Method and device for obtaining impedance

Abstract

The present application provides a method and device for obtaining impedance, which can effectively obtain the impedance of an antenna and its impedance matching circuit. The method is applied to an antenna and its impedance matching circuit, wherein the impedance matching circuit is connected between the antenna and a near field communication NFC chip, wherein the NFC chip includes a transmitting circuit and a receiving circuit, and the method includes: obtaining NFC data output by the NFC chip, wherein the NFC data includes average power supply current TXI data of its power supply output by the transmitting circuit, and / or field signal strength indication FSSI data output by the receiving circuit; and determining the impedance of the antenna and the impedance matching circuit according to the NFC data.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of NFC, and more specifically, to a method and device for obtaining impedance. Background Art

[0002] Near Field Communication (NFC) chips receive and send wireless signals through antennas. An impedance matching circuit is provided between the NFC chip and the antenna to match the impedance of the antenna to ensure the antenna's transceiver performance. Usually, the impedance matching circuit needs to be debugged based on the impedance of the antenna and its impedance matching circuit. Therefore, how to effectively detect the impedance of the antenna and its impedance matching circuit has become a problem that needs to be solved. Summary of the invention

[0003] The embodiments of the present application provide a method and device for obtaining impedance, which can effectively obtain the impedance of an antenna and its impedance matching circuit.

[0004] In a first aspect, a method for obtaining impedance is provided, the method being applied to an antenna and an impedance matching circuit thereof, the impedance matching circuit being connected between the antenna and a near field communication NFC chip, the NFC chip comprising a transmitting circuit and a receiving circuit, the method comprising: obtaining NFC data output by the NFC chip, the NFC data comprising average power supply current TXI data of its power supply output by the transmitting circuit, and / or FSSI data output by the receiving circuit; and determining the impedance of the antenna and the impedance matching circuit according to the NFC data.

[0005] In one implementation, a first port of the transmitting circuit is connected to a first end of a first device in the impedance matching circuit, a first port of the receiving circuit is connected to a second end of the first device via a peripheral circuit, a second port of the transmitting circuit is connected to a first end of a second device in the impedance matching circuit, a second port of the receiving circuit is connected to a second end of the second device via a peripheral circuit, and a matching subcircuit formed by a portion of the impedance matching circuit other than the first device and the second device is connected to a second end of the first device and a second end of the second device.

[0006] In one implementation, at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the receiving circuit is disconnected, and a matching subcircuit formed by a portion of the impedance matching circuit other than the first device is connected to the second end of the first device.

[0007] In one implementation, the NFC data includes the TXI data and the FSSI data, and determining the impedance of the antenna and the impedance matching circuit according to the NFC data includes: determining a current value of the average power supply current according to the TXI data; determining an effective value of a voltage on an equivalent impedance formed by the matching subcircuit and the antenna according to the FSSI data; and determining a real part and an imaginary part of the impedance according to the current value of the average power supply current and the effective value of the voltage on the equivalent impedance.

[0008] In one implementation, determining the real part and the imaginary part of the impedance according to the current value of the average power supply current and the effective value of the voltage on the equivalent impedance includes:

[0009] The real part of the impedance is determined based on the current value of the average supply current and the following formula:

[0010] as well as,

[0011] The imaginary part of the impedance of the antenna and the impedance matching circuit is determined according to the current value of the average supply current, the effective value of the voltage on the equivalent impedance and the following formula:

[0012]

[0013] Wherein, VDD is the voltage of the power supply of the transmitting circuit, I avg1 and I avg2 The transmitting circuit has an internal resistance of R S1 and R S2 The current value of the average supply current, V rx1 and V rx2 The transmitting circuit has an internal resistance of R S1 and R S2 The effective value of the voltage on the equivalent impedance when

[0014] When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device;

[0015] When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V Sis the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

[0016] In one implementation, the receiving circuit has a function of detecting phase information, the NFC data includes the FSSI data, and determining the impedance of the antenna and the impedance matching circuit according to the NFC data includes: determining an effective value of a voltage on an equivalent impedance formed by the matching subcircuit and the antenna according to the FSSI data, and determining a phase difference between a phase value of the voltage on the equivalent impedance and a predetermined phase value; and determining a real part and an imaginary part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance and the phase difference.

[0017] In one implementation, when the first port of the transmitting circuit and the second port of the transmitting circuit are respectively connected to the first end of the first device and the first end of the second device, the predetermined phase value is the phase value of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected; when at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device, the predetermined phase value is the phase value of the voltage of the at least one port to ground when the impedance matching circuit is not connected.

[0018] In one implementation, determining the real part and the imaginary part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance and the phase difference includes:

[0019] The real part of the impedance of the antenna and the impedance matching circuit is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula:

[0020]

[0021] as well as,

[0022] The imaginary part of the impedance of the antenna and the impedance matching circuit is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula:

[0023]

[0024] Among them, V rx is the effective value of the voltage on the equivalent impedance, R S is the internal resistance of the transmitting circuit, is the phase difference;

[0025] When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device;

[0026] When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

[0027] In one implementation, the method further includes: when the transmitting circuit sequentially outputs signals of multiple frequencies within a specific frequency range, respectively obtaining multiple impedances of the impedance matching circuit at the multiple frequencies; and determining an impedance curve representing the impedance variation of the antenna and the impedance matching circuit with frequency based on a correspondence between the multiple impedances and the multiple frequencies.

[0028] In one implementation, the method further includes: debugging the impedance matching circuit according to the impedance curve.

[0029] In one implementation, the impedance matching circuit includes multiple devices, and the types of the multiple devices include at least one of inductance, resistance and capacitance, wherein the first device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel, and the second device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel.

[0030] In a second aspect, a device for obtaining impedance is provided, the device is applied to an antenna and an impedance matching circuit thereof, the impedance matching circuit is connected between the antenna and a near field communication NFC chip, the NFC chip includes a transmitting circuit and a receiving circuit, the device includes: an information acquisition module, used to obtain NFC data output by the NFC chip, the NFC data including average power supply current TXI data of its power supply output by the transmitting circuit, and / or FSSI data output by the receiving circuit; and an information processing module, used to determine the impedance of the antenna and the impedance matching circuit according to the NFC data.

[0031] In one implementation, a first port of the transmitting circuit is connected to a first end of a first device in the impedance matching circuit, a first port of the receiving circuit is connected to a second end of the first device via a peripheral circuit, a second port of the transmitting circuit is connected to a first end of a second device in the impedance matching circuit, a second port of the receiving circuit is connected to a second end of the second device via a peripheral circuit, and a matching subcircuit formed by a portion of the impedance matching circuit other than the first device and the second device is connected to a second end of the first device and a second end of the second device.

[0032] In one implementation, at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the receiving circuit is disconnected, and a matching subcircuit formed by a portion of the impedance matching circuit other than the first device is connected to the second end of the first device.

[0033] In one implementation, the information processing module is specifically used to: determine the current value of the average power supply current based on the TXI data; determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit and the antenna based on the FSSI data; determine the real part and imaginary part of the impedance of the antenna and the impedance matching circuit based on the current value of the average power supply current and the effective value of the voltage on the equivalent impedance.

[0034] In one implementation, the information processing module is specifically used to determine the real part of the impedance of the antenna and the impedance matching circuit according to the current value of the average power supply current and the following formula:

[0035] as well as,

[0036] The imaginary part of the impedance of the antenna and the impedance matching circuit is determined according to the current value of the average supply current, the effective value of the voltage on the equivalent impedance and the following formula:

[0037]

[0038] Wherein, VDD is the voltage of the power supply of the transmitting circuit, I avg1 and I avg2 The transmitting circuit has an internal resistance of R S1 and R S2 The current value of the average supply current, V rx1 and V rx2 The transmitting circuit has an internal resistance of R S1 and R S2The effective value of the voltage on the equivalent impedance when

[0039] When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device;

[0040] When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

[0041] In one implementation, the receiving circuit has a function of detecting phase information, and the information processing module is specifically used to: determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit and the antenna according to the FSSI data, and determine the phase difference between the phase value of the voltage on the equivalent impedance and a predetermined phase value; determine the real part and imaginary part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance and the phase difference.

[0042] In one implementation, when the first port of the transmitting circuit and the second port of the transmitting circuit are respectively connected to the first end of the first device and the first end of the second device, the predetermined phase value is the phase value of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected; when at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device, the predetermined phase value is the phase value of the voltage of the at least one port to ground when the impedance matching circuit is not connected.

[0043] In one implementation, the information processing module is specifically used to determine the real part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula:

[0044]

[0045] as well as,

[0046] The imaginary part of the impedance of the antenna and the impedance matching circuit is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula:

[0047]

[0048] Among them, V rx is the effective value of the voltage on the equivalent impedance, R S is the internal resistance of the transmitting circuit, is the phase difference;

[0049] When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device;

[0050] When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

[0051] In one implementation, the information processing module is further used to: when the transmitting circuit sequentially outputs signals of multiple frequencies within a specific frequency range, respectively obtain multiple impedances of the impedance matching circuit at the multiple frequencies; and determine an impedance curve representing the impedance variation of the antenna and the impedance matching circuit with frequency based on the correspondence between the multiple impedances and the multiple frequencies.

[0052] In one implementation, the impedance curve is used to debug the impedance matching circuit.

[0053] In one implementation, the impedance matching circuit includes multiple devices, and the types of the multiple devices include at least one of inductance, resistance and capacitance, wherein the first device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel, and the second device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel.

[0054] In a third aspect, a device for acquiring impedance is provided, the device comprising a processor and a memory, the memory being used to store instructions, and the processor being used to read the instructions and execute the method for acquiring impedance described in the first aspect or any possible implementation of the first aspect.

[0055] In a fourth aspect, an electronic device is provided, comprising: an NFC chip; an impedance matching network arranged between the NFC chip and an antenna; and an apparatus according to the second aspect or any possible implementation of the second aspect, or an apparatus according to the third aspect or any possible implementation of the third aspect, for obtaining the impedance of the antenna and the impedance matching network.

[0056] In the embodiment of the present application, by acquiring NFC data from the NFC chip, including the average power supply current TXI data of the power supply output by the transmitting circuit in the NFC chip, and / or the FSSI data output by the receiving circuit in the NFC chip, the impedance of the NFC antenna and its impedance matching circuit is calculated according to these NFC data, and then an impedance curve of the impedance changing with frequency can be obtained. In this way, when it is necessary to obtain the impedance curve to debug the impedance matching circuit based on the impedance curve, there is no need to disassemble the device and introduce flying wires, which avoids the problem of impedance deviation caused by flying wires causing a decrease in matching performance, and effectively improves the debugging efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic flow chart of the method for obtaining impedance according to an embodiment of the present application.

[0058] Figure 2 It is a schematic diagram of a possible architecture of an impedance matching circuit according to an embodiment of the present application.

[0059] Figure 3 is a schematic diagram of another possible impedance matching circuit architecture of an embodiment of the present application.

[0060] Figure 4 It is a schematic diagram of the architecture of another possible impedance matching circuit according to an embodiment of the present application.

[0061] Figure 5 yes Figure 2 A possible specific implementation of the architecture of the impedance matching circuit shown.

[0062] Figure 6 yes Figure 3 A possible specific implementation of the architecture of the impedance matching circuit shown.

[0063] Figure 7 yes Figure 4A possible specific implementation of the architecture of the impedance matching circuit shown.

[0064] Figure 8 is based on Figures 2 to 7 The obtained equivalent circuit diagram.

[0065] Fig. 9 It is a schematic diagram of the curve showing the real part of the impedance of the antenna and its impedance matching circuit changing with frequency.

[0066] Fig.10 It is a schematic diagram of the curve showing the imaginary part of the impedance of the antenna and its impedance matching circuit changing with frequency.

[0067] Fig.11 It is a schematic diagram of the Smith chart of the impedance of the antenna and its impedance matching circuit.

[0068] Fig.12 It is a schematic block diagram of a device for obtaining impedance according to an embodiment of the present application. DETAILED DESCRIPTION

[0069] The technical solution in this application will be described below in conjunction with the accompanying drawings.

[0070] An impedance matching circuit is set between the NFC chip and the antenna to match the impedance of the antenna to ensure the antenna's transceiver performance. The debugging of the impedance matching network needs to be carried out in the whole machine environment. Since the impedance matching network is set on the motherboard of the terminal device, it is generally necessary to disassemble the whole terminal device and its motherboard, lead out the flying wire from the port of the impedance matching network, and connect it to the network analyzer to measure the impedance of the antenna and its impedance matching network to determine whether it meets the matching requirements. If the matching degree does not meet the requirements, the above process needs to be repeated many times, which is time-consuming and labor-intensive, and it is easy to damage the motherboard. At the same time, the flying wire will also introduce a certain deviation, which will cause deviations in the debugging results and reduce the impedance matching performance.

[0071] To this end, the present application aims to provide a method for obtaining the impedance of an antenna and its impedance matching network, so as to solve the problem that the impedance of an antenna and its impedance matching network cannot be detected efficiently and accurately. By obtaining NFC data from an NFC chip, including the average power supply current TXI data of its power supply output by the transmitting circuit in the NFC chip, and / or the FSSI data output by the receiving circuit, the impedance of the NFC antenna and its impedance matching circuit is calculated based on these NFC data. When it is necessary to obtain an impedance curve to debug the impedance matching circuit based on the impedance curve, there is no need to disassemble the device multiple times and introduce flying wires, thereby avoiding the problem of impedance deviation caused by flying wires causing a decrease in matching performance, and effectively improving the debugging efficiency and accuracy.

[0072] In addition, in the mass production process, the impedance deviation caused by the consistency problem between the antenna and the peripheral matching device is usually determined by measuring the power consumption of the transmitting circuit of the NFC chip or the matching frequency deviation, which is not intuitive enough. The method of the present application can also more accurately determine the impedance deviation caused by the consistency problem between the antenna and the peripheral matching device during mass production testing.

[0073] Figure 1 FIG. 2 is a schematic flow chart of a method for obtaining impedance according to an embodiment of the present application. Figure 1 As shown, the method 100 for obtaining impedance is applied to the antenna 400 and its impedance matching circuit 200. The impedance matching circuit 200 is connected between the antenna 400 and the NFC chip 300. The NFC chip 300 includes a transmitting (Transmit, TX) circuit 310 and a receiving (Receive, RX) circuit 320. Figure 1 As shown, method 100 includes some or all of the following steps.

[0074] In step 110 , NFC data output by the NFC chip 300 is acquired.

[0075] The NFC data includes average power supply current TXI data of the power supply output by the transmitting circuit 310 and / or Field Signal Strength Indication (FSSI) data output by the receiving circuit 320 .

[0076] In step 120 , the impedance of the antenna 400 and its impedance matching circuit 200 are determined according to the NFC data.

[0077] It can be understood that the NFC data is, for example, data represented in the form of a binary information unit 0 or 1, including data output by the transmitting circuit 310 for representing the average power supply current of its power supply (recorded as TXI data), and / or FSSI data output by the receiving circuit 320. The TXI data and the FSSI data are, for example, data processed by an analog to digital converter (ADC) output by the transmitting circuit 310 and the receiving circuit 320, respectively.

[0078] In an embodiment of the present application, by acquiring NFC data from the NFC chip 300, including TXI data output by the transmitting circuit 310 in the NFC chip 300, and / or FSSI data output by the receiving circuit 320, the impedance of the antenna 400 and its impedance matching circuit 200 are calculated based on these NFC data, and then an impedance curve of impedance variation with frequency can be obtained. In this way, when it is necessary to obtain an impedance curve to debug the impedance matching circuit 200 based on the impedance curve, there is no need to disassemble the device multiple times and introduce flying wires, thereby avoiding the problem of impedance deviation caused by flying wires causing a decrease in matching performance, and effectively improving debugging efficiency and accuracy. Moreover, during mass production testing, the impedance deviation caused by the consistency problem between the peripheral matching device and the antenna 400 can be more accurately determined based on the impedance curve.

[0079] It can be understood that in step 120, the impedance obtained according to the NFC data is the total impedance of the antenna 400 and the impedance matching circuit 200. Hereinafter, the impedance of the antenna 400 and the impedance matching circuit 200 refers to the total impedance of the two.

[0080] The impedance matching circuit 200 is connected between the NFC chip 300 and the antenna 400, a port of the transmitting circuit 310 in the NFC chip 300 is connected to one end of a specific device in the impedance matching circuit 200, a port of the receiving circuit 320 in the NFC chip 300 is connected to the other end of the specific device through its peripheral circuit, and other parts of the impedance matching circuit 200 except the specific device form a matching sub-circuit 220, and the matching sub-circuit 220 is connected to the other end of the specific device.

[0081] The TXI data can be used to determine the current value I of the average power supply current of the power supply of the transmitting circuit 310. avg , that is I avg =f(TXI data), where f represents the current value I used to convert the TXI data into the average power supply current of the transmitting circuit 310 avg The operational relationship, or functional relationship.

[0082] The FSSI data can be used to determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400, such as the effective value of the fundamental component of the voltage, that is, V rx =g(FSSI data), where g represents the operational relationship or functional relationship used to convert the FSSI data into the effective value of the voltage on the equivalent impedance.

[0083] If the receiving circuit 320 has a function of detecting phase information, the FSSI data can also be used to determine the phase difference between the phase value of the voltage on the equivalent impedance and a predetermined phase value, where the predetermined phase value is the phase value of the voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected, or the phase value of the voltage between the first port TXP or the second port TXN to the ground when the impedance matching circuit 200 is not connected, that is, (FSSI data), It represents the operation relationship, or functional relationship, used to convert the FSSI data into the phase difference.

[0084] For example, the receiving circuit 320 includes an IQ demodulation module, and the IQ demodulation module has the function of demodulating the phase information from the FSSI data. (FSSI data), the phase information of the voltage on the equivalent impedance can be obtained.

[0085] The impedance matching circuit 200 includes a plurality of devices, the types of which include at least one of an inductor, a resistor, and a capacitor. As an example, Figures 2 to 4 Schematic diagram of several possible impedance matching circuit 200 architectures provided in the embodiments of the present application. Figure 2 It is a differential matching architecture. Figure 3 It is a balun architecture with a single-ended antenna. Figure 4 It is a structure without balun and matched with a single-ended antenna.

[0086] like Figure 2 and Figure 3 As shown, the first port TXP of the transmitting circuit 310 is connected to the first end of the first device 211 in the impedance matching circuit 200 (the left end in the figure), the first port RXP of the receiving circuit 320 is connected to the second end of the first device 211 (the right end in the figure) via the peripheral circuit 321, the second port TXN of the transmitting circuit 310 is connected to the first end of the second device 212 in the impedance matching circuit 200 (the left end in the figure), the second port RXN of the receiving circuit 320 is connected to the second end of the second device 212 (the right end in the figure) via the peripheral circuit 322, and the portion of the impedance matching circuit 200 other than the first device 211 and the second device 212 forms a matching sub-circuit 220, and the matching sub-circuit 220 is connected to the second end of the first device 211 and the second end of the second device 212.

[0087] like Figure 4As shown, at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to the first end (the left end in the figure) of the first device 211 in the impedance matching circuit 200, the first port RXP of the receiving circuit 320 is connected to the second end (the right end in the figure) of the first device 211 via the peripheral circuit 321, the second port RXN of the receiving circuit 320 is disconnected, and the portion of the impedance matching circuit 200 other than the first device 211 forms a matching sub-circuit 220, and the matching sub-circuit 220 is connected to the second end of the first device 211.

[0088] It should be understood that, as an example, Figure 4 The first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 shown in the figure are both connected to the first end of the first device 211. In other implementations, only the first port TXP may be connected to the first end of the first device 211 or only the second port TXN may be connected to the first end of the first device 211.

[0089] The first device 211 is one of the multiple devices in the impedance matching circuit 200 or a combination of at least two of the multiple devices connected in series or in parallel. The second device 212 is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel.

[0090] The first device 211 may be any one of an inductor, a resistor and a capacitor, or a combination of any several of them connected in series or in parallel. The second device 212 may be any one of an inductor, a resistor and a capacitor, or a combination of any several of them connected in series or in parallel.

[0091] As Figure 2 A possible specific implementation method is as follows: Figure 5 As shown, the impedance matching circuit 200 is a differential matching architecture, and the impedance matching circuit 200 includes an inductor L0, a capacitor C0, a capacitor C1, a capacitor C2, and a resistor R q The number of each device is 2 and they are symmetrically distributed. Inductor L0 and capacitor C0 can realize filtering function, capacitor C1 and capacitor C2 are used for impedance matching, and resistor R q The Q value of the antenna can be reduced. The first device 211 and the second device 212 are both inductors L0, and the remaining capacitors C0, C1, C2 and R q The matching subcircuit 220 and the antenna 400 form an equivalent impedance. E The resistor R connected to the first port RXP A and capacitor C A The peripheral circuit 321 of the receiving circuit 320 is formed, and the resistor R connected to the second port RXN Band capacitor C B The peripheral circuit 322 of the receiving circuit 320 is formed.

[0092] As Figure 3 A possible specific implementation method is as follows: Figure 6 As shown, the impedance matching circuit 200 is a balun structure, and the impedance matching circuit 200 includes an inductor L0, a capacitor C0, a capacitor C1, a capacitor C2, and a resistor R q and balun, where the number of inductors L0 and capacitors C0 is 2 and symmetrically distributed. Inductors L0 and capacitors C0 can achieve filtering functions, capacitors C1 and C2 are used for impedance matching, and resistors R q The Q value of the antenna can be reduced. The first device 211 and the second device 212 are both inductors L0, and the remaining capacitors C0, C1, C2 and R q The matching subcircuit 220 and the antenna 400 form an equivalent impedance. E The resistor R connected to the first port RXP A and capacitor C A The peripheral circuit 321 of the receiving circuit 320 is formed, and the resistor R connected to the second port RXN B and capacitor C B The peripheral circuit 322 of the receiving circuit 320 is formed.

[0093] As Figure 4 A possible specific implementation method is as follows: Figure 7 As shown, the impedance matching circuit 200 is a structure without a balun, and the impedance matching circuit 200 includes an inductor L0, a capacitor C0, a capacitor C1, a capacitor C2, and a resistor R q Inductor L0 and capacitor C0 can realize filtering function, capacitor C1 and capacitor C2 are used for impedance matching, and resistor R q The Q value of the antenna can be reduced. The first component 211 is the inductor L0, and the remaining capacitors C0, C1, C2 and R q The components form a matching sub-circuit 220 . Figure 7 It is taken as an example that both the first port TXP and the second port TXN are connected to the inductor L0. In practical applications, only one of TXP and TXN may be connected to the inductor L0. The equivalent impedance formed by the matching subcircuit 220 and the antenna 400 is denoted as Z E The resistor R connected to the first port RXP A and capacitor C A The peripheral circuit 321 forming the receiving circuit 320 has the second port RXN disconnected. Figure 7 This is just an example. Of course, a resistor R may also be connected between the second port RXN and the inductor L0. Band capacitor C B The peripheral circuit 322 is formed and the first port RXP is disconnected.

[0094] Understandably, Figures 2 to 4 The circuit structure shown in the block diagram can also have Figures 5 to 7 Other forms than those shown, as long as the circuit topology can meet Figures 2 to 4 The connection relationship shown can be used to obtain the impedance of the antenna 400 and its impedance matching circuit 200 by applying the method described in the embodiment of the present application.

[0095] According to the above Figures 2 to 7 , we can get Figure 8 The equivalent circuit diagram is shown in Figure 1. Figure 8 As shown, V S is the effective value of the voltage between the first port TXP and the second port TXN at a specific frequency point when the NFC chip 300 is not connected to the impedance matching circuit 200, for example, the effective value of the fundamental wave component of the voltage, refer to Figure 2 and Figure 3 The architecture shown; or, V S is the effective value of the voltage between at least one of the first port TXP and the second port TXN and the ground at a specific frequency point when the NFC chip 300 is not connected to the impedance matching circuit 200, for example, the effective value of the fundamental wave component of the voltage, refer to Figure 4 The architecture shown. S is the internal resistance of the transmitting circuit 310, which is usually adjustable. L +jX L is the series impedance of the impedance of the first device 211 and the impedance of the second device 212, with reference to Figure 2 and Figure 3 The architecture shown; or, R L +jX L is the impedance of the first device 211, and Figure 4 The remaining part of the impedance matching circuit except the first device 211 and the second device 212 forms a matching subcircuit 220. The impedance of the equivalent circuit formed by the matching subcircuit 220 and the antenna 400 is denoted as Z E . Z E The voltage on Figure 8 The voltage between the node A1 and the node A2 in FIG. 1 is the connection point between the matching subcircuit 220 and the first device 211, and the connection point between the matching subcircuit 220 and the second device 212, respectively. Figure 2 and Figure 3 Alternatively, node A1 and node A2 are the connection point and ground between the matching sub-circuit 220 and the first device 211, respectively, with reference to Figure 4The real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 are denoted as R and X, respectively. For different matching architectures, V S , R S , R L +jX L , Z E May be different.

[0096] A non-sinusoidal periodic oscillating voltage signal such as a square wave signal usually includes a fundamental wave and harmonics, wherein a sinusoidal wave component equal to the oscillation period is called a fundamental wave component, and its amplitude value divided by 2 is the effective value of the fundamental wave component.

[0097] The following is based on Figure 8 The equivalent circuit diagram shown describes in detail how to calculate the impedance of the antenna 400 and its impedance matching circuit 200 according to the NFC data reported by the NFC chip 300.

[0098] The transmitting circuit 310 of the NFC chip 300 includes a power supply for supplying power to the first port TXP and the second port TXN. The voltage of the power supply is denoted as VDD. The current value of the average power supply current of the power supply is I avg It can be obtained by converting the TXI data reported by the NFC chip 300, that is, I avg =f(TXI data). When the circuit implementation method of the transmitting circuit 310 inside the NFC chip 300 is different, the TXI data and the current value I avg The conversion relationship f between them may be different.

[0099] The receiving circuit 320 can detect the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400, that is, Figures 2 to 4 ,as well as Figure 8 The voltage between nodes A1 and A2 is shown in FIG. 1 , and the effective value of the voltage V rx It can be obtained by converting the FSSI data reported by the NFC chip 300, that is, V rx = g(FSSI data). When the receiving circuit 320 in the NFC chip 300 and its peripheral circuits are implemented differently, the FSSI data and the effective value V of the voltage on the equivalent impedance rx The conversion relationship g may be different.

[0100] If the receiving circuit 320 also has the function of detecting phase information, for example, the receiving circuit 320 has an IQ demodulation module, the phase of the voltage signal between the node A1 and the node A2 can be obtained by conversion according to the FSSI data reported by the NFC chip 300, and the phase difference between the predetermined phase values ​​is compared. Right now (FSSI data). When the circuit implementation methods of the receiving circuit 320 and its peripheral circuits are different, the FSSI data and the phase difference The conversion relationship h may be different.

[0101] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, respectively, the predetermined phase value is the phase value of the voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected, for example Figure 2 and Figure 3 As shown; when at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to the first end of the first device 211, the predetermined phase value is the phase value of the voltage of the at least one port to the ground when the impedance matching circuit 200 is not connected, for example Figure 4 shown.

[0102] The present application provides two methods for calculating the impedance of the antenna 400 and its impedance matching circuit 200 , which are described in detail below.

[0103] Method 1

[0104] The impedance calculation method of method 1 can be applied when the receiving circuit 320 does not have a function of detecting phase information.

[0105] In one implementation, the NFC data reported by the NFC chip 300 may include TXI data and FSSI data. In this case, in step 120, the impedance of the antenna 400 and its impedance matching circuit 200 is determined according to the NFC data, including: determining the current value of the average power supply current according to the TXI data, that is, I avg =f(TXI data); Determine the effective value V of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 according to the FSSI data rx , that is, V rx = g(FSSI data); according to the current value of the average supply current I avg , and the effective value V of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 rx , determine the real part R and imaginary part X of the impedance of the antenna 400 and its impedance matching circuit 200.

[0106] For example, the current value I of the average supply current can be avg , and the following formulas (1) to (3), determine the real part R of the impedance of the antenna 400 and its impedance matching circuit 200:

[0107]

[0108]

[0109]

[0110] For another example, the current value I of the average power supply current can be avg , the effective value V of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 rx , and the following formulas (4) to (7) determine the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200:

[0111] X=m1·(R s1 +R)+n1(4),

[0112]

[0113]

[0114]

[0115] Or, according to the current value of the average supply current I avg , the effective value V of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 rx , and the following formulas (8) to (11) determine the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200:

[0116] X=m2·(R s2 +R)+n2 (8),

[0117]

[0118]

[0119]

[0120] Wherein, in formula (1) to formula (11), VDD is the voltage of the power supply of the transmitting circuit 310, I avg1 and I avg2 The transmitting circuit 310 has an internal resistance of R S1 and R S2 The current value of the average supply current is V rx1 and V rx2 The transmitting circuit 310 has an internal resistance of R S1 and R S2 The effective value of the voltage on the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400.

[0121] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, for example Figure 2 and Figure 3 As shown, V S is the effective value of the fundamental wave component of the voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected, R L +jX L is the series impedance of the first device 211 and the second device 212, R L and X L are the real and imaginary parts of the series impedance respectively.

[0122] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are both connected to the first end of the first device 211, for example Figure 4 As shown, V S is the effective value of the fundamental wave component of the voltage of the first port TXP of the transmitting circuit 310 to the ground or the effective value of the fundamental wave component of the voltage of the second port TXN of the transmitting circuit 310 to the ground when the impedance matching circuit 200 is not connected, R L +jX L is the impedance of the first device 211, R L and X L are the real part and the imaginary part of the impedance of the first device 211 respectively.

[0123] Hereinafter, it is described how to obtain the above-mentioned formula (1) to formula (3).

[0124] refer to Figure 8 , for any pair of TXI data and FSSI data, we can get:

[0125] P=VDD·I avg =I 2 ·(R s +R) (12),

[0126] V s 2 =I 2 ·[(R s +R) 2 +X 2 ] (13),

[0127] Dividing formula (12) by formula (13), we get:

[0128]

[0129] The internal resistance of the transmitting circuit 310 is adjusted to be R S1and R S2 , we get two pairs of TXI data and FSSI data, which are:

[0130]

[0131] Assumptions:

[0132]

[0133] According to formula (14) and formula (16), we get:

[0134]

[0135] Furthermore, by transforming formula (17), we can obtain:

[0136] R e1 (R s1 + R) = (R s1 +R) 2 +X 2 (18)

[0137] R e2 (R s2 + R) = (R s2 +R) 2 +X 2 (19)

[0138] Subtracting formula (18) from formula (19), we get:

[0139] R e2 (R s2 +R)-R e1 (R s1 + R) = (R s2 +R) 2 -(R s1 +R) 2 (20)

[0140] By converting formula (20), the above formula (1) can be obtained. According to formula (1) to formula (3) and the TXI data reported by the NFC chip 300, the real part R of the impedance of the antenna 400 and its impedance matching circuit 200 can be calculated.

[0141] Hereinafter, it is described how to obtain the above-mentioned formulas (4) to (7), and (8) to (11).

[0142] Likewise, reference Figure 8 , for any pair of TXI data and FSSI data, we can get the above formula (12) and formula (13). Dividing formula (12) by formula (13), we can get the above formula (14). Let RS +R=t, then according to formula (14), we can get:

[0143] t 2 +X 2 =t·R e (twenty one),

[0144] refer to Figure 8 , we can get:

[0145]

[0146] Transforming formula (22), we get:

[0147]

[0148] Let R S +R=t, then according to formula (23), we get:

[0149]

[0150] Combining formula (21) and formula (24), we get:

[0151]

[0152] Transforming formula (25), we get:

[0153]

[0154] make

[0155] Combining formula (26) and formula (27), the above formula (4) and formula (8) can be obtained. According to formula (4) to formula (7) or formula (8) to formula (11), and the TXI data and FSSI data reported by the NFC chip 300, the imaginary part X of the impedance of the antenna 400 and its impedance matching circuit 200 can be calculated.

[0156] Method 2

[0157] The impedance calculation method of mode 2 can be applied when the receiving circuit 320 has the function of detecting phase information. Of course, when the receiving circuit 320 has the function of detecting phase information, mode 1 can also be used to calculate the impedance of the antenna 400 and its impedance matching circuit 200.

[0158] In one implementation, the NFC data reported by the NFC chip 300 may include FSSI data. In this case, in step 120, the impedance of the antenna 400 and its impedance matching circuit 200 is determined according to the NFC data, including: determining the effective value V of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 according to the FSSI data. rx , that is, V rx = g(FSSI data), and determine the phase difference between the phase value of the voltage on the equivalent impedance and the predetermined phase value Right now (FSSI data); According to the effective value V of the voltage of the matching sub-circuit 220 rx and phase difference The real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 are determined.

[0159] Among them, Figure 2 and Figure 3 As shown, the predetermined phase value is the phase value of the voltage between the first port TXP and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected; or Figure 4 As shown, the predetermined phase value is a phase value of a voltage of at least one of the first port TXP and the second port TXN of the transmitting circuit 310 to the ground.

[0160] For example, the effective value V of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 can be calculated based on the effective value V rx , the phase difference And the following formula (26) to formula (29) determine the real part of the impedance of the antenna 400 and its impedance matching circuit 200:

[0161]

[0162]

[0163]

[0164]

[0165] For another example, the effective value V of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 may be rx , Phase difference And the following formula (32) determines the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200:

[0166]

[0167] In formula (28) to formula (32), V rxis the effective value of the voltage on the equivalent impedance, R S is the internal resistance of the transmitting circuit 310, is the phase difference.

[0168] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, respectively, V S is the effective value of the fundamental wave component of the voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected, R L +jX L is the series impedance of the first device 211 and the second device 212, R L and X L are the real and imaginary parts of the series impedance respectively.

[0169] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are both connected to the first terminal of the first device 211, V S is the effective value of the fundamental wave component of the voltage of the first port TXP of the transmitting circuit 310 to the ground or the effective value of the fundamental wave component of the voltage of the second port TXN of the transmitting circuit 310 to the ground when the impedance matching circuit 200 is not connected, R L +jX L is the impedance of the first device 211, R L and X L are the real part and the imaginary part of the impedance of the first device 211 respectively.

[0170] The following describes how to obtain the above-mentioned formulas (28) to (32).

[0171] refer to Figure 8 , it is known that:

[0172]

[0173] Assumptions:

[0174]

[0175] Transforming formula (34), we get:

[0176] RR L +j(XX L )=(R s +R)m-Xn+j[Xm+(R s +R)n](35),

[0177] According to formula (35), we get:

[0178]

[0179] According to formula (36), the above formula (28) and formula (32) can be obtained. According to formula (28) to formula (32), and the FSSI data reported by the NFC chip 300, the real part R and the imaginary part X of the impedance of the antenna 400 and its impedance matching circuit 200 can be calculated.

[0180] When the receiving circuit 320 of the NFC chip 300 cannot detect V rx When the phase information of the NFC chip 300 is obtained, it is necessary to simultaneously obtain the TXI data and FSSI data of the transmitting circuit 310 under two different internal impedances, and then estimate the real part and imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200. rx When the magnitude and phase information of the voltage are obtained, only the FSSI data may be obtained to estimate the real part and the imaginary part of the impedance of the antenna 400 and the impedance matching circuit 200 thereof.

[0181] If the frequency of the transmitting circuit 310 is adjustable, that is, the transmitting circuit 310 can output a signal of any frequency within a certain frequency range, in one implementation, the method 100 further includes: when the transmitting circuit 310 sequentially outputs signals of multiple frequencies within the frequency range, respectively obtaining multiple impedances of the impedance matching circuit 200 at the multiple frequencies; and determining an impedance curve representing the impedance variation of the antenna 400 and its impedance matching circuit 200 with frequency based on the correspondence between the multiple impedances and the multiple frequencies.

[0182] When the transmitting circuit 310 sequentially outputs signals of multiple frequencies, the impedances of the antenna 400 and its impedance matching circuit 200 are calculated respectively. According to the corresponding relationship between the obtained multiple impedances and the multiple frequencies, an impedance curve of impedance variation with frequency can be plotted. For example, Fig. 9 and Fig.10 The curves are respectively showing the real part of the impedance of the antenna 400 and its impedance matching circuit 200 changing with frequency, and the curve of the imaginary part of the impedance changing with frequency. At this time, at the frequency position of 13.56 MHz, the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is 0, which is equivalent to a pure resistance.

[0183] Fig.11 A Smith chart showing the impedance of the antenna 400 and its impedance matching circuit 200 is shown. Fig.11 The curve inside the circle is the impedance curve of the antenna 400 and its impedance matching circuit 200, and the position marked by the triangle is the position of the impedance corresponding to 13.5MHz in the Smith chart. At this time, the position of the impedance corresponding to 13.56MHz is located on the real axis, that is, Fig.11The horizontal axis with the ordinate being 0 in the figure indicates that the impedance of the antenna 400 and its impedance matching circuit 200 has only a real part and an imaginary part of 0, which is equivalent to a pure resistance.

[0184] Based on the method 100 of the present application, an impedance curve of impedance variation with frequency can be obtained efficiently and accurately. When it is necessary to obtain an impedance curve to debug the impedance matching circuit 200 based on the impedance curve, there is no need to disassemble the device multiple times and introduce flying wires, thereby avoiding the problem of impedance deviation caused by flying wires causing a decrease in matching performance, and effectively improving debugging efficiency and accuracy. Moreover, during mass production testing, the impedance deviation caused by the consistency problem between the peripheral matching device and the antenna 400 can be more accurately determined based on the impedance curve.

[0185] The present application also provides a device 500 for obtaining impedance, such as Fig.12 As shown, the device 500 is applied to the antenna 400 and its impedance matching circuit 200, the impedance matching circuit 200 is connected between the antenna 400 and the near field communication NFC chip 300, the NFC chip 300 includes a transmitting circuit 310 and a receiving circuit 320, and the device 500 includes an information acquisition module 510 and an information processing module 520.

[0186] The information acquisition module 510 is used to obtain NFC data output by the NFC chip 300 , and the NFC data includes average power supply current TXI data of its power supply output by the transmitting circuit 310 , and / or FSSI data output by the receiving circuit 320 .

[0187] The information processing module 520 is used to determine the impedance of the antenna 400 and its impedance matching circuit 200 according to the NFC data acquired by the information acquisition module 510 .

[0188] In one implementation, the first port TXP of the transmitting circuit 310 is connected to the first end of the first device 211 in the impedance matching circuit 200, the first port RXP of the receiving circuit 320 is connected to the second end of the first device 211 via a peripheral circuit, the second port TXN of the transmitting circuit 310 is connected to the first end of the second device 212 in the impedance matching circuit 200, the second port RXN of the receiving circuit 320 is connected to the second end of the second device 212 via a peripheral circuit, and the matching subcircuit 220 formed by the portion of the impedance matching circuit 200 other than the first device 211 and the second device 212 and the antenna 400 is connected to the second end of the first device 211 and the second end of the second device 212.

[0189] In one implementation, at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to the first end of the first device 211 in the impedance matching circuit 200, the first port RXP of the receiving circuit 320 is connected to the second end of the first device 211 via a peripheral circuit, the second port RXN of the receiving circuit 320 is disconnected, and the matching subcircuit 220 formed by the portion of the impedance matching circuit 200 other than the first device 211 and the antenna 400 is connected to the second end of the first device 211.

[0190] In one implementation, the NFC data includes TXI data and FSSI data. Determining the impedance of the antenna 400 and its impedance matching circuit 200 according to the NFC data includes: determining the current value of the average power supply current according to the TXI data; determining the effective value of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 according to the FSSI data; and determining the real part and imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 according to the current value of the average power supply current and the effective value of the voltage on the equivalent impedance.

[0191] In one implementation, the information processing module 520 is specifically used to determine the real part of the impedance of the antenna 400 and its impedance matching circuit 200 according to the current value of the average power supply current and the following formula:

[0192]

[0193] The imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined according to the current value of the average supply current, the effective value of the voltage on the equivalent impedance and the following formula:

[0194]

[0195] or,

[0196]

[0197] Wherein, VDD is the voltage of the power supply of the transmitting circuit 310, I avg1 and I avg2 The transmitting circuit 310 has an internal resistance of R S1 and R S2 The current value of the average supply current when V rx1 and V rx2 The transmitting circuit 310 has an internal resistance of R S1 and R S2 The effective value of the voltage on the equivalent impedance when

[0198] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, respectively, V S is the effective value of the fundamental wave component of the voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected, R L +jX L is the series impedance of the first device 211 and the second device 212,

[0199] When at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to the first terminal of the first device 211, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit 200 is not connected, R L +jX L is the impedance of the first device 211.

[0200] In one implementation, the receiving circuit 320 has a function of detecting phase information, and the information processing module 520 is specifically used to: determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit 220 and the antenna 400 based on the FSSI data, and determine the phase difference between the phase value of the voltage of the matching subcircuit 220 and the predetermined phase value; determine the real part and imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 based on the effective value and phase difference of the voltage on the equivalent impedance.

[0201] In one implementation, when the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are respectively connected to the first end of the first device 211 and the first end of the second device 212, the predetermined phase value is the phase value of the voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected; when at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to the first end of the first device 211, the predetermined phase value is the phase value of the voltage of the at least one port to ground when the impedance matching circuit 200 is not connected.

[0202] In one implementation, determining the real part and the imaginary part of the impedance of the antenna 400 and the impedance matching circuit 200 thereof according to the effective value of the voltage on the equivalent impedance and the phase difference includes:

[0203] The real part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula:

[0204]

[0205] as well as,

[0206] The imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula:

[0207]

[0208] Among them, V rx is the effective value of the voltage on the equivalent impedance, R S is the internal resistance of the transmitting circuit 310, is the phase difference;

[0209] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, respectively, V S is the effective value of the fundamental wave component of the voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected, R L +jX L is the series impedance of the first device 211 and the second device 212;

[0210] When the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are connected to the first terminal of the first device 211, V S is the effective value of the fundamental wave component of the voltage of the first port TXP of the transmitting circuit 310 to the ground or the effective value of the fundamental wave component of the voltage of the second port TXN of the transmitting circuit 310 to the ground when the impedance matching circuit 200 is not connected, R L +jX L is the impedance of the first device 211.

[0211] In one implementation, the information processing module 520 is further used to: when the transmitting circuit 310 sequentially outputs signals of multiple frequencies within a specific frequency range, respectively obtain multiple impedances of the impedance matching circuit 200 at the multiple frequencies; and determine an impedance curve representing the impedance variation of the antenna 400 and its impedance matching circuit 200 with frequency according to the correspondence between the multiple impedances and the multiple frequencies. The impedance curve can be used, for example, to debug the impedance matching circuit 200.

[0212] In one implementation, the impedance matching circuit 200 includes multiple devices, and the types of the multiple devices include at least one of inductance, resistance and capacitance, wherein the first device 211 is one device among the multiple devices or a combination of at least two devices among the multiple devices connected in series or in parallel, and the second device 212 is one device among the multiple devices or a combination of at least two devices among the multiple devices connected in series or in parallel.

[0213] The present application also provides a device for acquiring impedance, the device comprising a processor and a memory, the memory is used to store instructions, and the processor is used to read the instructions and execute the method for acquiring impedance in any possible implementation manner described above.

[0214] The present application also provides an electronic device, comprising: an NFC chip 300; an impedance matching circuit 200 arranged between the NFC chip 300 and the antenna 400; and a device according to any of the above possible implementations, the device being used to obtain the impedance of the antenna 400 and its impedance matching circuit 200.

[0215] As an example but not limitation, the electronic device in the embodiment of the present application can be a portable or mobile computing device such as a terminal device, a mobile phone, a tablet computer, a laptop computer, a desktop computer, a gaming device, an in-vehicle electronic device or a wearable smart device, as well as other electronic devices such as an electronic database, a car, and an automated teller machine (ATM). The wearable smart device includes a device with full functions and large size that can realize full or partial functions without relying on a smart phone, such as a smart watch or smart glasses, and includes a device that only focuses on a certain type of application function and needs to be used in conjunction with other devices such as a smart phone, such as various types of smart bracelets and smart jewelry for vital sign monitoring.

[0216] It should be noted that, under the premise of no conflict, the various embodiments described in this application and / or the technical features in each embodiment can be arbitrarily combined with each other, and the technical solution obtained after the combination should also fall within the protection scope of this application.

[0217] The systems, devices and methods disclosed in the embodiments of the present application may be implemented in other ways. For example, some features of the method embodiments described above may be ignored or not performed. The device embodiments described above are merely schematic, and the division of units is merely a logical function division. There may be other division methods in actual implementation, and multiple units or components may be combined or integrated into another system. In addition, the coupling between the units or the coupling between the components may be direct coupling or indirect coupling, and the coupling may include electrical, mechanical or other forms of connection.

[0218] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described devices and equipment and the technical effects produced can refer to the corresponding processes and technical effects in the aforementioned method embodiments, and will not be repeated here.

[0219] It should be understood that the specific examples in the embodiments of the present application are only to help those skilled in the art to better understand the embodiments of the present application, rather than to limit the scope of the embodiments of the present application. Those skilled in the art can make various improvements and modifications based on the above embodiments, and these improvements or modifications all fall within the scope of protection of the present application.

[0220] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for obtaining impedance, characterized in that: The method is applied to an antenna and an impedance matching circuit thereof, wherein the impedance matching circuit is connected between the antenna and a near field communication NFC chip, wherein the NFC chip includes a transmitting circuit and a receiving circuit, and the method includes: Acquire NFC data output by the NFC chip, the NFC data including average power supply current TXI data output by the transmitting circuit for indicating its power supply and field signal strength indication FSSI data output by the receiving circuit; Determining a total impedance of the antenna and the impedance matching circuit according to the NFC data; Wherein, determining the total impedance of the antenna and the impedance matching circuit according to the NFC data includes: Determining a current value of the average supply current according to the TXI data; Determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit in the impedance matching circuit and the antenna according to the FSSI data; The real part and the imaginary part of the total impedance of the antenna and the impedance matching circuit are determined according to the current value of the average supply current and the effective value of the voltage on the equivalent impedance.

2. The method according to claim 1, characterized in that: The first port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the transmitting circuit is connected to the first end of the second device in the impedance matching circuit, the second port of the receiving circuit is connected to the second end of the second device via a peripheral circuit, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device and the second device is connected to the second end of the first device and the second end of the second device.

3. The method according to claim 1, characterized in that At least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the receiving circuit is disconnected, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device is connected to the second end of the first device.

4. The method according to any one of claims 1 to 3, characterized in that The step of determining the real part and the imaginary part of the total impedance of the antenna and the impedance matching circuit according to the current value of the average supply current and the effective value of the voltage on the equivalent impedance comprises: The real part of the total impedance of the antenna and the impedance matching circuit is determined according to the current value of the average supply current and the following formula: as well as, The imaginary part of the total impedance of the antenna and the impedance matching circuit is determined according to the current value of the average supply current, the effective value of the voltage on the equivalent impedance and the following formula: X=m1·(R s1 +R)+n1, or, X=m2·(R s2 +R)+n2, Wherein, VDD is the voltage of the power supply of the transmitting circuit, I avg1 and I avg2 The transmitting circuit has an internal resistance of R S1 and R S2 The current value of the average supply current, V rx1 and V rx2 The transmitting circuit has an internal resistance of R S1 and R S2 The effective value of the voltage on the equivalent impedance is, When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device, When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

5. The method according to any one of claims 1 to 3, characterized in that The method further comprises: When the transmitting circuit sequentially outputs signals of multiple frequencies within a specific frequency range, respectively obtaining multiple impedances of the antenna and the impedance matching circuit at the multiple frequencies; An impedance curve representing the variation of the total impedance of the antenna and the impedance matching circuit with frequency is determined according to the corresponding relationship between the multiple impedances and the multiple frequencies.

6. The method according to claim 5, characterized in that The method further comprises: The impedance matching circuit is debugged according to the impedance curve.

7. The method according to claim 2, characterized in that: The impedance matching circuit includes multiple devices, and the types of the multiple devices include at least one of inductance, resistance and capacitance, wherein the first device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel, and the second device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel.

8. A device for obtaining impedance, characterized in that: The device is applied to an antenna and an impedance matching circuit thereof, wherein the impedance matching circuit is connected between the antenna and a near field communication NFC chip, wherein the NFC chip includes a transmitting circuit and a receiving circuit, and the device includes: an information acquisition module, configured to acquire NFC data output by the NFC chip, wherein the NFC data includes average power supply current TXI data output by the transmitting circuit for indicating its power supply and field signal strength indication FSSI data output by the receiving circuit; and An information processing module, configured to determine a total impedance of the antenna and the impedance matching circuit according to the NFC data; The information processing module is specifically used for: Determining a current value of the average supply current according to the TXI data; Determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit in the impedance matching circuit and the antenna according to the FSSI data; The real part and the imaginary part of the total impedance of the antenna and the impedance matching circuit are determined according to the current value of the average supply current and the effective value of the voltage on the equivalent impedance.

9. The device according to claim 8, characterized in that The first port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the transmitting circuit is connected to the first end of the second device in the impedance matching circuit, the second port of the receiving circuit is connected to the second end of the second device via a peripheral circuit, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device and the second device is connected to the second end of the first device and the second end of the second device.

10. The device according to claim 8, characterized in that At least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the receiving circuit is disconnected, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device is connected to the second end of the first device.

11. The device according to any one of claims 8 to 10, characterized in that The information processing module is specifically used for: The real part of the total impedance of the antenna and the impedance matching circuit is determined according to the current value of the average supply current and the following formula: as well as, The imaginary part of the total impedance of the antenna and the impedance matching circuit is determined according to the current value of the average supply current, the effective value of the voltage on the equivalent impedance and the following formula: X=m1·(R s1 +R)+n1, or, X=m2·(R s2 +R)+n2, Wherein, VDD is the voltage of the power supply of the transmitting circuit, I avg1 and I avg2 The transmitting circuit has an internal resistance of R S1 and R S2 The current value of the average supply current, V rx1 and V rx2 The transmitting circuit has an internal resistance of R S1 and R S2 The effective value of the voltage on the equivalent impedance is, When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device, When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

12. The device according to any one of claims 8 to 10, characterized in that The information processing module is also used for: When the transmitting circuit sequentially outputs signals of multiple frequencies within a specific frequency range, respectively obtaining multiple impedances of the antenna and the impedance matching circuit at the multiple frequencies; An impedance curve representing the variation of the total impedance of the antenna and the impedance matching circuit with frequency is determined according to the corresponding relationship between the multiple impedances and the multiple frequencies.

13. The device according to claim 12, characterized in that The impedance curve is used to debug the impedance matching circuit.

14. The device according to claim 9, characterized in that The impedance matching circuit includes multiple devices, and the types of the multiple devices include at least one of inductance, resistance and capacitance, wherein the first device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel, and the second device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel.

15. A method for obtaining impedance, characterized in that: The method is applied to an antenna and an impedance matching circuit thereof, wherein the impedance matching circuit is connected between the antenna and a near field communication NFC chip, wherein the NFC chip includes a transmitting circuit and a receiving circuit, and the method includes: Acquire NFC data output by the NFC chip, wherein the NFC data includes field signal strength indication FSSI data output by the receiving circuit; Determining a total impedance of the antenna and the impedance matching circuit according to the NFC data; Wherein, determining the total impedance of the antenna and the impedance matching circuit according to the NFC data includes: Determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit in the impedance matching circuit and the antenna according to the FSSI data, and determine the phase difference between the phase value of the voltage on the equivalent impedance and a predetermined phase value; The real part and the imaginary part of the total impedance of the antenna and the impedance matching circuit are determined according to the effective value of the voltage on the equivalent impedance and the phase difference.

16. The method according to claim 15, characterized in that The first port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the transmitting circuit is connected to the first end of the second device in the impedance matching circuit, the second port of the receiving circuit is connected to the second end of the second device via a peripheral circuit, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device and the second device is connected to the second end of the first device and the second end of the second device.

17. The method according to claim 15, characterized in that At least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the receiving circuit is disconnected, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device is connected to the second end of the first device.

18. The method according to any one of claims 15 to 17, characterized in that When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, the predetermined phase value is the phase value of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device, the predetermined phase value is a phase value of a voltage of the at least one port to ground when the impedance matching circuit is not connected.

19. The method according to any one of claims 15 to 17, characterized in that The step of determining the real part and the imaginary part of the total impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance and the phase difference comprises: The real part of the total impedance of the antenna and the impedance matching circuit is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula: as well as, The imaginary part of the total impedance of the antenna and the impedance matching circuit is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula: Among them, V rx is the effective value of the voltage on the equivalent impedance, R S is the internal resistance of the transmitting circuit, is the phase difference, When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device, When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

20. The method according to any one of claims 15 to 17, characterized in that The method further comprises: When the transmitting circuit sequentially outputs signals of multiple frequencies within a specific frequency range, respectively obtaining multiple impedances of the antenna and the impedance matching circuit at the multiple frequencies; An impedance curve representing the variation of the total impedance of the antenna and the impedance matching circuit with frequency is determined according to the corresponding relationship between the multiple impedances and the multiple frequencies.

21. The method according to claim 20, characterized in that The method further comprises: The impedance matching circuit is debugged according to the impedance curve.

22. The method according to claim 16, characterized in that The impedance matching circuit includes multiple devices, and the types of the multiple devices include at least one of inductance, resistance and capacitance, wherein the first device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel, and the second device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel.

23. A device for obtaining impedance, characterized in that: The device is applied to an antenna and an impedance matching circuit thereof, wherein the impedance matching circuit is connected between the antenna and a near field communication NFC chip, wherein the NFC chip includes a transmitting circuit and a receiving circuit, and the device includes: An information acquisition module, used to obtain NFC data output by the NFC chip, wherein the NFC data includes field signal strength indication FSSI data output by the receiving circuit; An information processing module, configured to determine a total impedance of the antenna and the impedance matching circuit according to the NFC data; The receiving circuit has a function of detecting phase information, and the information processing module is specifically used for: Determine the effective value of the voltage on the equivalent impedance formed by the matching subcircuit in the impedance matching circuit and the antenna according to the FSSI data, and determine the phase difference between the phase value of the voltage on the equivalent impedance and a predetermined phase value; The real part and the imaginary part of the total impedance of the antenna and the impedance matching circuit are determined according to the effective value of the voltage on the equivalent impedance and the phase difference.

24. The device according to claim 23, characterized in that The first port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the transmitting circuit is connected to the first end of the second device in the impedance matching circuit, the second port of the receiving circuit is connected to the second end of the second device via a peripheral circuit, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device and the second device is connected to the second end of the first device and the second end of the second device.

25. The device according to claim 23, characterized in that At least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device in the impedance matching circuit, the first port of the receiving circuit is connected to the second end of the first device via a peripheral circuit, the second port of the receiving circuit is disconnected, and a matching subcircuit formed by a part of the impedance matching circuit other than the first device is connected to the second end of the first device.

26. The device according to any one of claims 23 to 25, characterized in that When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, the predetermined phase value is the phase value of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device, the predetermined phase value is a phase value of a voltage of the at least one port to ground when the impedance matching circuit is not connected.

27. The device according to any one of claims 23 to 25, characterized in that The information processing module is specifically used for: The real part of the total impedance of the antenna and the impedance matching circuit is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula: as well as, The imaginary part of the total impedance of the antenna and the impedance matching circuit is determined according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula: Among them, V rx is the effective value of the voltage on the equivalent impedance, R S is the internal resistance of the transmitting circuit, is the phase difference, When the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device respectively, V S is the effective value of the fundamental wave component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R L +jX L is the series impedance of the first device and the second device, When at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first terminal of the first device, V S is the effective value of the fundamental component of the voltage of the at least one port to the ground when the impedance matching circuit is not connected, R L +jX L is the impedance of the first device.

28. The device according to any one of claims 23 to 25, characterized in that The information processing module is also used for: When the transmitting circuit sequentially outputs signals of multiple frequencies within a specific frequency range, respectively obtaining multiple impedances of the antenna and the impedance matching circuit at the multiple frequencies; An impedance curve representing the variation of the total impedance of the antenna and the impedance matching circuit with frequency is determined according to the corresponding relationship between the multiple impedances and the multiple frequencies.

29. The device according to claim 28, characterized in that The impedance curve is used to debug the impedance matching circuit.

30. The device according to claim 24, characterized in that The impedance matching circuit includes multiple devices, and the types of the multiple devices include at least one of inductance, resistance and capacitance, wherein the first device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel, and the second device is one of the multiple devices or a combination of at least two of the multiple devices connected in series or in parallel.

31. A device for obtaining impedance, characterized in that: The device includes a processor and a memory, the memory is used to store instructions, and the processor is used to read the instructions and execute the method for acquiring impedance according to any one of claims 1 to 7, or execute the method for acquiring impedance according to any one of claims 15 to 22.

32. An electronic device, characterized in that: include: Near field communication NFC chip; An impedance matching network disposed between the NFC chip and the antenna; as well as, The device according to any one of claims 8 to 14, or the device according to any one of claims 23 to 30, is used to obtain the impedance of the antenna and the impedance matching network.

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