Multi-injection locking annular traveling wave oscillator, Doppler radar and detection equipment

Abstract

The invention relates to the field of integrated circuits, in particular to a multi-injection locking annular traveling wave oscillator, a Doppler radar based on the annular traveling wave oscillator and physiological feature detection equipment based on the annular traveling wave oscillator. Comprising 16 inductive elements. Four variable capacitors and four mirror image injection circuits. The inductive elements are sequentially connected end to end. And every two adjacent inductive elements form a phase shift channel and are sequentially distributed in four orthogonal directions. And the two phase shift channels in each direction are parallel to each other and are positioned on the inner side and the outer side of the same layer of the layout. The phase shift channels on the inner and outer sides in adjacent directions are alternately connected, and the wires between the phase shift channels are distributed on the upper and lower layers in the layout at equal intervals. The mirror image injection circuit and the variable capacitor are connected between the two phase shift channels in each direction and output injection signals with the phase difference of 180 degrees to the phase shift channels. According to the invention, the problems of limited injection locking range, high noise and insufficient phase uniformity of the existing oscillator for the Doppler radar are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of integrated circuits, and in particular to a multi-injection-locked ring traveling wave oscillator, and a Doppler radar and a physiological characteristic detection device based on the ring traveling wave oscillator. BACKGROUND

[0002] Respiration and heartbeat frequency are key indicators for assessing the life state of a human body, and have important value in disease diagnosis, health monitoring and emergency rescue. Non-contact vital sign detection technology (such as radar detection) gradually attracts attention because it is user-unaware and easy to deploy. For example, through a Doppler radar, echo signals caused by human chest wall movement can be efficiently and stably detected, and then used for monitoring the life characteristics of a human body in non-contact scenarios such as burn monitoring and earthquake rescue.

[0003] However, the traditional injection-locked Doppler radar structure as shown in Figure 1 is complex, requires a mixer to demodulate a signal, has high hardware cost, and has large mixer noise, which affects detection sensitivity. On this basis, a technician proposes another self-injection-locked radar based on a phase-locked loop (PLL), which uses an injection-locked oscillator as a demodulation core and has a bandpass filtering characteristic, which can reduce system complexity while ensuring overall performance. However, the inductor-capacitor (LC) oscillator of such a Doppler radar still has the problem of low injection sensitivity. For example, Figure 2 provides a simple structure ring oscillator, which has low power consumption, supports multi-phase operation, but has a relatively low working frequency and a relatively high phase noise, Figure 3 provides an LC oscillator with low phase noise, which is suitable for high-frequency operation, but has the problem of being unable to generate multiple phases, and needs to be combined with a complex circuit to generate multiple phases. Figure 4 proposes a ring traveling wave oscillator (RTWO) that combines the advantages of ring oscillators and LC oscillators, has low phase noise and multi-phase injection point capability when working at high frequency. However, the single injection circuit used by the traditional one has the problems of low injection efficiency, effective injection only in half of the oscillation period, and difficulty in controlling the common-mode level, which limits the locking range and affects the detection sensitivity. Figure 5 Further provides a ring traveling wave oscillator with a large injection locking range, but the circuit needs to work at a low oscillation amplitude, and the asymmetry of the Mobius ring causes the phase of the ring traveling wave oscillator to become uneven when working at low voltage, affecting its normal operation at low voltage. SUMMARY

[0004] In order to solve the problems of limited injection locking range, high noise and insufficient phase uniformity of the existing oscillators for Doppler radars, the application provides a multi-injection-locked ring wave oscillator, a Doppler radar and a physiological characteristic detection device based on the ring wave oscillator.

[0005] The technical scheme provided by the application is as follows: The multi-injection-locked ring wave oscillator comprises 16 inductive elements rf1-rf16, four variable capacitors Cv1-Cv4 and four mirror injection circuits, the inductive elements rf1-rf16 are sequentially connected and connected at the head and tail, and each two adjacent inductive elements form a phase-shifting channel.

[0006] In each two adjacent directions, the inboard phase-shifting channel and the outboard phase-shifting channel are electrically connected through two groups of wires respectively, and the two groups of wires are arranged on the upper and lower layers at the same position in the layout plane and have equal distances on the layout plane.

[0007] In each direction of the layout, the first end of the first inductive element in the inboard phase-shifting channel and the first end of the first inductive element in the outboard phase-shifting channel are used as two injection ports with a phase interval of 180° and are electrically connected with two output ends of a mirror injection circuit.

[0008] In addition, the tail end of the first inductive element in the inboard phase-shifting channel and the tail end of the first inductive element in the outboard phase-shifting channel are respectively connected with two ends of a variable capacitor.

[0009] As a further improvement of the application, the wire for connecting the inboard and outboard phase-shifting channels in adjacent directions is composed of a first diverging section connected to the first phase-shifting channel, a collinear section in the middle and a second diverging section connected to the second phase-shifting channel. The first diverging sections connected to the ends of the two phase-shifting channels in any direction are arranged along the upper and lower layers and extend to the inner side by 45°, and then overlap the upper and lower layers of the same point P in the layout plane. The second diverging sections connected to the ends of the two phase-shifting channels in the next direction are also arranged along the upper and lower layers and extend to the inner side by 45°, and then overlap the upper and lower layers of the same point Q in the layout plane. The collinear section comprises two sub-sections perpendicular to each other and having equal distances in the layout plane, and the two collinear sections are connected to the nodes P and Q along the upper and lower layers respectively.

[0010] As a further improvement of the present application, each mirror injection circuit is composed of 4 PMOS tubes P1~P4 and 5 NMOS tubes N1~N5. Among them, the sources of P1~P4 are connected to VDD; the drains of P1 and N1 are connected; the drains of P2 and N2 are connected; the gates of P1 and N1 are connected and serve as a positive input port Vinj+; the gates of P2 and N2 are connected and serve as an inverting input port Vinj﹣. The drains of P1, N1, P3, N3 are connected to the gates of P4, N4, and serve as an output port of one of the injection signals A; the drains of P2, N2, P4, N4 are connected to the gates of P3, N3, and serve as an output port of one of the injection signals B. The sources of N3, N4 are connected to the drain of N5; the gate of N5 is connected to a reference voltage signal Vbias; the sources of N1, N2, N5 are connected to VSS.

[0011] As a further improvement of the present application, the variable capacitors in each direction are arranged in the region between the two phase shift channels in that direction; both are located in the same layer as the inductive elements in the inner and outer phase shift channels.

[0012] As a further improvement of the present application, the variable capacitors in different directions are arranged in a rotationally symmetrical manner on the layout, with a rotation angle of 90°.

[0013] As a further improvement of the present application, the multi-injection-locked ring wave oscillator includes 8 injection ports respectively located on each phase shift channel, and the phase difference of the injection signals of the injection ports in adjacent phase shift channels is 45°.

[0014] As a further improvement of the present application, the variable capacitors are interdigital capacitors.

[0015] As a further improvement of the present application, the inductive elements are high-layer metal lines.

[0016] The present application also includes a Doppler radar that uses the multi-injection-locked ring wave oscillator as described above.

[0017] The present application also includes a physiological feature detection device for detecting the physiological features of a human body through non-contact vital sign detection technology, which uses the Doppler radar as described above to detect the phase change of the echo signal caused by the chest wall movement of the human body, and further extracts the breathing and heartbeat information.

[0018] The present application has the following beneficial effects: The multi-injection-locked ring wave oscillator provided by the application is provided with complementary injection circuits at 8 phase nodes of the ring, there is a 45-degree phase difference between the injection signals, and the 8 nodes of the ring wave oscillator are sequentially injected. The injection locking range is improved to 8 times of single injection, and the signal-to-noise ratio is improved by 9dB. The mirror injection circuit in the circuit adopts a complementary structure of parallel connection of NMOS and PMOS, and can effectively inject signals in the positive and negative half cycles of the oscillator, and the injection efficiency is twice that of the traditional circuit.

[0019] The application also optimizes the transmission path, spatial layout and performance of the ring wave oscillator from the aspects of circuit structure and layout design, so that the ring wave propagates at a consistent distance in each section of the ring, the standing wave is suppressed, the oscillation amplitude is reduced, and the locking range is expanded. Finally, the circuit layout of the ring wave oscillator in the form of a Mobius ring structure is in a strict rotational symmetry structure, which can significantly improve the stability of the circuit. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 A schematic diagram of the traditional Doppler radar introduced in the background art.

[0021] Figure 2 A circuit diagram of the ring oscillator introduced in the background art.

[0022] Figure 3 A circuit diagram of the LC oscillator introduced in the background art.

[0023] Figure 4 A circuit diagram of the ring wave oscillator and the injection locking circuit used by the ring wave oscillator introduced in the background art.

[0024] Figure 5 A circuit diagram of the ring wave oscillator with a large injection locking range introduced in the background art.

[0025] Figure 6 A circuit diagram of the multi-injection-locked ring wave oscillator provided in embodiment 1 of the application.

[0026] Figure 7 A circuit diagram of the mirror injection circuit used in embodiment 1 of the application.

[0027] Figure 8 A layout design of the multi-injection-locked ring wave oscillator provided in embodiment 1 of the application.

[0028] Figure 9 A circuit schematic diagram of the Doppler radar provided in embodiment 2 of the application. DETAILED DESCRIPTION

[0029] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing the specific embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] Embodiment 1 The embodiment provides a multi-injection-locked ring wave oscillator, and mirror injection circuits are arranged at 8 phase nodes in the ring wave oscillator. Each mirror injection circuit sequentially injects injection signals with a phase difference of 45° from each other into each phase node. The injection locking range can be increased to 8 times of single-node injection, that is, the equivalent signal power is increased to 64 times of single-node injection. Due to thermal noise non-correlation, the multi-injection only increases the noise power to 8 times, and the signal-to-noise ratio is increased by 9 dB. On this basis, the transmission path of the ring wave oscillator is arranged in a double-layer layout space according to the structure of a Mobius ring, so that the propagation distances of the wave in each section of the ring are consistent, and the standing wave is suppressed. In turn, the oscillation amplitude is reduced and the locking range of the oscillator is expanded.

[0032] Specifically, as Figure 6As shown, the multi-injection locked ring traveling wave oscillator provided in this embodiment includes 16 inductive elements rf1~rf16; 4 variable capacitors Cv1~Cv4; and 4 stub injection circuits. In practical applications, the variable capacitors in this RF device can be interdigitated capacitors; the inductive elements can be high-layer metal wires. In the ring traveling wave oscillator of this embodiment, the 16 inductive elements rf1~rf16 are connected sequentially and end-to-end; every two adjacent inductive elements form a phase-shifting channel, and the phase difference between adjacent phase-shifting channels is 45°; thus forming a full-cycle loop. The stub injection circuit adopts a mirror structure design and has two output ports for injection signals. Each stub injection circuit can be used to generate a set of injection signals A and B with a phase difference of 180° based on a set of differential input signals Vinj+ and Vinj-; and output them to the injection ports in the corresponding two phase-shifting channels. Eight injection ports utilize a complementary injection circuit to sequentially input signals with a 45° phase difference. After superposition, these signals are equivalent to a single signal, resulting in a 64-fold power increase. Simultaneously, the noise levels are independent, and the power is eight times the original, significantly improving the system's signal-to-noise ratio. A variable capacitor is used to change the frequency of the ring traveling-wave oscillator. Since the oscillation frequency of a ring traveling-wave oscillator consisting only of transmission lines is related to the size of the ring, achieving the target 20GHz frequency would require a very large transmission line loop, greatly increasing chip cost. Therefore, in practical designs, capacitors are added to the loop to reduce the frequency.

[0033] To optimize the transmission path in the traveling-wave ring oscillator, this embodiment sequentially distributes eight phase-shifting channels in four orthogonal directions at the layout level. Each direction includes two phase-shifting channels with a phase difference of 180°, which are parallel to each other and located on the inner and outer sides of the same layer of the layout. In the ring path formed by the various phase-shifting channels, the inner phase-shifting channel in the previous direction is connected to the outer phase-shifting channel in the next direction; the outer phase-shifting channel in the previous direction is connected to the inner phase-shifting channel in the next direction; thus forming a two-layer Möbius strip structure; the Möbius strip is approximately square in shape on the plane.

[0034] Specifically, such as Figure 6 As shown, a first phase-shifting channel and a fifth phase-shifting channel are arranged parallel to each other in the first direction; a second phase-shifting channel and a sixth phase-shifting channel are arranged parallel to each other in the second direction; a third phase-shifting channel and a seventh phase-shifting channel are arranged parallel to each other in the third direction; and a fourth phase-shifting channel and an eighth phase-shifting channel are arranged parallel to each other in the fourth direction. The first phase-shifting channel is located in the inner layer of the first direction; the second phase-shifting channel is located in the outer layer of the second direction; the third phase-shifting channel is located in the inner layer of the third direction; the fourth phase-shifting channel is located in the outer layer of the fourth direction; the fifth phase-shifting channel is located in the outer layer of the first direction; the sixth phase-shifting channel is located in the inner layer of the second direction; the seventh phase-shifting channel is located in the outer layer of the third direction; and the eighth phase-shifting channel is located in the inner layer of the fourth direction.

[0035] In addition, in the layout of the ring wave oscillator of the embodiment, the inner phase-shift channel and the outer phase-shift channel in two adjacent directions are respectively electrically connected by two groups of wires. The embodiment respectively arranges the two groups of wires on the upper and lower layers at the same position in the layout, and the distance of the two groups of wires on the layout is equal.

[0036] Based on the above connection relationship, the transmission path of the ring wave oscillator is as follows: first, starting from the first channel in the inner side of the first direction, in the counterclockwise direction, passing through the second channel in the outer side of the second direction; then passing through the third channel in the inner side of the third direction; then passing through the fourth channel in the outer side of the fourth direction; then passing through the fifth channel in the outer side of the first direction; then passing through the sixth channel in the inner side of the second direction; then passing through the seventh channel in the outer side of the third direction; then passing through the eighth channel in the inner side of the fourth direction; and then returning to the first channel in the inner side of the first direction, thereby forming a loop.

[0037] On this basis, in each direction of the layout, the head end of the first inductive element in the inner phase-shift channel and the head end of the first inductive element in the outer phase-shift channel are respectively connected to two injection ports with a phase interval of 180°, and are electrically connected to the two output ends of a mirror injection circuit. One end of the variable capacitor is connected to the tail end of the first inductive element in the inner phase-shift channel, and the other end is connected to the tail end of the first inductive element in the outer phase-shift channel.

[0038] Considering that the two adjacent phase-shift channels are always distributed on the inner and outer sides of the adjacent directions, and there are two wires connecting different phase-shift channels in the adjacent directions, in order to ensure that the lengths of the two wires are consistent and do not interfere with each other, the embodiment arranges the two wires on the upper and lower layers of the layout, and uses the following spatial layout method: The wires that realize the connection of the inner and outer phase-shift channels in the adjacent directions are composed of the first divergent segment connected to the preceding phase-shift channel, the collinear segment in the middle, and the second divergent segment connected to the subsequent phase-shift channel. The first divergent segments connected to the tail ends of the two phase-shift channels in any direction are respectively arranged along the upper and lower layers and extend by 45° to the inner side, thereby overlapping the upper and lower layers of the same point P in the layout plane. The second divergent segments connected to the head ends of the two phase-shift channels in the next direction are also respectively arranged along the upper and lower layers and extend by 45° to the inner side, thereby overlapping the upper and lower layers of the same point Q in the layout plane. The collinear segment includes two sub-segments that are perpendicular to each other and have equal distances in the layout plane; the two collinear segments are respectively connected to the P and Q nodes along the upper and lower layers.

[0039] With Figure 6The spatial distribution of the wires between the four moving channels between the first direction and the second direction is taken as an example: the first divergent segment at the end of the first moving channel turns 45 degrees to the side of the fifth channel, and the first divergent segment at the end of the fifth moving channel turns 45 degrees to the side of the first channel, and the two intersect at point P in the plane. Among them, the first divergent segment at the end of the first moving channel is located in the upper layer of the layout, and its end can be denoted as P1, and the first divergent segment at the end of the fifth moving channel is located in the lower layer of the layout, and its end can be denoted as P2.

[0040] The second divergent segment at the beginning of the second moving channel turns 45 degrees to the side of the sixth channel, and the second divergent segment at the beginning of the sixth moving channel turns 45 degrees to the side of the second channel, and the two intersect at point Q in the plane. Among them, the second divergent segment at the beginning of the second moving channel is located in the upper layer of the layout, and its end can be denoted as Q1, and the second divergent segment at the beginning of the sixth moving channel is located in the lower layer of the layout, and its end can be denoted as Q2.

[0041] Finally, P1 and Q1 are connected respectively according to the same trajectory on the upper and lower layers of the layout, and P2 and Q2 are connected. Then the corresponding collinear segments are formed. By analyzing the above path, it can be found that the trajectory of the wires between the first moving channel and the second moving channel is exactly the same as that of the wires between the fifth moving channel and the sixth moving channel, only with an angle deviation. And the paths of the two wires between different directions are rotationally symmetric about the central of the layout of the ring wave oscillator. Therefore, this can make the wave propagation distance consistent in each segment in the ring, and suppress the standing wave.

[0042] It needs to be emphasized that the spatial distribution of the wires between adjacent moving channels is not unique, and the above introduction is only one typical case. In other embodiments, the spatial layout of the wires can be further optimized. For example, the collinear segment can be adjusted from two perpendicular straight lines to a straight line directly connecting the two points PQ, etc. Only need to ensure that the two groups of wires in adjacent directions are arranged in the upper and lower layers of the same plane position in the layout without interference; and the distance of the two groups of wires on the layout is equal.

[0043] In practical applications, the mirror injection circuit capable of outputting an injection signal with a phase difference of 180° introduced in the foregoing can adopt, for example, Figure 7As shown, the circuit configuration consists of four PMOS transistors P1-P4 and five NMOS transistors N1-N5. The sources of P1-P4 are connected to VDD; P1 is connected to the drain of N1. P2 is connected to the drain of N2; P1 is connected to the gate of N1 and serves as the non-inverting input port Vinj+; P2 is connected to the gate of N2 and serves as the inverting input port Vinj-. The drains of P1, N1, P3, and N3 are connected to the gates of P4 and N4, serving as the output port for one of the injected signals A; the drains of P2, N2, P4, and N4 are connected to the gates of P3 and N3, serving as the output port for one of the injected signals B. The sources of N3 and N4 are connected to the drain of N5; the gate of N5 is connected to the reference voltage signal Vbias; the sources of N1, N2, and N5 are connected to VSS.

[0044] Analysis of the circuit structure of the mirror injection circuit provided in this embodiment reveals that the output port of each injected signal adopts a complementary structure of NMOS and PMOS in parallel, thus effectively injecting signals in both the positive and negative half-cycles of the oscillator, with an injection efficiency twice that of traditional circuits.

[0045] In practical applications, this embodiment arranges the variable capacitors and mirror injection circuits in each direction in the region between the two phase-shifting channels in that direction; both are located on the same layer as the inductive elements in the inner and outer phase-shifting channels. With this spatial layout, the variable capacitors and mirror injection circuits in different directions are arranged rotationally symmetrically on the layout, with a rotation angle of 90°.

[0046] Finally, the overall layout of the multi-injection locked ring traveling wave oscillator designed in this embodiment is as follows: Figure 8 As shown in the figure, the circuit has a strictly symmetrical structure, which helps to improve system stability and makes it suitable for low-power scenarios such as the Internet of Things.

[0047] Example 2 Based on the performance advantages of the multi-injection locked ring traveling wave oscillator provided in Embodiment 1, this embodiment further provides a Doppler radar, such as... Figure 9 As shown, this Doppler radar employs a multi-injection locked ring traveling wave oscillator, as described in Example 1, to construct the required phase-locked loop (PLL) structure. Because this ring traveling wave oscillator can expand the injection locking range, it can improve the radar's sensitivity and detection range. The oscillator improves the system's signal-to-noise ratio through multi-point signal injection. The optimized oscillator structure also helps to achieve low-amplitude, phase-uniform ring traveling wave oscillations, enhancing the performance stability of the Doppler radar.

[0048] On this basis, the embodiment also provides a physiological characteristic detection device for detecting the vital signs of a human body through a non-contact vital sign detection technology, the physiological characteristic detection device adopting the Doppler radar as described above, the Doppler radar being used to detect the phase change of an echo signal caused by the chest wall movement of the human body, and further extract the breathing and heartbeat information. Compared with other life detection technologies, the life detection based on the Doppler radar provided by the embodiment has higher stability, and is suitable for non-contact scenes such as burn monitoring and earthquake rescue.

[0049] Performance test In order to verify the performance of the multi-injection-locked ring wave oscillator provided by the present application, the technicians simulate and test the performance of the related radar transceiver system on the 22nm CMOS process. Through simulation verification, the chip can ensure uniform phase at an oscillation amplitude as low as 100mV, which represents extremely strong standing wave suppression performance, so that the system meets the design requirements. In order to verify the injection locking sensitivity of the system, the chip is tested for off-chip signal injection. Under a specific injection signal strength, by adjusting the frequency of the injection signal, it is observed whether the oscillator oscillates at the frequency of the injection signal. In the case that the oscillator can be locked, the maximum difference between the injection signal frequency and the oscillator itself is the injection locking range of the oscillator. When the injection locking range is too small to be distinguished (about 100kHz), it is considered that the sensitivity limit of the injection locking range of the oscillator. Through testing, the injection locking sensitivity of the chip is-90dBm, which is much higher than the existing similar design level. The test proves that the Mobius ring structure of the multi-injection-locked ring wave oscillator and the multi-injection-locked circuit structure proposed by the present application can ensure good phase uniformity at a low oscillation amplitude, thereby greatly improving the injection locking range of the oscillator.

[0050] The above-described embodiment only expresses one of the embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the application. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A multiple-injection-locked ring traveling wave oscillator, characterized by, It includes 16 inductive elements rf1~rf16; 4 variable capacitors Cv1~Cv4 and 4 image injection circuits, wherein, rf1~rf16 are connected in sequence and connected head to tail; In the layout, every two adjacent inductive elements constitute a phase shift channel, and 8 phase shift channels are sequentially and symmetrically distributed in four orthogonal directions; two phase shift channels in each direction are parallel to each other and located on the inner and outer sides of the same layer in the layout; wherein, the inner side phase shift channel in the previous direction is communicated with the outer side phase shift channel in the next direction; the outer side phase shift channel in the previous direction is communicated with the inner side phase shift channel in the next direction; thereby forming a two-layer Mobius ring structure; The two groups of wires for connecting the inner and outer phase shift channels in adjacent directions are arranged on the upper and lower layers at the same position in the layout, and the distances are equal; In each direction of the layout, the first end of the first inductive element in the inner and outer phase shift channels is respectively used as two injection ports with a phase interval of 180°, and is electrically connected with the two output ends of an image injection circuit; the two output ports of each image injection circuit are used for outputting a group of injection signals A and B with a phase difference of 180° according to a group of differential input signals; the tail end of the first inductive element in the inner and outer phase shift channels is connected with two ends of a variable capacitor.

2. The multiple-injection-locked ring traveling wave oscillator of claim 1, wherein: The wires for connecting the inner and outer phase shift channels in adjacent directions are composed of a first divergent segment connected to the first phase shift channel, a collinear segment in the middle, and a second divergent segment connected to the second phase shift channel; The first divergent segments connected to the tail ends of the two phase shift channels in any direction are respectively arranged on the upper and lower layers and extend to the inner side by 45°, thereby overlapping the upper and lower layers at the same point P in the layout plane; The second divergent segments connected to the head ends of the two phase shift channels in the next direction are also respectively arranged on the upper and lower layers and extend to the inner side by 45°, thereby overlapping the upper and lower layers at the same point Q in the layout plane; The collinear segments include two sub-segments perpendicular to each other and equal in distance in the layout plane; the two collinear segments are respectively connected to the P and Q nodes on the upper and lower layers.

3. The multiple-injection-locked ring traveling wave oscillator of claim 1, wherein: Each image injection circuit is composed of 4 PMOS tubes P1~P4 and 5 NMOS tubes N1~N5; wherein, the sources of P1~P4 are connected to VDD; the drains of P1 and N1 are connected; the drains of P2 and N2 are connected; the gates of P1 and N1 are connected and used as a positive input port Vinj+; the gates of P2 and N2 are connected and used as an inverting input port Vinj﹣; the drains of P1, N1, P3, N3 are connected to the gates of P4, N4, and are used as an output port of one of the injection signals A; the drains of P2, N2, P4, N4 are connected to the gates of P3, N3, and are used as an output port of one of the injection signals B; the sources of N3 and N4 are connected to the drain of N5; the gate of N5 is connected to a reference voltage signal Vbias; the sources of N1, N2 and N5 are connected to VSS.

4. The multiple-injection-locked ring traveling wave oscillator of claim 3, wherein: The variable capacitors in each direction are arranged between the two phase shift channels in the corresponding direction. The inductive elements in the inner and outer phase shift channels are located on the same layer.

5. The multiple-injection-locked ring traveling wave oscillator of claim 4, wherein: The variable capacitances in different directions and the mirror injection circuit positions are arranged in a rotationally symmetrical manner on the layout, with a rotation angle of 90°.

6. The multiple-injection-locked ring traveling wave oscillator of claim 5, wherein: It comprises 8 injection ports respectively located on each phase shift channel, and the phase difference of the injection signals of the injection ports in adjacent phase shift channels is 45°.

7. The multiple-injection-locked ring traveling wave oscillator of claim 1, wherein: The variable capacitance adopts an interdigital capacitor.

8. The multiple-injection-locked ring traveling wave oscillator of claim 1, wherein: The inductive element adopts a high-layer metal line.

9. A Doppler radar, characterized by: It adopts the multi-injection-locked ring traveling wave oscillator as claimed in any one of claims 1-8.

10. A physiological feature detection device for detecting a physiological feature of a human body by a non-contact vital sign detection technique, characterized by: It adopts the Doppler radar as claimed in claim 9, which is used to detect the phase change of the echo signal caused by the human chest wall movement, and further extract the breathing and heartbeat information.

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