Zero-power sensor based on transistor

Abstract

The invention relates to the technical field of microwave sensors, and discloses a transistor-based zero-power sensor, which comprises a first impedance matching network, a voltage-controlled tuning network, a sensing network and a high-impedance network, and is characterized in that the first impedance matching network is configured to perform impedance conversion on a microwave input signal; the voltage-controlled tuning network is configured to modulate a microwave input signal into a time-varying tuning signal; the sensing network is configured to screen out corresponding sensing signals within the bandwidth around the frequency of the sensing network in the tuning signals, and the sensing signals are related to external physical quantities; the sensing signal is reflected back to the voltage-controlled tuning network and then enters the high-impedance network; and the high-impedance state network is configured to be in a high-impedance state for the sensing signal, so that the sensing signal is secondarily reflected back to the voltage-controlled tuning network, and frequency mixing with the microwave input signal is carried out by utilizing the nonlinear characteristic of a nonlinear device contained in the voltage-controlled tuning network. According to the invention, an external AC signal can directly drive the sensing circuit to perform frequency conversion without AC-DC conversion, so that the energy utilization rate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of microwave sensors, and in particular to a transistor-based zero-power sensor. Background Art

[0002] With the rapid development of the Internet of Things (IoT) and smart cities, passive wireless sensors have shown broad application prospects in environmental monitoring, health care, smart homes and other fields. Their core advantages include low maintenance costs, long service life and simplified installation process. In addition, such sensors are usually small in size and light in weight, making them easy to integrate into various devices and systems.

[0003] In the future, with the development of wireless communication technology and the improvement of energy harvesting efficiency, passive wireless sensors will play a key role in more application scenarios.

[0004] Invention patent CN118310561A discloses a passive wireless sensor based on two reverse-connected varactor diodes (applicant: Chengdu Ximengtech Technology Development Co., Ltd.), which uses the time-varying reactance of a pair of reverse-connected varactor diodes and the interaction of the LC resonant circuit affected by the change of external physical quantities to achieve passive wireless sensing technology. However, due to the high turn-on voltage of the varactor diode, the patent uses a pair of reverse-connected diodes to generate tuned waves and mix, which requires a large turn-on power.

[0005] Invention patent CN118659760A discloses a passive wireless sensor based on piezoelectric resonator and varactor diode (applicant: Chengdu Ximengtech Technology Development Co., Ltd.), which uses the time-varying reactance of varactor diode and piezoelectric resonator to realize passive wireless sensing technology. The opening power of this patent is also large, and this patent lacks the means to flexibly adjust the inherent resonant frequency of the piezoelectric resonator in the circuit, which also has certain limitations in practical applications.

[0006] Invention patent CN110247288A discloses a room temperature semiconductor maser and its application (applicant: University of Electronic Science and Technology of China), which excites polaritons in transistors containing heterojunctions to a high energy level by pumping microwaves, and then uses a resonant network to make the polaritons excited to a high energy level transition downward to a specified energy level within the energy level region. This patent can only generate down-conversion signals through circuits f a = f p - f r ,in f a is the output signal frequency, f p is the input signal frequency, f rIt is the resonant frequency, and the input signal and output signal can only be output from two ports, so its applicability is weak.

[0007] Invention patent CN115940821A discloses a passive frequency conversion structure and passive frequency conversion method (applicant: Chengdu Enyang Technology Co., Ltd.), which feeds microwave signals into field effect transistors with maximum efficiency through an input matching network; the fed microwave signals are energy-gathered through a resonant network; an oscillation signal is generated through a passive crystal / ceramic resonator based on the microwave signal after energy convergence; in the field effect transistor, the fed microwave signal is mixed with the generated oscillation signal, and then the mixed signal is output through the input port. The oscillation signal is generated by a passive crystal / ceramic resonator, and the resonant network plays the role of energy convergence, which is only a qualitative inference and description. It is impossible to quantitatively calculate the size and change law of energy convergence, so the stability, accuracy and anti-interference ability of the sensor cannot be guaranteed. The applicability is also limited by the one-port input and output of microwave signals, and the patent does not propose an application example of combining external physical information with circuit mixing signals.

[0008] Invention patent CN118573122A discloses a passive frequency conversion structure, sensor, method and system (applicant: Zhejiang Longgan Technology Co., Ltd.), which uses the electron migration channel existing in the modulation element to establish a signal transmission channel between the ports, and realizes energy convergence through the first resonant circuit; on the other hand, the second resonant circuit is used to generate an oscillation signal, and the microwave signal fed in is mixed with the oscillation signal in the transistor, thereby realizing passive frequency conversion. The resonant network connected to the source of the modulation element is used for energy convergence and cannot be used as a sensing signal carrying a physical quantity. The sensing signal carrying a physical quantity is located between the gate of the modulation element and the resonant network connected to the gate, and the resonant frequency in the resonant circuit connected to the gate plays a role in adjusting the sensor so that the oscillation frequency of the second resonant circuit changes with the change of the sensing quantity. In addition, the resonant frequency of the resonant network connected to the gate and source of the adjustment element in this patent needs to be configured to be different, which will cause many inconveniences in circuit implementation. When the frequency of the sensing signal differs greatly from the frequency of the microwave input signal, it is also difficult to input and output two signals with large frequency differences from one port at the same time, and there are also limitations in practical applications.

[0009] Invention patent CN117889892B discloses a variable capacitance microwave direct-driven variable frequency sensor, system and control method (applicant: Chengdu Branch of Zhejiang Longgan Technology Co., Ltd.), which changes the resonant frequency by adding capacitance to the frequency conversion network of the sensor circuit, thereby changing the driven return frequency of the variable capacitance microwave direct-driven variable frequency sensor, solving the problem of limited variable frequency of the sensor due to the limited number of resonator models. This patent only considers the impact of the change in the capacitance value of the variable capacitor on the resonant frequency of the resonator. This method can only change the inherent resonant frequency of the resonator within a small range. If a large-scale change is required and the capacitance values ​​of different variable capacitors are different in large-scale production, it is also extremely difficult.

[0010] In recent years, technological advances have also promoted the improvement of passive sensor performance, such as improved energy harvesting materials and efficient signal processing algorithms, which enable them to work stably in complex environments. Passive wireless sensors have made significant progress in LC coupling, piezoelectric resonance and surface acoustic wave technology. LC coupling sensors improve energy transmission efficiency through material innovation and optimized coupling structure; piezoelectric resonators improve sensitivity and integration by using new materials; surface acoustic wave passive wireless sensors have also made significant progress in material innovation, miniaturization and integration, multifunctionality, wireless energy transmission, enhanced anti-interference ability and market application expansion in recent years. However, passive wireless sensors designed using the above technologies alone have certain limitations in terms of start-up power, transmission distance, anti-interference ability, etc. Summary of the invention

[0011] In order to solve the above problems, the present invention proposes a transistor-based zero-power sensor, which can realize the external AC signal directly driving the sensor circuit to operate in variable frequency without the need for AC / DC conversion, thereby improving energy utilization.

[0012] The technical solution adopted by the present invention is as follows: A transistor-based zero-power sensor comprises a first impedance matching network, a voltage-controlled tuning network, a sensing network and a high-impedance network, wherein: The first impedance matching network is configured to The microwave input signal is subjected to impedance transformation; The voltage-controlled tuning network is configured to modulate the microwave input signal into a time-varying tuning signal based on the characteristic of the intrinsic voltage-controlled capacitance variation of the drain-gate junction capacitance of the transistor; The sensing network is configured to filter out the tuning signal having a resonance frequency The corresponding sensing signal within the surrounding bandwidth is reflected to the transistor of the voltage-controlled tuning network, and the sensing signal is amplified by the transistor gain and then enters the high-impedance network; The high impedance network is configured to resonate at a frequency The sensor signal within the surrounding bandwidth is in a high impedance state, so that the sensor signal is reflected back to the transistor of the voltage-controlled tuning network for a second time, and due to the nonlinearity and gain amplification characteristics of the transistor, it is reflected in the transistor with a frequency of The microwave input signal is mixed and amplified, and finally the modulated mixed signal is output through the first impedance matching network.

[0013] Furthermore, the sensing signal is reflected back to the transistor of the voltage-controlled tuning network for a second time, and due to the nonlinearity and gain amplification characteristics of the transistor, it is reflected in the transistor with a frequency of The microwave input signal is mixed and amplified, and finally a modulated mixed signal is output through a first impedance matching network, including: Based on the nonlinearity, gain amplification characteristics of transistors and the Menley-Lowe formula, the resonant frequency Modulate to a frequency of The microwave input signal is connected to the first impedance matching network and the output frequency is , The mixed signal.

[0014] Furthermore, the resonant frequency It has an expressible relationship with the environmental physical quantity outside the sensor, that is, changes in the environmental physical quantity will cause the resonant frequency The deviation of the output signal is then measured to collect the environmental physical quantity.

[0015] Furthermore, the environmental physical quantities include temperature, pressure, current, voltage, humidity and gas concentration.

[0016] Furthermore, the sensing network or high-impedance network includes an LC resonant circuit, and the LC resonant circuit includes an inductor and a capacitor, or parasitic capacitance and parasitic inductance in the circuit and device.

[0017] Furthermore, the sensing network or high-impedance network includes an equivalent resonant circuit, the equivalent resonant circuit includes a transducer and a circuit structure consisting of a transducer and a capacitor and an inductor, and the transducer includes a piezoelectric resonator, a surface acoustic wave resonator or a bulk acoustic wave resonator.

[0018] Furthermore, the voltage-controlled tuning network includes a transistor and an inductor, the inductor is connected in series or in parallel with the transistor, the gate of the transistor is connected to the sensing network, and the source is connected to the high-impedance network.

[0019] Furthermore, the transistors of the voltage-controlled tuning network include bipolar transistors, unipolar transistors or high electron mobility transistors, the bipolar transistors include NPN transistors or PNP transistors, and the unipolar transistors include JFET junction field effect transistors, MOSFET metal oxide field effect transistors or MODFET modulation doped field effect transistors.

[0020] Furthermore, when the transistors of the voltage-controlled tuning network use bipolar transistors instead of unipolar transistors, the collector of the bipolar transistor is equivalent to the drain, the base is equivalent to the gate, and the emitter is equivalent to the source.

[0021] Furthermore, it also includes a second impedance matching network, which is configured to perform impedance matching on the sensing signal and output a frequency signal related to the physical quantity.

[0022] The beneficial effects of the present invention are: 1. Strong anti-interference performance: The signal output by the transistor-based zero-power sensor of the present invention is a modulated frequency-converting signal, and its anti-interference performance is significantly enhanced.

[0023] 2. AC direct drive frequency conversion mechanism: The present invention utilizes an AC signal to directly drive a circuit to generate a frequency conversion signal.

[0024] 3. Low energy consumption characteristics: Since the transistor-based zero-power sensor of the present invention does not perform AC-DC conversion, the energy loss of the system is effectively reduced.

[0025] 4. Single-port and dual-port input and output modes: When the input and output signal frequencies are similar, a single-port working mechanism can be implemented, and a single antenna can achieve two-way signal transmission; when there is a significant difference between the input and output frequencies, a dual-port working mechanism can be adopted, using two antennas to ensure the isolation of signal transmission.

[0026] 5. Compared with patent CN118310561A, the present invention is based on the transistor gain amplification characteristics, using the capacitance of the transistor junction capacitance to be affected by the voltage loaded at both ends to perform AC direct drive frequency conversion, and its turn-on threshold is significantly lower than the method of using a varactor diode to achieve AC direct drive frequency conversion function.

[0027] 6. Compared with patent CN118659760A, the present invention can effectively adjust the impedance characteristics of the transducer and readjust its inherent resonant frequency through the series-parallel structure of the transducer and the capacitor and inductor elements, thereby achieving precise control of the output signal frequency band.

[0028] In summary, the present invention utilizes the characteristic that the internal junction capacitance of the transistor changes with the change of the applied voltage to realize AC direct drive frequency conversion, avoiding energy loss in the AC-DC-AC conversion process; utilizing the design of transistor gain amplification to significantly reduce the driving threshold; and utilizing the nonlinear characteristics of the transistor itself to output a modulated frequency conversion signal with strong anti-interference performance. In addition, the present invention supports single-port and dual-port input and output, and flexibly adapts to different frequency conditions, while the optimized structure of the transducer and the capacitor and inductor elements realizes precise control of the output signal frequency band, significantly improving the system's performance and application flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is one of the principle diagrams of a transistor-based zero-power sensor according to Embodiment 1 of the present invention.

[0030] Figure 2 This is the second schematic diagram of the transistor-based zero-power sensor according to Embodiment 1 of the present invention.

[0031] Figure 3 This is a schematic diagram of a transistor-based zero-power sensor according to Embodiment 2 of the present invention.

[0032] Figure 4 This is a schematic diagram of a transistor-based zero-power sensor according to Embodiment 3 of the present invention.

[0033] Figure 5 This is a schematic diagram of a transistor-based zero-power sensor according to Embodiment 4 of the present invention.

[0034] Figure 6 This is a frequency spectrum diagram of the mixed signal output by port Port1 of embodiment 2 of the present invention.

[0035] Figure 7 This is a spectrum diagram of the frequency-selected signal output by port Port2 of embodiment 3 of the present invention.

[0036] Figure 8 This is a frequency spectrum diagram of the mixed signal output by port Port1 of embodiment 4 of the present invention.

[0037] Fig. 9 This is a tuning signal spectrum diagram of Example 2 of the present invention. DETAILED DESCRIPTION

[0038] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0039] Example 1 Since existing passive wireless sensors have certain limitations in terms of start-up power, transmission distance, anti-interference ability, etc., this embodiment provides a transistor-based zero-power sensor, including a first impedance matching network, a voltage-controlled tuning network, a sensor network, and a high-impedance network, wherein the first impedance matching network is configured to The microwave input signal is subjected to impedance transformation; the voltage-controlled tuning network is configured to modulate the microwave input signal into a time-varying tuning signal based on the characteristic of the inherent voltage-controlled capacitance change of the drain-gate junction capacitance of the transistor; the sensing network is configured to screen out the tuning signal that is consistent with the resonant frequency. The corresponding sensor signal within the surrounding bandwidth is reflected to the transistor of the voltage-controlled tuning network. The sensor signal is amplified by the transistor gain and then enters the high-impedance network; the high-impedance network is configured to be The sensing signal within the surrounding bandwidth is in a high impedance state (a term in this field, indicating that a node in the circuit has a relatively higher impedance than other points in the circuit), so that the sensing signal is reflected back to the transistor of the voltage-controlled tuning network for a second time, and due to the nonlinearity and gain amplification characteristics of the transistor, it is reflected in the transistor with a frequency of The microwave input signal is mixed and amplified, and finally the modulated mixed signal is output through the first impedance matching network.

[0040] Specifically, Figure 1 As shown, the zero-power sensor of this embodiment includes a first impedance matching network, a voltage-controlled tuning network, a sensing network, a high-impedance network, and a second impedance matching network (optional), wherein the voltage-controlled tuning network is composed of an inductor L1 in series with a transistor Q. The input frequency of port 1 is The microwave signal is transformed by the first impedance matching network and then fed into the transistor Q with the highest efficiency through the inductor L1. Since the capacitance of the junction capacitance of the transistor Q is affected by the voltage, the circuit composed of the inductor L1 and the junction capacitance has a time-varying reactance characteristic, thus generating a rich tuning signal. The tuning signal is a time-varying frequency signal. The signal enters the sensing network connected to the gate of the transistor Q. The sensing network will screen the tuning signal with the resonance frequency of the sensing network. The adjacent sensing signal is reflected back to transistor Q.

[0041] The sensing signal is amplified by the gain of transistor Q and then enters the high impedance network. The high impedance network is designed to have a frequency of The circuit in which the signals within a certain bandwidth are all in high impedance state, so the frequency is The signal cannot flow back to the ground through the high impedance network. At this time, the second impedance matching network is set to The network that is in an impedance matching state with the output transmitting antenna can output the signal from Port 2.

[0042] It should be noted that if the second impedance matching network is not configured, the frequency The signal within a certain bandwidth will be reflected back to transistor Q for the second time. Due to the nonlinearity and gain amplification characteristics of the transistor, the frequency is The frequency selection signal will be continuously input with a frequency of The microwave signal is mixed and amplified, and the mixed and amplified signal is calculated according to the Menley-Lowe formula:

[0043]

[0044] in, is the frequency The signal power of m and n is an integer, and the frequency and and The following relations are satisfied: .

[0045] It should be noted that the mixing signal contains a frequency of The input signal and frequency are When the second impedance matching network is not configured, the first impedance matching network is configured to simultaneously meet the frequency of The signal and frequency are The signal and frequency are The first and difference frequencies of the signal are input and output with the highest efficiency, so that the first and difference frequencies of the input signal and the mixed signal can be output through port 1.

[0046] Preferably, a transistor-based zero-power sensor schematic Figure 1 The exchange of positions between the medium sensing network and the high impedance network can also realize the acquisition of physical quantities, such as Figure 2 shown.

[0047] Preferably, Figure 1 and Figure 2 The sensor network can be replaced with transducer type sensing elements such as piezoelectric resonance type sensing elements, surface acoustic wave resonance type sensing elements, and bulk acoustic wave resonance type sensing elements.

[0048] Preferably, the high impedance characteristic of the transducer type sensing element to the frequency band near its resonant frequency is utilized. Figure 1 and Figure 2The medium and high impedance networks can be replaced with transducers such as piezoelectric type resonators, surface acoustic wave type resonators, and bulk acoustic wave type resonators.

[0049] Example 2 This embodiment provides a transistor-based zero-power sensor, which is described using a single-port two-way LC parallel resonant circuit. Figure 3 As shown, the zero power sensor of this embodiment includes a transistor Q, inductors L1-L3 and capacitors C1-C3. The input frequency from port 1 is The microwave signal is fed into transistor Q with the highest efficiency after impedance transformation through the impedance matching network formed by inductor L1 and capacitor C1. Fig. 9 As shown in the figure, since the capacitance of the junction capacitance of transistor Q is affected by voltage, the circuit composed of inductor L2 and the junction capacitance has a time-varying reactance characteristic, thus generating a rich tuning signal. The tuning signal is a time-varying frequency signal. This signal enters the sensing network composed of inductor L2 and capacitor C2 connected to the gate of transistor Q. The circuit will filter the sensing signal with a certain bandwidth that is close to the resonant frequency of inductor L2 and capacitor C2 in the tuning signal and reflect it back to transistor Q. The center frequency of the sensing circuit is for:

[0050] in, is the capacitance of capacitor C2, is the inductance value of inductor L2.

[0051] The sensing signal is amplified by the gain of transistor Q and enters the high impedance network composed of inductor L3 and capacitor C3, which has a frequency of The signals in a certain frequency band nearby are all in high impedance state, so the frequency is The signal cannot flow back to the ground through the high impedance network composed of inductor L3 and capacitor C3. The signal within a certain bandwidth near the signal will be reflected back to transistor Q for the second time. Due to the nonlinear characteristics and gain amplification characteristics of the transistor, the frequency is The frequency selection signal will be continuously input with a frequency of The microwave signal is mixed and amplified. According to the Menley-Lowe formula, the signal after mixing and amplification will contain a frequency of The signal and frequency are The first and difference frequencies, second and difference frequencies..., nth and difference frequencies of the signal.

[0052] It should be noted that the impedance matching network formed by the inductor L1 and the capacitor C1 is set to simultaneously meet the frequency The microwave frequency is The signal and frequency are The first and difference frequencies of the mixed signal can be input and output with the highest efficiency, so that the first and difference frequencies of the mixed signal can be output through port Port 1, such as Figure 6 shown.

[0053] Preferably, the capacitor C2 can be set as a sensing device whose capacitance is in an expressible relationship with external physical quantities (such as temperature, pressure, current, voltage, humidity, gas concentration, etc.), so that changes in the physical quantities of the external environment will cause the resonant frequency of the sensor network to change. Offset, the collection of external physical quantities can be achieved by analyzing the output frequency.

[0054] It should be noted that in Figure 3 The capacitor C3 in the circuit shown can also be set as a sensing device whose capacitance is in an expressible relationship with external physical quantities (such as temperature, pressure, current, voltage, humidity, gas concentration, etc.), so that changes in the physical quantities of the external environment will cause the resonant frequency of the high-impedance network Offset, resonant frequency for:

[0055] in, is the capacitance of capacitor C3, is the inductance of inductor L3. The analysis can also realize the collection of external physical quantities.

[0056] Example 3 This embodiment provides a zero-power sensor based on a transistor, which is described using a piezoelectric resonator circuit with two input and output ports. Figure 4 As shown, the zero power sensor of this embodiment includes a transistor Q, inductors L1-L4, capacitors C1-C3 and a piezoelectric transducer X1. The input signal from port 1 is a frequency of The alternating signal is transformed by the first impedance matching network formed by the inductor L1 and the capacitor C1, and then fed into the transistor Q by the inductor L2 with the highest efficiency. Since the capacitance of the junction capacitance of the transistor Q is affected by the voltage, a rich tuning signal will be generated. The tuning signal is a time-varying frequency signal. This signal enters the piezoelectric transducer connected to the gate of the transistor Q. The circuit will screen the tuning signal that is consistent with the natural frequency of the piezoelectric transducer. The similar frequency-selected signal is reflected back to transistor Q.

[0057] Since the piezoelectric resonator has an extremely high quality factor and can accumulate and amplify the amplitude of the oscillation signal through resonance, the harmonic frequency-selective signal will be more obvious and pure, and interference from other frequencies will be suppressed.

[0058] Preferably, the piezoelectric type transducer is designed to have a natural frequency A sensing device that can express a relationship with external physical quantities (such as temperature, pressure, current, voltage, humidity, gas concentration, etc.), so that changes in external physical quantities will cause the natural frequency of the piezoelectric transducer The physical quantity can be collected by analyzing the output frequency.

[0059] In addition, the frequency-selected signal reflected back to transistor Q enters the LC parallel resonant circuit composed of inductor L3 and capacitor C2 after gain amplification. The resonant circuit is designed to be The signals in a certain frequency band nearby are all in high impedance state, so the frequency is The signal cannot flow back to the ground through the resonant circuit composed of inductor L3 and capacitor C2, while other frequency signals will pass through the LC parallel resonant circuit composed of inductor L3 and capacitor C2, thus being greatly attenuated. The frequency-selected signal will be output at the highest power through the output matching network composed of inductor L4 and capacitor C3. Figure 7 shown.

[0060] Example 4 This embodiment provides a transistor-based zero-power sensor, which is described using an inductive parallel transducer with a single-port input and output. Figure 5 As shown, the zero-power sensor of this embodiment includes a transistor Q, inductors L1-L4, a capacitor C1 and a piezoelectric transducer X1. The input frequency of port 1 is The alternating signal is transformed by the impedance matching network formed by the inductor L1 and the capacitor C1, and then fed into the transistor Q by the inductor L2 with the highest efficiency. Since the capacitance of the junction capacitance of the transistor Q is affected by the voltage, a rich tuning signal will be generated. The tuning signal is a time-varying frequency signal. This signal enters the circuit in which the inductor L3 connected to the gate of the transistor Q is connected in parallel with the piezoelectric transducer. The natural resonant frequency of the piezoelectric transducer can be changed by connecting the inductor in parallel with the piezoelectric transducer. , which produces a natural frequency different from that of the piezoelectric type transducer Resonant frequency At the same time, the characteristic impedance of the piezoelectric transducer is changed to enhance the frequency selection characteristics of the circuit. The circuit will filter the frequency in the tuning signal. The similar frequency-selected signal is reflected back to transistor Q.

[0061] Preferably, the frequency-selective signal reflected back to transistor Q enters the inductor L4 after gain amplification, and the inductor L4 selects a self-resonant frequency close to the frequency The self-resonance of inductor L4 is used to obtain the frequency of The circuit in which the signals in a certain frequency band nearby are all in high impedance state, blocking the frequency The signal flows back to the ground through inductor L4.

[0062] Among them, the frequency The signal within a certain bandwidth will be reflected back to the transistor Q by the inductor L4. After mixing and amplification, the signal is output from port 1 after passing through an impedance matching network. The spectrum of the output signal is as follows: Figure 8 shown.

[0063] It should be noted that the inductance in parallel with the piezoelectric transducer and the parasitic parameters in the circuit are fixed values, so the frequency The natural frequency of the piezoelectric resonator An expressible relationship.

[0064] Preferably, the piezoelectric type transducer is designed to have a natural frequency A sensing device that can express a relationship with external physical quantities (such as temperature, pressure, current, voltage, humidity, gas concentration, etc.), so that changes in external physical quantities will cause the natural frequency of the piezoelectric transducer The shift of the resonant frequency The physical quantity can be collected by analyzing the output frequency.

[0065] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A transistor-based zero-power sensor, characterized in that: It includes a first impedance matching network, a voltage-controlled tuning network, a sensing network and a high-impedance network, wherein: The first impedance matching network is configured to The microwave input signal is subjected to impedance transformation; The voltage-controlled tuning network is configured to modulate the microwave input signal into a time-varying tuning signal based on the characteristic of the intrinsic voltage-controlled capacitance variation of the drain-gate junction capacitance of the transistor; The sensing network is configured to filter out the tuning signal having a resonance frequency The corresponding sensing signal within the surrounding bandwidth is reflected to the transistor of the voltage-controlled tuning network, and the sensing signal is amplified by the transistor gain and then enters the high-impedance network; The high impedance network is configured to resonate at a frequency The sensor signal within the surrounding bandwidth is in a high impedance state, so that the sensor signal is reflected back to the transistor of the voltage-controlled tuning network for a second time, and due to the nonlinearity and gain amplification characteristics of the transistor, it is reflected in the transistor with a frequency of The microwave input signal is mixed and amplified, and finally the modulated mixed signal is output through the first impedance matching network.

2. A transistor-based zero-power sensor according to claim 1, characterized in that: The sensing signal is reflected back to the transistor of the voltage-controlled tuning network for the second time, and due to the nonlinearity and gain amplification characteristics of the transistor, it is reflected in the transistor with a frequency of The microwave input signal is mixed and amplified, and finally a modulated mixed signal is output through a first impedance matching network, including: Based on the nonlinearity, gain amplification characteristics of transistors and the Menley-Lowe formula, the resonant frequency Modulate to a frequency of The microwave input signal is connected to the first impedance matching network and the output frequency is , The mixed signal.

3. A transistor-based zero-power sensor according to claim 1, characterized in that: The resonant frequency It has an expressible relationship with the environmental physical quantity outside the sensor, that is, changes in the environmental physical quantity will cause the resonant frequency The deviation of the output signal is then measured to collect the environmental physical quantity.

4. A transistor-based zero-power sensor according to claim 3, characterized in that: The environmental physical quantities include temperature, pressure, current, voltage, humidity and gas concentration.

5. A transistor-based zero-power sensor according to claim 1, characterized in that: The sensing network or high impedance network includes an LC resonant circuit, and the LC resonant circuit includes an inductor and a capacitor, or parasitic capacitance and parasitic inductance in circuits and devices.

6. A transistor-based zero-power sensor according to claim 1, characterized in that: The sensor network or high-impedance network includes an equivalent resonant circuit, which includes a transducer and a circuit structure composed of a transducer and a capacitor and an inductor. The transducer includes a piezoelectric resonator, a surface acoustic wave resonator or a bulk acoustic wave resonator.

7. A transistor-based zero-power sensor according to claim 1, characterized in that: The voltage-controlled tuning network includes a transistor and an inductor. The inductor is connected in series or in parallel with the transistor. The gate of the transistor is connected to the sensing network, and the source is connected to the high-impedance network.

8. A transistor-based zero-power sensor according to claim 1, characterized in that: The transistors of the voltage-controlled tuning network include bipolar transistors, unipolar transistors or high electron mobility transistors. The bipolar transistors include NPN transistors or PNP transistors. The unipolar transistors include JFET junction field effect transistors, MOSFET metal oxide field effect transistors or MODFET modulation doped field effect transistors.

9. A transistor-based zero-power sensor according to claim 8, characterized in that: When the transistors of the voltage-controlled tuning network are bipolar transistors instead of unipolar transistors, the collector of the bipolar transistor is equivalent to the drain, the base is equivalent to the gate, and the emitter is equivalent to the source.

10. A transistor-based zero-power sensor according to any one of claims 1 to 9, characterized in that: The system further includes a second impedance matching network, wherein the second impedance matching network is configured to perform impedance matching on the sensing signal and output a frequency signal related to the physical quantity.

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