A passive wireless temperature sensor

Abstract

The present invention discloses a passive wireless temperature sensor, which belongs to the field of wireless sensing. A passive wireless temperature sensor includes a receiving antenna, a radio frequency energy collection module, a protection module, a power management module, a modulation and demodulation module, a data management module, a temperature measurement module, an external sensor module, a wireless transmission module, a transmitting antenna, an auxiliary power supply, a wireless energy transmission module, and a receiving module. The present invention adopts a radio frequency energy collection module and a wireless energy transmission module to generate current through the principle of electromagnetic induction to power the circuit in the environment to be tested, thereby solving the power supply problem of the circuit in a special environment; a Schottky diode is used as a temperature measuring element, and a Schottky diode made of a special material is used as a temperature sampling element, which has the characteristics of high temperature resistance, high pressure, and high frequency, thereby solving the problem of failure of ordinary sensors in special environments; there is no direct power supply unit in the circuit of the environment to be tested, and there is no data transmission wiring, so the structure is simple and the layout is convenient.

Description

Technical Field

[0001] The invention relates to a passive wireless temperature sensor and belongs to the field of wireless sensing. Background Art

[0002] Temperature sensors are widely used in agricultural production, microelectronics process research and development and production, aerospace and other fields. However, in harsh environments, such as high temperature, closed, high-speed rotation, etc., accurate temperature measurement is still a very challenging problem. Active wired temperature sensing technology has problems such as power supply replacement, maintenance cost, safety hazards, temperature measurement limitations, large size, and inconvenient layout.

[0003] Research shows that the forward current of Schottky diodes is constant. Within a certain temperature range, there is a linear relationship between the forward voltage drop across the device and the temperature change. Using this characteristic, Schottky diodes can be used to manufacture temperature sensors. Compared with PN junction diodes, Schottky diodes have significant temperature sensitivity within a certain temperature range. Schottky diodes made of special materials and structures have the characteristics of high temperature resistance, high voltage, and high frequency, and are more suitable for high-precision temperature measurement in special environments.

[0004] Although Schottky diodes are used in the prior art to collect temperature based on the characteristics of the Schottky diode voltage and current characteristics that change with temperature, the solutions adopted are mostly to directly use AC to DC to power the circuit and use cables to transmit data. Such solutions must consider the tolerance of the power supply when the circuit is powered in a complex and special environment, and the setting and wiring of the entire system are very difficult; in confined spaces such as high-temperature boilers, mechanical pumps, and high-voltage electrical cabinets, wired power supply methods and complex data transmission lines cannot adapt to actual test environments. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a passive wireless temperature sensor for use in special environments; the passive wireless sensor of the present invention can be applied to temperature measurement in harsh environments, it can not only meet some strict requirements, but also solve the problem of power supply, no power supply is required in the test environment, and data transmission adopts wireless transmission, so that the wiring and structure of the entire system are very simple.

[0006] The first object of the present invention is to provide a passive wireless temperature sensor, including a receiving antenna, a radio frequency energy collection module, a protection module, a power management module, a modulation and demodulation module, a data management module, a temperature measurement module, an external sensor module, a wireless transmission module, a transmitting antenna, an auxiliary power supply, a wireless energy transmission module, and an external receiving module.

[0007] The transmitting antenna includes a signal transmitting antenna of a wireless transmitting module and a microwave transmitting antenna of a wireless energy transmitting module; the receiving antenna includes a signal receiving antenna of an external receiving module and a microwave receiving antenna of a radio frequency energy collection module.

[0008] Optionally, the RF energy collection module, protection module, power management module, modulation and demodulation module, data management module, temperature measurement module, external sensor module, wireless transmission module, and auxiliary power supply are set in the environment to be tested; the wireless energy transmission module and external receiving module are set away from the environment to be tested.

[0009] Optionally, the wireless energy transmission module includes a microwave generator, a capacitor, a transistor, and a microwave transmitting antenna; the microwave generator is connected to the base of the transistor through the capacitor, the collector of the transistor is connected in series with one end of the microwave transmitting antenna through the capacitor, and the other end of the microwave transmitting antenna is grounded to the emitter of the transistor and the negative pole of the microwave generator.

[0010] Optionally, the output end of the microwave receiving antenna is connected to the input end of the radio frequency energy collection module; the output end of the radio frequency energy collection module is connected to the input end of the protection module and the power management module; the output end of the protection module is connected to the input end of the modulation and demodulation module; the output end of the power management module is connected to the input end of the temperature measurement module and one end of the enable switch; the output end of the modulation and demodulation module is connected to the input end of the data management module; the output end of the data management module is connected to the input end of the power management module; the output end of the temperature measurement module is connected to the wireless transmission module; the output end of the external sensor module is connected to the data management module and the enable end of the enable switch; the input end of the wireless transmission module is connected to one end connected to the enable switch and the output end of the power management module; the signal transmitting antenna is connected to the output end of the wireless transmission module; and the auxiliary power supply is connected to the power management module.

[0011] Optionally, the RF energy collection module includes a microwave receiving antenna, an electromagnetic coil, an automatic impedance matching circuit, and an adaptive rectifier circuit; the microwave receiving antenna converts electromagnetic waves in space into alternating current through the principle of electromagnetic induction, and the alternating current is rectified and changed by the adaptive rectifier circuit to output direct current to provide a DC voltage for the circuit in the test environment; the adaptive rectifier circuit can also adjust the rectifier circuit series according to the power intensity of the external RF signal, and the automatic impedance matching circuit performs impedance matching according to the change of the series; the RF energy collection module is used to capture electromagnetic waves in space and convert them into electrical energy to provide energy for the circuit in the test environment; specifically, the microwave receiving antenna receives microwave changes in space, and the microwave changes will cause the magnetic field around the electromagnetic coil to change. After the magnetic field changes, current can be generated on the electromagnetic coil, and after rectification by the rectifier circuit, a stable current can be output, and the current size is 500μA, and a rated voltage output voltage V is generated through the current limiting circuit. out, the voltage is 2V; it can power other circuits and charge auxiliary power supplies.

[0012] Optionally, the protection module is used to limit the abnormally high output power of the radio frequency energy collection module and protect the internal components of the circuit behind the radio frequency energy collection module.

[0013] Optionally, the power management module includes a pre-detector, a main detector, a power selector, and a storage capacitor; the pre-detector can track the size of the RF radio frequency signal input power; the output of the main detector determines whether to use the auxiliary power supply; the power selector selects the auxiliary power supply mode or the passive mode; the storage capacitor is used to store excess energy; the power management module can select the working mode according to the input power size of the external RF radio frequency energy and the signal output by the pre-detector; the working modes are the auxiliary power supply mode and the passive mode, the auxiliary power supply mode is that the auxiliary power supply supplies power to the circuit in the environment to be tested, and the passive mode is that the RF energy collection module supplies power to the circuit in the environment to be tested. The pre-detector outputs a signal by comparing the output voltage of the RF energy collection module with the battery voltage. The power selector selects the power supply mode according to the output signal of the pre-detector, that is, the auxiliary power supply or the RF energy collection module. The storage capacitor is used to store the excess output voltage of the energy collection circuit.

[0014] Optionally, the modulation and demodulation module includes a modem and a clock generator; the modem is used for processing data and transmitting data to or receiving data from the data management module; the clock generator is used for generating a clock signal.

[0015] Optionally, the data management module is used for processing and storing data.

[0016] Optionally, the temperature measurement module includes a Schottky diode temperature sampling circuit and an AD conversion circuit; the Schottky diode temperature sampling circuit can collect the temperature in the environment to be measured; the AD conversion circuit can convert the analog voltage signal into a digital signal and transmit it to the wireless transmission module.

[0017] Optionally, the Schottky diode temperature sampling circuit includes a first Schottky diode D 1 and the second Schottky diode D 2 , the first operational amplifier A 1 , the second operational amplifier A 2 The MOS tube and inductor that constitute the circuit, and the resistor R in series with the second Schottky diode 1 , the first Schottky diode is connected to one end of the first operational amplifier, and the other end of the first operational amplifier is connected to the anode of the second Schottky diode and the input of the second operational amplifier respectively; the output voltage of the first operational amplifier is V 2 , the output voltage of the second operational amplifier is V1 , MOS tube M of the temperature measurement module 2 The drain current is a variable current I ptat , MOS tube M 1 The drain current is a reference current I 1 The Schottky diode temperature sensing circuit uses Schottky diodes of different sizes as temperature measuring elements. The voltage difference between the first Schottky diode and the second Schottky diode generates a PTAT voltage analog quantity, and the output current I ptat The calculation formula of size is formula (1):

[0018]

[0019] Where k is the Boltzmann constant, T is the temperature, N is the junction area ratio of the first Schottky diode to the second Schottky diode, q is the electron charge, and R is the resistance R 1 The first Schottky diode and the second Schottky diode are respectively at a given bias current I D Under this condition, a voltage drop V is generated across the first Schottky diode and the second Schottky diode respectively. D , the calculation formula of its size is formula (2):

[0020]

[0021] Among them, R s is the equivalent resistance corresponding to the first Schottky diode and the second Schottky diode, I s is the saturation current corresponding to the first Schottky diode and the second Schottky diode.

[0022] Optionally, the input voltage of the AD conversion circuit is the output voltage V of the temperature acquisition module. 2 , the output is a square wave signal corresponding to the temperature.

[0023] Optionally, the wireless transmitting module includes capacitors, inductors, transistors, and a signal transmitting antenna that constitute a circuit; the input of the wireless transmitting module is the temperature square wave data output by the AD conversion circuit of the temperature sampling module, and the signal transmitting antenna can transmit the collected temperature square wave data to an external receiving module.

[0024] Optionally, the first Schottky diode D 1 and the second Schottky diode D 2 The anode metal material is any one of aluminum, gold, molybdenum, nickel and titanium, and the semiconductor material is any one of Si, GaN, diamond and SiC.

[0025] Optionally, the external receiving module includes a signal receiving wire, an inductor, a diode, a capacitor, and an operational amplifier; the signal receiving antenna is connected to the operational amplifier via the inductor.

[0026] Optionally, the external sensor module includes a chopper amplifier, a multiplexer, a programmable gain amplifier, and a successive approximation register AD converter; the chopper amplifier is used to enhance the external signal while suppressing 1 / f noise and offset voltage; the multiplexer is used to receive multiple external sensor signals; the programmable gain amplifier is used to adjust the signal amplitude to provide the signal to the AD converter with a suitable input range; the successive approximation register AD converter is used to achieve a medium conversion rate and low power consumption; the entire external sensor module is used to receive external instructions to put the system into sleep, wake-up, hold and other states.

[0027] Optionally, the wireless transmission module is used to send all data in real time within a specified working frequency band.

[0028] The second object of the present invention is to provide an application of the above-mentioned passive wireless temperature sensor for temperature collection in a high-temperature, closed, high-speed rotating environment.

[0029] The beneficial effects of the present invention are:

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] (1) The present invention uses a wireless energy transmitting module to be set far away from the environment to be tested, and a radio frequency energy receiving module is set in the environment to be tested. The microwave receiving antenna of the radio frequency energy receiving module can capture the electromagnetic waves emitted by the wireless energy transmitting module in space, and the adaptive rectification circuit of the radio frequency energy receiving module converts the AC signal into a DC signal to power the circuit in the environment to be tested and the auxiliary power supply. This setting method makes it possible for the test module in the environment to be tested to not require a direct power supply unit, thereby solving the power supply problem of the test system in special environments;

[0032] (2) In the present invention, the Schottky diode temperature sampling circuit of the temperature measurement module can collect temperature data in the environment to be measured, and after the analog signal is converted into a square wave digital signal by the AD conversion circuit, it is sent out through the transmitting module at a specific working frequency band, and the receiving module set at the remote end can receive the temperature data of the environment to be measured, thus solving the problem of data transmission wiring in special environments;

[0033] (3) In the present invention, the Schottky diode temperature sampling circuit of the temperature acquisition module uses a Schottky diode as a temperature measuring element, and reflects the temperature change according to the characteristic that the Schottky diode voltage changes linearly with the temperature; the Schottky diode made of special materials used in the present invention as a temperature sampling element has the characteristics of high temperature resistance, high pressure and high frequency, and solves the problem of failure of ordinary sensors in special environments;

[0034] (4) The passive wireless sensor of the present invention has no direct power supply unit and no data transmission cable, and has a simple structure and convenient layout. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a schematic diagram of the local structure of the present invention;

[0037] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0038] Figure 3 This is a circuit diagram of the wireless energy transmission module of the present invention;

[0039] Figure 4 The circuit diagram of the radio frequency energy collection module of the present invention;

[0040] Figure 5 This is the Schottky diode temperature sampling circuit diagram of the temperature measurement module of the present invention;

[0041] Figure 6 It is an AD conversion circuit diagram of the temperature measurement module of the present invention;

[0042] Figure 7 It is a current pulse conversion diagram in the AD conversion circuit of the temperature measurement module of the present invention;

[0043] Figure 8 The wireless transmission module circuit diagram of the present invention;

[0044] Fig. 9 The circuit diagram of the external receiving module of the present invention;

[0045] Fig.10 A temperature data curve diagram of a passive wireless sensor of the present invention measured in a closed environment;

[0046] Fig.11 This is a graph of actual temperature data in a closed environment in an embodiment of the present invention. DETAILED DESCRIPTION

[0047] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0048] Embodiment 1:

[0049] like Figure 2 As shown, a passive wireless temperature sensor of this embodiment includes a microwave receiving antenna, a signal receiving antenna, a radio frequency energy collection module, a protection module, a power management module, a modulation and demodulation module, a data management module, a temperature measurement module, an external sensor module, a wireless transmission module, a wireless energy transmission module, a receiving module, a signal transmission antenna, a microwave transmission antenna, and an auxiliary power supply. The output end of the microwave receiving antenna is connected to the input end of the radio frequency energy collection module; the output end of the radio frequency energy collection module is connected to the input end of the protection module and the power management module; the output end of the protection module is connected to the input end of the modulation and demodulation module; the output end of the power management module is connected to the input end of the temperature measurement module and one end of the enable switch; the output end of the modulation and demodulation module is connected to the input end of the data management module; the output end of the data management module is connected to the input end of the power management module; the output end of the temperature measurement module is connected to the wireless transmission module; the output end of the external sensor module is connected to the data management module and the enable end of the enable switch; the input end of the wireless transmission module is connected to one end connected to the enable switch and the output end of the power management module; the signal transmission antenna is connected to the output end of the wireless transmission module; and the auxiliary power supply is connected to the power management module.

[0050] like Figure 3 As shown, the wireless energy transmitting module includes Agilent's microwave signal generator, capacitors C1, C2 and C3, a transistor, and a microwave transmitting antenna; the microwave generator is connected to the base of the transistor through the capacitor C1, the collector of the transistor is connected in series with one end of the antenna through the capacitor, and the other end of the microwave transmitting antenna is grounded to the emitter of the transistor and the negative pole of the microwave generator.

[0051] like Figure 4As shown, the RF energy collection module includes a microwave receiving antenna, an electromagnetic coil, an automatic impedance matching circuit, and an adaptive rectifier circuit; the microwave receiving antenna converts electromagnetic waves in space into alternating current through the principle of electromagnetic induction, and the alternating current is rectified and changed by the adaptive rectifier circuit to output direct current to provide a DC voltage for the circuit in the test environment; the adaptive rectifier circuit can also adjust the rectifier circuit series according to the power intensity of the external RF signal, and the automatic impedance matching circuit performs impedance matching according to the change of the series; the RF energy collection module is used to capture electromagnetic waves in space and convert them into electrical energy to provide energy for the circuit in the test environment; specifically, the microwave receiving antenna receives microwave changes in space, and the microwave changes will cause the magnetic field around the electromagnetic coil to change. After the magnetic field changes, current can be generated on the electromagnetic coil, and after rectification by the rectifier circuit, a stable current can be output, and the current size is 500μA, and a rated voltage output voltage V is generated through the current limiting circuit. out , the voltage is 2V; it can power other circuits and charge auxiliary power supplies.

[0052] like Figure 5 As shown, the Schottky diode temperature sensing circuit of the temperature measuring module includes a first Schottky diode D 1 and the second Schottky diode D 2 , the first operational amplifier A 1 , the second operational amplifier A 2 The MOS tube and inductor that constitute the circuit, as well as the second Schottky diode D 2 The series resistor R 1 , the first Schottky diode D 1 With the first operational amplifier A 1 One end of the first operational amplifier A 1 The other end is connected to the second Schottky diode D 2 The positive pole of the second operational amplifier A 2 The input of the first operational amplifier A is connected; 1 The output voltage is V 2 , the second operational amplifier A 2 The output voltage is V 1 , MOS tube M of the temperature measurement module 2 The drain current is a variable current I ptat , MOS tube M 1 The drain current is a reference current. The Schottky diode temperature sensing circuit uses Schottky diodes of different sizes as temperature measuring elements. The first Schottky diode D 1 With the second Schottky diode D 2 The voltage difference between them generates a PTAT voltage analog quantity, and the output current I ptat The calculation formula of size is formula (1):

[0053]

[0054] Where k is the Boltzmann constant, T is the temperature, and N is the first Schottky diode D 1 With the second Schottky diode D 2 The junction area ratio, q is the electron charge, and R is the resistance R 1 The resistance of the first Schottky diode D 1 and the second Schottky diode D 2 At a given bias current I D Next, the first Schottky diode D 1 and the second Schottky diode D 2 A voltage drop V is generated at both ends D , the calculation formula of its size is formula (2):

[0055]

[0056] Among them, R s The first Schottky diode D 1 With the second Schottky diode D 2 The corresponding equivalent resistance, I s The first Schottky diode D 1 and the second Schottky diode D 2 The corresponding saturation current.

[0057] The AD conversion circuit of the temperature acquisition module is as follows Figure 6 As shown, Figure 7 As shown, the input voltage of the AD conversion circuit is the output voltage V of the temperature acquisition module. 2 , the output is a square wave signal corresponding to the temperature.

[0058] like Figure 8 As shown, the receiving module includes a signal receiving wire, an inductor, a diode, a capacitor, and an operational amplifier; the signal receiving antenna is connected to the operational amplifier through the inductor.

[0059] The microwave receiving antenna of the RF energy collection module will receive the microwaves emitted by the wireless energy transmission module. The receiving frequency band of the microwave receiving antenna is 13.56MH z When the coil of the RF energy harvesting module senses the change of microwaves, a current will be generated, and a voltage V will be output from the output end of the energy harvesting module. out This voltage is used to power the Schottky diode temperature sampling circuit, AD conversion circuit, and transmitter module of the temperature measurement module. The V DD The V outConnected; V of AD conversion circuit DD The V out Connected; V of the transmitter module cc The V out are connected.

[0060] The input end of the transmitting module is connected to the output end of the AD conversion circuit of the temperature sampling module. The square wave signal generated by the output end of the AD conversion circuit passes through the transmitting module, and the square wave signal corresponding to the collected temperature is sent out through the signal transmitting antenna; the receiving module far away from the environment to be tested can receive the signal emitted by the transmitting module, and the receiving frequency of the signal receiving antenna is 935.6MH z .

[0061] In the present invention, the system is powered by radio frequency energy. In order to prevent the system from not being able to work properly due to the long-term weakness of the external microwave signal, an auxiliary power supply is connected to the system. When the microwave signal input power is large, the system uses the microwave signal for power supply, and the excess power is used to charge the battery. Otherwise, the battery function is used.

[0062] In the present invention, when the microwave receiving antenna receives a microwave signal, the radio frequency energy collection circuit can convert the received microwave signal into a DC signal and has a boosting effect. Since the microwave signal strength is uncertain, in order to improve efficiency, an adaptive rectifier circuit is used in the radio frequency energy collection circuit, and the rectifier circuit level is selected according to the microwave signal input power, and the impedance automatic matching circuit performs impedance matching to maximize efficiency. According to the strength of the microwave signal, the power selector selects the battery mode or the passive mode.

[0063] In order to better reduce power consumption, the external sensor module includes a chopper amplifier, a multiplexer, a programmable gain amplifier, and a successive approximation register AD converter. The chopper amplifier is used to boost the external signal while suppressing 1 / f noise and offset voltage; the multiplexer is used to receive multiple external sensor signals; the programmable gain amplifier is used to adjust the signal amplitude provided to the AD converter to provide a suitable input range; the successive approximation register AD converter is used to achieve a medium conversion rate and low power consumption; the entire external sensor module is used to receive external instructions to put the system into sleep, wake-up, hold and other states.

[0064] The protection module adopts an RF limiter to limit abnormal high input power and protect internal devices.

[0065] The temperature measurement module adopts SiC Schottky diode. Compared with ordinary pn junction diodes, SiC Schottky diodes have the characteristics of high temperature resistance, high voltage and high frequency; in the range of 300K-400K, it has significant temperature sensitivity.

[0066] Embodiment 2

[0067] This embodiment uses a constant temperature and humidity chamber to simulate a closed space environment, and uses the passive wireless temperature sensor described in Example 1 to collect temperature. The collection process and results are as follows:

[0068] The radio frequency energy collection module, protection module, power management module, modulation and demodulation module, data management module, temperature measurement module, external sensor module, wireless transmission module and auxiliary power supply of the present invention are arranged in a constant temperature and humidity chamber. The interior of the constant temperature and humidity chamber is a closed environment. The temperature change range of the constant temperature and humidity chamber is set to 45-100°C, the change time is 15min, and the humidity is set to 45%. The wireless energy transmission module is arranged 60CM away from the constant temperature and humidity chamber, and the external receiving module is arranged 10M away from the constant temperature and humidity chamber. The temperature in the constant temperature and humidity chamber is increased from 40 degrees Celsius to 100 degrees Celsius. The test time is 15 minutes. The measured temperature data are shown in Table 1, and the measured temperature change trend is shown in the attached figure. Fig.10 As shown;

[0069] Table 1: Data collected by the passive wireless temperature sensor in the constant temperature and humidity chamber

[0070] Time / min 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Temperature / ℃ 45 50 55 59 64 68 70 76 81 84 88 91 94 97

[0071] The actual temperature and time variation data in the constant temperature and humidity chamber returned by the temperature sensing line in the constant temperature and humidity chamber are shown in Table 2. The temperature variation trend is as follows: Fig.11 As shown;

[0072] Table 2: Actual temperature data in constant temperature and humidity chamber

[0073] Time / min 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Temperature / ℃ 45 50 55 61 66 70 75 79 85 90 92 95 97 99

[0074] It can be seen from Table 1 and Table 2 that in this embodiment, the temperature measurement results measured by the passive wireless temperature sensor provided by the present invention are consistent with the actual temperature change trend, which solves the difficulty of wiring in a closed environment and reflects the application value of the passive wireless sensor.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A passive wireless temperature sensor, characterized in that: It includes a receiving antenna, a radio frequency energy collection module, a protection module, a power management module, a modulation and demodulation module, a data management module, a temperature measurement module, an external sensor module, a wireless transmission module, a transmitting antenna, an auxiliary power supply, a wireless energy transmission module, and an external receiving module; The transmitting antenna includes a signal transmitting antenna of a wireless transmitting module and a transmitting antenna of a wireless energy transmitting module; the receiving antenna includes a signal receiving antenna of an external receiving module and a receiving antenna of a radio frequency energy collection module; The transmitting antenna of the wireless energy transmitting module is a microwave transmitting antenna, and the receiving antenna of the radio frequency energy collection module is a microwave receiving antenna; The output end of the microwave receiving antenna is connected to the input end of the radio frequency energy collection module; the output end of the radio frequency energy collection module is connected to the protection module and the first input end of the power management module; the output end of the protection module is connected to the input end of the modulation and demodulation module; the output end of the power management module is connected to the input end of the temperature measurement module and one end of the enable switch; the output end of the modulation and demodulation module is connected to the first input end of the data management module; the output end of the data management module is connected to the second input end of the power management module; the output end of the temperature measurement module is connected to the first input end of the wireless transmission module; the output end of the external sensor module is connected to the second input end of the data management module and the enable end of the enable switch; the second input end of the wireless transmission module is connected to the end of the enable switch that is not connected to the output end of the power management module; the signal transmission antenna is connected to the output end of the wireless transmission module; the auxiliary power supply is connected to the power management module; The radio frequency energy collection module, protection module, power management module, modulation and demodulation module, data management module, temperature measurement module, external sensor module, wireless transmission module, and auxiliary power supply are arranged in the environment to be tested; the wireless energy transmission module and external receiving module are arranged away from the environment to be tested; The temperature measurement module includes a Schottky diode temperature sampling circuit and an AD conversion circuit; the Schottky diode temperature sampling circuit collects the temperature in the environment to be measured; the AD conversion circuit converts the analog voltage signal into a digital signal and transmits it to the wireless transmission module; The Schottky diode temperature sampling circuit comprises a first Schottky diode and a second Schottky diode, a first operational amplifier, a second operational amplifier, a MOS tube M1 and a MOS tube M2, and a resistor R1 connected in series with the second Schottky diode. The anode of the first Schottky diode and the drain of the MOS tube M1 are connected to an input end of the first operational amplifier. The other input end of the first operational amplifier is respectively connected to the second end of the resistor R1, the drain of the MOS tube M2, and an input end of the second operational amplifier. The first end of the resistor R1 is connected to the anode of the second Schottky diode; the cathode of the first Schottky diode and the cathode of the second Schottky diode are grounded; the output voltage of the first operational amplifier is V 2. The output end of the first operational amplifier is connected to the gate of the MOS tube M1 and the MOS tube M2; the output voltage of the second operational amplifier is V 1. The output end of the second operational amplifier is connected to the gate of the third MOS tube, the source of the third MOS tube is connected to the voltage VDD, the output end of the second operational amplifier is connected to the drain of the third MOS tube, the other input end of the second operational amplifier, and one end of the second resistor through a capacitor, and the other end of the second resistor is grounded. The current of the drain of the MOS tube M2 of the temperature measurement module is a variable current. I ptat , the drain current of MOS tube M1 is a reference current I 1; The source of MOS tube M1 and the source of MOS tube M2 are connected to voltage VDD, and the voltage difference between the first Schottky diode and the second Schottky diode generates a PTAT voltage analog quantity, and the output current I ptat The calculation formula of size is formula (1): （1） in k is the Boltzmann constant, T is the temperature, N is the junction area ratio of the second Schottky diode to the first Schottky diode, q is the electron charge, R is the resistance value of resistor R1; the first Schottky diode and the second Schottky diode are respectively I D Under this condition, a voltage drop is generated across the first Schottky diode and the second Schottky diode. V D , the calculation formula of its size is formula (2): （2） in, R S is the equivalent resistance corresponding to the first Schottky diode and the second Schottky diode, I S is the saturation current corresponding to the first Schottky diode and the second Schottky diode.

2. A passive wireless temperature sensor according to claim 1, characterized in that: The wireless energy transmitting module includes a microwave generator, a first capacitor, a second capacitor, a transistor, and a microwave transmitting antenna; the microwave generator is connected to the base of the transistor through the first capacitor, the collector of the transistor is connected in series with one end of the microwave transmitting antenna through the second capacitor, and the other end of the microwave transmitting antenna is grounded to the emitter of the transistor and the negative pole of the microwave generator.

3. A passive wireless temperature sensor according to claim 1, characterized in that: The radio frequency energy collection module includes a microwave receiving antenna, an automatic impedance matching circuit, and an adaptive rectification circuit; the microwave receiving antenna converts electromagnetic waves in space into alternating current through the principle of electromagnetic induction, and the alternating current is rectified and changed by the adaptive rectification circuit to output direct current to provide a direct current voltage for the circuit in the environment to be tested; The adaptive rectifier circuit adjusts the rectifier circuit level according to the power strength of the external RF signal, and the automatic impedance matching circuit performs impedance matching according to the change of the level; the RF energy collection module is used to capture electromagnetic waves in space and convert them into electrical energy to provide energy for the circuits in the environment to be tested.

4. A passive wireless temperature sensor according to claim 1, characterized in that: The input of the wireless transmitting module is the temperature square wave data output by the AD conversion circuit of the temperature measuring module, and the signal transmitting antenna of the wireless transmitting module transmits the collected temperature square wave data to the external receiving module.

5. A passive wireless temperature sensor according to claim 1, characterized in that: The anode metal material of the first Schottky diode and the second Schottky diode is any one of aluminum, gold, molybdenum, nickel and titanium, and the semiconductor material is any one of Si, GaN, diamond and SiC.

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