Reflection Circuit, Communication Method, and Communication System

Abstract

An embodiment of the present application discloses a reflection circuit, a communication method, and a communication system. The reflection circuit includes: a transceiver circuit, a transformer, a signal generation circuit, a control circuit, and a logic circuit; the primary coil of the transformer is connected to the transceiver circuit, the secondary coil of the transformer is connected to the signal generation circuit, and the signal generation circuit and the secondary coil form an oscillator; the secondary coil and the signal generation circuit are respectively connected to the control circuit, and the control circuit is connected to the logic circuit, wherein: the logic circuit is used to generate a control signal; the control circuit is used to adjust the amplitude of the output signal of the oscillator according to the control signal; the logic circuit is further used to modulate the output signal of the oscillator when the amplitude of the output signal of the oscillator is the largest; the transceiver circuit is used to transmit the output signal of the oscillator modulated by the logic circuit.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and in particular, to a reflection circuit, a communication method, and a communication system. Background Art

[0002] Radio Frequency Identification (RFID) inherits the concept of radar. Generally, an RFID system includes a reader and an electronic tag. The basic working principle of the RFID system is as follows: The reader sends a radio frequency signal with a specific frequency through a transmitting antenna. When the electronic tag enters the effective working area of the reader, an induced current is generated, so that the electronic tag is activated by obtaining energy. Then the electronic tag transmits its own encoded information through an internal antenna; the reader receives the reflected signal sent from the electronic tag through the antenna, and after demodulating and decoding the reflected signal through a signal processing module, the reader sends the valid information to the background host system for relevant processing; the host system identifies the identity of the electronic tag according to logical operations, makes corresponding processing and control for the identity, and finally sends a signal to control the reader to complete different reading and writing operations.

[0003] However, the signal will attenuate during the communication between the reader and the electronic tag, resulting in a short communication distance of the RFID system. Summary of the Invention

[0004] The present application provides a reflection circuit, a communication method, and a communication system. By injection locking, the communication distance of the RFID system is increased.

[0005] In a first aspect, an embodiment of the present application provides a reflection circuit, including:

[0006] a transceiver circuit, a transformer, a signal generating circuit, a control circuit, and a logic circuit;

[0007] The main coil of the transformer is connected to the transceiver circuit, and the secondary coil of the transformer is connected to the signal generating circuit; the secondary coil and the signal generating circuit are respectively connected to the control circuit, the control circuit is connected to the logic circuit, and the signal generating circuit and the secondary coil form an oscillator, where:

[0008] the logic circuit is configured to generate a control signal;

[0009] the control circuit is configured to adjust the amplitude of the output signal of the oscillator according to the control signal;

[0010] the logic circuit is further configured to modulate the output signal of the oscillator when the amplitude of the output signal of the oscillator is the largest;

[0011] The transceiver circuit is used to transmit the output signal of the oscillator modulated by the logic circuit.

[0012] It should be noted that this reflection circuit is applied to the electronic tag in the RFID system. When the amplitude of the output signal of the oscillator is the largest, that is, injection locking occurs between the electronic tag and the reader / writer. At this time, the output signal of the oscillator is modulated so that the output signal of the oscillator carries the data information to be sent by the electronic tag, realizing that the electronic tag can send data information to the reader / writer with the output signal of the largest amplitude, which is beneficial to resisting attenuation and increasing the communication distance.

[0013] The signal generation circuit includes a variable capacitor. The first port and the second port of the variable capacitor are respectively connected to the secondary coil, and the control port of the variable capacitor is connected to the control circuit; the control circuit is specifically configured to: adjust the capacitance value of the variable capacitor according to the control signal to adjust the amplitude of the output signal of the oscillator.

[0014] It can be seen that in this embodiment, the control circuit changes the free oscillation frequency of the oscillator by adjusting the capacitance value of the variable capacitor. When the free oscillation frequency of the oscillator is close to the frequency of the signal sent by the reader / writer, injection locking can occur with the reader / writer. At this time, a reflection signal with the largest amplitude can be sent to the reader / writer, and the data information required by the electronic tag is carried by this reflection signal, thereby resisting attenuation and increasing the communication distance.

[0015] In some possible embodiments, the signal generation circuit further includes a negative resistance circuit and a current source. The first port and the second port of the negative resistance circuit are respectively connected to the first port and the second port of the variable capacitor. The third port of the negative resistance circuit is connected to the positive electrode of the current source, the negative electrode of the current source is grounded, and the control port of the current source is connected to the control circuit; the negative resistance circuit is used to compensate for the loss of the oscillator during the oscillation process; the logic circuit is used to turn on or off the current source when the output signal of the oscillator is the largest, adjust the amplitude of the output signal of the oscillator, and modulate the output signal of the oscillator.

[0016] It can be seen that in this embodiment, the negative resistance circuit compensates for the loss of the oscillator during the oscillation process, ensuring that the oscillator can always achieve injection locking with the reader / writer and increasing the communication endurance; by controlling the turning on or off of the current source, the output signal can be modulated when the amplitude of the output signal of the oscillator is the largest, so that the output signal carries data information, realizing the transmission of data information to the reader / writer with the reflection signal of the largest amplitude and increasing the communication distance.

[0017] In some possible embodiments, the control circuit includes an amplitude detection circuit, a capacitance selection circuit, and an amplitude modulation circuit; one end of the amplitude detection circuit is connected to the opposite-named terminal of the secondary coil, one end of the capacitance selection circuit is connected to the control port of the variable capacitor, one end of the amplitude modulation circuit is connected to the control port of the current source, and the other ends of the amplitude detection circuit, the capacitance selection circuit, and the amplitude modulation circuit are all connected to the logic circuit; the amplitude detection circuit is configured to detect the amplitude of the output signal of the oscillator; the logic circuit is configured to generate the control signal when the amplitude of the output signal of the oscillator does not reach the maximum; the capacitance selection circuit is configured to adjust the capacitance value of the variable capacitor according to the control signal; the logic circuit is configured to turn on or off the current source through the amplitude modulation circuit when the output signal of the oscillator is at the maximum, and adjust the amplitude of the output signal of the oscillator to modulate the output signal of the oscillator.

[0018] In some possible embodiments, the negative resistance circuit includes a first MOS transistor and a second MOS transistor; the gate of the first MOS transistor is connected to the drain of the second MOS transistor and is connected to the first port of the variable capacitor; the drain of the first MOS transistor is connected to the gate of the second MOS transistor and is connected to the second port of the variable capacitor; the source of the first MOS transistor is connected to the source of the second MOS transistor and is connected to the positive electrode of the current source.

[0019] In some possible embodiments, the variable capacitor includes a switched-capacitor array or a voltage-controlled capacitor; in the case where the variable capacitor is a switched-capacitor array, the first port and the second port of the variable capacitor are respectively connected to the secondary coil, specifically including: the first port of the switched-capacitor array is connected to the same-named end of the secondary coil, and the second port of the switched-capacitor array is connected to the opposite-named end of the secondary coil; the first port and the second port of the negative resistance circuit are respectively connected to the first port and the second port of the variable capacitor, specifically including: the gate of the first MOS transistor and the drain of the second MOS transistor are interconnected with the first port of the switched-capacitor array; the drain of the first MOS transistor and the gate of the second MOS transistor are interconnected with the second port of the switched-capacitor array; in the case where the variable capacitor is a voltage-controlled capacitor, the first port and the second port of the variable capacitor are respectively connected to the secondary coil, specifically including: the first port of the voltage-controlled capacitor is connected to the same-named end of the secondary coil, and the second port of the voltage-controlled capacitor is connected to the opposite-named end of the secondary coil; the first port and the second port of the negative resistance circuit are respectively connected to the first port and the second port of the variable capacitor, specifically including: the gate of the first MOS transistor, the drain of the second MOS transistor are interconnected with the first port of the voltage-controlled capacitor, and the drain of the first MOS transistor and the gate of the second MOS transistor are interconnected with the second port of the voltage-controlled capacitor.

[0020] In some possible embodiments, the transceiver circuit includes an antenna and an impedance transformation circuit. One end of the impedance transformation circuit is connected to the antenna, and the other end of the impedance transformation circuit is connected to the same-named end of the primary coil, and the opposite-named end of the primary coil is grounded; the impedance transformation circuit is configured to perform impedance transformation on the modulated output signal of the oscillator to enhance the transmission power of the output signal of the oscillator.

[0021] It can be seen that in this embodiment, by providing an impedance transformation circuit in the transceiver circuit, the impedance transformation circuit performs impedance transformation on the modulated output signal of the oscillator output by the secondary coil to enhance the transmission power of the modulated output signal, so that the modulated output signal is more resistant to attenuation and further increases the communication distance.

[0022] In some possible embodiments, the transceiver circuit includes a high-impedance differential antenna. One end of the high-impedance differential antenna is connected to the same-named end of the primary coil, and the other end of the high-impedance differential antenna is connected to the opposite-named end of the primary coil.

[0023] It can be seen that in this embodiment, since the high-impedance differential antenna itself has an impedance transformation function, the high-impedance differential antenna can perform impedance transformation on the modulated output signal of the oscillator, enhance the transmission power of the modulated output signal of the oscillator, so that the output signal can better resist attenuation and further increase the communication distance.

[0024] In a second aspect, an embodiment of the present application provides a communication method applied to a transmitter. The method includes:

[0025] Generating a control signal;

[0026] Adjusting the amplitude of the output signal of the oscillator according to the control signal;

[0027] Modulating the output signal of the oscillator when the amplitude of the output signal of the oscillator is the largest;

[0028] Transmitting the modulated output signal of the oscillator.

[0029] In some possible implementation manners, the transmitter includes a variable capacitor. Adjusting the amplitude of the output signal of the oscillator according to the control signal includes: adjusting the capacitance value of the variable capacitor according to the control signal to adjust the amplitude of the output signal of the oscillator.

[0030] In some possible implementation manners, the transmitter includes a current source. The method further includes: the negative resistance circuit compensates for the loss of the oscillator during the oscillation process; modulating the output signal of the oscillator when the amplitude of the output signal of the oscillator is the largest includes: turning on or off the current source when the output signal of the oscillator is the largest to adjust the amplitude of the output signal of the oscillator so as to modulate the output signal of the oscillator.

[0031] In some possible implementation manners, generating the control signal includes: detecting the amplitude of the output signal of the oscillator; generating the control signal when the amplitude of the output signal of the oscillator does not reach the maximum.

[0032] In a third aspect, an embodiment of the present application provides a communication system, including:

[0033] The communication system includes a reader and a plurality of transmitters, and each transmitter includes a reflection circuit as described in any one of the embodiments in the first aspect;

[0034] The reader is configured to send a downlink excitation signal to each of the plurality of transmitters respectively, where the frequencies of the downlink excitation signals between any two transmitters are different;

[0035] The transmitter is configured to send a modulated uplink reflection signal to the reader via the reflection circuit of the transmitter.

[0036] It can be seen that the reader can send multiple downlink excitation signals with different frequencies to multiple transmitters. Each transmitter adjusts the capacitance value to achieve injection locking with the reader respectively. Therefore, each transmitter can send a different frequency and the modulated uplink reflection signal with the largest amplitude to the reader. Thus, after the reader receives the modulated reflection signals sent by multiple transmitters, it can first filter out the modulated reflection signals sent by each transmitter through a filter, and then demodulate the modulated reflection signals of each transmitter to obtain the data information sent by each transmitter. Therefore, while increasing the communication distance between the reader and the transmitter through injection locking, the reader can also perform data transmission with multiple transmitters simultaneously, improving the communication efficiency.

[0037] In a fourth aspect, an embodiment of the present application provides a communication method applied to a communication system. The communication system includes a reader and multiple transmitters, and each of the transmitters includes a reflection circuit as described in any one of the embodiments in the first aspect. The method includes:

[0038] The reader sends downlink excitation signals to each of the multiple transmitters respectively, where the frequencies of the downlink excitation signals between any two of the transmitters are different;

[0039] The transmitter sends a modulated uplink reflection signal to the reader via the reflection circuit of the transmitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of a reflection circuit provided by an embodiment of the present application;

[0041] Figure 2 It is a schematic diagram of another reflection circuit provided by an embodiment of the present application;

[0042] Figure 3 It is a schematic diagram of a signal generation circuit provided by an embodiment of the present application;

[0043] Figure 4 It is a schematic diagram of a negative resistance circuit provided by an embodiment of the present application;

[0044] Figure 5 It is a schematic diagram of yet another reflection circuit provided by an embodiment of the present application;

[0045] Figure 6 It is a schematic diagram of yet another reflection circuit provided by an embodiment of the present application;

[0046] Figure 7A schematic diagram of a pulse signal provided by an embodiment of the present application;

[0047] Figure 8 Another schematic diagram of a reflection circuit provided by an embodiment of the present application;

[0048] Figure 9 A schematic diagram of a transceiver circuit provided by an embodiment of the present application;

[0049] Figure 10 Another schematic diagram of a transceiver circuit provided by an embodiment of the present application;

[0050] Figure 11 A schematic diagram of a communication system provided by an embodiment of the present application;

[0051] Figure 12 A schematic diagram of the flowchart of a communication method provided by an embodiment of the present application;

[0052] Figure 13 A schematic diagram of the flowchart of a communication method provided by an embodiment of the present application. Detailed implementation manners

[0053] First of all, it should be noted that the transmitter and the electronic tag involved in the present application are essentially the same in the RFID communication system and do not need to be distinguished in detail.

[0054] The following will introduce in detail the specific structure diagram of the reflection circuit applied to the transmitter or the electronic tag with reference to the accompanying drawings.

[0055] Refer to Figure 1 , Figure 1 A schematic diagram of a reflection circuit provided by an embodiment of the present application. The reflection circuit provided by the embodiment of the present application includes:

[0056] The reflection circuit includes a transceiver circuit 10, a transformer 20, a signal generation circuit 30, a control circuit 40, and a logic circuit 50.

[0057] Among them, the primary coil of the transformer 20 is connected to the transceiver circuit 10, the secondary coil of the transformer 20 is connected to the signal generation circuit 30, and the secondary coil and the signal generation circuit 30 are respectively connected to the control circuit 40, and the signal generation circuit 30 is connected to the logic circuit 50. Among them, the signal generation circuit 30 and the secondary coil of the transformer 20 form an oscillator, and this oscillator can be injection-locked with the reader, that is to say, the frequency of the output signal of this oscillator will be locked to the frequency of the RF signal sent by the reader, rather than oscillating following its own free oscillation frequency. In this way, it is ensured that the frequency of the reflection signal reflected by the transmitter is consistent with the frequency of the RF signal sent by the reader, so as to facilitate the reader to demodulate the reflection signal reflected by the transmitter.

[0058] Specifically, the logic circuit 50 is configured to generate a control signal and send the control signal to the control circuit 40;

[0059] The control circuit 40 is configured to adjust the amplitude of the output signal of the oscillator according to the control signal;

[0060] The logic circuit 50 is further configured to modulate the output signal of the oscillator when the amplitude of the output signal of the oscillator is the maximum;

[0061] The transceiver circuit 10 is configured to transmit the modulated output signal of the oscillator modulated by the logic circuit 50.

[0062] It can be seen that in the embodiment of the present application, the signal generating circuit 30 can form an oscillator with the secondary coil of the transformer. The control circuit 40 adjusts the amplitude of the output signal of the oscillator so that the oscillator can emit an output signal with the maximum amplitude, thereby causing injection locking between the oscillator and the reader-writer. In this way, it is ensured that the frequency of the reflected signal of the transmitter is consistent with the frequency of the RF signal transmitted by the reader-writer, facilitating the reader-writer to demodulate the reflected signal of the transmitter; and, due to injection locking, the transmitter can send a modulated signal with the maximum amplitude to the reader-writer, which can resist attenuation and increase the communication distance.

[0063] Refer to Figure 2 , Figure 2 which is a schematic diagram of another reflection circuit provided by the embodiment of the present application. The content that is the same as that in the embodiment shown in Figure 4 will not be described again here.

[0064] As Figure 2 shown, the signal generating circuit 30 includes a variable capacitor 301. The secondary coil is connected to the first port X1 and the second port X2 of the variable capacitor 301 in a differential manner, that is, the first port X1 and the second port X2 are respectively connected to the same-named end and the different-named end of the secondary coil, and the center tap of the secondary coil is grounded. Therefore, the control circuit 40 can adjust the capacitance value of the variable capacitor 301 through the control port X3 according to the control signal to adjust the amplitude of the output signal of the oscillator.

[0065] As Figure 3 shown, the signal generating circuit 30 further includes a negative resistance circuit 302 and a current source 303. Among them, the first port Y1 and the second port Y2 of the negative resistance circuit 302 are respectively connected to the first port X1 and the second port X2 of the variable capacitor 301, and the third port Y3 of the negative resistance circuit 302 is connected to the positive pole of the current source 303. The negative pole of the current source 303 is grounded, and the control port Z1 of the current source 303 is connected to the control circuit 40;

[0066] Among them, the negative resistance circuit 302 is used to compensate for the losses during the oscillation process of the oscillator, that is, the negative resistance circuit is used to generate negative resistance to offset the positive resistance generated by the oscillator during the oscillation process, so that the oscillator can continue to oscillate.

[0067] The logic circuit 50 is used to turn on or off the current source 303 when the output signal of the oscillator is at its maximum, adjust the amplitude of the output signal of the oscillator, modulate the output signal of the oscillator, and thus load the data information to be sent by the transmitter on the output signal of the oscillator.

[0068] Exemplarily, the logic circuit can modulate the output signal of the oscillator according to the data information to be sent to the reader (for example, the identity information of the electronic tag), so as to load the data information on the output signal of the oscillator.

[0069] Specifically, before the output signal of the oscillator reaches the maximum value, the output signal is not modulated. Therefore, the output signal of the oscillator sent by the transceiver circuit 10 does not carry any data information. Even if the reader receives this output signal, it cannot demodulate any content. When the output signal of the oscillator reaches the maximum, the logic circuit 50 modulates the output signal of the oscillator through the control circuit 40, that is, modulates the output signal by controlling the opening or closing of the current source 303. Exemplarily, for an electronic tag, the data information to be sent is to be sent in digital information, that is, to send data information in a bit string of 0s and 1s. Therefore, if the current bit to be sent is 1, the logic circuit 50 turns on the current source 303 through the control circuit 40. At this time, the amplitude of the output signal of the oscillator is relatively large. If the current bit to be sent is 0, the current source 303 can be turned off. At this time, the amplitude of the output signal of the oscillator is relatively small. Therefore, the output signal reflected by the electronic tag to the reader is a signal with alternating high and low amplitudes. In this way, the logic circuit 50 can make the output signal carry the data information to be sent by the electronic tag by modulating the amplitude of the output signal of the oscillator; after receiving such an output signal, the reader can demodulate according to the amplitude of the output signal to obtain the corresponding bit string of 0s and 1s. For example, the high-amplitude part is bit 1, and the low-amplitude part is bit 0, so as to enable the electronic tag to send data information to the reader when the amplitude of the output signal of the oscillator is at its maximum, and improve the communication distance.

[0070] Of course, in actual applications, it is also possible to let the output signal with a relatively small amplitude carry bit 1 and let the output signal with a relatively large amplitude carry bit 0. The present application does not limit the modulation method of the output signal.

[0071] Exemplarily, such as Figure 4As shown, the negative resistance circuit 302 includes a first MOS transistor 3021 and a second MOS transistor 3022. Among them, the first MOS transistor 3021 and the second MOS transistor 3022 can be N-channel or P-channel MOS transistors. In this application, P-channel MOS transistors are used as an example for illustration, but the type of MOS transistor is not limited. For example, junction field effect transistors can also be used in actual applications.

[0072] Specifically, the gate G of the first MOS transistor 3021 is connected to the drain D of the second MOS transistor 3022 and is connected to the first port X1 of the variable capacitor 301; the drain D of the first MOS transistor 3021 is connected to the gate G of the second MOS transistor 3022 and is connected to the second port X2 of the variable capacitor 301; the source S of the first MOS transistor 3021 is connected to the source S of the second MOS transistor 3022 and is connected to the positive pole of the current source 303.

[0073] Refer to Figure 5 , Figure 5 It is a schematic diagram of another reflection circuit according to an embodiment of the present application.

[0074] As Figure 5 shown, the control circuit 40 includes an amplitude detection circuit 401, a capacitance selection circuit 402, and an amplitude modulation circuit 403. Among them, one end of the amplitude detection circuit 401 is connected to the opposite-name end of the secondary coil, one end of the capacitance selection circuit 402 is connected to the control port X3 of the variable capacitor, and one end of the amplitude modulation circuit is connected to the control port Z4 of the current source 303; in addition, the other ends of the amplitude detection circuit 401, the capacitance selection circuit 402, and the amplitude modulation circuit 403 are all connected to the logic circuit 50.

[0075] The amplitude detection circuit 401 is configured to detect the amplitude of the output signal of the oscillator and feed back the amplitude of the output signal to the logic circuit; the logic circuit 50 is configured to generate the control signal and send the control signal to the capacitance selection circuit 402 when it is determined that the amplitude of the output signal of the oscillator does not reach the maximum, so that the capacitance selection circuit 402 adjusts the capacitance value of the variable capacitor 301, thereby adjusting the amplitude of the output signal of the oscillator. When the amplitude of the output signal of the oscillator reaches the maximum, a second control signal is generated and sent to the transceiver circuit 10, and the second control signal is used to instruct the transceiver circuit 10 to send the output signal of the oscillator to the reader; the amplitude modulation circuit 403 is configured to control the negative resistance circuit 302 to compensate for the loss of the oscillator during the oscillation process, that is, to control the negative resistance circuit 302 to compensate for the loss of the oscillator during the oscillation process through the control port Y4 of the negative resistance circuit 302.

[0076] Exemplarily, the logic circuit 50 controls the capacitance selection circuit 402 to adjust the capacitance value of the variable capacitor 301, and multiple adjustments may be required. Exemplarily, if the logic circuit 50 determines that the amplitude of the current output signal of the oscillator has not reached the maximum, it generates a control signal corresponding to the current adjustment and sends the control signal to the capacitance selection circuit 402. Then, the capacitance selection circuit 402 adjusts the capacitance value of the variable capacitor 301 according to the control signal; after adjusting the capacitance value of the variable capacitor 301; since the amplitude detection circuit 401 is connected to the secondary coil, the amplitude of the output signal of the oscillator can be obtained and sent to the logic circuit 50.

[0077] If the logic circuit 50 determines that the amplitude of the output signal after adjusting the capacitance value is greater than or equal to the amplitude of the current output signal, it continues to generate a new control signal and continues to adjust the capacitance value of the variable capacitor 301; if the logic circuit 50 determines that the amplitude of the output signal after adjusting the capacitance value is less than the amplitude of the current output signal, it determines the capacitance value before adjustment, which can make the amplitude of the output signal of the oscillator the largest. Therefore, the logic circuit 50 instructs the capacitance selection circuit 402 to restore the variable capacitor 301 to the capacitance value before adjustment, and modulates the output signal of the oscillator at this time through the amplitude modulation circuit 403, that is, controls the turning on or off of the current source through the amplitude modulation circuit 403, and modulates the output signal through the amplitude modulation.

[0078] Exemplarily, the control signal generated by the logic circuit 50 for the current adjustment indicates that the capacitance value of the variable capacitance value is increased by 10F. After the adjustment, if it is determined that the capacitance value before adjustment can make the output signal of the oscillator the largest, the capacitance selection circuit 401 is re-instructed to reduce the capacitance value of the variable capacitor 301 by 10F, so that the capacitance value of the variable capacitor 301 can be restored to the capacitance value before adjustment, and the amplitude of the output signal of the oscillator can reach the maximum.

[0079] Refer to Figure 6 , Figure 6 which is a schematic diagram of another reflection circuit provided by the embodiment of the present application.

[0080] As Figure 6 shown, the variable capacitor 301 is a switched capacitor array. The first port X1 of the switched capacitor array is connected to the same-name end of the secondary coil, the second port X2 of the switched capacitor array is connected to the different-name end of the secondary coil, and the gate of the first MOS transistor 3022 and the drain of the second MOS transistor are connected to the first port X of the switched capacitor array, and the drain of the first MOS transistor and the gate of the second MOS transistor are connected to the second port of the switched capacitor array.

[0081] Specifically, the switched-capacitor array includes N capacitor branch circuits, where N is an integer greater than or equal to 2. Each capacitor branch circuit is composed of a switching transistor and a capacitor connected in series. The switching transistor can be an N-channel or P-channel MOS transistor, and this application does not limit it. Here, an N-channel MOS transistor is taken as an example for illustration. Moreover, the types of the switching transistors in any two capacitor branch circuits can be the same or different, and the capacitance values of the two capacitors in any two capacitor branch circuits can be the same or different.

[0082] Exemplarily, the N capacitor branch circuits are connected in parallel, and the drains D of the switching transistors in the N capacitor branch circuits are connected to each other and connected to port Y1 of the negative resistance circuit; the source S of the switching transistor in each capacitor branch circuit is connected to one end of the capacitor in this capacitor branch circuit, and the other end of the capacitor is connected to port Y2 of the auxiliary circuit. The gate G of the switching transistor in each capacitor branch circuit is connected to control port X3, and a pulse signal is input to each switching transistor through this control port X3.

[0083] Therefore, the capacitor selection circuit 402 can input different pulse signals to the N capacitor branch circuits, so that some capacitor branch circuits are turned on and some capacitor branch circuits are turned off. Then, by changing the pulse signal input to a certain capacitor branch circuit, the conduction and cutoff of this capacitor branch circuit are controlled to change the number of capacitor branch circuits in the conduction state in the capacitor array, and further change the capacitance value of the variable capacitor 301.

[0084] Exemplarily, as Figure 7 shown, the pulse signal given by the capacitor selection circuit 402 to the first capacitor branch circuit is a high-level signal, and only the first capacitor branch circuit is turned on. At this time, the capacitance value of the variable capacitor is the capacitance value C1 of this capacitor branch circuit; then, the logic circuit 50 indicates that the capacitance value of the variable capacitor needs to be increased. At this time, the pulse signal given by the capacitor selection circuit 402 to the second capacitor branch circuit is also a high level, so that the first and second capacitor branch circuits are both turned on, and the capacitance value of the variable capacitor becomes C1 + C2, thereby increasing the capacitance value of the variable capacitor, and further increasing the amplitude of the output signal of the variable oscillator.

[0085] Therefore, the logic circuit 50 can send a control signal to the capacitor selection circuit 402, and this control signal includes the capacitance value that needs to be adjusted. The capacitor selection circuit 402 can then determine the capacitor branch circuits that need to be turned on or off according to the capacitance value that needs to be adjusted, so as to adjust the capacitance value of the variable capacitor 301.

[0086] Refer to Figure 8 , Figure 8 which is a schematic diagram of another reflection circuit provided by an embodiment of this application.

[0087] As shown Figure 8 in Figure 8 , the variable capacitor 301 is a voltage-controlled capacitor. Among them, the first port X1 of the voltage-controlled capacitor is connected to the same-named end of the secondary coil, the second port of the voltage-controlled capacitor is connected to the different-named end of the secondary coil, the gate of the first MOS transistor 3022, the drain of the second MOS transistor 3023 are connected to the first port X1 of the voltage-controlled capacitor, the drain of the first MOS transistor 3022 and the gate of the second MOS transistor 3022 are connected to the second port X2 of the voltage-controlled capacitor. And the control port X3 of the voltage-controlled capacitor is connected to the capacitor selection circuit 402. Therefore, the capacitor selection circuit 402 changes the capacitance value of the voltage-controlled capacitor by inputting different voltage values to the voltage-controlled capacitor.

[0088] Refer to Figure 9 , Figure 9 which is a schematic diagram of a transceiver circuit provided by an embodiment of the present application.

[0089] As shown Figure 9 in Figure 9 , the transceiver circuit 10 includes an antenna 101 and an impedance transformation circuit 102. One end of the impedance transformation circuit 102 is connected to the antenna 101, the other end of the impedance transformation circuit 102 is connected to the same-named end of the primary coil, and the different-named end of the primary coil is grounded; among them, the impedance transformation circuit 102 is used to perform impedance transformation on the modulated output signal of the oscillator to enhance the transmission power of the modulated output signal of the oscillator so as to resist attenuation.

[0090] It should be noted that the impedance transformation circuit 102 is optional. In actual applications, the impedance transformation circuit 102 may not be designed, and the antenna 101 may be directly connected to the same-named end of the primary coil.

[0091] Refer to Figure 10 , Figure 10 which is a schematic diagram of another transceiver circuit provided by an embodiment of the present application.

[0092] The transceiver circuit 10 includes a high-impedance differential antenna 103. One end of the high-impedance differential antenna 103 is connected to the same-named end of the primary coil, and the other end is connected to the different-named end of the primary coil. Compared with an ordinary antenna, the high-impedance differential antenna 103 has a built-in impedance transformation function. Therefore, there is no need to additionally design an impedance transformation circuit.

[0093] Refer to Figure 11 , Figure 11 which is a schematic diagram of a communication system provided by an embodiment of the present application. The communication system includes a reader 1401 and a plurality of transponders 1402, and each transponder 1402 includes the above-mentioned reflection circuit. Among them:

[0094] A reader-writer 1401 is used to send a downlink excitation signal to each of a plurality of reflectors 1402 respectively, wherein the frequencies of the downlink excitation signals between any two reflectors 1402 are different. The reader-writer 1401 can transmit downlink excitation signals with different frequencies to different reflectors 1402. As Figure 11 shown, the reader-writer 1401 can send a downlink excitation signal with a frequency of f1 to a reflector 1402 at time t1, and send a downlink excitation signal with a frequency of f2 to another transmitter at time t2, wherein f1 and f2 are different.

[0095] A reflector 1402 is used to send a modulated uplink reflection signal to the reader-writer 1401 through the reflection circuit of the reflector 1402, and the reflector 1402 is any one of the plurality of reflectors.

[0096] It can be understood that the amplitude of the modulated uplink reflection signal is the largest, and the frequency of the modulated uplink reflection signal of each reflector is the same as the frequency of the downlink excitation signal received by the reflector 1402. Specifically, after each reflector 1402 receives the downlink excitation signal sent by the reader-writer, it starts to adjust the capacitance value in the reflection circuit, so that the amplitude of the uplink reflection signal reflected by the reflector 1402 is the largest, that is, each reflector 1402 and the reader-writer 1401 are injection-locked. At this time, each reflector 1402 modulates the uplink reflection signal transmitted by itself by controlling the on or off of the current source, so that each reflector 1402 sends data information to the reader-writer through the modulated uplink reflection signal.

[0097] It can be seen that since injection locking occurs between each reflector 1402 and the reader-writer 1401, each reflector 1402 sends a modulated uplink reflection signal with a different frequency to the reader-writer, and the frequency of the modulated uplink and downlink reflection signals sent by each reflector 1402 is the same as the frequency of the downlink excitation signal received by the reflector 1402. Therefore, after the reader-writer receives the modulated reflection signals sent by a plurality of reflectors 1402, it can first filter out the modulated uplink reflection signals of each reflector 1402 through a filter, and demodulate the uplink reflection signal according to the amplitude of the modulated reflection signal to obtain the data information sent by each reflector 1402, realizing data transmission with a plurality of reflectors 1402 simultaneously and improving the communication efficiency.

[0098] Refer to Figure 12 , Figure 12Schematic diagram of a communication method provided by an embodiment of the present application. This method is applied to a transponder, i.e., an electronic tag. The transponder includes the reflection circuit in any of the above embodiments; the reflection circuit includes: a transceiver circuit, a transformer, a signal generation circuit, a control circuit, and a logic circuit; the transceiver circuit is connected to the primary coil of the transformer, and the secondary coil of the transformer is connected to the signal generation circuit; the secondary coil and the signal generation circuit are respectively connected to the control circuit, the control circuit is connected to the logic circuit, and the signal generation circuit and the secondary coil form an oscillator. The method includes the following steps:

[0099] 1201: The transponder generates a control signal.

[0100] Exemplarily, the control signal can be generated by the logic circuit in the transponder. Specifically, the logic circuit judges the amplitude of the output signal of the oscillator. When the amplitude of the output signal of the oscillator does not reach the maximum value, the control signal is generated and sent to the control circuit. Among them, the implementation process of judging the amplitude of the output signal of the oscillator can refer to the above implementation method and will not be described again.

[0101] 1202: The transponder adjusts the amplitude of the output signal of the oscillator according to the control signal.

[0102] Exemplarily, the transponder can adjust the amplitude of the output signal of the oscillator through the above control circuit. That is, through the control circuit, the capacitance value of the oscillator is adjusted according to the control signal, and then the amplitude of the output signal of the oscillator is adjusted. Among them, the implementation process of adjusting the capacitance value of the oscillator can refer to the above implementation process and will not be described again.

[0103] 1203: When the amplitude of the output signal of the oscillator is the largest, the transponder modulates the output signal of the oscillator.

[0104] The transponder can modulate the output signal of the oscillator by controlling the current source. For the specific modulation of the output signal of the oscillator, refer to the above modulation process and will not be described again.

[0105] 1204: The transponder sends the modulated output signal of the oscillator.

[0106] It can be seen that when the transponder makes the output signal of the oscillator the largest, that is, when the oscillator is locked with the reader / writer, the output signal of the oscillator is modulated, that is, the data information to be sent by the transponder is loaded on the output signal. Therefore, the electronic tag can send data information to the reader / writer with the output signal of the maximum amplitude, and thus can resist attenuation and increase the communication distance of RFID.

[0107] Refer to Figure 13 , Figure 13Schematic flowchart of a communication method provided by an embodiment of this application. This method is applied to a communication system. The communication system includes a reader-writer and multiple reflectors, where each reflector includes the above-mentioned reflection circuit. This method includes the following steps:

[0108] 1301: The reader-writer sends a downlink excitation signal to each of the multiple reflectors respectively.

[0109] Among them, the frequencies of the downlink excitation signals between any two reflectors are different.

[0110] 1302: The reflector sends a modulated uplink reflection signal to the reader-writer through the reflection circuit of the reflector.

[0111] Each reflector sends a modulated uplink transmission signal to the reader-writer through its respective reflection circuit. Among them, the implementation manner of the modulated uplink reflection signal sent by each reflector can refer to the above process and will not be described again.

[0112] Therefore, the amplitude of the modulated reflection signal sent by each reflector is the largest, and the frequency of the modulated uplink reflection signal of each reflector is the same as the frequency of the downlink excitation signal received by the reflector, that is, each reflector is injection-locked to the reader-writer respectively.

[0113] It can be seen that the reader-writer can send multiple downlink excitation signals with different frequencies to multiple reflectors, and each reflector is injection-locked to the reader-writer respectively by adjusting the capacitance value. Therefore, each reflector can send a modulated uplink reflection signal with a different frequency to the reader-writer. Therefore, after receiving the reflection signals sent by multiple reflectors, the reader-writer can first filter out the modulated uplink reflection signal sent by each reflector through a filter, and then demodulate according to the modulated uplink reflection signal to obtain the data information sent by each reflector, so that the reader-writer can realize data transmission with multiple reflectors simultaneously and improve communication efficiency.

[0114] In the embodiments of this application, "at least one" refers to one or more, and "multiple" refers to two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one (item)" or similar expressions below refer to any combination of these items, including any combination of single item (item) or multiple items (items). For example, at least one (item) of a, b, or c can represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, c can be single or multiple.

[0115] Also, unless otherwise stated, the ordinal numbers such as "first" and "second" mentioned in the embodiments of the present application are used to distinguish multiple objects, and are not used to limit the order, time sequence, priority or importance degree of the multiple objects. For example, the first information and the second information are only used to distinguish different information, rather than indicating differences in the content, priority, sending order or importance degree of these two types of information.

[0116] The above has introduced the embodiments of the present application in detail. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A reflection circuit, characterized in that, it includes: a transceiver circuit, a transformer, a signal generation circuit, a control circuit, and a logic circuit; The main coil of the transformer is connected to the transceiver circuit, the secondary coil of the transformer is connected to the signal generation circuit, and the signal generation circuit and the secondary coil form an oscillator; the secondary coil and the signal generation circuit are respectively connected to the control circuit, and the control circuit is connected to the logic circuit, where: The logic circuit is used to generate a control signal; The control circuit is used to adjust the amplitude of the output signal of the oscillator according to the control signal; The logic circuit is further used to modulate the output signal of the oscillator when the amplitude of the output signal of the oscillator is the largest; The transceiver circuit is used to transmit the output signal of the oscillator modulated by the logic circuit.

2. The circuit according to claim 1, characterized in that, The signal generation circuit includes a variable capacitor, the first port and the second port of the variable capacitor are respectively connected to the secondary coil, and the control port of the variable capacitor is connected to the control circuit; The control circuit is specifically used for: adjusting the capacitance value of the variable capacitor according to the control signal to adjust the amplitude of the output signal of the oscillator.

3. The circuit according to claim 2, characterized in that, The signal generation circuit further includes a negative resistance circuit and a current source, the first port and the second port of the negative resistance circuit are respectively connected to the first port and the second port of the variable capacitor, the third port of the negative resistance circuit is connected to the positive pole of the current source, the negative pole of the current source is grounded, and the control port of the current source is connected to the control circuit; The negative resistance circuit is used to compensate for the loss of the oscillator during the oscillation process; The logic circuit is used to turn on or off the current source when the output signal of the oscillator is the largest, adjust the amplitude of the output signal of the oscillator, and modulate the output signal of the oscillator.

4. The circuit according to claim 3, characterized in that, The control circuit includes an amplitude detection circuit, a capacitance selection circuit, and an amplitude modulation circuit; One end of the amplitude detection circuit is connected to the opposite-name end of the secondary coil, one end of the capacitance selection circuit is connected to the control port of the variable capacitor, one end of the amplitude modulation circuit is connected to the control port of the current source, and the other ends of the amplitude detection circuit, the capacitance selection circuit, and the amplitude modulation circuit are all connected to the logic circuit; The amplitude detection circuit is used to detect the amplitude of the output signal of the oscillator; The logic circuit is used to generate the control signal when the amplitude of the output signal of the oscillator does not reach the maximum; The capacitance selection circuit is used to adjust the capacitance value of the variable capacitor according to the control signal; The logic circuit is used to turn on or off the current source through the amplitude modulation circuit when the output signal of the oscillator is at its maximum, so as to adjust the amplitude of the output signal of the oscillator and modulate the output signal of the oscillator.

5. The circuit according to claim 3 or 4, wherein, the negative resistance circuit includes a first MOS transistor and a second MOS transistor; the gate of the first MOS transistor is connected to the drain of the second MOS transistor and is connected to the first port of the variable capacitor; the drain of the first MOS transistor is connected to the gate of the second MOS transistor and is connected to the second port of the variable capacitor; the source of the first MOS transistor is connected to the source of the second MOS transistor and is connected to the positive pole of the current source.

6. The circuit according to claim 5, wherein, the variable capacitor includes a switched capacitor array or a voltage-controlled capacitor; when the variable capacitor is a switched capacitor array, the first port and the second port of the variable capacitor are respectively connected to the secondary coil, specifically including: the first port of the switched capacitor array is connected to the same-named end of the secondary coil, and the second port of the switched capacitor array is connected to the opposite-named end of the secondary coil; the first port and the second port of the negative resistance circuit are respectively connected to the first port and the second port of the variable capacitor, specifically including: the gate of the first MOS transistor and the drain of the second MOS transistor are connected to the first port of the switched capacitor array; the drain of the first MOS transistor and the gate of the second MOS transistor are connected to the second port of the switched capacitor array; when the variable capacitor is a voltage-controlled capacitor, the first port and the second port of the variable capacitor are respectively connected to the secondary coil, specifically including: the first port of the voltage-controlled capacitor is connected to the same-named end of the secondary coil, and the second port of the voltage-controlled capacitor is connected to the opposite-named end of the secondary coil; the first port and the second port of the negative resistance circuit are respectively connected to the first port and the second port of the variable capacitor, specifically including: the gate of the first MOS transistor, the drain of the second MOS transistor are connected to the first port of the voltage-controlled capacitor, and the drain of the first MOS transistor and the gate of the second MOS transistor are connected to the second port of the voltage-controlled capacitor.

7. The circuit according to claim 6, wherein, the transceiver circuit includes an antenna and an impedance transformation circuit. One end of the impedance transformation circuit is connected to the antenna, and the other end of the impedance transformation circuit is connected to the same-named end of the primary coil, and the opposite-named end of the primary coil is grounded; the impedance transformation circuit is used to perform impedance transformation on the modulated output signal of the oscillator to enhance the transmission power of the output signal of the oscillator.

8. The circuit according to claim 6, wherein, the transceiver circuit includes a high-impedance differential antenna. One end of the high-impedance differential antenna is connected to the same-named end of the primary coil, and the other end of the high-impedance differential antenna is connected to the opposite-named end of the primary coil.

9. A communication method, wherein, Applied to a transmitter, the transmitter includes an oscillator, and the method includes: Generating a control signal; Adjusting the amplitude of the output signal of the oscillator according to the control signal; Modulating the output signal of the oscillator when the amplitude of the output signal of the oscillator is maximum; Transmitting the modulated output signal of the oscillator.

10. The method according to claim 9, wherein, the oscillator includes a variable capacitor, and the adjusting the amplitude of the output signal of the oscillator according to the control signal includes: Adjusting the capacitance value of the variable capacitor according to the control signal to adjust the amplitude of the output signal of the oscillator.

11. The method according to claim 9 or 10, wherein, the transmitter includes a current source, and the method further includes: A negative resistance circuit compensates for the loss of the oscillator during oscillation; The modulating the output signal of the oscillator when the amplitude of the output signal of the oscillator is maximum includes: When the output signal of the oscillator is maximum, turning on or off the current source to adjust the amplitude of the output signal of the oscillator so as to modulate the output signal of the oscillator.

12. The method according to claim 11, wherein, the generating the control signal includes: Detecting the amplitude of the output signal of the oscillator; Generating the control signal when the amplitude of the output signal of the oscillator does not reach the maximum.

13. A communication system, wherein, it includes: The communication system includes a reader and a plurality of transmitters, and each transmitter includes a reflection circuit according to any one of claims 1-8; The reader is configured to send a downlink excitation signal to each of the plurality of transmitters respectively, wherein the frequencies of the downlink excitation signals between any two of the transmitters are different; The transmitter is configured to send a modulated uplink reflection signal to the reader through the reflection circuit of the transmitter.

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