A radio frequency sensor and a wireless sensing device

Abstract

This invention provides a radio frequency (RF) sensor and a wireless sensing device, belonging to the field of communication technology. The RF sensor includes an RF carrier generator, a piezoelectric sensor, and a phase modulator. The RF carrier generator generates an RF carrier signal; the piezoelectric sensor converts a physical excitation signal into a sensing voltage signal; the phase modulator has an RF signal input terminal, an RF signal output terminal, and a modulation electrode, which is disposed between the RF signal input terminal and the RF signal output terminal. The RF signal input terminal is connected to the RF carrier generator, and the modulation electrode is connected to the piezoelectric sensor. This RF sensor eliminates the high-power, complex modulation device and uses passive, low-power acoustic devices to complete the signal chain processing, thereby significantly reducing system power consumption, simplifying the system structure, and clearing obstacles for miniaturizing RF sensors.

Description

Technical Field

[0001] This invention relates to the field of communication technology, and in particular to a radio frequency sensor and a wireless sensing device. Background Technology

[0002] Wireless sensing technology, with its advantages of high sensitivity, wide response frequency band, and strong anti-interference capability, has gained widespread attention and application in many fields such as IoT monitoring, industrial equipment diagnostics, medical and health monitoring, and underwater environment exploration. As these fields continue to demand more intelligent and portable sensing devices, wireless sensing devices have become the mainstream direction of industry development.

[0003] Currently, for wireless sensor nodes to achieve wireless transmission of sensor signals, they need to rely on radio frequency communication components to modulate and transmit the sensor signals. For example... Figure 1 As shown, for ultrasonic or vibration sensors, the sensing signal generated by external physical excitation is an analog signal. In existing wireless sensor nodes, a voltage-controlled oscillator and a phase-locked loop work together to output a digital radio frequency (RF) fundamental signal. The sensing signal generated by the sensor needs to be converted into a digital signal by a high-speed analog-to-digital converter (ADC), and then processed by a complex digital baseband (MCU / DSP) for filtering, encoding, and other processing before it can be input into a mixer to perform mixing and modulation with the RF fundamental signal, thereby completing the wireless communication of the sensing signal with the RF signal output.

[0004] However, these wireless sensor nodes rely on high-power RF signal generation and modulation devices (such as phase-locked loops, mixers, and high-frequency power amplifiers) and analog-to-digital conversion devices (such as analog-to-digital converters and digital baseband demodulation modules) to achieve stable wireless output of sensor signals. Furthermore, the sensing unit and the RF signal generation and modulation unit are assembled as two independent devices within the wireless sensor node. All of these factors contribute to the drawbacks of excessive power consumption, complex structure, and large module size in wireless sensor nodes, posing significant challenges to the pursuit of miniaturization and long battery life in traditional wireless sensor nodes.

[0005] Therefore, it is necessary to design a radio frequency sensor and a wireless sensing device to solve the above problems. Summary of the Invention

[0006] This invention provides a radio frequency sensor and a wireless sensing device to improve the problems of complex architecture, excessive power consumption, and large module size of existing radio frequency sensors.

[0007] In a first aspect, the present invention provides a radio frequency sensor comprising a radio frequency carrier generator, a piezoelectric sensor, and a phase modulator.

[0008] The radio frequency carrier generator is used to generate a radio frequency carrier signal; the piezoelectric sensor is used to convert a physical excitation signal into a sensing voltage signal; the phase modulator has a radio frequency signal input terminal, a radio frequency signal output terminal, and a modulation electrode. The radio frequency signal input terminal and the radio frequency signal output terminal are located at both ends of the phase modulator, and the modulation electrode is located between the radio frequency signal input terminal and the radio frequency signal output terminal. The radio frequency signal input terminal is connected to the radio frequency carrier generator, and the modulation electrode is connected to the piezoelectric sensor.

[0009] In one example of the present invention, the radio frequency carrier generator includes an acoustic resonator and a radio frequency oscillation circuit, the acoustic resonator being connected to the radio frequency oscillation circuit, and the radio frequency oscillation circuit being connected to the radio frequency signal input terminal.

[0010] In one example of the present invention, the acoustic resonator, piezoelectric sensor and phase modulator are integrated on the same piezoelectric structure.

[0011] In one example of the present invention, the piezoelectric structure includes a substrate and a piezoelectric layer, the piezoelectric layer being disposed on the substrate, and the material of the piezoelectric layer including at least one of scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, and lithium niobate.

[0012] In one example of the present invention, the radio frequency sensor further includes a radio frequency signal amplifier, and the radio frequency signal output terminal is connected to the radio frequency signal amplifier.

[0013] In one example of the present invention, the radio frequency signal amplifier and the radio frequency oscillation circuit are integrated into one unit.

[0014] In one example of the present invention, the radio frequency sensor further includes a sensing signal amplifier, the sensing signal output terminal of the piezoelectric sensor is connected to the sensing signal amplifier, and the sensing signal amplifier is connected to the modulation electrode.

[0015] In one example of the present invention, the sensing signal amplifier and the radio frequency oscillation circuit are integrated into one unit.

[0016] In one example of the present invention, the radio frequency sensor further includes an antenna, which is connected to the radio frequency signal output terminal.

[0017] In a second aspect, the present invention also provides a wireless sensing device comprising a radio frequency sensor as described in any of the above examples.

[0018] The radio frequency (RF) sensor of this invention uses an RF carrier generator to replace the voltage-controlled oscillator (VCO) and phase-locked loop (PLL) to generate an RF carrier signal in analog form. This RF carrier signal is then input into a phase modulator for transmission. Simultaneously, the sensing voltage signal generated by the piezoelectric sensor can be directly input to the phase modulator without analog-to-digital conversion, thus performing phase modulation on the RF carrier signal. This allows the phase modulator to output an RF signal with modulation information, enabling wireless communication of the sensing voltage signal. This RF sensor eliminates high-power, complex modulation devices such as PLLs, high-speed analog-to-digital converters, and digital baseband modulators, instead employing passive, low-power acoustic devices to complete the signal chain processing, thereby significantly reducing system power consumption and simplifying the system structure. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other embodiments based on these drawings without inventive effort.

[0020] In the attached diagram:

[0021] Figure 1 A schematic diagram of the structure of an existing wireless sensor node; Figure 2 This is a schematic diagram of the structure of a radio frequency sensor in one embodiment of the present invention; Figure 3 This is the admittance curve of an acoustic resonator in one embodiment of the present invention; Figure 4 This is a schematic diagram of the physical excitation signal of the piezoelectric sensor in one embodiment of the present invention; Figure 5 This is a schematic diagram of the acoustic-electric signal conversion of a piezoelectric sensor in one embodiment of the present invention; Figure 6 This is a schematic diagram of the phase modulator in one embodiment of the present invention; Figure 7 This is a schematic diagram illustrating the working principle of a phase modulator in one embodiment of the present invention; Figure 8 This is a waveform diagram of a phase modulator receiving a radio frequency carrier signal, a sensing voltage signal, and a radio frequency modulated signal output by modulating the sensing voltage signal in one embodiment of the present invention. Figure 9 This is a graph showing the relationship between the transmission coefficient of the phase modulator and the frequency of the received radio frequency carrier signal in one embodiment of the present invention; Figure 10 This is a diagram showing the electroacoustic phase modulation characteristics of a phase modulator in one embodiment of the present invention.

[0022] The attached figures are labeled as follows: 10. Piezoelectric MEMS chip; 20. CMOS chip; 100. RF carrier generator; 110. Acoustic resonator; 120. RF oscillation circuit; 200. Piezoelectric sensor; 300. Sensing signal amplifier; 400. Phase modulator; 410. RF signal input terminal; 420. Modulation electrode; 430. RF signal output terminal; 500. RF signal amplifier; 600. Antenna. Detailed Implementation

[0023] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0024] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0025] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the invention. However, it will be apparent to those skilled in the art that embodiments of the invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the invention.

[0026] In the first aspect, please see Figure 2 This application discloses a radio frequency sensor, which includes a radio frequency carrier generator 100, a piezoelectric sensor 200, and a phase modulator 400.

[0027] like Figure 2 and Figure 7As shown, the radio frequency carrier generator 100 generates a radio frequency carrier signal, which is an analog signal. The piezoelectric sensor 200 senses external physical excitation and converts the physical excitation signal into a sensing voltage signal. The types of physical excitation include ultrasound, vibration, and pressure. The sensing voltage signal is an analog signal, which can be directly input to the modulation electrode 420 of the phase modulator 400 to achieve phase modulation of the radio frequency carrier signal without analog-to-digital conversion.

[0028] like Figure 2 , Figures 6 to 8 As shown, the phase modulator 400 has a radio frequency (RF) signal input terminal 410, an RF signal output terminal 430, and a modulation electrode 420. The RF signal input terminal 410 and the RF signal output terminal 430 are located at opposite ends of the phase modulator 400. The modulation electrode 420 is located between the RF signal input terminal 410 and the RF signal output terminal 430, and covers a preset modulation area of ​​the phase modulator 400. The RF signal input terminal 410 is connected to the RF carrier generator 100, and is used to receive the RF carrier signal and transmit it from the RF carrier generator 100 to the RF signal output terminal 430 on the phase modulator 400. The modulation electrode 420 is connected to the piezoelectric sensor 200, and is used to apply a sensing voltage signal to the modulation area to achieve phase modulation of the RF carrier signal using the sensing voltage signal, thereby causing the RF signal output terminal 430 to output an RF signal with modulation information.

[0029] like Figure 2 and Figure 3As shown, in some embodiments, the RF carrier generator 100 includes an acoustic resonator 110 and an RF oscillation circuit 120. The acoustic resonator 110 is connected to the RF oscillation circuit 120, and the RF oscillation circuit 120 is connected to the RF signal input terminal 410 of the phase modulator 400. The RF carrier generator 100 integrates the high-frequency acoustic resonator 110 into the RF oscillation circuit 120. The acoustic resonator 110, as a passive, low-power acoustic device, has a high quality factor (Q value). The acoustic resonator 110 can act as a frequency selection element to frequency-lock the alternating carrier signal generated by the RF oscillation circuit 120, so that the RF oscillation circuit 120 outputs a low-phase-noise RF carrier signal of a preset frequency, thereby eliminating the need to introduce a high-power phase-locked loop circuit. The acoustic resonator 110 can be a thin-film bulk acoustic resonator (FBAR), a surface acoustic wave (SAW) resonator, a Lamb wave resonator, or a solid-state assembled resonator (SMR). The resonant frequency of this type of acoustic resonator 110 is determined by the thickness of the piezoelectric material layer and the electrode structure within the device. By adjusting the thickness of the piezoelectric material layer of the acoustic resonator 110, the RF carrier generator 100 can output RF carrier signals covering different RF communication frequency bands, such as Sub-GHz, 2.4 GHz ISM, or higher frequency 5G / 6G bands.

[0030] like Figure 4 and Figure 5 As shown, in some embodiments, the piezoelectric sensor 200 can employ ultrasonic sensing transducers, such as piezoelectric micromechanical transducers (PMUTs), capacitive micromechanical transducers (CMUTs), piezoelectric cantilever beam-based electromechanical transducers, and piezoelectric diaphragm-based electromechanical transducers. The piezoelectric sensor 200 utilizes the acousto-electric conversion capability of the piezoelectric structure to convert external physical excitation signals into analog sensing voltage signals. The resonant frequency of this type of piezoelectric sensor 200 can be adaptively designed by adjusting the radius, thickness, and residual stress of the piezoelectric layer, achieving a wide frequency response range from a few hertz to tens of megahertz.

[0031] like Figure 2 As shown, in some embodiments, the radio frequency sensor further includes a sensing signal amplifier 300. The sensing signal output terminal of the piezoelectric sensor 200 is connected to the sensing signal amplifier 300, and the sensing signal amplifier 300 is connected to the modulation electrode 420. The sensing signal amplifier 300 amplifies the amplitude of the sensing voltage signal output by the piezoelectric sensor 200 and inputs the amplified sensing voltage signal to the modulation electrode 420 of the phase modulator 400.

[0032] like Figures 6 to 10As shown, the phase modulator 400 employs an acoustic modulation device and includes a piezoelectric structure, a radio frequency (RF) signal input terminal 410, an RF signal output terminal 430, and a modulation electrode 420. The RF signal input terminal 410, the RF signal output terminal 430, and the modulation electrode 420 are disposed on the same side surface of the piezoelectric structure. The RF signal input terminal 410 and the RF signal output terminal 430 are located at opposite ends of the piezoelectric structure. The modulation electrode 420 is located between the RF signal input terminal 410 and the RF signal output terminal 430 and covers the modulation area. The RF signal input terminal 410 is connected to an RF carrier generator 100, which receives the RF carrier signal and transmits it from the RF carrier generator 100 to the RF signal output terminal 430 on the piezoelectric structure. The modulation electrode 420 is connected to a piezoelectric sensor 200, which applies a sensing voltage signal to the modulation area of ​​the piezoelectric structure. When a modulation voltage is applied to the piezoelectric structure, the modulation region on the piezoelectric structure alters the propagation speed of the radio frequency carrier signal within the structure based on the electroacoustic effect, thereby causing a phase change in the radio frequency carrier signal that is linearly related to the modulation voltage. The modulation sensitivity of the phase shifter in the phase modulator 400 (i.e., the phase shift generated per volt) can be altered by adjusting the acoustic waveguide length and electrode structure of the piezoelectric mechanism to accommodate sensing voltage signals of different amplitudes and achieve radio frequency carrier phase modulation from narrowband to broadband.

[0033] like Figure 2 As shown, in some embodiments, the radio frequency sensor further includes an antenna 600, which is connected to the radio frequency signal output terminal 430 of the phase modulator 400. The antenna 600 is used to transmit radio frequency signals modulated by the phase modulator 400 to the outside.

[0034] like Figure 2 As shown, in some embodiments, the radio frequency sensor further includes a radio frequency signal amplifier 500. The radio frequency signal output terminal 430 of the phase modulator 400 is connected to the radio frequency signal amplifier 500, and the radio frequency signal amplifier 500 is connected to the antenna 600. The radio frequency signal amplifier 500 amplifies and processes the modulated radio frequency signal before outputting it to the antenna 600 for wireless transmission.

[0035] like Figure 2As shown, in some embodiments, the acoustic resonator 110, piezoelectric sensor 200, and phase modulator 400 can be integrated on the same piezoelectric structure to achieve process consistency and high integration of the RF sensor; for example, the acoustic resonator 110, piezoelectric sensor 200, and phase modulator 400 can be integrated on the same piezoelectric MEMS chip 10, while the RF oscillation circuit 120 can be integrated separately on the CMOS chip 20. The piezoelectric structure includes a substrate and a piezoelectric layer, with the piezoelectric layer disposed on the substrate. The substrate can be any base material that meets the growth requirements of the piezoelectric layer. As an example, the substrate can include any one or more combinations of semiconductor materials and insulating materials. When a semiconductor material is selected for the substrate, it can be, for example, single-crystal silicon (Si), single-crystal germanium (Ge), silicon-germanium (SiGe), silicon carbide (SiC), gallium arsenide (GaAs), indium arsenide (InAs), or other III / V compound semiconductors. Besides the semiconductor materials listed above, the substrate can also be Si / SiGe, Si / SiC, silicon-on-insulator (SOI), germanium-on-insulator (GOI), or silicon-germanium-on-insulator (SGOI), etc. When an insulating material is selected as the substrate, the insulating material can be an organic insulator, an inorganic insulator, or a combination thereof. Since silicon substrates have good thermal conductivity and can serve as the room-temperature thermal boundary of the device, this application uses a silicon substrate as an example for detailed description. The piezoelectric layer material can be a thin film or bulk material with piezoelectric properties and electroacoustic effects. For example, piezoelectric layer materials can include scandium-doped aluminum nitride (AlScN), zinc oxide (ZnO), lead zirconate titanate (PZT), or lithium niobate (LiNbO3), etc.

[0036] In addition, the modulation electrode 420 in the phase modulator 400 is disposed on the piezoelectric layer. The modulation electrode 420 can be any conductive material that is compatible with the piezoelectric process. For example, the material of the modulation electrode 420 can be molybdenum (Mo), tungsten (W), aluminum (Al), copper (Cu), or platinum (Pt).

[0037] like Figure 2As shown, in some embodiments, when the RF sensor includes a sensing signal amplifier 300, the sensing signal amplifier 300 and the RF oscillation circuit 120 are integrated on the same CMOS chip 20. In some embodiments, when the RF sensor includes an RF signal amplifier 500, the RF signal amplifier 500 and the RF oscillation circuit 120 are integrated on the same CMOS chip 20. In some embodiments, when the RF sensor includes both a sensing signal amplifier 300 and an RF signal amplifier 500, the RF oscillation circuit 120, the sensing signal amplifier 300, and the RF signal amplifier 500 can all be integrated on the same CMOS chip 20. In the above embodiments, the RF sensor only requires one CMOS chip 20 and a piezoelectric MEMS chip 10 to integrate all sub-devices, thereby achieving a compact system-in-package and significantly reducing the module area of ​​the system.

[0038] In a second aspect, this application also provides a wireless sensing device that includes the radio frequency sensor in any of the above embodiments.

[0039] The technical solution of the present invention will be described in detail below through specific embodiments. Unless otherwise stated, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by conventional methods in the art.

[0040] Example like Figure 2 As shown, this embodiment provides a radio frequency (RF) sensor, which includes an acoustic resonator 110, an RF oscillation circuit 120, a piezoelectric sensor 200, a sensing signal amplifier 300, a phase modulator 400, an RF signal amplifier 500, and an antenna 600. The acoustic resonator 110 is connected to the RF oscillation circuit 120 to form an RF carrier generator 100, and the RF oscillation circuit 120 is connected to the RF signal input terminal 410 of the phase modulator 400. The piezoelectric sensor 200 is connected to the sensing signal amplifier 300, and the sensing signal amplifier 300 is connected to the modulation electrode 420 of the phase modulator 400. The RF signal output terminal 430 of the phase modulator 400 is connected to the RF signal amplifier 500, and the RF signal amplifier 500 is connected to the antenna 600. The radio frequency oscillation circuit 120, the sensing signal amplifier 300, and the radio frequency signal amplifier 500 are integrated on the CMOS chip 20. The acoustic resonator 110, the piezoelectric sensor 200, and the phase modulator 400 can be integrated on the piezoelectric MEMS chip 10. The piezoelectric structure of the piezoelectric MEMS chip 10 uses an aluminum nitride scandium thin film as a unified piezoelectric layer with a thickness of 1 μm.

[0041] like Figure 3As shown in the nanoconductance curve of the acoustic resonator 110, the acoustic resonator 110 in the RF sensor exhibits high Q-value characteristics near a frequency of 2.46 GHz. The RF carrier generator 100, composed of the acoustic resonator 110 and the RF oscillation circuit 120, can generate a high-amplitude, low-noise RF carrier signal at a frequency of 2.46 GHz. The piezoelectric sensor 200 can respond to an ultrasonic signal of 500 kHz and successfully outputs induced voltages in the millivolt to volt range during underwater testing. Figures 8 to 9 As shown, the sensing voltage signal output by the piezoelectric sensor 200 is amplified by the sensing signal amplifier 300 and then output to the phase modulator 400, successfully driving the phase modulator 400 to complete the phase modulation of the transmitted radio frequency carrier signal, thus verifying the functional feasibility of the radio frequency sensor.

[0042] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A radio frequency sensor, characterized in that, include: Radio frequency carrier generator, which is used to generate radio frequency carrier signals; Piezoelectric sensors are used to convert physical excitation signals into sensing voltage signals; A phase modulator has a radio frequency (RF) signal input terminal, an RF signal output terminal, and a modulation electrode. The modulation electrode is disposed between the RF signal input terminal and the RF signal output terminal. The RF signal input terminal is connected to the RF carrier generator, and the modulation electrode is connected to the piezoelectric sensor.

2. The radio frequency sensor according to claim 1, characterized in that, The radio frequency carrier generator includes an acoustic resonator and a radio frequency oscillation circuit. The acoustic resonator is connected to the radio frequency oscillation circuit, and the radio frequency oscillation circuit is connected to the radio frequency signal input terminal.

3. The radio frequency sensor according to claim 2, characterized in that, The acoustic resonator, piezoelectric sensor, and phase modulator are integrated on the same piezoelectric structure.

4. The radio frequency sensor according to claim 3, characterized in that, The piezoelectric structure includes a substrate and a piezoelectric layer, wherein the piezoelectric layer is disposed on the substrate, and the material of the piezoelectric layer includes at least one of scandium-doped aluminum nitride, zinc oxide, lead zirconate titanate, and lithium niobate.

5. The radio frequency sensor according to claim 2, characterized in that, The radio frequency sensor also includes a radio frequency signal amplifier, and the radio frequency signal output terminal is connected to the radio frequency signal amplifier.

6. The radio frequency sensor according to claim 5, characterized in that, The radio frequency signal amplifier and the radio frequency oscillation circuit are integrated into one unit.

7. The radio frequency sensor according to claim 2, characterized in that, The radio frequency sensor also includes a sensing signal amplifier, the sensing signal output terminal of the piezoelectric sensor is connected to the sensing signal amplifier, and the sensing signal amplifier is connected to the modulation electrode.

8. The radio frequency sensor according to claim 7, characterized in that, The sensor signal amplifier and the radio frequency oscillation circuit are integrated into one unit.

9. The radio frequency sensor according to claim 1, characterized in that, The radio frequency sensor also includes an antenna, which is connected to the radio frequency signal output terminal.

10. A wireless sensing device, characterized in that, The wireless sensing device includes the radio frequency sensor according to any one of claims 1 to 9.

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