Frequency conversion circuit, wireless tag circuit, device and system

Abstract

The utility model relates to the technical field of communication, and provides a frequency conversion circuit, a wireless tag circuit, a device and a system. The frequency conversion circuit is used for receiving a downlink radio frequency signal and sending an uplink frequency conversion signal, and comprises an impedance changing module, an impedance conversion module and a frequency conversion module, the impedance conversion module is electrically connected with the impedance changing module and the frequency conversion module. The impedance changing module can be switched between different first impedance values; the impedance conversion module receives an input downlink radio frequency signal and performs impedance conversion on the first impedance value to obtain a second impedance value; the frequency conversion module comprises a modulation element, a first inductor and a passive piezoelectric resonator. According to the utility model, the frequency conversion circuit is improved, so that the uplink and downlink frequency conversion transmission is realized, the circuit cost is further reduced, the requirement on the power sensitivity of the frequency conversion circuit can be reduced, and the application scene of the Internet of Things of the wireless tag terminal is further expanded.

Description

Technical Field

[0001] This utility model relates to the field of communication technology, and in particular to a frequency conversion circuit, a wireless tag circuit, a device and a system. Background Technology

[0002] The current operating distance of wireless tag terminals is insufficient for most IoT application scenarios. For example, RFID is mostly used for inventory counting, with a counting distance typically less than 10 meters. When used in sensing scenarios, it is often limited to temperature sensors, and the wireless communication distance under optimal conditions is usually less than 5 meters. The limited range of RFID is mainly due to communication congestion caused by the high-power transmission of the reader at the same uplink and downlink frequency. Some existing wireless tag terminals use uplink and downlink frequency conversion transmission, but these employ relatively high-cost directional couplers, circulators, and other components, and still require relatively high power sensitivity from the frequency conversion circuit, which limits their application scenarios to some extent. Therefore, there is still room for further improvement. Summary of the Invention

[0003] To solve at least one of the technical problems in the prior art, the present invention provides a frequency conversion circuit, a wireless tag circuit, a device, and a system.

[0004] In a first aspect, this utility model provides a frequency conversion circuit for receiving downlink radio frequency signals and transmitting uplink frequency conversion signals, characterized in that it includes an impedance changing module, an impedance transformation module, and a frequency conversion module; the impedance transformation module is electrically connected to both the impedance changing module and the frequency conversion module.

[0005] The impedance changing module is configured to switch between different first impedance values;

[0006] The impedance transformation module is configured to receive the input downlink radio frequency signal and perform impedance transformation on the first impedance value to obtain a second impedance value; the magnitude of the second impedance value is M times the magnitude of the first impedance value, where M is greater than 1.

[0007] The frequency conversion module includes a modulation element, an inductor, and a passive piezoelectric resonator. The first modulation port of the modulation element is electrically connected to the impedance transformation module, the second modulation port of the modulation element is electrically connected to the first end of the inductor, the second end of the inductor is grounded, the third modulation port of the modulation element is electrically connected to the first end of the passive piezoelectric resonator, and the second end of the passive piezoelectric resonator is grounded.

[0008] The aforementioned frequency conversion circuit, firstly, avoids the distance limitation problem caused by high-power co-frequency blocking in the prior art due to the use of different frequencies for uplink and downlink transmission; secondly, because an impedance transformation module is used that can be configured to switch between different impedance values, such as 0Ω and 50Ω, when the impedance is 0Ω, the downlink RF signal can enter the frequency conversion module with extremely low loss. Compared with the prior art where the front-end link of the frequency conversion module uses common non-impedance transformation modules such as directional couplers and circulators (the fixed impedance of these non-impedance transformation modules introduces fixed losses that cannot be reduced), this application can reduce the power sensitivity requirements of the frequency conversion module (or, in other words, improve the overall power sensitivity).

[0009] Furthermore, the impedance transformation module uses a balun with a turns ratio of N:1 (N is greater than 1), including a first port and a second port with a higher turns ratio, and a third port and a fourth port with a lower turns ratio. The first port of the balun is used to receive downlink RF signals and output uplink frequency conversion signals. The second port of the balun is electrically connected to the frequency conversion module. The third and fourth ports of the balun are electrically connected to the impedance transformation module.

[0010] Furthermore, the impedance changing module includes an impedance switching circuit, a control circuit, and an energy management circuit. The control circuit is electrically connected to both the impedance switching circuit and the energy management circuit. The impedance switching circuit is also electrically connected to the third and fourth ports of the balun.

[0011] Furthermore, it also includes inductor two, the first end of which is electrically connected to the third modulation port of the modulation element, and the second end of inductor two is grounded.

[0012] Furthermore, the uplink frequency conversion signal is output from the first modulation port, the second modulation port and / or the third modulation port of the modulation element to the impedance transformation module.

[0013] Furthermore, the modulation element is a transistor.

[0014] Furthermore, the transistor is a junction field-effect transistor, a metal-oxide-semiconductor field-effect transistor, a two-dimensional electron gas transistor, or a high electron mobility transistor.

[0015] Furthermore, the passive piezoelectric resonator is a crystal resonator, a ceramic resonator, a surface acoustic wave piezoelectric resonator, or a MEMS piezoelectric resonator.

[0016] Furthermore, it also includes a sensing module, which is electrically connected to the control circuit.

[0017] A second aspect of this utility model provides a wireless tag circuit, including an antenna module and the aforementioned frequency conversion circuit, wherein the antenna module is electrically connected to the impedance transformation module.

[0018] A third aspect of this utility model provides a wireless tag device, including a housing and a frequency conversion circuit or a wireless tag circuit as described above, wherein all or part of the frequency conversion circuit or the wireless tag circuit is disposed in the housing.

[0019] A third aspect of this utility model provides a wireless tag system, including a reader and a plurality of wireless tag circuits or a plurality of wireless tag devices as described above; the reader is used to send downlink radio frequency signals to the wireless tag circuits or wireless tag devices, and to receive uplink frequency conversion signals returned by the wireless tag circuits or wireless tag devices that meet preset communication rules.

[0020] Compared with the prior art, this application has at least the following beneficial effects:

[0021] Because uplink and downlink use different frequencies for transmission, the distance limitation problem of uplink and downlink same frequency transmission in existing technologies is avoided;

[0022] Because the impedance transformation module is configured to switch between different impedance values, the downlink RF signal can be configured to enter the frequency conversion module with extremely low loss. Compared with the common non-impedance transformation modules such as directional couplers and circulators used in the front-end link of the frequency conversion module in the prior art (the fixed loss introduced by the fixed impedance of these non-impedance transformation modules cannot be reduced), this application can reduce the power sensitivity requirements of the frequency conversion module (or improve the overall power sensitivity).

[0023] Compared with the expensive frequency conversion circuits such as circulators used in the prior art, this application uses low-cost circuits or devices such as baluns, which can save circuit costs while ensuring the power sensitivity of the whole machine, and further expand the Internet of Things application scenarios of wireless tag terminals. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a frequency converter circuit structure provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a frequency converter circuit structure provided in another embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the inverter module structure provided in one embodiment of the present invention;

[0027] Figure 4 This is a schematic diagram of a frequency converter circuit structure provided in another embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of a wireless tag circuit structure provided in an embodiment of the present invention;

[0029] Figure 6This is a schematic diagram of a wireless tag system structure provided in an embodiment of the present invention.

[0030] Figure reference numerals: 10-Frequency conversion circuit; 11-Impedance changing module; 12-Impedance transformation module; 13-Frequency conversion module; 14-Antenna module; 15-Sensing module; 100-Wireless tag device; 111-Impedance switching circuit; 112-Control circuit; 113-Energy management circuit; 121-Balon; 131-Modulation element; 132-Inductor 1; 133-Passive piezoelectric resonator; 134-Inductor 2; 135-Impedance matching network 1; 200-Reader. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] For ease of understanding, the concepts and terms that may appear in this application are explained below.

[0033] Tags: Also known as electronic tags, smart tags, transponders, etc., they are typically composed of coupling elements and chips. Based on their function, they can be divided into identification tags and sensing tags; the former only provides identification functionality, while the latter provides both identification and sensing capabilities.

[0034] Reader: Also known as a reader / writer, gateway, reading device, transceiver, communicator, etc. It is typically used to read (and sometimes write) tag information. Readers can be handheld, fixed devices, or mounted on mobile platforms.

[0035] A carrier signal is a high-frequency signal that does not carry information itself but serves as the physical basis for transmitting low-frequency signals (such as voice and data). Modulation techniques can be used to add modulation to the amplitude, frequency, or phase of a baseband signal, forming a modulated carrier signal. Without a low-frequency signal, the amplitude and phase of a high-frequency signal are usually fixed. After a low-frequency signal is added, the amplitude or phase of the high-frequency signal will change with the variation of the low-frequency signal.

[0036] Downlink: For communication between a reader and a tag, it refers to the direction of signal flow from the reader to the tag. For a single tag or the frequency converter circuit within the tag, it refers to the direction of signal flow from outside the tag (or outside the frequency converter circuit) to inside the tag (or inside the frequency converter circuit).

[0037] Uplink: For communication between the reader and the tag, it refers to the direction of signal flow from the tag to the reader. For a single tag or the frequency converter circuit within the tag, it refers to the direction of signal flow from inside the tag (or inside the frequency converter circuit) to outside the tag (or outside the frequency converter circuit).

[0038] Power sensitivity refers to the minimum input signal power required for a circuit to function properly. For example, for a reader receiver, it means the minimum input signal power required for the receiver to correctly demodulate while ensuring a specific communication quality (such as bit error rate BER); for a frequency converter circuit, it means the minimum input signal power required to achieve a specific frequency conversion output.

[0039] Baseband data refers to unmodulated electrical signals directly emitted by the signal source. For digital baseband signals, it is a discrete pulse sequence composed of 0s and 1s, such as binary data output by a computer.

[0040] like Figure 1 As shown, the frequency conversion circuit of this application includes an impedance changing module 11, an impedance transformation module 12, and a frequency conversion module 13. The impedance transformation module 12 is electrically connected to the impedance changing module 11 and the frequency conversion module 13, respectively.

[0041] The impedance changing module 11 includes at least two different first impedance values, such as 0Ω and 50Ω, or 0Ω and 25Ω, or 0Ω and 75Ω; or 0Ω, 25Ω, 50Ω, and 100Ω; and is configured to switch between different first impedance values; for example, switching between 0Ω and 50Ω; or switching between 0Ω and 25Ω; or switching between 0Ω and 75Ω.

[0042] The frequency conversion module 13 is configured to convert the downlink radio frequency signal into an uplink frequency conversion signal when the downlink radio frequency signal power is greater than the first power threshold, and the downlink radio frequency signal and the uplink frequency conversion signal have different frequencies; when the downlink radio frequency signal power is less than the first power threshold, no uplink frequency conversion signal is generated.

[0043] The impedance transformation module 12 is configured to receive the input downlink RF signal and perform impedance transformation on the first impedance value switched by the impedance transformation module 11 to obtain the corresponding second impedance value. When the signal power of the downlink RF signal entering the frequency conversion module 13 after passing through the second impedance value is greater than the first power threshold, the module receives and outputs the uplink frequency conversion signal sent by the frequency conversion module 13.

[0044] The aforementioned frequency conversion circuit, firstly, avoids the distance limitation problem caused by high-power co-frequency blocking in the prior art due to the use of different frequencies for uplink and downlink transmission; secondly, since an impedance transformation module is used, it can be configured to switch between different first impedance values, such as 0Ω and 50Ω. When the impedance is 0Ω, the downlink RF signal can enter the frequency conversion module with extremely low loss. Compared with the prior art, which uses common non-impedance transformation modules such as directional couplers and circulators in the front-end link of the frequency conversion module (the fixed impedance of these non-impedance transformation modules introduces fixed losses that cannot be reduced), this application can reduce the power sensitivity requirements of the frequency conversion module (or, in other words, improve the overall power sensitivity).

[0045] In some embodiments, the magnitude of the second impedance value is M times the magnitude of the first impedance value, where M is greater than 1, and preferably, M is greater than 10.

[0046] exist Figure 1 In this circuit, the general workflow of the frequency converter is as follows: First, the impedance transformation module 12 receives the downlink RF signal. Initially, the impedance transformation module 11 operates at a default first impedance value. The default first impedance value is selected based on the second impedance value obtained after impedance transformation by the impedance transformation module 12, ensuring that the power of the downlink RF signal received by the frequency converter module 13 is below a first power threshold (in other words, if the downlink RF signal power is less than the first power threshold, the frequency converter module 13 cannot generate an uplink frequency conversion signal). At this time, most of the downlink RF signal received by the impedance transformation module 12 enters the impedance transformation module 11. When the impedance transformation condition is met, the impedance transformation module 11 switches from the default first impedance value to a different first impedance value, for example, to zero ohms. At this time, the second impedance value obtained after impedance transformation is still zero ohms, and more powerful downlink signals enter the frequency converter module 13, thereby enabling the frequency converter module 13 to meet the frequency conversion condition, that is, the downlink RF signal power is greater than the first power threshold, and thus convert the downlink RF signal into an uplink frequency conversion signal. The frequencies of the downlink RF signal and the uplink frequency conversion signal are different. The uplink frequency conversion signal generated by the frequency conversion module 13 is then output through the impedance transformation module 12.

[0047] The aforementioned "impedance change conditions" can be that the impedance change module 11 is controlled by external commands or internal preset commands, and that there is sufficient electrical energy to support the operation of changing the impedance.

[0048] The frequency converter module 13 can be any passive or extremely low power frequency converter circuit.

[0049] In some embodiments, the frequency conversion module 13 can generate a frequency shift with an absolute value not less than a first value, where "frequency shift" refers to the frequency difference between uplink and downlink radio frequency signals. It should be understood that the frequency shift reaching the first value means that the frequency conversion capability of the frequency conversion module 13 covers a frequency shift range from 0Hz to the first value. For example, "the frequency conversion module 13 can generate a frequency shift with an absolute value not less than 1MHz" means that the frequency conversion module 13 can generate a frequency shift with an absolute value from 0Hz to not less than 1MHz.

[0050] In some embodiments, the first value may be 1MHz, 5MHz, 10MHz, 15MHz, 20MHz, or 30MHz, etc.

[0051] The impedance changing module 11 can be any circuit that satisfies the aforementioned functions.

[0052] In some embodiments, the impedance changing module 11 can be a commercially available RFID chip or a functionally modified RFID circuit.

[0053] The impedance transformation module 12 can be any circuit that satisfies the aforementioned functions.

[0054] In some embodiments, the impedance transformation module 12 may be an impedance transformation circuit, such as a balance-unbalance converter (Balun) or an unbalanced converter.

[0055] Compared with the expensive frequency conversion circuits such as circulators used in the prior art, this application uses low-cost circuits or devices such as baluns, which can save circuit costs and further expand the Internet of Things application scenarios of wireless tag terminals.

[0056] Please refer to Figure 2 , Figure 2 A specific implementation structure of the frequency converter circuit is shown. The impedance transformation module 12 uses a balun with a turns ratio of N:1 (N is greater than 1) and includes four ports: a first port P1 and a second port P2 with a higher turns ratio, and a third port P3 and a fourth port P4 with a lower turns ratio. The first port P1 and the third port P3 are located on the same side, and the second port P2 and the fourth port P4 are located on the same side. The first port P1 is used to receive downlink RF signals and output uplink frequency conversion signals; the second port P2 is electrically connected to the frequency converter module 13; and the third port P3 and the fourth port P4 are electrically connected to the impedance transformation module 11.

[0057] In this embodiment, the impedance changing module 11 includes an impedance switching circuit 111, a control circuit 112, and an energy management circuit 113. The control circuit 112 is electrically connected to the impedance switching circuit 111 and the energy management circuit 113, respectively.

[0058] Impedance switching circuit 111 receives instructions from control circuit 112 and performs corresponding impedance switching operations. Impedance switching circuit 111 can switch between different first impedance values, for example, between 0Ω and 50Ω; or between 0Ω and 25Ω; or between 0Ω and 75Ω.

[0059] The impedance switching circuit 111 is set with a default impedance value. The default impedance value can be the maximum value among the aforementioned different impedance values, or it can be any other impedance value that is not 0Ω. The aforementioned "default" refers to the initial value or preset state that the system, software, or parameters automatically adopt when they are not subject to external (including command) intervention. Specifically, the default impedance value refers to the impedance value at which the impedance switching circuit 111 is initially in operation.

[0060] The energy management circuit 113 is used to provide the power required for the operation of the control circuit 112.

[0061] exist Figure 2 In this circuit, the energy management circuit 113 can be electrically connected to or not electrically connected to the impedance transformation circuit 12. When electrically connected to the impedance transformation circuit 12, the energy management circuit 113 collects and converts the downlink radio frequency signal sent through the impedance transformation circuit 12 into electrical energy. When not electrically connected to the impedance transformation circuit 12, the energy management circuit 113 can also collect and convert downlink radio frequency signals sent from other links into electrical energy, or collect and convert electrical energy in other ways.

[0062] The control circuit 112 is used to generate control commands to cause the impedance switching circuit 111 to perform impedance switching operations.

[0063] It is understandable that there are multiple ways to trigger the control circuit 112 to generate the aforementioned control command.

[0064] In some embodiments, the aforementioned control command can be generated by triggering the control circuit 112 via a downlink radio frequency signal carrying a trigger command. In this manner, Figure 2The control circuit 112 and the impedance transformation circuit 12 are differentially connected at their balanced outputs. Similar to the communication between the RFID tag and reader in the EPC Class 1 Generation 2 protocol, during the communication process, the reader actively sends an interrogation command each time, and the tag returns a 16-bit random number to communicate with the reader. Specifically, the downlink radio frequency signal received by the frequency converter circuit carries the interrogation command. After demodulating the downlink radio frequency signal, the control circuit 112 generates a control command corresponding to a 16-bit binary random number represented by 0 and 1. Taking the impedance switching circuit 111 switching between two first impedance values ​​of 0Ω and 50Ω as an example, when responding to the control command of binary 1, the impedance switching circuit 111 switches to the first impedance value of 0Ω. At this time, the second impedance value at the unbalanced end of the impedance transformation circuit 12 is still 0Ω (i.e., 0Ω*N). 2 =0Ω, at this time M=N 2 The downlink RF signal enters the frequency conversion module 13 with low loss, enabling the frequency conversion module 13 to meet the frequency conversion conditions. The frequency conversion module 13 generates an uplink frequency conversion signal, which is then output through the impedance transformation circuit 12. When responding to the control command of binary 0, the impedance switching circuit 111 switches to the first impedance value of 50Ω. At this time, the second impedance value of the unbalanced end of the impedance transformation circuit 12 is 800Ω (taking N=4 as an example, 50Ω*16=800Ω, at this time M=N). 2 =16), the downlink RF signal needs to undergo high loss before entering the frequency conversion module 13, so the frequency conversion module 13 cannot meet the frequency conversion conditions and cannot generate the uplink frequency conversion signal. The impedance transformation circuit 12 cannot output the uplink frequency conversion signal. For digital baseband signals such as the identification code and CRC of the tag or frequency conversion circuit, the transmission process is similar to the transmission process of the aforementioned 16-bit random number.

[0065] In the aforementioned frequency conversion circuit, since the impedance switching circuit can be configured to switch between low impedance (e.g., 0Ω) and high impedance, such as between 0Ω and 50Ω, when the impedance is 0Ω, the downlink RF signal can enter the frequency conversion module with extremely low loss. Compared with the common non-impedance transformation modules such as directional couplers and circulators used in the front-end link of the frequency conversion module in the prior art (the fixed loss introduced by the fixed impedance of these non-impedance transformation modules cannot be reduced), this application can reduce the power sensitivity requirements of the frequency conversion module (or, in other words, improve the overall power sensitivity of the frequency conversion circuit).

[0066] In some embodiments, the control circuit 112 can be triggered to generate the aforementioned control command by a preset command inside the control circuit 112. A common method is the RFID tag-only method, which can be further divided into the following scenarios:

[0067] Scenario 1: The frequency converter circuit is activated by the energy of the downlink radio frequency signal. After that, the frequency converter circuit autonomously triggers the control circuit 112 to generate the aforementioned control command according to the internal preset command. In this scenario, the downlink radio frequency signal does not carry the trigger command. The downlink radio frequency signal is only used to enable the frequency converter circuit to generate the uplink frequency conversion signal. The power required for the operation of the control circuit 112 and other components in the frequency converter circuit is provided by an additional battery or by harvesting other ambient energy.

[0068] Scenario 2: The inverter circuit activates autonomously and triggers the control circuit 112 to generate the aforementioned control command according to the internal preset command. In this scenario, the downlink radio frequency signal does not carry the trigger command; the downlink radio frequency signal is only for the inverter circuit to generate the uplink inverter signal. The power required for the operation of the control circuit 112 and other components in the inverter circuit is provided by an additional battery or by harvesting other ambient energy.

[0069] Understandably, for the two scenarios mentioned above, Figure 2 At least one of the control circuit 112 and the energy management circuit 113 is electrically connected to the impedance transformation circuit 12. The control circuit 112 and / or the energy management circuit 113 can be used to determine whether the reader has entered its effective communication range. Specifically, the energy, frequency, and other parameters of the received downlink radio frequency signal can be used as the activation criteria for the frequency conversion circuit.

[0070] For example, in applications with relatively clean electromagnetic environments, the energy level of the received downlink radio frequency signal can be used as the activation criterion for the frequency converter circuit. Specifically, the energy management circuit 113 can collect the downlink radio frequency signal energy and determine whether the collected energy exceeds a preset second threshold within a certain period of time. If it does, it is determined that the reader has entered the effective communication range, and the frequency converter circuit is activated; otherwise, the frequency converter circuit is not activated.

[0071] For example, in applications with relatively clean electromagnetic environments, the frequency of the received downlink radio frequency signal can be used as the activation criterion for the frequency converter circuit. Specifically, the control circuit 112 can demodulate whether the frequency of the received downlink radio frequency signal is the target frequency. If it is confirmed to be the target frequency, it is determined that the reader has entered the effective communication range, and the frequency converter circuit is activated at this time; otherwise, the frequency converter circuit is not activated.

[0072] For example, in applications with complex electromagnetic environments, the energy and frequency of the downlink radio frequency signal can be used simultaneously as the activation criteria for the frequency converter circuit. Specifically, on the one hand, the energy management circuit 113 collects the energy of the downlink radio frequency signal and determines whether the collected energy exceeds a preset second threshold within a certain period of time; on the other hand, the control circuit 112 demodulates whether the frequency of the received downlink radio frequency signal is the target frequency. When the energy of the downlink radio frequency signal exceeds the second threshold and its frequency is also the target frequency, it is determined that it has entered the effective communication range of the reader, and the frequency converter circuit is activated; otherwise, the frequency converter circuit is not activated.

[0073] It should be noted that the aforementioned "entering the effective communication range of the reader" refers to the relative relationship between the tag or frequency converter circuit and the reader. This could mean that the reader is fixed and the tag or frequency converter circuit is movable; or that the reader is movable and the tag or frequency converter circuit is fixed; or that both the reader and the tag or frequency converter circuit are movable.

[0074] Unlike the aforementioned control commands that can be generated by triggering the control circuit 112 with a downlink RF signal carrying a trigger command, in the two scenarios described above, since there is no query command from the reader, the frequency converter circuit does not need to generate a corresponding random number response command. Instead, the frequency converter circuit may autonomously generate control commands corresponding to the identity code, CRC, sensor data, etc. The operation process of the impedance switching circuit 111 in response to the aforementioned control commands to generate or not generate an uplink frequency converter signal (which can be regarded as loading various types of data such as identity code, CRC, and sensor data onto the uplink frequency converter signal) has been described previously and will not be repeated here.

[0075] It should be noted that, based on the power supply method of the tag or frequency converter circuit, they can be divided into passive, semi-active, and active methods. For passive methods, the tag or frequency converter circuit obtains energy by receiving radio frequency signals transmitted by the reader to temporarily power itself and complete information exchange with the reader. For semi-active methods, an internal energy storage element (such as a battery) is installed, and the built-in power supply powers the internal circuitry of the tag or frequency converter circuit. When the tag or frequency converter circuit is within the communication coverage area of ​​the reader, it can rely on radio frequency energy or the built-in power supply to activate the tag or frequency converter circuit. The energy source for subsequent processing after the tag or frequency converter circuit enters the working state is similar to that of the passive method. For active methods, the energy required for operation is entirely provided by a power source (such as a battery). This application does not limit the power supply method of the tag or frequency converter circuit.

[0076] Please refer to Figure 3 , Figure 3A specific structure of a frequency converter module is provided according to one embodiment. The frequency converter module 13 includes a modulation element 131, an inductor 132 and a passive piezoelectric resonator 133. The second modulation port and the third modulation port of the modulation element 131 are electrically connected to the inductor 132 and the passive piezoelectric resonator 133, respectively, and its first modulation port is used to receive downlink radio frequency signals.

[0077] Modulation element 131 is used to receive downlink radio frequency signals (e.g., frequency f). d ), and generate an uplink frequency conversion signal (e.g., frequency f). u ).

[0078] Inductor 132 is configured in a high-impedance state to form a band-stop reflection filter for the radio frequency signal from modulation element 131. The filtered radio frequency signal is then sent via modulation element 131 to passive piezoelectric resonator 133 for secondary reflection filtering. Passive piezoelectric resonator 133 reflects the filtered resonant signal (frequency of the second resonant frequency) back to modulation element 131 for mixing with the downlink radio frequency signal. In other words, the frequency-converted signal (frequency f) u ) is a downlink radio frequency signal (frequency f d ) and the selected second resonant frequency (frequency f) r2 The resonant signal is obtained by mixing in the modulation element 131, and the frequency relationship of the three is: f u =f d ±n·f r2 , where n is a positive integer.

[0079] It is understandable that actual inductors have parasitic capacitance, which, together with the inductor's inductance, can form an equivalent LC parallel network, exhibiting high resistance near the self-resonant frequency.

[0080] It should be noted that the first modulation port of the modulation element 131 receives the downlink radio frequency signal, and the generated frequency conversion signal exhibits isotropic or direction-independent transmission characteristics inside the modulation element 131. Therefore, from the perspective of the three ports of the modulation element 131, the frequency conversion signal exists simultaneously. Thus, depending on the actual needs, a signal output channel can be set to output the frequency conversion signal from the three ports simultaneously, or the frequency conversion signal can be output from any two of the three ports of the modulation element 131 simultaneously, or the frequency conversion signal can be output from one of the three ports of the modulation element 131.

[0081] In some embodiments, the frequency conversion module 13 further includes an impedance matching network 135 electrically connected to the first modulation port of the modulation element 131, which is used to reduce radio frequency losses on the signal transmission path. It is understood that when the operating bandwidth of the impedance matching network 135 covers the frequencies of the downlink radio frequency signal and the uplink frequency conversion signal, the downlink radio frequency signal and the uplink frequency conversion signal can share the same port input and output.

[0082] When the impedance matching network 135 operates only at the downlink RF signal frequency, the uplink conversion signal can be output from one of the bypass ports electrically connected to the first modulation port, the second modulation port, and / or the third modulation port, such as... Figure 3 As shown. It is understood that impedance matching networks that only allow the uplink frequency conversion signal to pass through can also be set on each bypass. For example, impedance matching network 2 136 is set on the bypass electrically connected to the first modulation port, so as to allow the uplink frequency conversion signal to pass through and reach the impedance transformation module 12 with high efficiency; impedance matching network 3 137 is set on the bypass electrically connected to the second modulation port, so as to allow the uplink frequency conversion signal to pass through and reach the impedance transformation module 12 with high efficiency; and impedance matching network 4 138 is set on the bypass electrically connected to the third modulation port, so as to allow the uplink frequency conversion signal to pass through and reach the impedance transformation module 12 with high efficiency.

[0083] In some embodiments, the frequency converter module 13 further includes an inductor 134 electrically connected to the third modulation port of the modulation element 131. The inductor 134 and the passive piezoelectric resonator 133 further constitute an equivalent LC parallel resonant network. The inductor 134 is used to adjust the inherent resonant frequency and reflection bandwidth of the passive piezoelectric resonator 133, thereby balancing the power sensitivity and anti-interference capability of the frequency converter circuit.

[0084] The modulation element 131 in any of the above embodiments is preferably a transistor, such as a bipolar transistor or a unipolar transistor.

[0085] In some embodiments, the unipolar transistor is preferably a field-effect transistor. The field-effect transistor is preferably a junction field-effect transistor (JFET), a metal-oxide-semiconductor field-effect transistor (MOSFET), a two-dimensional electron gas transistor, or a high electron mobility transistor (HEMT).

[0086] In some embodiments, the modulation element is a field-effect transistor, with a first modulation port as the drain, a second modulation port as the source, and a third modulation port as the gate, and the frequency conversion signal is led out from the first modulation port.

[0087] In some embodiments, the modulation element is a field-effect transistor, with a first modulation port as the source, a second modulation port as the drain, and a third modulation port as the gate, and the frequency conversion signal is led out from the first modulation port.

[0088] In some embodiments, the modulation element is a field-effect transistor, with a first modulation port as the gate, a second modulation port as the source, and a third modulation port as the drain, and the frequency conversion signal is led out from the first modulation port.

[0089] In some embodiments, the modulation element is a bipolar transistor, with a first modulation port as the collector, a second modulation port as the emitter, and a third modulation port as the base, and the frequency conversion signal is drawn out from the first modulation port.

[0090] In some embodiments, the modulation element is a bipolar transistor, with a first modulation port as the emitter, a second modulation port as the collector, and a third modulation port as the base, and the frequency conversion signal is drawn out from the first modulation port.

[0091] In some embodiments, the modulation element is a bipolar transistor, with a first modulation port as the base, a second modulation port as the emitter, and a third modulation port as the collector, and the frequency conversion signal is drawn out from the first modulation port.

[0092] It is understood that passive piezoelectric resonators 133 include, but are not limited to, crystal resonators, ceramic resonators, surface acoustic wave piezoelectric resonators, and MEMS piezoelectric resonators.

[0093] Please refer to Figure 4 ,exist Figure 1 or Figure 2 In addition to the above, a sensing module 15 is also included. The sensing module 15 is electrically connected to the impedance changing module 11. The sensing module 15 provides digital sensing data and includes a sensing element and an analog-to-digital converter. The impedance changing module 11 receives and stores the digital sensing data, and maps the digital sensing data into control commands that enable the impedance switching circuit 111 to perform impedance switching operations when needed, thereby realizing data transmission by amplitude modulation of the uplink frequency conversion signal.

[0094] In some embodiments, Figure 2 Based on this, the sensing module 15 is electrically connected to the control circuit 112 and the energy management circuit 113 in the impedance change module 11. The control circuit 112 also includes a storage element, in which the sensing data can be stored. The energy management circuit 113 provides the power required for the sensing module 15 to operate.

[0095] This application also provides a frequency conversion method, which is applied to the frequency conversion circuit of any of the foregoing embodiments, and its working steps are roughly as follows:

[0096] Step 1: Receive downlink radio frequency signals;

[0097] Step 2: Activate the frequency converter circuit;

[0098] Step 3: The frequency converter circuit returns the amplitude-modulated uplink frequency converter signal.

[0099] In step two, the activation criteria of the frequency converter circuit can be based on parameters such as the energy and / or frequency of the downlink radio frequency signal received by the frequency converter circuit.

[0100] In step three, the frequency converter circuit is triggered to return an amplitude-modulated uplink frequency converter signal by a downlink radio frequency signal carrying a trigger command; or, the frequency converter circuit is triggered to return an amplitude-modulated uplink frequency converter signal by a preset command inside the frequency converter circuit.

[0101] Please refer to Figure 5 The invention provides a wireless tag circuit according to one embodiment, which, based on the frequency conversion circuit of any of the aforementioned embodiments, further includes an antenna module 14, which is electrically connected to the frequency conversion circuit 10. The antenna module 11 is configured to receive downlink radio frequency signals in free space and to transmit uplink frequency conversion signals into free space; wherein the carrier frequency of the uplink frequency conversion signal is different from that of the downlink radio frequency signal.

[0102] In some embodiments, Figure 1 Based on this, the antenna module 14 is electrically connected to the impedance transformation module 12.

[0103] In some embodiments, Figure 2 Based on this, the antenna module 14 is electrically connected to the first port of the impedance transformation module 12.

[0104] In some embodiments, Figure 2 Based on this, the antenna module 14 is electrically connected to the first port of the impedance transformation module 12. The impedance transformation module 12 is not electrically connected to the energy management circuit 113 and the control circuit 112. The energy management circuit 113 and the control circuit 112 are respectively electrically connected to the antenna module 14. In this embodiment, the impedance changing module 11 obtains the trigger command, energy, and / or frequency information carried by the downlink radio frequency signal without going through the impedance transformation module 12.

[0105] It is understood that the frequency conversion circuit in any of the above embodiments also includes a matching circuit. The matching circuit can be disposed on any electrical signal transmission path on which it is desired to reduce radio frequency transmission loss. For example, a matching circuit is disposed on the electrical signal transmission path between the antenna module 14 and the impedance transformation module 12; or, a matching circuit is disposed on the electrical signal transmission path between the impedance transformation module 12 and the impedance change module 11; or, a matching circuit is disposed on the electrical signal transmission path between the impedance transformation module 12 and the frequency conversion module 13; or, a matching circuit is disposed on the electrical signal transmission path between the modulation element 131 and the first resonant network 132; or the antenna module itself has matching characteristics, for example, the antenna module itself is provided with a matching circuit from 377Ω (space impedance) to 50Ω (general radio frequency impedance); or the antenna module itself is provided with a matching circuit from 377Ω to 25Ω.

[0106] This application also provides a wireless tag device 100, which includes a housing and the wireless tag circuit disclosed in any of the foregoing embodiments. All or part of the wireless tag circuit is disposed within the housing, which protects the wireless tag circuit to improve its mechanical performance, environmental performance, and service life.

[0107] In some embodiments, the wireless tag circuitry is entirely disposed on the encapsulation housing, and the encapsulation housing is made of a wave-transparent material at least at the position corresponding to the antenna module 14.

[0108] In some implementations, the antenna module 14 of the wireless tag circuit is located outside the enclosure, while other modules are located inside the enclosure. The enclosure is provided with a communication interface that is electrically connected to the antenna module 14.

[0109] This application also provides a wireless tag system, such as Figure 6 As shown, it includes a reader 200 and several wireless tag devices 100 disclosed in any of the foregoing embodiments;

[0110] The reader 200 is used to send downlink radio frequency signals to the wireless tag device 100 and to receive uplink frequency conversion signals returned by the wireless tag device 100 that meet preset communication rules, wherein the uplink frequency conversion signal (frequency f) d ) and downlink radio frequency signal (frequency f u The carrier frequencies are different.

[0111] The aforementioned preset communication rules can be the aforementioned RFID communication rules, such as the EPC Class 1 Generation 2 protocol; or the RFID tag talk only method. There are no restrictions on the specific communication rules.

[0112] This application also provides a wireless communication method applied to a reader, the main steps of which are as follows:

[0113] Step 1: Send downlink radio frequency signal;

[0114] Step 2: Receive and parse the amplitude-modulated uplink frequency conversion signal to obtain frequency conversion information.

[0115] In step two, the frequency conversion information includes, but is not limited to, handshake information, identity coding information, sensor information, encryption information, location information, verification information, etc.

[0116] This application also provides a wireless communication method applied to the aforementioned wireless tag system, the main steps of which are as follows:

[0117] Step 1: Reader 200 sends downlink radio frequency signals;

[0118] In step one, the downlink radio frequency signal sent by the reader 200 is used to provide radio frequency power to the wireless tag device 300 within a specific communication range, thereby waking up the wireless tag device 300 to work.

[0119] Step 2: The wireless tag device 100 receives the downlink radio frequency signal and returns an amplitude-modulated uplink frequency conversion signal to the reader 200; wherein the carrier frequency of the uplink frequency conversion signal is different from that of the downlink radio frequency signal.

[0120] Step 3: The transceiver 200 receives and parses the uplink frequency conversion signal to obtain frequency conversion information.

[0121] In step three, the frequency conversion information includes, but is not limited to, handshake information, identity coding information, sensor information, encryption information, location information, verification information, etc.

[0122] Although the present invention has been described herein with reference to illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and improvements can be made to the components and / or layout of the subject combination within the scope of the present invention. Besides variations and improvements to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A frequency conversion circuit for receiving downlink radio frequency signals and transmitting uplink frequency conversion signals, characterized in that, It includes an impedance changing module, an impedance transformation module, and a frequency conversion module; the impedance transformation module is electrically connected to both the impedance changing module and the frequency conversion module. The impedance changing module is configured to switch between different first impedance values; The impedance transformation module is configured to receive the input downlink radio frequency signal and perform impedance transformation on the first impedance value to obtain the corresponding second impedance value; the magnitude of the second impedance value is M times the magnitude of the first impedance value, where M is greater than 1. The frequency conversion module includes a modulation element, an inductor, and a passive piezoelectric resonator. The first modulation port of the modulation element is electrically connected to the impedance transformation module, the second modulation port of the modulation element is electrically connected to the first end of the inductor, the second end of the inductor is grounded, the third modulation port of the modulation element is electrically connected to the first end of the passive piezoelectric resonator, and the second end of the passive piezoelectric resonator is grounded.

2. The frequency conversion circuit according to claim 1, characterized in that, The impedance transformation module uses a balun with a turns ratio of N:1, including a first port and a second port with a higher turns ratio, and a third port and a fourth port with a lower turns ratio. The first port of the balun is used to receive downlink RF signals and output uplink frequency conversion signals. The second port of the balun is electrically connected to the frequency conversion module. The third and fourth ports of the balun are electrically connected to the impedance transformation module, where N is greater than 1.

3. The frequency conversion circuit according to claim 2, characterized in that, The impedance changing module includes an impedance switching circuit, a control circuit, and an energy management circuit. The control circuit is electrically connected to both the impedance switching circuit and the energy management circuit. The impedance switching circuit is also electrically connected to the third and fourth ports of the balun.

4. The frequency conversion circuit according to claim 1, characterized in that, It also includes inductor two, the first end of which is electrically connected to the third modulation port of the modulation element, and the second end of inductor two is grounded.

5. The frequency converter circuit according to claim 1, characterized in that, The uplink frequency conversion signal is output from the first modulation port, the second modulation port and / or the third modulation port of the modulation element to the impedance conversion module.

6. The frequency conversion circuit according to claim 1, characterized in that, The modulation element is a transistor.

7. The frequency conversion circuit according to claim 6, characterized in that, The transistor is a junction field-effect transistor, a metal-oxide-semiconductor field-effect transistor, a two-dimensional electron gas transistor, or a high electron mobility transistor.

8. The frequency converter circuit according to any one of claims 1-7, characterized in that, The passive piezoelectric resonator is a crystal resonator, ceramic resonator, surface acoustic wave piezoelectric resonator, or MEMS piezoelectric resonator.

9. The frequency conversion circuit according to claim 3 or 4, characterized in that, It also includes a sensing module, which is electrically connected to the control circuit.

10. A wireless tag circuit, characterized in that, It includes an antenna module and a frequency conversion circuit as described in any one of claims 1-9, wherein the antenna module is electrically connected to the impedance transformation module.

11. A wireless tag device, characterized in that, It includes a housing and a frequency conversion circuit as described in any one of claims 1-9 or a wireless tag circuit as described in claim 10, wherein all or part of the frequency conversion circuit or wireless tag circuit is disposed in the housing.

12. A wireless tag system, characterized in that, It includes a reader and several wireless tag circuits as described in claim 10 or several wireless tag devices as described in claim 11; the reader is used to send downlink radio frequency signals to the wireless tag circuits or wireless tag devices, and to receive uplink frequency conversion signals returned by the wireless tag circuits or wireless tag devices that meet preset communication rules.

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