CN109086641B - Adaptive tuning tag integrated with passive wireless sensor - Google Patents
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- G—PHYSICS
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- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
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- G06K7/10316—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves using at least one antenna particularly designed for interrogating the wireless record carriers
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- G—PHYSICS
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- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
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- G06K7/10297—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092
Abstract
The invention discloses a self-adaptive tuning tag integrated with a passive wireless sensor, which comprises a tag antenna, a tag chip and a sensing chip which are integrated into a whole; the tag antenna comprises a microstrip line and a feed network, and is used for receiving an energy signal sent by a reader-writer or an ultrahigh frequency power supply; the tag chip comprises a self-adaptive tuning circuit, a power management circuit, a demodulation circuit, a modulation circuit, a digital baseband, a main control and data processing unit and a nonvolatile memory which are sequentially connected; the sensing chip comprises a sensing quantization module which is connected with the main control and data processing unit; the tag antenna is connected with the adaptive tuning circuit of the tag chip. Therefore, the self-adaptive tuning tag integrated with the passive wireless sensor improves the tag identification distance and the data transmission accuracy, and also improves the environmental adaptability, reliability and service life of the sensor.
Description
Technical Field
The invention relates to the field of radio frequency identification and passive sensors, in particular to an adaptive tuning tag integrated with a passive wireless sensor.
Background
Radio Frequency Identification (RFID) is a non-contact automatic Identification technology, and has been widely used in many industries. A typical RFID system includes a tag, a reader/writer, and an application system, where the tag does not need to be powered by a battery, and is powered by a reader/writer interrogation signal, and when the tag is within an effective reading range of the reader/writer, it generates an induced current in the tag through electromagnetic wave coupling to be used by other circuits in the chip, and performs signal transmission in a reflection manner. In many sensor application occasions, due to the limitation of conditions such as power supply modes, equipment space and safety, the sensor is required to have the characteristics of passive and wireless performance, and the like, and the sensor can be applied to the application fields such as temperature monitoring and vibration monitoring of power equipment. Based on the reasons, the sensor and the ultrahigh frequency RFID technology are combined, so that the sensor has the remarkable characteristics of passive power supply, wireless transmission, small size, long service life and the like. Adopt the integration of hyperfrequency RFID technique and temperature sensing chip as patent 201710436238.2, realize the wireless passive temperature measurement of cubical switchboard, and have advantages such as chip is small and long-life. However, in many applications, due to a complex environment, the performance of the RFID technology is reduced, and the tuning frequency is shifted, which may shorten the reading distance of the tag or deteriorate the reliable data transmission.
In order to realize the maximum transmission of energy between the tag and the reader-writer, the impedance of the tag chip and the input impedance of the antenna are subjected to conjugate matching during the design of the RFID tag, so that the maximum power transmission is realized. Maximum power transmission determines the tag maximum and minimum read distances. When the sensor tag is installed on a metal surface, the impedance of the antenna changes, and the reading distance of the tag is rapidly shortened, so as to solve the defect of the ultrahigh frequency RFID technology, a maximum energy transfer method (impedance conjugate matching) is usually adopted to design an anti-metal tag and a broadband tag antenna, and a matching network can be added in the tag antenna design or a chip resonant circuit to enable the tag to have broadband characteristics.
Patent 103022649a discloses an impedance-adjustable tag antenna of a UHF-band RFID system, which is designed to have a wide frequency band, and performs impedance matching adjustment by adjusting the height and width of a pi-type matching network. However, the matching network cannot be adjusted after the antenna is manufactured, and impedance self-adjustment cannot be realized in practical application.
The impedance-adjustable tag antenna disclosed in patent 20131011910.2 realizes tuning by adjusting the included angle between two arms of a dipole antenna, but the method has the problems of difficult adjustment, inaccurate adjustment, poor reliability and the like in application, and is not suitable for being integrated with a sensor because the antenna is a two-dimensional structure.
Patent 201720672864.7 discloses an impedance adjusting tag antenna, which employs a metal reflection plate and a guiding pole plate for elastic connection, and adjusts the capacitance value by adjusting the position of the guiding pole plate, thereby adjusting the input impedance. The method has the problems that the impedance adjustment cannot be accurate and stable in practical application, the reliability of the elastic column is reduced in long-term use, and the like, and the rapid and accurate impedance matching cannot be realized.
In addition, there are other methods that have been disclosed, such as adding an impedance automatic matching network in the reader circuit, which is composed of a measuring bridge, a capacitor array network and a controller, scanning all capacitor combinations by using a tuning algorithm, and finding a path with the shortest distance to zero in a two-dimensional plane for amplitude and phase offset, thereby obtaining a group of capacitance values for impedance matching. The method can realize the self-adaptive adjustment of the reader-writer and the tag impedance to a certain extent, but the method aims at the reader-writer end for adjustment and is not suitable for being integrated into a tag chip to solve the problem of the impedance matching inside the tag.
In some applications, such as wireless passive sensors installed inside a closed complex metal structure device, nearby metals and liquids will change the rf electromagnetic field, causing the tuning circuit to no longer tune. The impedance of the temperature measurement label disclosed in patent 201710436238.2 does not have the automatic regulating function, has realized the tuning when the sensor label is applied to cubical switchboard cable joint temperature monitoring, but same sensor label when plum blossom contact temperature monitoring is applied, near metal construction of sensor label mounted position or when airtight environment is moist, will make tuning frequency take place to squint, the circuit detune, and then lead to the label to read the distance and shorten.
The impedance adjusting methods disclosed in patent 103022649a and patent 20131011910.2 belong to special designs of tag antennas, and patent 201720672864.7 belongs to mechanical impedance adjustment, and although these methods can reduce the influence of frequency variation on the antenna impedance to some extent, they do not sacrifice the performance of all frequency bands. In addition, in practical application, the methods need to be finely designed and adjusted according to different scenes, and when the environment of the application scene is slightly changed, the methods are not suitable any more. These disadvantages greatly reduce the environmental suitability and reliability of the sensor tag, limiting the wide application of the sensor tag.
The disclosed method for adding an impedance automatic matching network into a reader-writer antenna aims at adjusting the reader-writer end and cannot solve the problem of impedance matching between a tag antenna and an internal chip.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide a self-adaptive tuning tag integrated with a passive wireless sensor, which improves the tag identification distance and the accuracy of data transmission, and also improves the environmental adaptability, reliability and service life of the sensor.
In order to achieve the purpose, the invention provides an adaptive tuning tag integrated with a passive wireless sensor, which comprises a tag antenna, a tag chip and a sensing chip which are integrated into a whole; the tag antenna comprises a microstrip line and a feed network, and is used for receiving an energy signal sent by a reader-writer or an ultrahigh frequency power supply; the tag chip comprises a self-adaptive tuning circuit, a power management circuit, a demodulation circuit, a modulation circuit, a digital baseband, a main control and data processing unit and a nonvolatile memory which are sequentially connected; the sensing chip comprises a sensing quantization module which is connected with the main control and data processing unit; the tag antenna is connected with the adaptive tuning circuit of the tag chip.
In a preferred embodiment, the adaptive tuning circuit includes a variable capacitor array, a power detection circuit, a first sigma-delta analog-to-digital converter, and an adaptive control circuit, which are connected in sequence.
In a preferred embodiment, the sensing quantization module comprises a digital sensing module and an analog sensing module.
In a preferred embodiment, the digital sensing module is used for outputting digital signals and storing the digital signals into the nonvolatile memory through the main control and data processing unit.
In a preferred embodiment, the analog sensing module is configured to output an analog signal, perform analog-to-digital conversion through the programmable gain control amplifier and the second sigma-delta analog-to-digital converter, and store the analog signal in the nonvolatile memory through the main control and data processing unit.
In a preferred embodiment, after receiving a radio frequency signal transmitted by a tag antenna, a tag chip performs power supply conversion and adaptive tuning, and starts a sensing chip to perform state monitoring and store state monitoring data into a nonvolatile memory; and after receiving the command signal of the reader-writer, the tag chip modulates the feedback signal in the nonvolatile memory and transmits the modulated feedback signal to the tag antenna.
In a preferred embodiment, the feedback signal includes condition monitoring data, sensor calibration data, power calibration data, radio frequency signal power detection values, and sensor identification.
In a preferred embodiment, the condition monitoring data is temperature or humidity or pressure or vibration.
In a preferred embodiment, the tag chip further comprises a clock circuit for generating the reference clock.
Compared with the prior art, the self-adaptive tuning tag integrated with the passive wireless sensor improves the tag identification distance and the accuracy of data transmission, and also improves the environmental adaptability, reliability and service life of the sensor.
Drawings
Fig. 1 is a schematic structural diagram of an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention.
Fig. 2 is a workflow diagram of an adaptive tuning tag integrating a passive wireless sensor according to an embodiment of the invention.
Fig. 3 is a schematic circuit diagram of a variable capacitance array in an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of an equivalent circuit of a binary weighted varactor array in an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention.
Fig. 5 is a schematic circuit diagram of a power detection circuit in an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention.
Fig. 6 is a schematic circuit diagram of an adaptive control circuit in an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention.
Detailed Description
The following detailed description of the present invention is provided in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited to the specific embodiments.
Throughout the specification and claims, unless explicitly stated otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element or component but not the exclusion of any other element or component.
As shown in fig. 1 to 6, fig. 1 is a schematic structural diagram of an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention; FIG. 2 is a workflow diagram of an adaptive tuning tag integrating a passive wireless sensor according to an embodiment of the invention; FIG. 3 is a schematic diagram of the electrical schematic of a variable capacitance array in an adaptive tuning tag integrating a passive wireless sensor according to an embodiment of the present invention; FIG. 4 is a schematic diagram of an equivalent circuit of a binary weighted varactor array in an adaptive tuning tag incorporating a passive wireless sensor, according to an embodiment of the present invention; FIG. 5 is a schematic circuit diagram of a power detection circuit in an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention; fig. 6 is a schematic circuit diagram of an adaptive control circuit in an adaptive tuning tag integrated with a passive wireless sensor according to an embodiment of the present invention.
The adaptive tuning tag integrated with the passive wireless sensor comprises a tag antenna 11, a tag chip 12 and a sensing chip 13 which are integrated into a whole; the tag antenna 11 comprises a microstrip line and a feed network, and the tag antenna 11 is used for receiving an energy signal sent by a reader-writer or an ultrahigh frequency power supply; the tag chip 12 includes a self-adaptive tuning circuit 101, a power management circuit 102, a demodulation circuit 103, a modulation circuit 104, a digital baseband 105, a main control and data processing unit 106, and a nonvolatile memory 107, which are connected in sequence; the sensing chip 13 includes a sensing quantization module, which is connected to the main control and data processing unit 106; the tag antenna 11 is connected to the adaptive tuning circuit 101 of the tag chip 12.
In a preferred embodiment, the adaptive tuning circuit 101 includes a variable capacitor array 1011, a power detection circuit 1012, a first sigma-delta analog-to-digital converter 1013, and an adaptive control circuit 1014, which are connected in sequence.
In a preferred embodiment, the sensing quantization module includes a digital quantity sensing module 1301 and an analog quantity sensing module 1301'; the digital sensing module 1301 is used for outputting a digital signal and storing the digital signal into the nonvolatile memory 107 through the main control and data processing unit 106; the analog sensing module 1301' is used to output an analog signal, perform analog-to-digital conversion through the programmable gain control amplifier 1302 and the second sigma-delta analog-to-digital converter 1303, and store the analog signal in the nonvolatile memory 107 through the main control and data processing unit 106.
In a preferred embodiment, after receiving the radio frequency signal transmitted by the tag antenna 11, the tag chip 12 performs power conversion and adaptive tuning, and starts the sensor chip 13 to perform status monitoring and store status monitoring data in the nonvolatile memory 107; when the tag chip 12 receives the command signal from the reader/writer, the feedback signal in the nonvolatile memory 107 is modulated and transmitted to the tag antenna 11.
In a preferred embodiment, the feedback signal comprises status monitoring data, sensor calibration data, power calibration data, a radio frequency signal power detection value, and a sensor identification; the state monitoring data is temperature, humidity, pressure or vibration; the tag chip 12 also includes a clock circuit 108 to generate a reference clock.
In practical application, the tag antenna 11 is used for receiving an energy signal sent by a reader-writer or an ultrahigh frequency power supply, is connected with the tag chip 12, performs signal transmission, and communicates with an external reader-writer; after receiving a radio frequency signal transmitted by the tag antenna 11, the tag chip 12 performs power conversion and adaptive tuning, starts the sensing chip 13 to perform state monitoring and stores monitoring data, and after receiving a reader/writer instruction signal, modulates a feedback signal in the memory and transmits the modulated feedback signal to the tag antenna 11, wherein the feedback signal comprises state monitoring data, sensor calibration data, power calibration data, a radio frequency signal power detection value and a sensor identifier; the sensing chip 13 measures the device state quantity, which may be temperature/humidity/pressure/vibration, etc., and quantizes and stores the monitoring data.
The working process of the self-adaptive tuning tag integrated with the passive wireless sensor comprises the following steps:
(1) and (3) starting a label: the tag antenna 11 firstly induces radio frequency Continuous Waves (CW) to activate tags within an identification range, and converts a received radio frequency signal into direct current supply voltage through a power management unit inside the tag chip 12 to provide energy for the self-tuning circuit to work;
(2) self-adaptive tuning: the tag chip 12 starts a self-tuning circuit, firstly measures a radio frequency signal power value through a power detection circuit, performs analog-to-digital conversion through a first sigma-delta digital-to-analog converter (sigma-delta ADC)1013, compares the radio frequency signal power value with an adaptive control circuit 1014, performs initial tuning and fine tuning on the variable capacitor array 1011 according to control logic, compares power detection values before and after change when the variable capacitor array 1011 changes a capacitance value (increases or decreases) according to the control logic, and continues to adjust the variable capacitor array 1011 according to the change direction when the power detection value increases after the change, which indicates that the tuning is correct; when the power detection value is reduced after the change, stopping the current change direction, adjusting towards the opposite direction, continuously increasing the power detection value, and when the power detection value is reduced for the first time, returning to the previous state, and ending the coarse adjustment mode; starting a fine tuning mode until the power detection value repeatedly changes at the maximum value, judging the change times through a counter, stopping changing when the change times reach 4 times, and completing self-adaptive tuning, wherein at the moment, the capacitor array 1011 is set to represent the optimal impedance matching of the antenna and the chip under the current working environment and the working frequency, and although the resonant frequency and the frequency of the signal transmitted by the reader are not completely the same, the resonant frequency is very close to the frequency of the transmitted signal. After the self-tuning is completed, the rest circuits of the chip are started to supply power, meanwhile, the current power detection value is stored in the nonvolatile memory 107, and the power detection value is sent to the reader after modulation. By adopting the self-tuning circuit, the alternating voltage obtained by the chip is increased, the low-voltage input performance of the chip is improved, and the tag identification distance and the data transmission accuracy are improved.
(3) The sensor chip 13 starts monitoring and storing: the sensing module of the sensing chip 13 is divided into a digital value and an analog value, the digital value sensing module 1301 outputs a digital quantization value changing with the temperature/humidity/pressure/vibration, for example, a digital temperature sensor uses a temperature-dependent pulse Transformation (TPC) to generate a clock pulse signal having a linear relation with the temperature, and a temperature-independent reference clock is used as a time-to-digital converter (TDC), i.e., a counter, to quantize the Pulse Width (PW) value, so as to obtain the digital quantization value of the PW value changing with the temperature. The digital quantity sensor module 1301 is directly connected with the main control and data processing unit 106 to perform operations such as data storage, calibration, modulation and transmission; the analog sensing module 1301' outputs an analog signal that changes along with the temperature, humidity, pressure, and vibration, and the analog signal is amplified by a programmable gain control (AGC) amplifier 1302, analog-to-digital converted by a second sigma-delta digital-to-analog converter (sigma-delta ADC)1303, and then is connected to the main control and data processing unit 106 to perform operations such as data storage, calibration, modulation and transmission.
(4) Tag writing and data sending: after the self-tuning is completed, the rest circuits of the chip are started to supply power, a reference clock is generated through a clock circuit 108 and is normally communicated with the reader-writer through a main control and data processing unit 106, the tag chip 12 is demodulated through a demodulation circuit to judge and execute a write operation or read operation instruction, when the write instruction is executed, the data is coded through a digital baseband 105, and the data is written into a nonvolatile memory 107 under the action of a clock; when executing a read instruction, the main control and data processing unit 106 sends the data in the nonvolatile memory 107 to the modulation circuit 104 for modulation, and as for the tag chip 12, an ASK (amplitude shift keying) backscatter modulator is used, and adaptive matching of chip impedance and antenna impedance is performed only in a non-modulation state, so that the chip acquisition energy is maximized, and the tag is in a "reception state"; when the chip backscatters signals, the impedance of the chip is changed through the modulation circuit, so that the power reaching the interface of the antenna and the chip is completely reflected, and the sensing signal transmission is completed.
According to the function requirement, the sensing data reading implementation mode can adopt a continuous monitoring reading mode or a continuous monitoring polling reading mode:
(1) when the monitoring and reading are carried out continuously, a reader-writer is adopted to carry out continuous power supply and data communication, and (temperature/humidity/pressure/vibration) sensing data is subjected to coding modulation through a digital baseband 105 and a modulation circuit 104 and is sent to the reader-writer in a backscattering mode, so that the method is suitable for real-time equipment state monitoring service application;
(2) when the label chip 12 and the sensing chip 13 are continuously monitored, an ultrahigh frequency power supply is adopted to supply power to the label chip 12 and the sensing chip 13, the sensing chip 13 stores monitoring data (temperature/humidity/pressure/vibration) in a nonvolatile memory (Flash or EEPROM) through the label chip 12, a reader-writer is used for reading the monitoring data in the memory during inspection, and the method is suitable for the mobile inspection business application of equipment.
The first embodiment is as follows: the variable capacitor array 1011 is further defined on the basis of fig. 1, as shown in fig. 3, the variable capacitor array provided by the present embodiment includes an equivalent capacitor array 31 and a binary weighted variable capacitor array 32, and the equivalent capacitor array with a larger capacitance value is adopted in the coarse tuning mode, so that the capacitance value can be rapidly adjusted to make the resonant frequency close to the transmitting frequency; the fine tuning mode adopts the unit fraction value (with smaller capacitance value) binary weighted variable capacitance tube array 32, so that the capacitance value is more finely tuned, and higher frequency resolution is realized in a very small frequency range.
The equivalent capacitor array 31 is composed of fixed value capacitors 301C 1-301 Cn and switches 302K 1-302 Kn, in the embodiment, PMOS tubes are adopted to form the fixed value capacitors and the switches, 32 capacitors with capacitance values of C are adopted to be cascaded, and the equivalent capacitor array 31 is rapidly adjusted by taking unit capacitance values as step lengths.
The binary weighted varactor array 32 is composed of fixed value capacitors 303a 303C, the embodiment adopts unit fraction value binary weighted capacitance values, the capacitance values of the fixed value capacitors 303a 303C are 1/8C, 1/4C and 1/2C, respectively, and the fine tuning capacitance variation value is: 0. 1/8C, 1/4C, 3/8C, 1/2C, 5/8C, 3/4C, 7/8C.
Example two: binary system adds weight varactor array 32 and on embodiment one' S basis, further prescribes a limit to the varactor, as shown in fig. 4, the varactor adopts back-to-back series connection PMOS varactor 303a 303c, couple together the substrate of two PMOS varactors, S and D couple together, form the inversion varactor, improve the nonlinearity of varactor in high capacitance district and low capacitance district, in the high-low capacitance district, the capacitance value of varactor is inconspicuous along with control voltage change, improve the stability of capacitance value.
The P and N ends of the antenna are connected to a VDD power supply end and a ground end through a diode, so that the voltage of the end points is VDD/2, and the S and D ends of the variable capacitance tube are connected, and the voltage is VDD/2; the control signal voltage output by the adaptive control circuit 1014 is connected to the substrates of the varactors 303a 303C, and is alternately changed between VDD and 0V, and the varactor array 32 is controlled to work at a high capacitance value and a low capacitance value by the control signal, the maximum capacitance value is 7/8C, the minimum capacitance value is 0, and the capacitance adjustment step size is 1/8C.
Example three: the power detection circuit 1012 is further limited to fig. 1, and as shown in fig. 5, includes a diode detector circuit 51, a chopper circuit 52, a low-noise programmable gain amplifier circuit 53, and a synchronous detector circuit 54. The radio frequency signal is detected by the diode detection circuit 51 to output a direct current or slowly-changed alternating current signal, the chopping circuit 52 performs chopping modulation, the modulated alternating current signal is subjected to controllable gain amplification by the low-noise programmable gain amplification circuit 53, the amplified alternating current signal is demodulated by the synchronous detection circuit 54, and the demodulated signal is subjected to analog-to-digital conversion by the first sigma-delta digital-to-analog converter (sigma-delta ADC)1013 to complete the collection of the radio frequency power detection value.
The diode detection circuit 51 is composed of a radio frequency filter capacitor 5101, a resistor 5102, resistors 5103 and 5104, a matching resistor 5105, detection diodes 5106 and 5107, and filter capacitors 5108 and 5109. The radio frequency filter capacitor 5101 and the resistor 5102 form a high-pass filter for filtering direct-current noise; resistors 5103 and 5104 form a 3dB attenuator for attenuating large signals, and the detection linear range and the anti-burning capacity of the diode are improved; the matching resistor 5105 performs impedance matching to ensure that the power of the radio frequency signal is transmitted to the maximum; the detector diodes 5106 and 5107 employ planar doped barrier diodes or low barrier schottky diodes, detect by using the square law region of the detector diodes so that the output voltage is proportional to the square of the input radio frequency signal power, and measure the radio frequency signal power value by measuring the detection voltage value.
The chopper circuit 52 is composed of switches 5201 and 5202 and a chopper driver 5203. The switches 5201 and 5202 perform balanced chopper modulation on the weak signal output by the detection diode, and transfer the noise spectral density to improve the detection sensitivity of the weak signal; the chopper driver 5203 outputs a chopper signal, and controls the switches 5201 and 5202 to perform square wave modulation, in which a 220Hz square wave is used as the chopper signal in this embodiment.
The low-noise programmable gain amplifier circuit 53 is composed of a dc blocking capacitor 5301 and a low-noise programmable gain amplifier 5302. The low-noise programmable gain amplifier 5302 can be formed by a first-stage operational amplifier which is formed by a low-noise and high-gain JFET (junction field effect transistor), wherein the amplification factor is 500 times, a programmable switch, an attenuation circuit and a differential operational amplifier are adopted, the amplification factor is 10-100 times, the overall amplification factor is 5000-50000 times, and the amplitude of an output signal is within the range of 0-3V.
The synchronous detection circuit 54 is composed of a switch 5401 and a filter 5402, the switch 5401 and the filter 5402 (low-pass or band-pass) form the synchronous detection circuit under the control of the chopper driver 5203, and the signal output by the amplifying circuit 53 is demodulated to realize synchronous amplification of the detection signal output by the diode detection circuit 51, so that subsequent circuit acquisition is facilitated.
Example four: the adaptive control circuit 1014 is further defined on the basis of fig. 1, as shown in fig. 6. The delay unit 61, the numerical comparator 62, the bidirectional shift register 63, the loop counter 64, and the direction counter 65. The voltage signal Vt collected by the ADC analog-to-digital converter 1013 is delayed by the delay unit 61 to form Vt1, Vt represents a current detection value, Vt1 represents a previous detection value, Vt and Vt1 are sent to the value comparator 62 for comparison, and when Vt > Vt1 outputs a logic high level 1, otherwise, a logic low level 0 is output. A high level 1 indicates that the current voltage detection value is larger than the voltage detection value before the change at the previous moment, which indicates that the change direction of the capacitor array 101 is correct; a low level of 0 and a high level of 1 indicate the opposite, the direction counter 64 is initially 0.
The bidirectional shift register 63 uses a 32-bit bidirectional shift register to store and change control signals, the 32-bit control signals control 32 switches in the equivalent capacitor array 31, the high 16 bits of the initial value D1[ n-1:0] of the register are 0, the low 16 bits are 1(0.. 01.. 1), which represents that after initialization, the left half part of the switch of the equivalent capacitor array 31 is controlled to be closed, the right half part of the switch is controlled to be opened, when the switch moves towards the left, the capacitance value is reduced again, the resonance frequency is increased, and the right shift and the left shift of the switch change are opposite. When the output of the numerical comparator 62 is logic high level 1, the bidirectional shift register 63 moves to the right, and 0 is compensated to the left, which means that the capacitance decreases and the resonant frequency increases; the bidirectional shift register 63 is shifted to the left, and 1 is complemented to the right, which means that the capacitance is increased and the resonant frequency is reduced. When the power detection value of the equivalent capacitor array 31 is reduced for the first time, the S terminal of the bidirectional shift register 63 outputs 1, returns to the previous state, and ends the coarse tuning mode.
The cycle counter 64 adopts a 3-bit cycle counter, the counting state changes in a cycle of 000-111-000, and the varactors 303 a-303 c of the binary weighted varactor array 32 are controlled to change, wherein the control signal is logic level 1, which represents that the varactors are at a high capacitance value, and the control signal is logic level 0, which represents that the varactors are at a low capacitance. When coarse tuning is finished and EN is 1, fine tuning mode is started, the initial value D2[3:0] of the cycle counter 64 is 000, the capacitance value changes from minimum to maximum in the positive cycle, and from maximum to minimum in the reverse cycle. When the tuning frequency is close to the transmitting frequency, the switch state is repeatedly changed, the change times are judged through the direction counter 65, and when the change times reach 4 times, a high level is output to finish fine tuning, so that the self-adaptive tuning is completed.
In a possible implementation manner, the power management circuit 102, the demodulation circuit 103, the modulation circuit 104, the digital baseband 105, the main control and data processing unit 106, the nonvolatile memory 107, and the clock circuit 108 are implemented by using the existing mature technology of the radio frequency tag, and the detailed description of the present invention is omitted.
In a possible implementation manner, the sensing chip 13 may adopt the prior art, such as the temperature sensing chip 13, and the basic principle is to use the temperature-dependent pulse conversion (TPC) to generate a clock pulse signal having a linear relationship with the temperature, and to quantize the PW value by using a temperature-independent reference clock as a time-to-digital converter (TDC), i.e. a counter, so as to obtain a digital quantized value of the PW value varying with the temperature, which will not be described in detail herein.
In conclusion, the self-adaptive tuning tag integrated with the passive wireless sensor has the following beneficial effects:
1. compared with the existing active sensor, the temperature/humidity/vibration/pressure sensing chip 13, the RFID tag chip 12 and the tag antenna 11 are integrated, meanwhile, the self-adaptive tuning technical scheme is adopted in the RFID tag chip 12, and the sensor can always keep circuit tuning when being applied in a complex environment such as a wide frequency range, a sealed and moist metal box body or an outdoor metal body and the like while realizing various wireless passive sensors, so that the environmental adaptability, the reliability and the service life of the sensor are improved;
2. compared with the existing RFID tag impedance matching technology, the invention not only carries out impedance matching in the design of the chip antenna, but also realizes self-adaptive impedance tuning in the tag chip 12, thereby greatly reducing the complexity of artificial impedance adjustment, increasing the alternating voltage obtained by the chip, improving the low-voltage input performance of the chip, improving the tag identification distance and the accuracy rate of data transmission, and in addition, greatly simplifying the complexity of impedance adjustment under different application environments, and being more easy for popularization and application of products;
3. compared with the RFID reader-writer impedance matching technology, the invention realizes self-adaptive impedance matching inside the tag chip 12, reduces the requirement on the reader-writer, simultaneously has shorter matching time, improves the performance of the tag, and is more easy for the field application of the tag;
4. compared with the existing sensor label, the invention not only has the advantages of adaptive tuning and matching, but also can send the radio frequency coupling power detection value to the reader-writer to provide signal strength detection data for RFID wireless positioning or equipment offset, thereby greatly expanding other applications of the sensor label.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.
Claims (7)
1. A self-adaptive tuning tag integrated with a passive wireless sensor is characterized by comprising a tag antenna, a tag chip and a sensing chip which are integrated into a whole;
the tag antenna comprises a microstrip line and a feed network, and is used for receiving an energy signal sent by a reader-writer or an ultrahigh frequency power supply;
the tag chip comprises a self-adaptive tuning circuit, a power management circuit, a demodulation circuit, a modulation circuit, a digital baseband, a main control and data processing unit and a nonvolatile memory which are sequentially connected;
the sensing chip comprises a sensing quantization module which is connected with the main control and data processing unit;
the tag antenna is connected with the adaptive tuning circuit of the tag chip;
the adaptive tuning circuit comprises a variable capacitor array, a power detection circuit, a first sigma-delta analog-to-digital converter and an adaptive control circuit which are sequentially connected;
after receiving the radio-frequency signal transmitted by the tag antenna, the tag chip performs power supply conversion and adaptive tuning, starts the sensing chip to perform state monitoring, and stores state monitoring data into the nonvolatile memory;
and after receiving the instruction signal of the reader-writer, the tag chip modulates the feedback signal in the nonvolatile memory and transmits the modulated feedback signal to the tag antenna.
2. The adaptive tuning tag of integrated passive wireless sensor of claim 1, wherein the sensing quantization module comprises a digital sensing module and an analog sensing module.
3. The adaptive tuning tag of integrated passive wireless sensor of claim 2, wherein the digital sensing module is configured to output a digital signal and store the digital signal in the nonvolatile memory through the main control and data processing unit.
4. The adaptive tuning tag of claim 2, wherein the analog sensing module is configured to output an analog signal, perform analog-to-digital conversion through the programmable gain control amplifier and the second sigma-delta analog-to-digital converter, and store the analog signal in the nonvolatile memory through the main control and data processing unit.
5. The adaptive tuning tag of integrated passive wireless sensors of claim 1, wherein the feedback signal comprises the status monitoring data, sensor calibration data, power calibration data, radio frequency signal power detection value, and sensor identification.
6. The adaptive tuning tag of integrated passive wireless sensors of claim 5, wherein the condition monitoring data is temperature, humidity, pressure, or vibration.
7. The adaptive tuning tag of an integrated passive wireless sensor of claim 1, wherein the tag chip further comprises a clock circuit to generate a reference clock.
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| CN109781342A (en) * | 2019-02-22 | 2019-05-21 | 武汉市聚芯微电子有限责任公司 | Barometer calibration method and device |
| CN112070196B (en) * | 2019-06-11 | 2023-09-15 | 四川谦泰仁投资管理有限公司 | Passive RFID chip with external battery and tag |
| CN110334556B (en) * | 2019-07-05 | 2021-09-24 | 电子科技大学 | Encoding method based on transistor passive frequency conversion RFID tag circuit |
| CN110929534B (en) * | 2019-08-27 | 2023-05-05 | 北京万物纵横科技有限公司 | Active tag inventory system with double modes and multiple IDs |
| WO2021052340A1 (en) * | 2019-09-16 | 2021-03-25 | 电子科技大学 | Passive wireless magnetic field characteristic sensing tag and sensing system |
| CN110598497A (en) * | 2019-09-16 | 2019-12-20 | 电子科技大学 | Long-distance passive wireless magnetic field quantity sensing label |
| CN110728338B (en) * | 2019-09-26 | 2023-05-02 | 北京智博晟源科技有限公司 | RFID reader-writer system and power calibration method |
| CN113131943B (en) * | 2019-12-30 | 2022-09-23 | 无锡华润上华科技有限公司 | Sensor detection circuit and electronic device |
| WO2022160231A1 (en) * | 2021-01-29 | 2022-08-04 | 华为技术有限公司 | Method and apparatus for reading data |
| CN113239711B (en) * | 2021-04-28 | 2022-08-26 | 河北稳控科技有限公司 | Composite electronic sensor and communication lag compensation method thereof |
| CN113295082B (en) * | 2021-05-20 | 2022-11-29 | 浙江波誓盾科技有限公司 | Crack detection method, crack detection system, computer device and readable storage medium |
| CN113283565B (en) * | 2021-06-02 | 2024-01-26 | 上海宜链物联网有限公司 | Automatic tuning system and method for antenna impedance of RFID tag chip |
| CN113255387B (en) * | 2021-06-25 | 2021-12-03 | 中关村芯海择优科技有限公司 | Frequency self-adaptive adjusting system and method for tag antenna |
| CN113283259B (en) * | 2021-07-19 | 2021-10-08 | 江西博星数码科技有限公司 | RFID-based multi-tag radio frequency identification system and method |
| CN113725588A (en) * | 2021-08-31 | 2021-11-30 | 中煤科工集团重庆研究院有限公司 | Multi-frequency antenna combination structure and method for mining radio wave perspective |
| CN114189212B (en) * | 2022-02-16 | 2022-05-17 | 卓捷创芯科技（深圳）有限公司 | Method and circuit for automatically compensating RFID resonance frequency statistics and temperature drift |
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| CN102693446B (en) * | 2012-06-01 | 2016-01-20 | 昆腾微电子股份有限公司 | Contactless IC card and radio-frequency interface circuit thereof and tuning methods |
| CN102831457B (en) * | 2012-08-24 | 2015-06-24 | 广州中盈物流科讯有限公司 | Passive RFID ((Radio Frequency Identification Device) temperature sensor label |
| CN104361388B (en) * | 2014-11-18 | 2018-03-06 | 中国科学院半导体研究所 | A kind of ultra-high frequency wireless sensing label |
| CN208622114U (en) * | 2018-09-13 | 2019-03-19 | 国网浙江省电力有限公司宁波供电公司 | The self-adapting tuning label of integrating passive wireless sensor |
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