Low power wireless sensor circuits, sensors and sensor networks

Abstract

The present invention provides a low-power wireless sensor circuit, a sensor and a sensor network, which relate to the field of sensor technology. The low-power wireless sensor circuit receives an FM control signal through a receiving antenna, converts the FM control signal into an AM control voltage through a frequency amplitude converter, and then converts the AM control voltage into a state control level through a state control module to control the working state of the low-power wireless sensor. The low-power wireless sensor circuit provided by the present invention not only realizes the control of the working state of the low-power wireless sensor, but also greatly reduces the circuit power consumption, meeting the power consumption requirements of the self-powered wireless sensor network.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a low-power wireless sensor circuit, a sensor and a sensor network. Background Art

[0002] Since the energy of a self-powered wireless sensor network comes from the environment and is very weak, the power consumption of the wireless sensor nodes is very strict, for example, less than 1mW.

[0003] In order to make the sensor nodes and the sink nodes communicate with each other, the existing wireless sensors need to add receivers to the sensor nodes. However, since the sink nodes and sensor nodes do not use the same clock, they cannot be synchronized, which requires the receiver to be always on. However, since the energy consumption of traditional FM receivers (current is mA level) is high, if the receiver is always on, it will generate high power consumption, which will make the self-powered wireless sensor network unbearable. Summary of the invention

[0004] The present invention provides a low-power wireless sensor circuit, a sensor and a sensor network to solve the above problems existing in the prior art.

[0005] The present invention provides a low-power wireless sensor circuit, comprising: a power supply circuit, a sensor, a voltage-controlled oscillator circuit, a transmitting antenna, a receiving antenna, a frequency-amplitude converter, and a state control module;

[0006] The power supply circuit is used to provide a working voltage;

[0007] The power supply end of the sensor is connected to the power supply circuit, and the output end of the sensor is connected to the first input end of the voltage-controlled oscillator circuit; the sensor is used to collect environmental parameters and convert the environmental parameters into parameter voltages, which are output through the output end;

[0008] The power supply end of the voltage-controlled oscillator circuit is connected to the power supply circuit, and the output end of the voltage-controlled oscillator circuit is connected to the transmitting antenna; the voltage-controlled oscillator circuit is used to convert the parameter voltage into an oscillation frequency signal and output it through the output end;

[0009] The transmitting antenna is used to transmit the oscillation frequency signal;

[0010] The receiving antenna is used to receive FM control signals;

[0011] The input end of the frequency amplitude converter is connected to the receiving antenna, and the output end of the frequency amplitude converter is connected to the input end of the state control module; the frequency amplitude converter is used to convert the FM control signal into an AM control voltage and output it through the output end;

[0012] The power supply end of the state control module is connected to the power supply circuit, and the output end of the state control module is connected to the second input end of the voltage-controlled oscillator circuit; the state control module is used to convert the AM control voltage into a state control level and output it through the output end; the state control level is used to control the working state of the low-power wireless sensor.

[0013] According to a low-power wireless sensor circuit provided by the present invention, the frequency-amplitude converter includes a transformer and a capacitor;

[0014] The primary coil of the transformer is connected to the receiving antenna, and the FM control signal is input from the primary coil of the transformer;

[0015] The secondary coil inductance of the transformer is connected in parallel with the capacitor to output an AM control voltage.

[0016] According to a low-power wireless sensor circuit provided by the present invention, the state control module includes at least one cascaded comparator;

[0017] The input end of each comparator is connected to the output end of the frequency amplitude converter, the power supply end of each comparator is connected to the power supply circuit, and the output end of each comparator is connected to the second input end of the voltage-controlled oscillator circuit.

[0018] According to a low-power wireless sensor circuit provided by the present invention, the transmitting antenna and the receiving antenna form a pair of orthogonal polarization antennas.

[0019] According to a low-power wireless sensor circuit provided by the present invention, the polarization direction of the transmitting antenna is vertical linear polarization, and the polarization direction of the receiving antenna is horizontal linear polarization;

[0020] Or, the polarization direction of the transmitting antenna is horizontal linear polarization, and the polarization direction of the receiving antenna is vertical linear polarization.

[0021] According to a low-power wireless sensor circuit provided by the present invention, the polarization direction of the transmitting antenna is left-hand circular polarization, and the polarization direction of the receiving antenna is right-hand circular polarization;

[0022] Or, the polarization direction of the transmitting antenna is right-hand circular polarization, and the polarization direction of the receiving antenna is left-hand circular polarization.

[0023] According to a low-power wireless sensor circuit provided by the present invention, the operating current of the state control module is less than 1 mA.

[0024] According to a low-power wireless sensor circuit provided by the present invention, the power supply circuit includes a thermoelectric generator TEG, an energy management circuit and an energy storage unit.

[0025] The present invention also provides a low-power wireless sensor, comprising any one of the low-power wireless sensor circuits described above.

[0026] The low-power consumption wireless sensor network of the present invention comprises the low-power consumption wireless sensor mentioned above.

[0027] The low-power wireless sensor circuit provided by the present invention receives an FM control signal through a receiving antenna, converts the FM control signal into an AM control voltage through a frequency amplitude converter, and then converts the AM control voltage into a state control level through a state control module, which not only realizes the control of the working state of the low-power wireless sensor, but also greatly reduces the power consumption of the circuit, meeting the power consumption requirements of the self-powered wireless sensor network. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 The present invention provides a schematic diagram of a low-power wireless sensor node structure in the prior art.

[0030] Figure 2 The present invention provides a low-power wireless sensor circuit schematic diagram.

[0031] Figure 3 It is a structural schematic diagram of the voltage-controlled oscillator circuit provided by the present invention.

[0032] Figure 4 It is a schematic diagram of frequency amplitude conversion provided by the present invention.

[0033] Figure 5 It is a principle diagram of the state control module provided by the present invention.

[0034] Figure 6 Schematic diagram of two cascade comparators provided by the present invention.

[0035] Figure 7 It is a schematic diagram of a voltage-controlled oscillator circuit provided by the present invention when the number of cascaded comparators is two.

[0036] Figure 8 It is a schematic diagram of a low-power wireless sensor circuit provided by the present invention when the number of cascaded comparators is two.

[0037] Fig. 9 Schematic diagram of three cascade comparators provided by the present invention.

[0038] Fig.10 It is a schematic diagram of frequency amplitude conversion of a variable resonant frequency provided by the present invention when the number of cascaded comparators is three.

[0039] Fig.11 It is a schematic diagram of a low-power wireless sensor circuit provided by the present invention when the number of cascaded comparators is three. DETAILED DESCRIPTION

[0040] Since the energy of a self-powered wireless sensor network comes from the environment and is very weak, the power consumption of the wireless sensor nodes is very strict, for example, less than 1mW.

[0041] Figure 1 It is a schematic diagram of a low-power wireless sensor node structure in the prior art, such as Figure 1 As shown in the figure, in order to further reduce the system power consumption, an existing low-power wireless sensor has omitted ADC sampling, MCU and wireless transceiver in design, and only uses the analog signal of the temperature sensor to control the VCO (voltage-controlled oscillator circuit) to obtain the relationship between temperature and frequency. The VCO outputs through the buffer and transmits the FM frequency modulation signal through the antenna.

[0042] However, this structure has a disadvantage, that is, the wireless sensor nodes can only send signals, but cannot receive instructions from the sink node, so the wireless sensor nodes cannot be controlled. In order to enable the sensor nodes and the sink node to communicate with each other, a receiver needs to be added to the sensor node, but since the sink node and the sensor node do not have the same clock, they cannot be synchronized, which requires the receiver to be always on.

[0043] However, the energy consumption of traditional FM receivers (current is at the mA level) is unaffordable in self-powered wireless sensor nodes. Therefore, the present invention proposes a low-power (current is at the uA level) frequency-to-amplitude conversion receiving method, which compares and judges the converted amplitude, greatly reduces the receiving current, and thus reduces power consumption.

[0044] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Combine the following Figures 2 to 11 The invention describes a low-power wireless sensor circuit, a sensor and a sensor network.

[0046] Figure 2 Schematic diagram of a low-power wireless sensor circuit provided by the present invention. Figure 2 As shown, the low-power wireless sensor circuit provided by the present invention at least includes: a power supply circuit, a sensor, a voltage-controlled oscillator circuit, a transmitting antenna, a receiving antenna, a frequency-amplitude converter, and a state control module.

[0047] The power supply circuit is used to provide a working voltage;

[0048] The power supply end of the sensor is connected to the power supply circuit, and the output end of the sensor is connected to the first input end of the voltage-controlled oscillator circuit; the sensor is used to collect environmental parameters and convert the environmental parameters into parameter voltages, which are output through the output end;

[0049] The power supply end of the voltage-controlled oscillator circuit is connected to the power supply circuit, and the output end of the voltage-controlled oscillator circuit is connected to the transmitting antenna; the voltage-controlled oscillator circuit is used to convert the parameter voltage into an oscillation frequency signal and output it through the output end;

[0050] The transmitting antenna is used to transmit the oscillation frequency signal;

[0051] The receiving antenna is used to receive FM control signals;

[0052] The input end of the frequency amplitude converter is connected to the receiving antenna, and the output end of the frequency amplitude converter is connected to the input end of the state control module; the frequency amplitude converter is used to convert the FM control signal into an AM control voltage and output it through the output end;

[0053] The power supply end of the state control module is connected to the power supply circuit, and the output end of the state control module is connected to the second input end of the voltage-controlled oscillator circuit; the state control module is used to convert the AM control voltage into a state control level and output it through the output end; the state control level is used to control the working state of the low-power wireless sensor.

[0054] Specifically, the low-power wireless sensor circuit provided by the present invention at least includes: a power supply circuit, a sensor, a voltage-controlled oscillator circuit, a transmitting antenna, a receiving antenna, a frequency-amplitude converter, and a state control module.

[0055] The power supply circuit is used to provide working voltage;

[0056] The power supply end of the sensor is connected to the power supply circuit, and the output end of the sensor is connected to the first input end of the voltage-controlled oscillator circuit; the sensor is used to collect environmental parameters and convert the environmental parameters into parameter voltages, which are output through the output end;

[0057] The power supply end of the voltage-controlled oscillator circuit is connected to the power supply circuit, and the output end of the voltage-controlled oscillator circuit is connected to the transmitting antenna; the voltage-controlled oscillator circuit is used to convert the parameter voltage into an oscillation frequency signal and output it through the output end;

[0058] The transmitting antenna is used to transmit the oscillation frequency signal;

[0059] The receiving antenna is used to receive FM control signals;

[0060] The input end of the frequency amplitude converter is connected to the receiving antenna, and the output end of the frequency amplitude converter is connected to the input end of the state control module; the frequency amplitude converter is used to convert the FM control signal into an AM control voltage and output it through the output end;

[0061] The power supply end of the state control module is connected to the power supply circuit, and the output end of the state control module is connected to the second input end of the voltage-controlled oscillator circuit; the state control module is used to convert the AM control voltage into a state control level and output it through the output end; the state control level is used to control the working state of the low-power wireless sensor.

[0062] Optionally, the power supply circuit includes a thermoelectric generator TEG, an energy management circuit and an energy storage unit.

[0063] Specifically, the power supply circuit includes a thermoelectric generator TEG, an energy management circuit and an energy storage unit.

[0064] Thermoelectric generator TEG is a power generation device that uses the Seebeck effect to directly convert thermal energy into electrical energy. After the thermoelectric generator generates electrical energy, the energy management circuit collects the electrical energy to form an operating voltage, and can also store excess electrical energy in the energy storage unit.

[0065] In this embodiment, the power supply end of the sensor is connected to the power supply circuit, and the output end of the sensor is connected to the first input end of the voltage-controlled oscillator circuit; the sensor is used to collect environmental parameters and convert the environmental parameters into parameter voltages, which are output through the output end.

[0066] In this embodiment, there are many options for the sensor, such as a pressure sensor, a temperature sensor, and a photoelectric sensor, etc. The following description will take the temperature sensor as an example.

[0067] The temperature sensor collects environmental parameters through the ambient temperature, and converts the environmental parameters into parameter voltages which are input into the voltage-controlled oscillator circuit to control the oscillation of the voltage-controlled oscillator circuit.

[0068] Figure 3 is a schematic diagram of the structure of a voltage-controlled oscillator circuit provided by an embodiment of the present invention, such as Figure 3In this embodiment, the voltage-controlled oscillator circuit includes: an inductor-capacitor voltage-controlled oscillator and a bias voltage generation network, and the inductor-capacitor voltage-controlled oscillator includes an active network and a passive oscillation network. The bias voltage generation network is used to generate a bias voltage, and the bias voltage is input to the active network to ensure that the passive oscillation network outputs a voltage and generates oscillation according to the temperature output by the sensor.

[0069] Among them, the LC voltage-controlled oscillator refers to an oscillation circuit (VCO) whose output frequency corresponds to the input control voltage. The frequency of the oscillator VCO is a function of the input signal voltage. The working state of the oscillator or the component parameters of the oscillation circuit are controlled by the input control voltage, which can constitute a voltage-controlled oscillator.

[0070] A bias voltage is generated through a bias voltage generating network; the bias voltage is input into an active network to ensure that the passive oscillation network starts oscillation, and the bias voltage is reduced after starting oscillation to maintain the oscillation of the passive oscillation network; the temperature output voltage is received through the passive oscillation network for oscillation to obtain a converted oscillation frequency signal.

[0071] Among them, the bias voltage gradually decreases after the passive oscillation network starts to oscillate; when the LC voltage-controlled oscillator VCO is first powered on, in order to start the LC voltage-controlled oscillator VCO, the bias voltage Vbias cannot be too low, otherwise the LC voltage-controlled oscillator VCO will not oscillate due to too small current. After the LC voltage-controlled oscillator VCO oscillates, the bias voltage Vbias can be reduced, that is, a small current is used to maintain the LC voltage-controlled oscillator VCO oscillation.

[0072] The bias voltage generating network comprises: a double-converted single amplifier, an amplitude detector and a comparator; the double-converted single amplifier is connected to the differential output end of the LC voltage-controlled oscillator; the amplitude detector is respectively connected to the double-converted single amplifier and the comparator, and the comparator is connected to the active network;

[0073] Converting the differential output signal of the LC voltage-controlled oscillator into a single-ended signal through the dual-to-single amplifier;

[0074] The single-ended signal is converted into a level voltage value by the amplitude detector, wherein the amplitude of the single-ended signal and the output level voltage value are in a positive relationship;

[0075] The comparator compares the level voltage value of the amplitude detector with the reference voltage value and outputs a bias voltage.

[0076] The passive oscillation network comprises: a first inductor and a second inductor connected in series, a first varactor diode and a second varactor diode;

[0077] The positive end of the first varactor diode and the positive end of the second varactor diode are both connected to the temperature sensor to receive the temperature output voltage, change the capacitance of the first varactor diode and the second varactor diode to oscillate, and obtain a converted oscillation frequency signal;

[0078] The first inductor is connected to the negative end of the first varactor diode, and the second inductor is connected to the negative end of the second varactor diode to provide a bias voltage.

[0079] The active network includes: a first triode and a second triode, a first capacitor C1 and a second capacitor C2;

[0080] A first capacitor C1 is connected between the drain of the first transistor and the gate of the second transistor, and a second capacitor C2 is connected between the gate of the first transistor and the drain of the second transistor;

[0081] The gate of the first transistor is connected to the output end of the comparator through a first bias resistor, and the gate of the second transistor is connected to the output end of the comparator through a second bias resistor, so as to respectively receive the bias voltage to ensure that the passive oscillation network starts oscillation, and the bias voltage is reduced after the oscillation starts to maintain the oscillation of the passive oscillation network;

[0082] The first inductor is connected to the drain of the first transistor, and the second inductor is connected to the drain of the second transistor to provide an operating voltage;

[0083] The drains of the first transistor and the second transistor are grounded.

[0084] The temperature sensor is connected to the positive end of the first varactor diode and the positive end of the second varactor diode respectively through a third bias resistor.

[0085] Specifically, the specific structure of the voltage controlled oscillator circuit LC VCO in this embodiment is as follows: Figure 3 As shown, the voltage controlled oscillator circuit LC VCO includes: an inductor capacitor voltage controlled oscillator VCO and a bias voltage generating network.

[0086] The bias voltage generating network includes: a dual-converter single amplifier O, an amplitude detector E1 and a comparator ADC; the dual-converter single amplifier O is connected to the differential output end of the inductor-capacitor voltage-controlled oscillator VCO; the amplitude detector is respectively connected to the dual-converter single amplifier O and the comparator ADC, and the comparator ADC is connected to the active network.

[0087] Specifically, the differential output signal Vop / Von of the LC voltage controlled oscillator VCO is converted into a single-ended signal Vo=Vop-Von through a double-to-single amplifier O;

[0088] The single-ended signal Vo is converted into a level voltage value Vout by an amplitude detector E1, wherein the amplitude of the single-ended signal Vo and the output level voltage value Vout are in a positive relationship;

[0089] The comparator ADC compares the level voltage value Vout of the amplitude detector E1 with the reference voltage value Vref, and outputs a bias voltage, wherein the reference voltage value Vref is half of the maximum voltage value output by the amplitude detector E1.

[0090] In order to further reduce the power consumption of the LC voltage controlled oscillator VCO, this embodiment uses an amplitude detector E1 to detect the output amplitude of the LC voltage controlled oscillator VCO, and converts it into a bias voltage Vbias of the VCO through a comparator ADC, that is, the larger the amplitude of the LC voltage controlled oscillator VCO, the smaller the bias voltage Vbias. The reduction of the bias voltage Vbias will reduce the current of the LC voltage controlled oscillator VCO, thereby reducing power consumption.

[0091] Continue to see Figure 3 , the inductor-capacitor voltage-controlled oscillator (VCO) includes an active network and a passive oscillation network.

[0092] The passive oscillator network includes:

[0093] A first inductor L1 and a second inductor L2 connected in series;

[0094] A first varactor diode D1 and a second varactor diode D2, wherein the positive end of the first varactor diode D1 and the positive end of the second varactor diode D2 are both connected to a temperature sensor to receive a temperature output voltage Vctrl output by the temperature sensor, and the capacitance of the first varactor diode D1 and the second varactor diode D2 are changed to oscillate, thereby obtaining an oscillation frequency signal after conversion;

[0095] The first inductor L1 is connected to the negative end of the first varactor diode D1 , and the second inductor L2 is connected to the negative end of the second varactor diode D2 to provide a bias voltage.

[0096] In this embodiment, the passive resonant network LC is composed of M1 and M2 to form an active negative resistance network to provide energy for oscillation, and the frequency is .

[0097] The oscillation frequency is changed by changing the capacitance of the varactor diode through Vctrl. Vctrl is the temperature output voltage from the temperature sensor, so that the tested temperature can be converted into the oscillation frequency of the inductor capacitor voltage-controlled oscillator VCO. It is transmitted through FM wireless and used for data analysis at the aggregation node to complete the temperature measurement of the temperature sensor.

[0098] When the LC VCO is first powered on, in order to start the LC VCO, the bias voltage Vbias cannot be too low, otherwise the LC VCO will not oscillate due to too small current. After the LC VCO oscillates, the bias voltage Vbias can be reduced, that is, a small current is used to maintain the LC VCO oscillation.

[0099] In order to make the crystal start and maintain oscillation, the LC voltage-controlled oscillator VCO of this embodiment requires an active network to compensate for the crystal loss. Specifically, the active network includes:

[0100] A first transistor M1 and a second transistor M2;

[0101] The first capacitor C1 and the second capacitor C2 are connected between the drain of the first transistor M1 and the gate of the second transistor M2, and the second capacitor C2 is connected between the gate of the first transistor M1 and the drain of the second transistor M2.

[0102] The gate of the first transistor M1 is connected to the output end of the comparator ADC through the first bias resistor R1, and the gate of the second transistor M2 is connected to the output end of the comparator ADC through the second bias resistor R2, so as to respectively receive the bias voltage Vbias to ensure that the passive oscillation network starts oscillation, and the bias voltage Vbias decreases after the oscillation starts to maintain the oscillation of the passive oscillation network;

[0103] The first inductor L1 is connected to the drain of the first transistor M1, and the second inductor L2 is connected to the drain of the second transistor M2 to provide an operating voltage;

[0104] The drains of the first transistor M1 and the second transistor M2 are grounded.

[0105] For NMOS tube threshold voltage Vthn, it is as follows (1):

[0106]

[0107] Among them, Vth0 is the threshold voltage of the MOS tube when Vsb=0, Vsb is the voltage between the source and the base, is the body effect coefficient, It is a semiconductor parameter. Let the substrate voltage Vbody be greater than 0, that is, the source voltage Vb>0. If the base voltage Vs=0, then the voltage Vsb between the source and the base is less than zero. From the formula, we can see that the threshold voltage Vthn is reduced.

[0108] The drain current Id is positively correlated with (VGS-Vthn). If the drain current Id remains unchanged and the threshold voltage Vthn decreases, the turn-on voltage VGS can be reduced, that is, VDD can be further reduced.

[0109] The active network of this embodiment presents a negative impedance. The first transistor M1 and the second transistor M2 can both be NMOS transistors, and the mutual coupling pair they form constitutes an active negative resistance. LC forms a passive resonant network, the series inductor L=L1+L2, L1=L2, the first variable capacitance diode D1 and the second variable capacitance diode D2 provide capacitance, and the equivalent capacitance of the two in series is recorded as C. This capacitance C is variable with the temperature output voltage Vctrl, then the frequency is .

[0110] The first inductor L1 and the second inductor L2 provide power supply VDD for the first transistor M1 and the second transistor M2 respectively, and provide bias voltage for the negative ends of the first varactor diode D1 and the second varactor diode D2; the temperature output voltage Vctrl provides control voltage to the positive ends of the first varactor diode D1 and the second varactor diode D2 through the third bias resistor R3.

[0111] In addition, the first capacitor C1 and the second capacitor C2 are AC coupling capacitors between the gate and drain of the first transistor M1 and the second transistor M2, which provide a mutual coupling path in AC and isolate VDD in DC because the DC bias of the first transistor M1 and the second transistor M2 is provided by the bias voltage Vbias through the first bias resistor R1 and the second bias resistor R2.

[0112] Vbody is the substrate voltage of M1 and M2. Generally, the substrate voltage is 0. Here, the substrate voltage Vbody is made greater than 0 in order to reduce the threshold Vth of M1 and M2. This can reduce the VDD voltage and the current of M1 and M2.

[0113] Optionally, the transmitting antenna and the receiving antenna form a pair of orthogonal polarization antennas.

[0114] Optionally, the polarization direction of the transmitting antenna is vertical linear polarization, and the polarization direction of the receiving antenna is horizontal linear polarization;

[0115] Or, the polarization direction of the transmitting antenna is horizontal linear polarization, and the polarization direction of the receiving antenna is vertical linear polarization.

[0116] Optionally, the polarization direction of the transmitting antenna is left-hand circular polarization, and the polarization direction of the receiving antenna is right-hand circular polarization;

[0117] Or, the polarization direction of the transmitting antenna is right-hand circular polarization, and the polarization direction of the receiving antenna is left-hand circular polarization.

[0118] Specifically, the transmitting antenna and the receiving antenna form a pair of orthogonal polarization antennas.

[0119] Specifically, the polarization direction of the transmitting antenna is vertical linear polarization, and the polarization direction of the receiving antenna is horizontal linear polarization;

[0120] Or, the polarization direction of the transmitting antenna is horizontal linear polarization, and the polarization direction of the receiving antenna is vertical linear polarization.

[0121] Specifically, the polarization direction of the transmitting antenna is left-hand circular polarization, and the polarization direction of the receiving antenna is right-hand circular polarization;

[0122] Or, the polarization direction of the transmitting antenna is right-hand circular polarization, and the polarization direction of the receiving antenna is left-hand circular polarization.

[0123] In this embodiment, since the aggregation nodes do not use the same clock to communicate with each other and cannot be synchronized, the sensor nodes use two antennas for sending and receiving (TX antenna / RX antenna). In order to eliminate the mutual interference between the transmitting and receiving antennas, the present invention uses orthogonal polarized transmitting and receiving antennas, for example, the TX antenna / RX antenna is vertical linear polarization / horizontal linear polarization, or the TX antenna / RX antenna is left-hand circular polarization / right-hand circular polarization.

[0124] Optionally, the frequency amplitude converter includes a transformer and a capacitor;

[0125] The primary coil of the transformer is connected to the receiving antenna, and the FM control signal is input from the primary coil of the transformer;

[0126] The secondary coil inductance of the transformer is connected in parallel with the capacitor to output an AM control voltage.

[0127] Specifically, Figure 4 The present invention provides a schematic diagram of frequency-amplitude conversion, wherein (a) is a schematic diagram of the principle of frequency-to-amplitude conversion, and (b) is a schematic diagram of the conversion curve between input FM wave frequency and output amplitude.

[0128] The frequency amplitude converter includes a transformer and a capacitor C;

[0129] like Figure 4 As shown in (a), a first end of the primary coil of the transformer is connected to the receiving antenna, a second end is grounded, and the FM control signal is input from the primary coil of the transformer;

[0130] The secondary coil inductance of the transformer is connected in parallel with the capacitor C to output an AM control voltage, wherein a first end of the capacitor C is connected to an input end of the state control module, and a second end is grounded.

[0131] The transformer secondary coil is connected in parallel with capacitor C, and the FM wave is input from the transformer primary coil. Due to the resonance between the secondary coil inductance and capacitor C, the conversion curve between the FM wave frequency and the output amplitude is obtained as shown in the figure below: Figure 4As shown in (b) in the figure. f0 is the resonant frequency of the secondary coil inductance and capacitor C, and f1 is any operating frequency. It can be seen from the figure that the curve is bandpass, and f0 has the largest output amplitude. The larger the frequency difference between f1 and f0, the smaller the output amplitude corresponding to f1.

[0132] Optionally, the state control module includes at least one cascaded comparator;

[0133] The input end of each comparator is connected to the output end of the frequency amplitude converter, the power supply end of each comparator is connected to the power supply circuit, and the output end of each comparator is connected to the second input end of the voltage-controlled oscillator circuit.

[0134] Specifically, Figure 5 It is the principle diagram of the state control module provided by the present invention, such as Figure 5 shown.

[0135] The state control module includes at least one cascaded comparator;

[0136] The input end of each comparator is connected to the output end of the frequency amplitude converter, the power supply end of each comparator is connected to the power supply circuit, and the output end of each comparator is connected to the second input end of the voltage controlled oscillator circuit.

[0137] In this embodiment, the amplitude of different FM frequency conversions is determined by a comparator. Assume that the wireless sensor circuit supports FM1, ..., FM n These n FM signals are converted into frequency signals v1, ..., v by the frequency amplitude converter. n These n amplitude signals satisfy the monotonic v1<…<v n When there is no input signal in the receiving circuit, it is equivalent to the input signal frequency being 0 (dc). Figure 4 From (b) in the figure, we can see that dc is further away from f0, so the output amplitude is smaller, set to v DC v0 is the output amplitude corresponding to the resonant frequency f0, then the relationship between the comparator level and amplitude is set to v DC <vref1<v1<…<vrefn<v n ≤v0.

[0138] Optionally, the operating current of the state control module is less than 1 mA.

[0139] Specifically, since the frequency amplitude converter does not require current, the current of the state control module is less than 1mA, that is, at the uA level. Therefore, compared with traditional solutions, the low-power wireless sensor circuit provided by the present invention increases the current very little and is very suitable for use in self-powered wireless sensor networks to achieve control of wireless sensor nodes.

[0140] In this embodiment, the sensor converts the temperature into frequency and sends it out through the transmitting antenna. The receiving antenna converts the command state of the aggregation node into amplitude to control the sensor node. The sensor node receives the command FM signal sent by the aggregation node, and different frequencies represent different commands. After the frequency is converted to amplitude, the converted amplitude (in) is compared and judged, and the control signal (c1, ..., cn) is output. Among them, the highest bit cn of the control signal is used to control whether the VCO works normally.

[0141] In some embodiments, when the state control module includes two cascaded comparators, Figure 6 is a schematic diagram of two cascaded comparators provided by an embodiment of the present invention, such as Figure 6 shown.

[0142] use Figure 6 The two comparators in the circuit are connected to a VCO with adjustable center frequency of the frequency band to form a voltage controlled oscillator circuit. Figure 7 is a schematic diagram of a voltage-controlled oscillator circuit provided by an embodiment of the present invention when the number of cascaded comparators is two, such as Figure 7 shown.

[0143] Figure 8 is a schematic diagram of a low-power wireless sensor circuit provided by an embodiment of the present invention when the number of cascaded comparators is two, such as Figure 8 The state control module includes two cascaded comparators, and the output control signals are c1 and c2, where c1 is connected to the Vctrl control terminal of the VCO, Vctrl is the temperature output voltage from the temperature sensor, and can convert the tested temperature into the oscillation frequency of the inductor capacitor voltage-controlled oscillator VCO, and c2 (the output signal includes 0 or 1) is connected to the pd terminal of the VCO. When the pd signal is 1, the VCO is powered off and does not work, and when the pd signal is 0, the VCO works normally.

[0144] When the number of cascaded comparators is two, refer to Figure 7 At this time, the switches T1 and T2 are controlled by Vctrl to select whether the third capacitor C3 and the fourth capacitor C4 are used, thereby changing the center frequency of the VCO frequency band.

[0145] In some embodiments, when the state control module includes three cascaded comparators, Fig. 9 is a schematic diagram of three cascaded comparators provided by an embodiment of the present invention, such as Fig. 9 shown.

[0146] use Fig. 9 The three comparators in the circuit are connected to a VCO with adjustable center frequency of the frequency band to form a voltage controlled oscillator circuit. Fig.101 is a schematic diagram of frequency-amplitude conversion of a variable resonant frequency provided by an embodiment of the present invention when the number of cascaded comparators is three, wherein (a) is a schematic diagram of the principle of frequency-to-amplitude conversion, and (b) is a schematic diagram of a conversion curve between input FM wave frequency and output amplitude, as shown in FIG. Fig.10 shown.

[0147] Fig.11 is a schematic diagram of a low-power wireless sensor circuit provided by an embodiment of the present invention when the number of cascaded comparators is three, such as Fig.11 The state control module includes three cascaded comparators, and the output control signals are c1, c2 and c3, among which c1 is connected to the Vctrl control terminal of the frequency amplitude converter of the variable resonant frequency, c2 is connected to the Vctrl control terminal of the VCO, Vctrl is the temperature output voltage from the temperature sensor, which can convert the tested temperature into the oscillation frequency of the inductor capacitor voltage controlled oscillator VCO, c3 (output signal includes 0 or 1) is connected to the pd terminal of the VCO, when the pd signal is 1, the VCO is powered off and does not work, when the pd signal is 0, the VCO works normally.

[0148] When the number of cascaded comparators is two, refer to Fig.10 In (a), based on the fifth capacitor C5, the switch T1 is controlled by Vctrl at this time to select whether to use the sixth capacitor C6, thereby changing the resonant frequency f0 of the frequency amplitude converter. The low-power wireless sensor circuit provided by the present invention receives the FM control signal through the receiving antenna, and converts the FM control signal into an AM control voltage through the frequency amplitude converter, and then converts the AM control voltage into a state control level through the state control module to control the working state of the low-power wireless sensor. Since the frequency amplitude converter does not require current, and the working current of the state control module is less than 1mA, the low-power wireless sensor circuit not only realizes the control of the working state of the wireless sensor, but also greatly reduces the circuit power consumption, meeting the power consumption requirements of the self-powered wireless sensor network.

[0149] Based on any of the above embodiments, in the low-power wireless sensor circuit provided by the present invention, there are two inputs to the receiving circuit, namely, one of two control FM signals from the sink node: FM1 and FM2.

[0150] FM 1 represents that the wireless sensor node continues to work normally, and FM 2 represents that the wireless sensor node turns off transmission. Assume that FM 2 is a sine wave with a frequency of f0, and FM 1 is a sine wave with a frequency that deviates greatly from f0. When the VCO pd signal is 1, the VCO is powered off and does not work. When the pd signal is 0, the VCO works normally.

[0151] The state control module in comes from the output of the receiving circuit. When the input is FM 2 signal, the output amplitude of the receiving circuit is v0. At this time, the comparator cn output is 1, and the VCO is powered off and does not work.

[0152] When the input is FM 1 signal, the output amplitude of the receiving circuit is less than v refn , the comparator cn output is 0, and the VCO works normally.

[0153] It can be seen that the low-power wireless sensor circuit provided by the present invention achieves the purpose of controlling the sensor node (for example, whether the VCO works or is powered off and does not work) by converging the FM signals (for example, FM1 and FM2) of the node.

[0154] An embodiment of the present invention further discloses a low-power wireless sensor, comprising the low-power wireless sensor circuit described in any one of the above embodiments.

[0155] The low-power wireless sensor provided by the present invention receives the FM control signal through the receiving antenna in the low-power wireless sensor circuit, converts the FM control signal into an AM control voltage through a frequency amplitude converter, and then converts the AM control voltage into a state control level through a state control module to control the working state of the low-power wireless sensor. Since the frequency amplitude converter does not require current and the working current of the state control module is at the uA level, the circuit power consumption of the low-power wireless sensor is greatly reduced during operation, meeting the power consumption requirements of the self-powered wireless sensor network.

[0156] The embodiment of the present invention further discloses a wireless sensor network, comprising a plurality of low-power wireless sensors as described above.

[0157] The low-power wireless sensor network provided by the present invention comprises a plurality of low-power wireless sensors as described above, which are connected through a convergence node, and receive FM control signals through a receiving antenna in a low-power wireless sensor circuit, and convert the FM control signals into AM control voltages through a frequency amplitude converter, and then convert the AM control voltages into state control levels through a state control module, so as to control the working state of the low-power wireless sensor. Since the frequency amplitude converter does not require current, and the working current of the state control module is at the uA level, the circuit power consumption of the low-power wireless sensor is greatly reduced during operation, thus meeting the power consumption requirements of the self-powered wireless sensor network.

[0158] It should also be noted that the terms "first", "second", etc. in the embodiments of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first" and "second" are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-power wireless sensor circuit, characterized in that: include: Power supply circuit, sensor, voltage-controlled oscillator circuit, transmitting antenna, receiving antenna, frequency amplitude converter, state control module; The power supply circuit is used to provide a working voltage; The power supply end of the sensor is connected to the power supply circuit, and the output end of the sensor is connected to the first input end of the voltage-controlled oscillator circuit; the sensor is used to collect environmental parameters and convert the environmental parameters into parameter voltages, which are output through the output end; The power supply end of the voltage-controlled oscillator circuit is connected to the power supply circuit, and the output end of the voltage-controlled oscillator circuit is connected to the transmitting antenna; the voltage-controlled oscillator circuit is used to convert the parameter voltage into an oscillation frequency signal and output it through the output end; The transmitting antenna is used to transmit the oscillation frequency signal; The receiving antenna is used to receive FM control signals; The input end of the frequency amplitude converter is connected to the receiving antenna, and the output end of the frequency amplitude converter is connected to the input end of the state control module; the frequency amplitude converter is used to convert the FM control signal into an AM control voltage and output it through the output end; The power supply end of the state control module is connected to the power supply circuit, and the output end of the state control module is connected to the second input end of the voltage-controlled oscillator circuit; the state control module is used to convert the AM control voltage into a state control level and output it through the output end; the state control level is used to control the working state of the low-power wireless sensor.

2. The low-power wireless sensor circuit according to claim 1, characterized in that: The frequency amplitude converter includes a transformer and a capacitor; The primary coil of the transformer is connected to the receiving antenna, and the FM control signal is input from the primary coil of the transformer; The secondary coil inductance of the transformer resonates with the capacitor to output an AM control voltage.

3. The low-power wireless sensor circuit according to claim 1, characterized in that: The state control module includes at least one cascaded comparator; The input end of each comparator is connected to the output end of the frequency amplitude converter, the power supply end of each comparator is connected to the power supply circuit, and the output end of each comparator is connected to the second input end of the voltage-controlled oscillator circuit.

4. The low-power wireless sensor circuit according to claim 1, characterized in that: The transmitting antenna and the receiving antenna form a pair of orthogonal polarization antennas.

5. The low-power wireless sensor circuit according to claim 4, characterized in that: The polarization direction of the transmitting antenna is vertical linear polarization, and the polarization direction of the receiving antenna is horizontal linear polarization; Or, the polarization direction of the transmitting antenna is horizontal linear polarization, and the polarization direction of the receiving antenna is vertical linear polarization.

6. The low-power wireless sensor circuit according to claim 4, characterized in that: The polarization direction of the transmitting antenna is left-hand circular polarization, and the polarization direction of the receiving antenna is right-hand circular polarization; Or, the polarization direction of the transmitting antenna is right-hand circular polarization, and the polarization direction of the receiving antenna is left-hand circular polarization.

7. The low-power wireless sensor circuit according to claim 1, characterized in that: The operating current of the state control module is less than 1 mA.

8. The low-power wireless sensor circuit according to claim 1, characterized in that: The power supply circuit includes a thermoelectric generator TEG, an energy management circuit and an energy storage unit.

9. A low-power wireless sensor, characterized in that: The low-power wireless sensor circuit comprises the low-power consumption wireless sensor circuit according to any one of claims 1 to 8.

10. A low-power wireless sensor network, characterized in that: The invention comprises the low power consumption wireless sensor as claimed in claim 9.

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