (e.g., Vtank) to the output signal. This can be achieved by using high-pass and low-pass filters on Vtank and Vinj, respectively. In a more specific application, a mixer circuit system is used to first mix the injected signal and the oscillator signal to an intermediate frequency (IF), and then a phase frequency detector is used.

[0020] In various embodiments, the corresponding injection locking stage is locked before activating the feedback loop to tune the phase. For example, the same mixer used for phase detection can identify lock based on the beat frequency, and an RMS detector can be buffered and connected to a counter and latch to detect the unlocked state. When implemented in a radar system, a first chirp can be initiated, and the voltage range of the varactor diode is defined based on the magnitude of the chirp. The RMS circuit is used to detect injection locking. If lock is not detected, the injection signal can be increased until injection lock is confirmed. Another chirp can be initiated to verify lock. Feedback can then be used to initiate a chirp sequence to ensure phase matching as characterized herein.

[0021] In a specific example embodiment, a device includes an injection locking circuit configured to receive an injection signal and includes a mixer and a lock detection circuit. The lock detection circuit detects a lock state relationship between the injection signal and an output signal from the injection locking circuit. If the lock state relationship indicates an unlocked condition, the phase / amplitude of the output signal is adjusted. If the lock state relationship indicates a locked state, an FM continuous wave (FMCW) linear frequency modulation signal can be transmitted. Such methods can be performed using multiple such injection locking circuits, for example, multiple such injection locking circuits can be used to amplify the FMCW signal for transmission, or amplify received reflections of the FMCW signal (for example, mixed with an injection signal for generating a transmission from which the reflections were received). Various embodiments further include a phase-locked loop oscillator circuit and an amplifier, the phase-locked loop oscillator circuit generating an injection signal for driving the injection locking circuit, and the amplifier being configured to amplify a phase-modulated version of the output signal.

[0022] Injection locking circuits can be implemented in various ways. In some embodiments, a mixer is configured to combine an injection signal and a representation of an output signal from the injection locking circuit and provide an output indicating the phase difference between the injection signal and the output signal. In certain embodiments, the injection locking circuit adjusts the phase of the output signal in response to a tuning voltage, for example by using a varactor diode. The lock detection circuit can adjust the phase / amplitude of the output signal by setting a voltage range for the tuning voltage. For example, the lock detection circuit can include capacitor circuitry configured to cause the tuning voltage to assume a voltage within a tuning range. This tuning voltage affects the phase change of the output signal, thereby facilitating locking.

[0023] Various embodiments relate to feedforward control of the phase adjustment of an injection signal. For example, a feedforward circuit can be configured to set an operating voltage of an injection-locked circuit based on an injection signal from the injection circuit. In certain feedforward implementations, the injection-locked circuit adjusts the phase of an output signal generated using the injection signal based on a tuning voltage. The feedforward circuit responds to the output of the injection oscillator by setting a voltage range for the tuning voltage. In various scenarios, it has been recognized / discovered that using this phase locking method, the frequency range over which injection locking can be achieved can be increased and amplitude variation can be reduced.

[0024] Various embodiments relate to methods for injection locking. According to certain embodiments, a method is performed as follows. A plurality of injection-locked circuits are driven with associated injection signals, wherein each of the plurality of injection-locked circuits includes a mixer and a lock detection circuit to adjust the phase of an output signal generated based on the injection signal. In each of the plurality of injection-locked circuits, a lock state relationship between the injection signal and an output signal from the injection-locked circuit is detected using the lock detection circuit. In response to the lock state relationship indicating an unlocked condition, the phase of the output signal is adjusted. In response to the lock state relationship indicating a locked condition, an FM continuous wave (FMCW) chirp signal is output.

[0025] In various embodiments, a phase-locked loop oscillator circuit is used to drive each of the injection-locked circuits, wherein an injection signal is used to drive the amplifier. In some implementations, a mixer is used to combine the phase-modulated output of the injection-locked circuit with a signal corresponding to the injection signal, and the lock state relationship is detected based on the output of the mixer. In certain implementations, the mixer provides an output indicating the phase difference between the injection signal and the output signal, and the phase of the output signal is adjusted based on the phase difference.

[0026] The phase of the output signal can be adjusted in various ways. In some embodiments, a tuning voltage supplied to the injection-locking circuit is set within a voltage range, and this voltage range is used to cause the injection-locking circuit to adjust the phase of the resulting output signal. In certain embodiments, the tuning voltage of a varactor diode is adjusted, and the varactor diode is used to adjust the phase of the output signal.

[0027] Another embodiment relates to a device comprising an antenna, an oscillator, an amplifier, an injection-locked circuit, and a feedback circuit. The oscillator is configured and arranged to generate an oscillating FM continuous wave (FMCW) radar injection signal. The injection-locked circuit is configured to use the FMCW injection signal to generate an output signal and adjust the phase of the output signal based on a tuning voltage to provide the phase-modulated FMCW signal to the amplifier. The amplifier is configured and arranged to output an amplified version of the phase-modulated FMCW signal to the antenna for transmission. The feedback circuit is configured and arranged to provide the tuning voltage by comparing the phase of the amplifier output with the phase of the injection signal. In response to the comparison indicating a corresponding phase difference, the feedback circuit sets the tuning voltage to cause the injection-locked circuit to adjust the phase of the output signal. For example, the injection-locked circuit may transmit an amplified version of the phase-modulated FMCW output signal in response to the comparison indicating a corresponding phase match.

[0028] As characterized in one or more embodiments herein, the feedback circuit may include a mixer circuit that mixes an injection signal with an amplified version of the injection signal output by an amplifier, and a lock detection circuit that detects a corresponding phase difference. A capacitor circuit adjusts the output voltage of the mixer circuit to provide the adjusted output as a tuning voltage.

[0029] Turning now to the accompanying drawings, Figure 1A An injection-locking device 100 that can be implemented according to the present disclosure is shown. Device 100 includes injection-locking circuitry 110, including a phase tuning component 111 and an amplifier 112 (which can be implemented in common circuitry and / or the same circuit), and feedback circuitry, including a mixer 140 and a feedback circuit block 170. Feedback circuit block 170 provides lock detection and control for phase tuning component 111. Phase tuning component 111 adjusts the phase of an output signal generated by the injection-locking circuitry based on an injection signal, which can be generated by an oscillator 120. This phase adjustment can be based on an input from feedback circuit block 170, and amplifier 112 amplifies the phase-adjusted injection signal. For example, feedback circuit block 170 can control phase tuning component 111 by mixing the output of amplifier 112 with the injection signal to detect a phase difference. If the phases differ, phase tuning component 111 is controlled to modify the phase of the output signal from amplifier 112.

[0030] In various embodiments, feedback circuit block 170 includes an injection lock detector 150 (e.g., which may be implemented using an RMS detector and / or a voltage monitor) and a tuning circuit 160 (e.g., a filter that ensures stability of the phase-locked loop). If injection lock detector 150 detects a phase difference (e.g., a mixer output indicates that the phase of the signal output from injection locking circuitry 110 is not locked to the phase of the injected signal), tuning circuit 160 adjusts the output provided to phase tuning component 111 so that the phase of the injected signal is modified.

[0031] In some embodiments, the injection locking method performed by mixer 140 is implemented during an initialization event, during which a dummy FMCW signal is generated and used to assess injection locking. If no error is observed from injection locking, a full FMCW sequence is initiated. For example, if no error is observed, the output of mixer 140 can be zero or negligible (e.g., there is no feedback between the injection locking detector and the tuning circuit).

[0032] In some embodiments, one or more phase shifting circuits are used to shift the phase of the signal provided to mixer 140. For example, a 90-degree phase shifting circuit 130 is shown and can be used to shift the phase of the output signal provided to mixer 140 from injection locking circuitry 110. In some embodiments, respective 45-degree phase shifting circuits are used to shift the phases of the injection signal and the output signal provided to mixer 140, respectively, which has a similar effect to using the 90-degree phase shifting circuit 130.

[0033] Figure 1B Shows that it can be Figure 1A 1 . An embodiment of an injection-locked circuit system for use with a feedback circuit block 170 of a device in FIG. The injection-locked detector 150 includes an RMS detection circuit system including a square root circuit component (151), an averaging circuit component (152), and a squaring circuit component (153) as shown. Exemplary functions for characterizing signals at various locations in the circuit are also shown. A tuning circuit 160, such as a low-pass filter, can be implemented using capacitive circuit system including a capacitor C1 coupled to a resistor R1 and a capacitor C2 connected as shown.

[0034] Figure 1C Another embodiment of an injection locking circuit system is shown, which can be used with Figure 1AThe device is used in conjunction with the feedback circuit block 170 of the device to provide a tuning voltage (Vtune) for controlling the phase tuning component 111 (e.g., a filter such as a low-pass filter). The phase detector 150 is used to detect the phase difference between the injected signal and the amplified signal, in response to which the corresponding capacitors C1 and C2 and resistor R1 set a window in which Vtune is set. In this scenario, when the phase is mismatched, the mixer 140 can effectively act as a phase detector by providing an output, to which the circuit system 150 responds.

[0035] Figure 2 An injection-locked device 200 with a feedforward circuit system 222 according to the present disclosure is shown. For example, the device 200 can be implemented in a manner similar to that shown in the device 100 in Figure 1. The feedforward circuit system 222 is used to control the frequency (and associated phase) tuning of the injection-locked stage 210 based on the injection signal provided to it. For example, the device may also include a feedback circuit system, the feedback circuit system including a mixer 240 and a tuning circuit system 270, the mixer 240 mixing the injection signal with the output from the injection-locked stage 210, the tuning circuit 270 generating a voltage signal for tuning the injection-locked stage when the injection signal is out of phase with the output of the injection-locked stage. Feedback can be used to facilitate alignment of feedforward compensation for different chirp bandwidths. In various embodiments, the mixer 240 and the tuning circuit system 270 can be ignored when performing the feedforward operation.

[0036] Feedforward circuitry 222 can operate in various ways to suit a particular embodiment. For example, injection locking stage 210 can include a varactor diode driven by a tuning voltage (Vtune). The varactor diode covers a frequency range, and a smaller or larger voltage range can be set to facilitate phase locking. A DAC can be used to set a voltage range within which a tuning range corresponding to the desired linear frequency modulation bandwidth for the injection signal can be defined. Mixer 240 is used together with an RMS detector in 270 to detect the beat frequency. In these examples, the amplitude of the injection signal can be kept constant.

[0037] Figure 3Radar device 300 according to the present disclosure is shown. Device 300 includes an FMCW generator 310, injection locking circuitry 320, and amplifier 330, which together generate a radar signal and transmit the radar signal via antenna 340. The device includes receiver circuitry for receiving reflections of the transmitted radar signal, including antenna 342 and amplifier 360. Mixer 370 mixes an amplified version of the received reflections from amplifier 360 with the FMCW signal and may provide an output to circuitry 380 for processing in determining the distance to an object 390. Phase locking circuitry 350 may be implemented and operated to provide phase lock with respect to mixer 370.

[0038] The injection locking circuit 320 is used to adjust the phase of the output signal from the amplifier 330 based on the phase mismatch between the injection signal and the output of the amplifier 330. For example, such a method may include mixing the output of the amplifier 330 with the injection signal, detecting whether phase lock exists, and adjusting the tuning input (e.g., a tuning voltage applied to a varactor diode) to modify the generation of the output signal from the amplifier 330. Figure 1A Various such methods may be performed in a manner consistent with the description herein or otherwise.

[0039] Those skilled in the art will recognize that, unless otherwise indicated, the various terms used in the specification (including the claims) represent the simple meaning of the art. As an example, the specification describes and / or illustrates aspects useful for implementing the claimed disclosure by various circuits or circuit systems, which may be described or used as terms such as blocks, modules, devices, systems, units, controllers, generators, oscillators, detectors, mixers, and / or other circuit types (e.g., reference numerals 150, 160, and 170 of FIG. 1 may depict blocks / modules described herein). Such circuits or circuit systems are used together with other components to illustrate how certain embodiments are performed in form or structure, steps, functions, operations, or activities. For example, in some of the above-described embodiments, one or more modules are discrete logic circuits or programmable logic circuits configured and arranged to implement these operations / activities, as may be performed in the methods shown in the accompanying drawings. In certain embodiments, such programmable circuits are one or more computer circuits including memory circuits for storing and accessing a program executed as a set of one or more instructions (and / or configuration data defining the manner in which the programmable circuits execute), and the algorithms or processes described herein in conjunction with the tuning of the injection signals are used by such programmable circuits to perform the relevant steps, functions, operations, and activities. Depending on the application, the instructions (and / or configuration data) may be configured to be implemented in logic circuits, where the instructions (whether represented in the form of object code, firmware, or software) are stored in and accessible from the memory (circuit). As another example, where the specification may refer to "a first [type of structure]," "a second [type of structure]," and so forth (e.g., in the context of amplifiers and receiver amplifiers), where [type of structure] may be replaced with terms such as ["circuit," "circuitry," and others], the adjectives "first" and "second" or "receiver" are not necessarily used to indicate any description of the structure or to provide any substantive meaning; rather, such adjectives are merely used in conjunction with the English antecedent to distinguish one similarly named structure from another similarly named structure (e.g., "a first circuit configured to adjust..." is interpreted as "a circuit configured to adjust..."). It should also be understood that the terminology is used for convenience only, and that, in actual use, the orientation of the disclosed structures may differ from that shown in the figures. Accordingly, these terms should not be interpreted in a limiting manner.

[0040] Based on the above discussion and illustrations, those skilled in the art will readily recognize that various modifications and changes may be made to the various embodiments without strictly following the exemplary embodiments and applications shown and described herein. For example, Figure 1AAspects of the invention may be implemented separately, such as a separate phase adjustment device implemented with the circuitry in block 170 and mixer 140, which may be useful for various types of injection locking. Block 170 may also be implemented in conjunction with mixer 140 and injection locking circuitry 111 as different embodiments, and may also be implemented for different types of injection locking. As another example, the methods illustrated in the figures may involve steps performed in various orders, which retain one or more aspects of the embodiments herein, or may include fewer or more steps. For example, Figure 1A The feedback circuit shown can be used with various injection locking circuits (such as Figure 3 As another example, Figure 3 The device shown may be implemented for non-radar functions, for example using various other types of signaling methods in which injection signals are utilized.Such modifications do not depart from the true spirit and scope of the aspects of the present disclosure, including those set forth in the claims.

Claims

1. A device, characterized in that include: a plurality of injection locking circuits for receiving an injection signal for generating an FM continuous wave (FMCW) chirp signal, each injection locking circuit comprising a mixer to combine the injection signal with a representation of an output signal from the injection locking circuit, each injection locking circuit further comprising a lock detection circuit; and In each of the injection locking circuits, the lock detection circuit detects a lock state relationship between a phase of the injection signal and a phase of an output signal from the injection locking circuit, thereby: In response to the locked state relationship indicating an unlocked condition, adjusting the phase of the output signal, and In response to the lock status relationship indicating a lock condition, the output signal corresponding to the FM continuous wave (FMCW) chirp signal is transmitted.

2. The device according to claim 1, characterized in that Also included is a phase-locked loop circuit for generating the injection signal to drive each of the plurality of injection-locked circuits, each of the injection-locked circuits having an amplifier configured to provide the output signal using the injection signal having a phase set by the injection-locked circuit.

3. The device according to claim 1, characterized in that In each of the plurality of injection locked circuits, the mixer is configured to combine the injection signal and a representation of the output signal and to provide an output indicative of a phase difference between the injection signal and the output signal.

4. The device according to claim 1, characterized in that Each of the plurality of injection-locked circuits further includes an injection circuit and a feedforward circuit. The injection circuit is configured to generate the injection signal, and the feedforward circuit is configured to set an operating voltage of the injection-locked circuit based on the injection signal.

5. The device according to claim 4, characterized in that Each of the injection locking circuits is configured to set the phase of the output signal in response to a tuning voltage and the injection signal; and The feedforward circuit is configured and arranged to respond to the output of the injection circuit by setting a voltage range of the tuning voltage.

6. The device according to claim 1, characterized in that The injection locking circuit is configured to adjust the phase of the output signal generated from the injection signal in response to a tuning voltage; and The lock detection circuit is configured to adjust the phase of the output signal by setting a voltage range of the tuning voltage.

7. The device according to claim 6, characterized in that The lock detection circuit includes capacitor circuitry configured to cause the tuning voltage to assume a voltage within a tuning range.

8. The device according to claim 1, characterized in that Each of the plurality of injection locking circuits includes a varactor configured to adjust the phase of the output signal based on a tuning voltage output of the lock detection circuit.

9. A method, characterized in that include: driving a plurality of injection-locked circuits with associated injection signals for generating an FM continuous wave (FMCW) chirp signal, wherein each of the plurality of injection-locked circuits includes a mixer and a lock detection circuit; as well as In each of the plurality of injection locking circuits, detecting a locked state relationship between a phase of the injection signal and a phase representation of an output signal from the injection locking circuit using the lock detection circuit, and in response to the locked state relationship indicating: unlock condition, adjust the phase of the output signal, and In response to a lock condition, the output signal corresponding to the FM continuous wave (FMCW) chirp signal is transmitted.

10. A device, characterized in that include: antenna; an oscillator configured and arranged to generate an oscillating injection signal for producing an FM continuous wave (FMCW) radar injection signal; amplifier; an injection locking circuit configured and arranged to generate a phase-modulated FMCW output signal with the amplifier based on the injection signal and a tuning voltage, the amplifier configured and arranged to provide the output signal to the antenna for transmission; as well as a feedback circuit, including a lock detection circuit and a tuning circuit; the lock detection circuit being configured and arranged to detect a lock state relationship between a phase of the injection signal and a phase representation of an output signal from the injection locking circuit, and in response to the lock state relationship indicating an unlock condition, adjust the phase of the output signal, and in response to the lock condition, transmit the output signal corresponding to the FM continuous wave (FMCW) chirp signal; and The tuning circuit is configured and arranged to supply a tuning voltage by: comparing the phase of the output signal with the phase of the injected signal; and In response to the comparison indicating a corresponding phase difference, the tuning voltage is set to cause the injection locking circuit to adjust the phase of the output signal.

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