Mobile sensing radar sensor

Abstract

The invention belongs to the field of radar sensor design, and particularly provides a mobile sensing radar sensor, which is used for solving the problems of complicated circuit structure, high power consumption, large chip area, high manufacturing cost and the like in the prior art. The antenna comprises a microstrip patch antenna and a class oscillator. Wherein the class oscillator not only can generate a transmission signal, but also can perform frequency mixing on a received reflection signal and a local oscillation signal, and outputs an intermediate frequency signal containing Doppler frequency shift information; moreover, when the class oscillator works, the transistor realizes amplification and frequency mixing functions at the same time, and the transformer realizes conversion from differential output to a single-ended signal and ensures the balance of differential output of the class oscillator at the same time; on the basis, the invention provides the mobile sensing radar sensor with a novel structure, the structure can be effectively simplified, the power consumption is reduced, the efficiency is improved, the detection range is expanded, the research, development and manufacturing cost of the mobile sensing radar sensor can be greatly reduced, and large-scale marketization application is facilitated.

Description

Technical Field

[0001] The present invention belongs to the field of radar sensor design, and specifically provides a motion sensing radar sensor. Background Art

[0002] Motion sensing sensors are widely used in intelligent devices such as home sensing and intelligent transportation. Among them, motion sensing sensors based on continuous wave Doppler radar have the advantages of simple structure and low production cost.

[0003] For continuous wave Doppler radar, the transmitted signal It is expressed as: ,in, represents the amplitude of the signal, represents the standard carrier angular frequency, Indicates time, Indicates the initial phase of the signal; received signal It is expressed as: ,in, represents the attenuation factor, represents the Doppler shift frequency, represents the Doppler frequency shift time; on this basis, the traditional structure of the mobile sensing sensor based on continuous wave Doppler radar is as follows Figure 1 As shown, the microstrip patch antenna includes two paths, which are used for transmitting and receiving RF signals respectively; the continuous wave signal generator generates a high-frequency carrier signal (RF signal) as a transmitting signal, which is amplified by a power amplifier and then propagated into space from the transmitting port of the microstrip patch antenna, thereby generating a Doppler effect with moving objects in space; the reflected signal enters from the receiving port of the microstrip patch antenna, the received signal is amplified by a low-noise amplifier, and then mixed with the local oscillator signal generated by the continuous wave signal generator through a mixer, and the intermediate frequency signal output by the mixer can be amplified by an operational amplifier and converted into a digital signal for further signal processing, thereby realizing the monitoring function of moving targets.

[0004] However, the circuit structure of the above-mentioned mobile sensing sensor based on continuous wave Doppler radar is relatively complex. The RF signal passes through multiple devices from transmission to reception, and crosstalk between devices is likely to occur, causing abnormal operation of the sensor. In addition, the continuous wave signal generator, power amplifier, low noise amplifier, mixer and other devices will bring additional power consumption to the sensor, resulting in high power consumption of the sensor. In addition, more devices will also lead to an excessively large chip area, such as Figure 2As shown in the figure, in order to meet the integration requirements, the chip needs multiple pins. Pin 1 and Pin 2 represent power pins, which are responsible for providing power supply voltage to each device; Pin 3 represents the transmitting pin of the RF signal, and Pin 4 represents the receiving pin of the RF signal, which is usually connected to the microstrip patch antenna; Pin 5 and Pin 6 represent the intermediate frequency output pins of the mixer; the more devices integrated on the chip, the larger the area of ​​a single chip, and the higher the processing cost of a single chip. At the same time, the number of pins of the chip will further increase, resulting in higher and higher chip packaging costs, making the manufacturing cost of the sensor higher and higher. Summary of the invention

[0005] The purpose of the present invention is to provide a mobile sensing radar sensor with a new structure to solve the problems existing in the prior art, such as complex circuit structure, high power consumption, large chip area, and high manufacturing cost.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A motion sensing radar sensor comprises: a microstrip patch antenna and a quasi-oscillator; wherein the quasi-oscillator generates a transmission signal and propagates it into space through the microstrip patch antenna, and generates a reflection signal after the transmission signal reaches a moving object in space, and the reflection signal is received by the quasi-oscillator through the microstrip patch antenna, and the reflection signal is mixed with a local oscillation signal through the quasi-oscillator, and the quasi-oscillator outputs an intermediate frequency signal containing Doppler frequency shift information.

[0008] Furthermore, the quasi-oscillator includes: transistors M1~M2, capacitors C1~C4, resistor R1, transformer and bias network; the transistor M1 and the transistor M2 form a cross-coupled transistor pair, the collector of the transistor M1 is connected to the base of the transistor M2 and the capacitor C2 is connected between the two electrodes, the collector of the transistor M2 is connected to the base of the transistor M1 and the capacitor C3 is connected between the two electrodes, the emitter of the transistor M1 is connected to the emitter of the transistor M2 and leads to the intermediate frequency signal output end; the bias network provides bias for the base of the transistor M1 and the transistor M2 The primary coil L1 of the transformer and the capacitor C1 form an LC resonant cavity. After the primary coil L1 and the capacitor C1 are connected in parallel, the two ends are respectively connected to the collectors of the transistor M1 and the transistor M2, and the center tap of the primary coil L1 is connected to the power supply voltage VDD; one end of the secondary coil L2 of the transformer is used as the RF signal transmitting / receiving end, and the other end is grounded; one end of the resistor R1 is connected to the intermediate frequency signal output end, and the other end is grounded; one end of the capacitor C4 is connected to the intermediate frequency signal output end, and the other end is grounded.

[0009] Furthermore, the bias network includes: resistors R2~R5 and transistor M3, the collector of transistor M3 is connected to resistor R4 and then to power supply voltage VDD, the emitter of transistor M3 is connected to resistor R5 and then to ground, the base of transistor M3 is connected to resistor R2 and then to the base of transistor M1, the base of transistor M3 is connected to resistor R3 and then to the base of transistor M2, and the base of transistor M3 is connected to the collector.

[0010] Furthermore, the motion sensing radar sensor also includes: an operational amplifier circuit, the intermediate frequency signal is amplified by the operational amplifier and then processed at the next level to achieve the monitoring function of the moving target.

[0011] Based on the above technical solution, the beneficial effects of the present invention are:

[0012] The present invention creatively proposes a quasi-oscillator, which can not only generate a transmitting signal, but also mix the received reflected signal with a local oscillation signal to output an intermediate frequency signal containing Doppler frequency shift information; and when the quasi-oscillator is working, the transistors M1 and M2 simultaneously realize the amplification and mixing functions, and the transformer realizes the conversion of the differential output to a single-ended signal while ensuring the balance of the differential output of the quasi-oscillator, thereby enabling the quasi-oscillator to simultaneously realize the transmitting and receiving functions of the radar sensor; on this basis, the present invention provides a mobile sensing radar sensor with a new structure, which can effectively simplify the structure, reduce power consumption, improve efficiency, expand the detection range, and can greatly reduce the research and development and manufacturing costs of the mobile sensing radar sensor, which is conducive to large-scale market applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The figure is a schematic diagram of the structure of a mobile sensing sensor based on continuous wave Doppler radar in the prior art.

[0014] Figure 2 The figure is a schematic diagram of the integrated circuit arrangement of a mobile sensing sensor based on continuous wave Doppler radar in the prior art.

[0015] Figure 3 It is a schematic diagram of the structure of the motion sensing radar sensor in the present invention.

[0016] Figure 4 It is a schematic diagram of the structure of the oscillator-like circuit of the motion sensing radar sensor in the present invention.

[0017] Figure 5 Schematic diagram of the integrated circuit layout of the motion sensing radar sensor in the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0019] This embodiment provides a new type of mobile sensing radar sensor, which works in the C band. The specific structure is as follows Figure 3 As shown, it includes: a microstrip patch antenna, a quasi-oscillator and an operational amplifier circuit; wherein the quasi-oscillator generates a transmitting signal and propagates it into space through the microstrip patch antenna, and a reflected signal is generated after the radio frequency signal reaches a moving object in space, and the reflected signal is received by the quasi-oscillator through the microstrip patch antenna, and the reflected signal is mixed with a local oscillation signal through the quasi-oscillator, and the quasi-oscillator outputs an intermediate frequency signal containing Doppler frequency shift information, and the intermediate frequency signal is amplified by the operational amplifier and then processed at the next level, so as to realize the monitoring function of the moving target.

[0020] Furthermore, oscillators such as Figure 4 As shown, it includes: transistors M1~M3, capacitors C1~C4, resistors R1~R5 and a transformer; the transistor M1 and the transistor M2 form a cross-coupled transistor pair to provide a negative resistance, the collector of the transistor M1 is connected to the base of the transistor M2 and the capacitor C2 is connected between the two electrodes, the collector of the transistor M2 is connected to the base of the transistor M1 and the capacitor C3 is connected between the two electrodes, the transistor M1 is connected to the emitter of the transistor M2 and leads to an intermediate frequency signal output end (IF); the primary coil L1 of the transformer and the capacitor C1 form an LC resonant cavity, the primary coil L1 and the capacitor C1 are connected in parallel, and the two ends are connected to the collectors of the transistor M1 and the transistor M2 respectively, and the center tap of the primary coil L1 is connected to the power supply voltage VDD; one end of the secondary coil L2 of the transformer is used as a radio frequency signal transmitter The transmitting / receiving end (TX / RX) and the other end are grounded, and the RF signal transmitting / receiving end (TX / RX) is connected to the microstrip patch antenna; the resistors R2~R4 and the transistor M3 form a bias network, so that the transistors M1 and M2 both work in the amplification area, the collector of the transistor M3 is connected to the resistor R4 and then to the power supply voltage VDD, the emitter of the transistor M3 is connected to the resistor R5 and then to the ground, the base of the transistor M3 is connected to the resistor R2 and then to the base of the transistor M1, the base of the transistor M3 is connected to the resistor R3 and then to the base of the transistor M2, and the base of the transistor M3 is connected to the collector; one end of the resistor R1 is connected to the intermediate frequency signal output end, and the other end is grounded to limit power consumption; one end of the capacitor C4 is connected to the intermediate frequency signal output end, and the other end is grounded to realize the function of the RF signal to the ground.

[0021] In terms of working principle:

[0022] The present invention provides a quasi-oscillator, wherein transistors M1 and M2 feed back their amplified output signals to a resonant circuit, the feedback signals are adjusted in phase and amplitude with the input signals through the resonant circuit, the positive feedback makes the output signal enhanced at the resonant frequency, and continues to be amplified by the transistors M1 and M2, the output signal passes through the resonant circuit again, and is fed back to the input end of the transistor through capacitors C2 and C3, forming a closed-loop feedback, when the system gain is equal to the feedback path and meets the phase balance condition, the quasi-oscillator will stably generate a local sinusoidal wave output signal, the signal is coupled to a microstrip patch antenna through a transformer (inductors L1 and L2), transmitted through the antenna and propagated in the air, when the signal propagates to a moving object, a part of the signal will be absorbed by the target object, and the other part will be reflected by the target object, the microstrip patch antenna receives the reflected radio frequency signal, the radio frequency signal and the locally generated sinusoidal wave intrinsic signal generate a mixing effect in the transistors M1 and M2, generate a sum frequency, a difference frequency and harmonics of two frequencies, the radio frequency signal is filtered out through the capacitor C4, thereby retaining the required difference frequency signal, and realizing the mixing function.

[0023] In summary, the present invention provides a mobile sensing radar sensor with a novel structure, the core circuit of which only includes a quasi-oscillator, which can not only generate a transmitting signal, but also mix the received reflected signal with the local oscillation signal to output an intermediate frequency signal containing Doppler frequency shift information. Obviously, the present invention effectively simplifies the circuit structure and reduces the circuit power consumption through the creative design of the quasi-oscillator. Moreover, since the circuit has no directionality, the transmitting signal and the receiving signal can use the same antenna feed port, and the transmitting and receiving signals are co-polarized signals, thus avoiding the polarization loss caused by orthogonal polarization common-aperture antennas, reducing the loss of the transmitting and receiving links, and improving the detection range of the mobile sensing radar sensor. In addition, the novel structure provided by the present invention can greatly reduce the chip size, such as Figure 5 As shown, the chip only needs 3 pins in total, pin A is the power supply pin, pin B is the RF signal transmission / reception pin, and pin C is the intermediate frequency output pin. This structure can adopt a surface mount package (SOT), reducing the packaging cost of the chip; and, since the RF signal transmission / reception shares the same pin, the microstrip patch antenna can adopt a smaller two-layer board design, reducing the cost of the antenna.

[0024] The above description is only a specific implementation mode of the present invention. Any feature disclosed in this specification, unless otherwise stated, can be replaced by other alternative features that are equivalent or have similar purposes; all the disclosed features, or all the steps in the methods or processes, except for mutually exclusive features and / or steps, can be combined in any way.

Claims

1. A mobile sensing radar sensor, include: Microstrip patch antenna and quasi-oscillator; characterized in that the quasi-oscillator generates a transmission signal and propagates it into space through the microstrip patch antenna, and a reflection signal is generated after the transmission signal reaches a moving object in space, and the reflection signal is received by the microstrip patch antenna to the quasi-oscillator, and the reflection signal is mixed with a local oscillation signal through the quasi-oscillator, and the quasi-oscillator outputs an intermediate frequency signal containing Doppler frequency shift information.

2. The motion sensing radar sensor according to claim 1, It is characterized in that The oscillator includes: transistors M1~M2, capacitors C1~C4, resistor R1, transformer and bias network; transistor M1 and transistor M2 form a cross-coupled transistor pair, the collector of transistor M1 is connected to the base of transistor M2 and the capacitor C2 is connected between the two electrodes, the collector of transistor M2 is connected to the base of transistor M1 and the capacitor C3 is connected between the two electrodes, the emitters of transistor M1 and transistor M2 are connected and lead to the intermediate frequency signal output end; the bias network provides bias for the bases of transistor M1 and transistor M2, And both the transistor M1 and the transistor M2 work in the amplification area; the primary coil L1 of the transformer and the capacitor C1 form an LC resonant cavity, and the two ends of the primary coil L1 and the capacitor C1 are respectively connected to the collectors of the transistor M1 and the transistor M2 after being connected in parallel, and the center tap of the primary coil L1 is connected to the power supply voltage VDD; one end of the secondary coil L2 of the transformer is used as the RF signal transmitting / receiving end, and the other end is grounded; one end of the resistor R1 is connected to the intermediate frequency signal output end, and the other end is grounded; one end of the capacitor C4 is connected to the intermediate frequency signal output end, and the other end is grounded.

3. The motion sensing radar sensor according to claim 2, It is characterized in that The bias network includes: resistors R2~R5 and transistor M3, the collector of transistor M3 is connected to resistor R4 and then to power supply voltage VDD, the emitter of transistor M3 is connected to resistor R5 and then to ground, the base of transistor M3 is connected to resistor R2 and then to the base of transistor M1, the base of transistor M3 is connected to resistor R3 and then to the base of transistor M2, and the base of transistor M3 is connected to the collector.

4. The motion sensing radar sensor according to claim 1, It is characterized in that The motion sensing radar sensor also includes: an operational amplifier circuit, the intermediate frequency signal is amplified by the operational amplifier and then processed at the next level to realize the monitoring function of the moving target.

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