A motion sensing radar sensor

Abstract

The present invention belongs to the field of radar sensor design, and specifically provides a mobile sensing radar sensor to solve the problems of complex circuit structure, high power consumption, large chip area, high manufacturing cost, etc. in the prior art. The present invention includes: a microstrip patch antenna and a quasi-oscillator; wherein the quasi-oscillator can generate a transmission signal and mix the received reflected signal with the local oscillation signal to output an intermediate frequency signal containing Doppler frequency shift information; and when the quasi-oscillator is working, the transistor simultaneously realizes the amplification and mixing functions, and the transformer realizes the conversion of differential output to single-ended signal while ensuring the balance of the differential output of the quasi-oscillator; 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 mobile sensing radar sensors, which is conducive to large-scale market applications.

Description

Technical Field

[0001] This invention belongs to the field of radar sensor design, and specifically provides a mobile sensing radar sensor. Background Technology

[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 manufacturing cost.

[0003] For continuous wave Doppler radar, the transmitted signal Represented as: ,in, Indicates the amplitude of the signal. Indicates the standard carrier angular frequency. Indicates time, Indicates the initial phase of the signal; received signal Represented as: ,in, Indicates the attenuation factor. Indicates the Doppler frequency shift. This represents the Doppler frequency shift time; based on this, the traditional structure of motion sensing sensors based on continuous wave Doppler radar is as follows: Figure 1 As shown, the microstrip patch antenna includes two paths, one for transmitting and the other for receiving radio frequency signals. A continuous wave signal generator generates a high-frequency carrier signal (radio frequency signal) as the transmitted signal. The transmitted signal is amplified by a power amplifier and then propagated into space through the transmit port of the microstrip patch antenna, where it interacts with moving objects in space using the Doppler effect. The reflected signal enters through the receive 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 by a mixer. 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 function of monitoring moving targets.

[0004] However, the aforementioned mobile sensing sensor circuit structure based on continuous wave Doppler radar is quite complex. The radio frequency signal passes through multiple components from transmission to reception, and crosstalk between these components can easily occur, leading to sensor malfunction. Furthermore, components such as the continuous wave signal generator, power amplifier, low-noise amplifier, and mixer all contribute to additional power consumption, resulting in high sensor power consumption. In addition, the large number of components also leads to an excessively large chip area, such as… Figure 2As shown, to meet integration requirements, the chip needs multiple pins. Pins 1 and 2 represent power supply pins, responsible for providing power voltage to each device; pin 3 represents the RF signal transmission pin, and pin 4 represents the RF signal reception pin, usually connected to a microstrip patch antenna; pins 5 and 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 on the chip will further increase, leading to higher and higher chip packaging costs, which in turn increases the manufacturing cost of the sensor. Summary of the Invention

[0005] The purpose of this invention is to provide a novel mobile sensing radar sensor to solve the problems of complex circuit structure, high power consumption, large chip area, and high manufacturing cost in the existing technology.

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

[0007] A mobile sensing radar sensor includes a microstrip patch antenna and a similar oscillator. The similar oscillator generates a transmitted signal and propagates it into space through the microstrip patch antenna. After the transmitted signal reaches a moving object in space, it generates a reflected signal. The reflected signal is received by the microstrip patch antenna and sent to the similar oscillator. The reflected signal is mixed with a local oscillation signal by the similar oscillator, and the similar oscillator outputs an intermediate frequency signal containing Doppler frequency shift information.

[0008] Furthermore, the oscillator includes: transistors M1-M2, capacitors C1-C4, resistor R1, transformer, and bias network; transistors M1 and M2 form a cross-coupled pair, the collector of transistor M1 is connected to the base of transistor M2 and capacitor C2 is connected between the two electrodes, the collector of transistor M2 is connected to the base of transistor M1 and capacitor C3 is connected between the two electrodes, the emitters of transistors M1 and M2 are connected, and an intermediate frequency signal output terminal is led out; the bias network provides bias to the bases of transistors M1 and M2. The transformer is configured such that transistors M1 and M2 operate in the amplification region. The primary coil L1 of the transformer and capacitor C1 form an LC resonant cavity. The primary coil L1 and capacitor C1 are connected in parallel, and their two ends are connected to the collectors of transistors M1 and M2, respectively. 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 serves as the RF signal transmitter / receiver, and the other end is grounded. One end of resistor R1 is connected to the intermediate frequency signal output terminal, and the other end is grounded. One end of capacitor C4 is connected to the intermediate frequency signal output terminal, 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 the 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. The base and collector of transistor M3 are connected.

[0010] Furthermore, the mobile sensing radar sensor also includes an operational amplifier circuit, where the intermediate frequency signal is amplified by the operational amplifier and then processed for the next stage of signal processing to achieve the function of monitoring moving targets.

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

[0012] This invention creatively proposes a type of oscillator that can both generate a transmitted signal and mix the received reflected signal with a local oscillation signal to output an intermediate frequency signal containing Doppler frequency shift information. Furthermore, during operation, transistors M1 and M2 simultaneously perform amplification and mixing functions, while the transformer converts the differential output to a single-ended signal, ensuring the balance of the oscillator's differential output. This allows the oscillator to simultaneously perform the transceiver functions of a radar sensor. Based on this, this invention provides a novel structure for a mobile sensing radar sensor, which effectively simplifies the structure, reduces power consumption, improves efficiency, expands the detection range, and significantly reduces the R&D and manufacturing costs of mobile sensing radar sensors, facilitating large-scale market application. Attached Figure Description

[0013] Figure 1 This 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 This is a schematic diagram of the integrated circuit layout of a mobile sensing sensor based on continuous wave Doppler radar in the prior art.

[0015] Figure 3 This is a schematic diagram of the structure of the mobile sensing radar sensor in this invention.

[0016] Figure 4 This is a schematic diagram of the oscillator-like circuit of the mobile sensing radar sensor in this invention.

[0017] Figure 5 This is a schematic diagram of the integrated circuit layout of the mobile sensing radar sensor in this invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0019] This embodiment provides a novel mobile sensing radar sensor that operates in the C-band, and its specific structure is as follows: Figure 3 As shown, it includes: a microstrip patch antenna, a pseudo-oscillator, and an operational amplifier circuit; wherein, the pseudo-oscillator generates a transmitted signal and propagates it into space through the microstrip patch antenna. After the radio frequency signal reaches a moving object in space, it generates a reflected signal. The reflected signal is received by the microstrip patch antenna and sent to the pseudo-oscillator. The reflected signal is mixed with the local oscillation signal by the pseudo-oscillator. The pseudo-oscillator outputs an intermediate frequency signal containing Doppler frequency shift information. The intermediate frequency signal is amplified by the operational amplifier and then processed for the next stage of signal processing to realize the function of monitoring moving targets.

[0020] Furthermore, oscillators such as Figure 4 As shown, the system includes: transistors M1-M3, capacitors C1-C4, resistors R1-R5, and a transformer; transistors M1 and M2 form a cross-coupled pair to provide a negative resistance. The collector of transistor M1 is connected to the base of transistor M2, and capacitor C2 is connected between the two electrodes. The collector of transistor M2 is connected to the base of transistor M1, and capacitor C3 is connected between the two electrodes. The emitters of transistors M1 and M2 are connected, and an intermediate frequency (IF) signal output terminal is led out. The primary coil L1 of the transformer and capacitor C1 form an LC resonant cavity. The two ends of the primary coil L1 and capacitor C1 are connected in parallel and then connected to the collectors of transistors M1 and M2, respectively. 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 serves as the RF signal transmitter. The transmitter / receiver (TX / RX) is connected to the microstrip patch antenna, with the other end grounded. Resistors R2-R4 and transistor M3 form a bias network, ensuring that transistors M1 and M2 operate in the amplification region. The collector of transistor M3 is connected to resistor R4 and then to the power supply voltage VDD. The emitter of transistor M3 is connected to resistor R5 and then grounded. 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. The base and collector of transistor M3 are also connected. One end of resistor R1 is connected to the intermediate frequency (IF) signal output terminal, and the other end is grounded to limit power consumption. One end of capacitor C4 is connected to the IF signal output terminal, and the other end is grounded to enable the RF signal to ground function.

[0021] In terms of working principle:

[0022] This invention provides a type of oscillator in which transistors M1 and M2 feed their amplified output signals back to a resonant circuit. The feedback signal is phase- and amplitude-adjusted with the input signal through the resonant circuit. Positive feedback enhances the output signal at the resonant frequency and continues to be amplified by transistors M1 and M2. The output signal then passes through the resonant circuit again and is fed back to the input of the transistors through capacitors C2 and C3, forming a closed-loop feedback. When the system gain is equal to the feedback path and the phase balance condition is met, the type of oscillator will stably generate a local sine wave output signal. The signal is coupled to a microstrip patch antenna through transformers (inductors L1 and L2), transmitted through the antenna, and propagates in the air. When the signal propagates to a moving object, part of the signal is absorbed by the target object, and the other part is reflected by the target object. The microstrip patch antenna receives the reflected radio frequency signal. The radio frequency signal and the locally generated sine wave intrinsic signal undergo a mixing effect in transistors M1 and M2, generating a sum frequency, difference frequency, and harmonics of two frequencies. The radio frequency signal is filtered out by capacitor C4, thereby retaining the required difference frequency signal and realizing the mixing function.

[0023] In summary, this invention provides a novel mobile sensing radar sensor with a core circuit consisting only of a quasi-oscillator. This quasi-oscillator not only generates a transmitted signal but also mixes the received reflected signal with the local oscillation signal to output an intermediate frequency signal containing Doppler frequency shift information. Clearly, this invention effectively simplifies the circuit structure and reduces power consumption through the ingenious design of the quasi-oscillator. Furthermore, since the circuit is non-directional, the transmitted and received signals can use the same antenna feed, resulting in co-polarized signals. This avoids the polarization loss associated with orthogonally polarized common-aperture antennas, reduces transmission and reception link losses, and improves the detection range of the mobile sensing radar sensor. In addition, the novel structure provided by this invention can significantly reduce chip size, such as… Figure 5 As shown, the chip requires only 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) form, which reduces the chip packaging cost. Furthermore, since the RF signal transmission / reception share the same pin, the microstrip patch antenna can adopt a smaller two-layer board design, which reduces the cost of the antenna.

[0024] The above description is merely a specific embodiment of the present invention. Any feature disclosed in this specification may be replaced by other equivalent or similar features unless otherwise specified. All disclosed features, or steps in all methods or processes, may be combined in any way except for mutually exclusive features and / or steps.

Claims

1. A motion sensing radar sensor, comprising: 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 generates a reflection signal 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; The oscillator comprises: a transistor M1, a transistor M2, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a resistor R1, a transformer and a 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 the intermediate frequency signal output terminal is led out; the bias network is the transistor M1 and the transistor M2. The base provides bias and makes both transistor M1 and 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.

2. The motion sensing radar sensor according to claim 1, characterized in that: The bias network includes: resistor R2, resistor R3, resistor R4, resistor 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.

3. The motion sensing radar sensor according to claim 1, 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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