NFC matching circuit debugging method, NFC matching circuit and electronic equipment

Abstract

The invention discloses a debugging method of an NFC matching circuit, the NFC matching circuit and electronic equipment. The debugging method comprises the following steps: connecting a resonance circuit with two transmitting ends of an NFC controller, and connecting an impedance matching circuit with an NFC antenna; when the resonant circuit and the impedance matching circuit are in a disconnected state, the resonant circuit is debugged, and when the actually measured resonant frequency of the resonant circuit is configured to be equal to a target resonant frequency, the target element parameter of the resonant circuit is determined, and the target resonant frequency is greater than or equal to the working frequency of the NFC antenna; and when the resonance circuit and the impedance matching circuit are in a disconnected state, debugging the matching impedance from the input end of the impedance matching circuit to the ground, and when the matching impedance of the impedance matching circuit meets a first condition and a second condition at the same time, determining a target element parameter of the impedance matching circuit. The NFC matching circuit debugged by the method is low in cost, and the efficiency and the performance of signal transmission are guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of NFC technology, and in particular to a debugging method for an NFC matching circuit, an NFC matching circuit and an electronic device. Background Art

[0002] When the NFC antenna is a single-ended antenna (i.e. one terminal of the antenna is grounded), a suitable single-ended matching circuit is required to connect to the NFC controller. The traditional single-ended matching circuit uses a balun method to connect the single-ended input of the NFC antenna to the differential output of the NFC controller. The single-ended matching circuit containing a balun requires a special material such as a balun, which is expensive, and the active power that can be output to the NFC antenna (used to generate a magnetic field) is limited because it is limited by the current carrying capacity of the balun and the loss caused by the balun, which affects the transmission performance of the NFC antenna. Summary of the invention

[0003] The embodiments of the present invention provide a debugging method of an NFC matching circuit, an NFC matching circuit, and an electronic device to solve the problems of high cost and limited transmission performance of existing NFC antenna matching.

[0004] A debugging method for an NFC matching circuit, comprising: Connect the resonant circuit to the two transmitting terminals of the NFC controller, and connect the impedance matching circuit to the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the resonant circuit, and determining target element parameters of the resonant circuit when a measured resonant frequency of the resonant circuit is configured to be equal to a target resonant frequency, wherein the target resonant frequency is greater than or equal to an operating frequency of the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the matching impedance from the input end of the impedance matching circuit to the ground, and when the matching impedance of the impedance matching circuit satisfies the first condition and the second condition at the same time, determining the target element parameter of the impedance matching circuit; The first condition is that the impedance curve of the impedance matching circuit has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna; The second condition is that the matching impedance corresponding to the operating frequency of the NFC antenna is configured to be equal to the target impedance.

[0005] Preferably, the resonant circuit comprises a resonant inductor and a resonant capacitor; a first end of the resonant inductor is connected to a transmitting end of the NFC controller, and a second end of the resonant inductor is used to be connected to the impedance matching circuit; a first end of the resonant capacitor is connected to another transmitting end of the NFC controller, and a second end of the resonant capacitor is used to be connected to the impedance matching circuit; The step of debugging the resonant circuit when the resonant circuit and the impedance matching circuit are in a disconnected state, and determining a target component parameter of the resonant circuit when the measured resonant frequency of the resonant circuit is configured to be equal to a target resonant frequency, comprises: Controlling the resonant circuit and the impedance matching circuit to be in a disconnected state, debugging the resonant circuit, and obtaining a measured resonant frequency of a series circuit formed by the resonant inductor and the resonant capacitor; If the measured resonant frequency is greater than the target resonant frequency, increasing the initial inductance value of the resonant inductor and / or the initial capacitance value of the resonant capacitor; If the measured resonant frequency is less than the target resonant frequency, reducing the initial inductance value of the resonant inductor and / or the initial capacitance value of the resonant capacitor; If the measured resonant frequency is equal to the target resonant frequency, the initial inductance value of the resonant inductor and the initial capacitance value of the resonant capacitor are respectively determined as the target inductance value of the resonant inductor and the target capacitance value of the resonant capacitor.

[0006] Preferably, when the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the matching impedance from the input end of the impedance matching circuit to the ground, and when the first condition and the second condition are simultaneously met, determining the target element parameters of the impedance matching circuit, comprises: When the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the matching impedance from the input end of the impedance matching circuit to the ground, and when the first condition and the second condition are met at the same time, determining the standard component parameters of the impedance matching circuit; When the resonant circuit and the impedance matching circuit are in a connected state, performing a performance test on the NFC matching circuit to obtain a first test result of the NFC matching circuit; Based on the first test result of the NFC matching circuit, standard component parameters of the impedance matching circuit are debugged to determine target component parameters of the impedance matching circuit.

[0007] Preferably, the impedance matching circuit comprises an EMC filter and a matching unit, the first end of the EMC filter is used to connect to the resonant circuit, the second end of the EMC filter is connected to the first end of the matching unit, and the second end of the matching unit is used to connect to the NFC antenna; The step of performing a performance test on the NFC matching circuit to obtain a first test result of the NFC matching circuit when the resonant circuit and the impedance matching circuit are in a connected state includes: Connecting a first end of the receiving circuit to a receiving end of the NFC controller, connecting a second end of the receiving circuit to an NFC antenna or to the NFC antenna through the matching unit, and performing a performance test on the NFC matching circuit when the resonant circuit and the EMC filter are in a connected state to obtain a first test result of the NFC matching circuit; wherein the first test result includes a measured transmission magnetic field strength and a measured receiving load modulation amplitude; The step of debugging the standard component parameters of the impedance matching circuit based on the first test result of the NFC matching circuit to determine the target component parameters of the impedance matching circuit includes: If the measured transmit magnetic field strength is greater than a preset magnetic field strength threshold, and the measured receive load modulation amplitude is greater than a preset load modulation amplitude threshold, the standard component parameters of the EMC filter are determined as target component parameters of the EMC filter, and the standard component parameters of the matching unit are determined as target component parameters of the matching unit; If the measured transmitted magnetic field strength is not greater than the preset magnetic field strength threshold, or the measured received load modulation amplitude is not greater than the preset load modulation amplitude threshold, the standard component parameters of the EMC filter are determined as the target component parameters of the EMC filter, and the standard component parameters of the matching unit are biased to determine the target component parameters of the matching unit.

[0008] Preferably, the impedance matching circuit includes a first matching capacitor and a second matching capacitor; a first end of the first matching capacitor is connected to the EMC filter, and a second end of the first matching capacitor is connected to the NFC antenna; a first end of the second matching capacitor is connected to a connection node between the EMC filter and the NFC antenna, and a second end of the second matching capacitor is grounded; The step of performing a deviation process on the standard component parameters of the matching unit to determine the target component parameters of the matching unit includes: The standard capacitance value of the first matching capacitor is determined as the target capacitance value of the first matching capacitor, and the difference between the standard capacitance value of the second matching capacitor and the preset change amount is determined as the target capacitance value of the second matching capacitor.

[0009] Preferably, the preset variation ranges from 0.025 times to 0.25 times the standard capacitance value of the second matching capacitor.

[0010] Preferably, the EMC filter comprises a filter inductor and a filter capacitor; a first end of the filter inductor is connected to the resonant circuit, and a second end of the filter inductor is connected to the impedance matching circuit; a first end of the filter capacitor is connected to a connection node between the filter inductor and the impedance matching circuit, and a second end of the filter capacitor is grounded; The target impedance is configured to be positively correlated with a target inductance value of the filter inductor.

[0011] Preferably, the debugging method of the NFC matching circuit further includes: When the resonant circuit and the impedance matching circuit are in a connected state, connecting a first end of the receiving circuit to a receiving end of the NFC controller, connecting a second end of the receiving circuit to a connection node between the EMC filter and the matching unit, performing a performance test on the NFC matching circuit, and obtaining a first receiving load modulation amplitude; When the resonant circuit and the impedance matching circuit are in a connected state, connecting a first end of the receiving circuit to a receiving end of the NFC controller, connecting a second end of the receiving circuit to a connection node between the matching unit and the NFC antenna, performing a performance test on the NFC matching circuit, and obtaining a second receiving load modulation amplitude; If the larger value of the first receiving load modulation amplitude and the second receiving load modulation amplitude is greater than a preset load modulation amplitude threshold, the target component parameters of the receiving circuit are determined, and the second end of the receiving circuit is determined to be connected to a connection node corresponding to the larger value.

[0012] Preferably, the target resonant frequency is 15 MHz.

[0013] Preferably, the debugging method of the NFC matching circuit further includes: Obtain target performance indicators corresponding to target application scenarios; Performing a performance test on the NFC matching circuit to obtain a measured performance indicator of the NFC matching circuit; When the measured performance index of the NFC matching circuit does not meet the target performance index, the target element parameter of the resonant circuit is adjusted.

[0014] Preferably, the obtaining of target performance indicators corresponding to the target application scenario includes: Obtain the target transmit power corresponding to the target application scenario; The performing a performance test on the NFC matching circuit to obtain a measured performance index of the NFC matching circuit includes: Performing a performance test on the NFC matching circuit to obtain a measured transmission power of the NFC matching circuit; When the measured performance index of the NFC matching circuit does not meet the target performance index, adjusting the target component parameters of the resonant circuit includes: When the measured transmission power of the NFC matching circuit is less than the target transmission power, the target inductance value of the resonant inductor is increased and / or the target capacitance value of the resonant capacitor is increased.

[0015] Preferably, the obtaining of target performance indicators corresponding to the target application scenario includes: Obtain the target receiving load modulation amplitude corresponding to the target application scenario; The performing a performance test on the NFC matching circuit to obtain a measured performance index of the NFC matching circuit includes: Performing a performance test on the NFC matching circuit to obtain a measured receiving load modulation amplitude of the NFC matching circuit; When the measured performance index of the NFC matching circuit does not meet the target performance index, adjusting the target component parameters of the resonant circuit includes: When the measured receiving load modulation amplitude of the NFC matching circuit is less than the target receiving load modulation amplitude, the target inductance value of the resonant inductor is reduced and / or the target capacitance value of the resonant capacitor is reduced.

[0016] An NFC matching circuit includes a resonant circuit and an impedance matching circuit; The resonant circuit is connected to two transmitting ends of the NFC controller and is used to perform resonance processing on the differential output of the NFC controller and output a single-ended signal; The first end of the impedance matching circuit is connected to the resonant circuit, and the second end of the impedance matching circuit is used to connect to the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, the measured resonant frequency of the resonant circuit is configured to be equal to a target resonant frequency, and the target resonant frequency is greater than or equal to an operating frequency of the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, the matching impedance from the input end of the impedance matching circuit to the ground satisfies the first condition and the second condition at the same time; The first condition is that the impedance curve of the impedance matching circuit has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna; The second condition is that the matching impedance corresponding to the operating frequency of the NFC antenna is configured to be equal to the target impedance.

[0017] Preferably, the resonant circuit comprises a resonant inductor and a resonant capacitor; a first end of the resonant inductor is connected to a transmitting end of the NFC controller, and a second end of the resonant inductor is connected to the impedance matching circuit; a first end of the resonant capacitor is connected to another transmitting end of the NFC controller, and a second end of the resonant capacitor is connected to the impedance matching circuit; When the resonant circuit and the impedance matching circuit are in a disconnected state, the measured resonant frequency of the series circuit formed by the resonant inductor and the resonant capacitor is configured to be equal to a target resonant frequency, and the target resonant frequency is 15 MHz.

[0018] Preferably, the impedance matching circuit comprises an EMC filter and a matching unit; The EMC filter comprises a filter inductor and a filter capacitor; a first end of the filter inductor is connected to the resonant circuit, and a second end of the filter inductor is connected to the matching unit; a first end of the filter capacitor is connected to a connection node between the filter inductor and the matching unit, and a second end of the filter capacitor is grounded; the target impedance is configured to be positively correlated with a target inductance value of the filter inductor; The matching unit includes a first matching capacitor and a second matching capacitor; a first end of the first matching capacitor is connected to the EMC filter, and a second end of the first matching capacitor is connected to the NFC antenna; a first end of the second matching capacitor is connected to a connection node between the EMC filter and the NFC antenna, and a second end of the second matching capacitor is grounded; The target capacitance value of the second matching capacitor is configured to be equal to the difference between the standard capacitance value and the preset variation; The standard capacitance value is the capacitance value of the second matching capacitor adjusted when the resonant circuit and the impedance matching circuit are in a disconnected state and the matching impedance from the input end of the impedance matching circuit to the ground satisfies the first condition and the second condition at the same time; The preset change amount has a value range of 0.025 to 0.25 times the standard capacitance value of the second matching capacitor.

[0019] Preferably, the NFC matching circuit further includes a receiving circuit, a first end of the receiving circuit is connected to a receiving end of the NFC controller, a second end of the receiving circuit is connected to a connection node between the EMC filter and the matching unit, or a second end of the receiving circuit is connected to a connection node between the matching unit and the NFC antenna.

[0020] Preferably, the NFC matching circuit further includes an impedance resistor, a first end of the impedance resistor is connected to the impedance matching circuit, and a second end of the impedance resistor is connected to the NFC antenna, for reducing the Q value of the NFC antenna.

[0021] An electronic device comprising an NFC controller, an NFC antenna and the above-mentioned NFC matching circuit; The NFC matching circuit is connected to the NFC controller and the NFC antenna.

[0022] The embodiments of the present invention provide a debugging method of an NFC matching circuit, an NFC matching circuit and an electronic device. Single-ended matching is achieved through a resonant circuit. The two transmitting ends of the differential output of an NFC controller are converted into single-ended outputs through the resonant circuit. Since no balun is included, the cost is low and the path loss is small, so that the single-ended output active power of the EMC filter is large; the EMC filter can effectively suppress high-order resonance in the signal transmission process, and avoid electromagnetic interference in the signal transmission process between the NFC controller and the NFC antenna; during the impedance matching process, the impedance matching circuit needs to make the overall impedance curve of the circuit composed of the EMC filter, the impedance matching circuit and the NFC antenna symmetrical based on the real axis to ensure that the matching impedance from the input end of the EMC filter to the ground is pure impedance, so that the signal can be transmitted based on a larger power and reduce signal reflection; and the matching impedance corresponding to the operating frequency of the NFC antenna is configured to be equal to the target impedance to ensure the efficiency and performance of signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0024] Figure 1 is a circuit diagram of a debugging method for an NFC matching circuit in one embodiment of the present invention; Figure 2 is an impedance curve diagram of an impedance matching circuit in one embodiment of the present invention; Figure 3 FIG. 4 is a circuit diagram of an NFC device according to an embodiment of the present invention.

[0025] In the figure: 1. NFC matching circuit; 11. resonant circuit; 12. impedance matching circuit; 121. EMC filter; 122. matching unit; 13. receiving circuit; 2. NFC controller; 3. NFC antenna. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0028] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to or coupled to other elements or layers, it may be directly on, adjacent to, connected to or coupled to other elements or layers, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to or directly coupled to other elements or layers, there may be no intervening elements or layers. It should be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below may be represented as a second element, component, region, layer or part.

[0029] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein for ease of description to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that the spatially relative terms are intended to include different orientations of the device in use and operation in addition to the orientations shown in the figures. For example, if the device in the accompanying drawings is flipped, then the elements or features described as "under other elements" or "under" or "under" will be oriented as "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0030] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0031] In order to fully understand the present invention, detailed structures and steps will be presented in the following description to illustrate the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0032] An embodiment of the present invention provides an NFC matching circuit 1, which is suitable for use in an NFC device, which is a device that communicates based on NFC (Near Field Communication). NFC is a short-range high-frequency wireless communication technology that allows electronic devices to perform contactless point-to-point data transmission when they are very close to each other. NFC technology is mainly based on the integration and evolution of RFID (radio frequency identification) and interconnection technology, and its operating frequency is usually 13.56MHz. An NFC device usually includes an NFC controller 2, an NFC antenna 3 and an NFC matching circuit 1, and the NFC matching circuit 1 is arranged between the NFC controller 2 and the NFC antenna 3. When two NFC devices are close enough (usually less than 10 cm), they can send and receive radio frequency signals through their respective antennas. These signals contain data exchanged between devices.

[0033] NFC devices generally include card emulation mode, peer-to-peer mode, and reader / writer mode. In card emulation mode, an NFC device can simulate a smart card, such as a bus card, access card, or bank card. At this time, other NFC devices or readers can identify this NFC device as a smart card and perform corresponding operations, such as reading card information or making payments. In peer-to-peer mode, two NFC devices can communicate directly without relying on other devices or networks. The data transmission rate in this mode is fast and is usually used to exchange files, contact information, or synchronize device settings. In reader / writer mode, an NFC device can act as a reader or writer to read or write data from other NFC tags or smart cards. This mode is widely used in scenarios such as ticketing, payment, and identity recognition.

[0034] The embodiment of the present invention provides a debugging method for an NFC matching circuit. The debugging method can be applied to a debugging device for implementing parameter debugging. The debugging device can be an electronic device integrating Antenna Tool or other software, such as Figure 1 As shown, the debugging method of the NFC matching circuit 1 includes: S1: Connect the resonant circuit 11 to the two transmitting terminals TXP / TXN of the NFC controller 2, and connect the impedance matching circuit 12 to the NFC antenna 3; S2: When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the resonant circuit 11 is debugged, and when the measured resonant frequency of the resonant circuit 11 is configured to be equal to the target resonant frequency, target component parameters of the resonant circuit 11 are determined, and the target resonant frequency is greater than or equal to the operating frequency of the NFC antenna 3; S3: When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the matching impedance from the input end to the ground of the impedance matching circuit 12 is debugged, and when the matching impedance of the impedance matching circuit 12 satisfies the first condition and the second condition at the same time, the target element parameters of the impedance matching circuit 12 are determined; The first condition is that the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna 3; The second condition is that the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance.

[0035] The resonant circuit 11 is a circuit composed of inductors, capacitors and possibly resistors for achieving a resonant effect. The impedance matching circuit 12 is a circuit for achieving an impedance matching function. The target component parameters are component parameters determined after debugging is completed.

[0036] The measured resonant frequency is the resonant frequency measured in real time. The target resonant frequency is the resonant frequency that needs to be controlled to be reached by the resonant circuit 11. The target resonant frequency is greater than or equal to the operating frequency of the NFC antenna 3. The operating frequency of the NFC antenna 3 is 13.56 MHz. The target resonant frequency can be set to 13.56 MHz or 15 MHz, which can be determined independently according to actual conditions.

[0037] As an example, in step S1, during the debugging process of the NFC matching circuit 1, the resonant circuit 11 needs to be connected to the two transmitting terminals TXP / TXN of the NFC controller 2; the impedance matching circuit 12 needs to be connected to the NFC antenna 3 so that the impedance matching circuit 12 and the NFC antenna 3 form an integral circuit. At this time, the component parameters of all components in the NFC matching circuit 1 are initial component parameters.

[0038] As an example, in step S2, when the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, for example, control Figure 1 Point C of the NFC matching circuit 1 shown is disconnected. At this time, the resonant circuit 11 is connected to the two transmitting terminals TXP / TXN of the NFC controller 2, and the resonant circuit 11 is debugged, and the measured resonant frequency corresponding to the resonant circuit 11 is collected by the measuring device. Then, the measured resonant frequency corresponding to the resonant circuit 11 is analyzed to evaluate whether the resonant circuit 11 reaches its corresponding target resonant frequency; if the measured resonant frequency reaches the target resonant frequency corresponding to the resonant circuit 11, the component parameters determined after debugging are determined as the target component parameters of the resonant circuit 11. For example, when the resonant circuit 11 includes a resonant inductor Ltx and a resonant capacitor Ctx arranged in series, the target component parameters determined include the target inductance value of the resonant inductor Ltx and the target capacitance value of the resonant capacitor Ctx.

[0039] As an example, in step S3, when the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, for example, control Figure 1 Point C of the NFC matching circuit 1 shown is disconnected. At this time, the impedance matching circuit 12 is connected to the NFC antenna 3, and the circuit composed of the impedance matching circuit 12 and the NFC antenna 3 is debugged, specifically including: debugging the matching impedance from the input end of the impedance matching circuit 12 to the ground, by adjusting the component parameters in the impedance matching circuit 12, when the matching impedance of the impedance matching circuit 12 measured in real time satisfies the preset first condition and the second condition at the same time, the component parameters determined after debugging can be directly determined as the target component parameters of the impedance matching circuit 12; the NFC matching circuit 1 can also be further debugged, and its component parameters are adjusted again to determine the target component parameters of the impedance matching circuit 12.

[0040] The first condition is that the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as the impedance of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna 3. The first resonance point, the second resonance point, and the third resonance point are three resonance points with increasing frequencies, and the resonance point here is the intersection of the impedance curve of the impedance matching circuit 12 and the real axis of the Smith chart. For example, Figure 2As shown, the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point and a third resonance point with increasing frequencies in the Smith chart, the second resonance point in the middle is the matching impedance corresponding to the operating frequency (i.e., 13.56 MHz) of the NFC antenna 3, the first resonance point coincides with the third resonance point, that is, the matching impedance of the first resonance point and the third resonance point is the same or nearly the same (i.e., the difference between the matching impedance of the first resonance point and the second resonance point is less than the preset threshold value), at this time, the impedance curve of the impedance matching circuit 12 is symmetrical based on the real axis of the Smith chart in the area close to the operating frequency of the NFC antenna 3, in this case, the matching impedance from the input end of the impedance matching circuit 12 to the ground is a pure resistance, so that the signal can be transmitted based on a larger power and reduce signal reflection.

[0041] The second condition is that the matching impedance corresponding to the working frequency of the NFC antenna 3 is configured to be equal to the target impedance, that is, the matching impedance corresponding to the working frequency of the NFC antenna 3 (that is, the matching impedance of 13.35MHz) is configured to be equal to the target impedance in real time, which helps to ensure the efficiency and performance of the signal transmission through the impedance matching circuit 12. The target impedance here is the impedance that needs to be controlled during the debugging of the NFC matching circuit 1. In other words, during the debugging process, it is necessary to first determine the target impedance according to the specific design of the impedance matching circuit 12 (including but not limited to its constituent elements, the connection relationship between elements, and element parameters, etc.). During the debugging process, it is detected whether the matching impedance corresponding to the working frequency of the NFC antenna 3 reaches the target impedance. If the matching impedance does not reach the target impedance, it is necessary to debug the element parameters of the impedance matching circuit 12; if the matching impedance reaches the target impedance, it is determined that the debugging is successful, and the element parameters determined after debugging can be directly determined as the target element parameters of the impedance matching circuit 12; the NFC matching circuit 1 can also be further debugged, and its element parameters can be adjusted again to determine the target element parameters of the impedance matching circuit 12.

[0042] That is to say, when the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the impedance matching circuit 12 and the NFC antenna 3 are connected, and the circuit constituted by the impedance matching circuit 12 and the NFC antenna 3 is debugged. Specifically, a signal is input to the input end of the impedance matching circuit 12, and the matching impedance from the input end of the impedance matching circuit 12 to the ground is monitored in real time. When the above-mentioned first condition and the second condition are met at the same time, it is determined that it meets the debugging success standard corresponding to the impedance matching circuit 12. At this time, the component parameters determined after debugging are determined as the target component parameters of the impedance matching circuit 12; the NFC matching circuit 1 can also be further debugged, and its component parameters are adjusted again to determine the target component parameters of the impedance matching circuit 12; when at least one of the above two conditions is not met, it is determined that it does not meet the debugging success standard corresponding to the impedance matching circuit 12. At this time, the component parameters of the impedance matching circuit 12 need to be debugged so that the finally debugged impedance matching circuit 12 can enable the signal to be transmitted based on a larger power and reduce signal reflection to ensure the efficiency and performance of signal transmission.

[0043] In this example, the resonant circuit 11 is connected to the two transmitting terminals TXP / TXN of the NFC controller 2, and the impedance matching circuit 12 is connected to the NFC antenna 3, so that the resonant circuit 11 can convert the two transmitting terminals TXP / TXN of the differential output of the NFC controller 2 into a single-ended output. Since it does not contain a balun, the cost is low, the path loss is small, and the output active power is large; during the impedance matching process, the impedance matching circuit 12 must meet the requirement that the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna 3, so as to ensure that the matching impedance from the input end of the impedance matching circuit 12 to the ground is pure resistance, so that the signal can be transmitted based on a larger power and reduce signal reflection; and it must meet the requirement that the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance, so as to ensure the efficiency and performance of signal transmission.

[0044] In one embodiment, if Figure 3 As shown, the resonant circuit 11 includes a resonant inductor Ltx and a resonant capacitor Ctx; a first end of the resonant inductor Ltx is connected to a transmitting end TXP of the NFC controller 2, and a second end of the resonant inductor Ltx is used to be connected to the impedance matching circuit 12; a first end of the resonant capacitor Ctx is connected to another transmitting end TXN of the NFC controller 2, and a second end of the resonant capacitor Ctx is used to be connected to the impedance matching circuit 12; Step S2, i.e., when the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the resonant circuit 11 is debugged, and when the measured resonant frequency of the resonant circuit 11 is configured to be equal to the target resonant frequency, the target component parameters of the resonant circuit 11 are determined, including: S21: When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the resonant circuit 11 is debugged to obtain a measured resonant frequency of a series circuit formed by a resonant inductor Ltx and a resonant capacitor Ctx; S22: if the measured resonant frequency is greater than the target resonant frequency, increasing the initial inductance value of the resonant inductor Ltx and / or the initial capacitance value of the resonant capacitor Ctx; S23: if the measured resonant frequency is less than the target resonant frequency, reducing the initial inductance value of the resonant inductor Ltx and / or the initial capacitance value of the resonant capacitor Ctx; S24: If the measured resonant frequency is equal to the target resonant frequency, the initial inductance value of the resonant inductor Ltx and the initial capacitance value of the resonant capacitor Ctx are respectively determined as the target inductance value of the resonant inductor Ltx and the target capacitance value of the resonant capacitor Ctx.

[0045] The target resonant frequency is the resonant frequency that the resonant circuit 11 needs to be controlled to reach. The resonant frequency of the resonant circuit 11 can be This formula determines that the resonant frequency of the resonant circuit 11 is negatively correlated with the target inductance value of the corresponding resonant inductor Ltx and the target capacitance value of the resonant capacitor Ctx. If the target resonant frequency is greater than or equal to the operating frequency of the NFC antenna 3, and the operating frequency of the NFC antenna 3 is 13.56 MHz, then the target resonant frequency can be set to 13.56 MHz or 15 MHz, which can be determined independently according to actual conditions. The initial inductance value of the resonant inductor Ltx refers to the inductance value of the resonant inductor Ltx before debugging, and the target inductance value of the resonant inductor Ltx refers to the inductance value of the resonant inductor Ltx after debugging. The initial capacitance value of the resonant capacitor Ctx refers to the capacitance value of the resonant capacitor Ctx before debugging, and the target capacitance value of the resonant capacitor Ctx refers to the capacitance value of the resonant capacitor Ctx after debugging.

[0046] As an example, when the resonance circuit 11 and the impedance matching circuit 12 are disconnected, for example, the control Figure 3Point C of the NFC matching circuit 1 shown is disconnected. At this time, the resonant circuit 11 is connected to the two transmitting terminals TXP / TXN of the NFC controller 2. The resonant circuit 11 is debugged, and the measured resonant frequency at both ends of the series circuit formed by the resonant inductor Ltx and the resonant capacitor Ctx is collected in real time by the measuring device, and the measured resonant frequency is compared with the target resonant frequency. When the measured resonant frequency is greater than the target resonant frequency, it is determined that the measured resonant frequency is larger and the resonant frequency of the resonant circuit 11 needs to be lowered. Therefore, the initial inductance value of the resonant inductor Ltx and / or the initial capacitance value of the resonant capacitor Ctx can be increased to achieve the purpose of lowering the resonant frequency of the resonant circuit 11. When the measured resonant frequency is less than the target resonant frequency, it is determined that the measured resonant frequency is small and the resonant frequency of the resonant circuit 11 needs to be increased. Therefore, the initial inductance value of the resonant inductor Ltx and / or the initial capacitance value of the resonant capacitor Ctx can be reduced to achieve the purpose of increasing the resonant frequency of the resonant circuit 11; when the measured resonant frequency is equal to the target resonant frequency, the initial inductance value of the resonant inductor Ltx and the initial capacitance value of the resonant capacitor Ctx are respectively determined as the target inductance value of the resonant inductor Ltx and the target capacitance value of the resonant capacitor Ctx, so that the impedance of the resonant circuit 11 at the target resonant frequency is small, which helps to ensure the effective transmission of the signal and reduce signal attenuation.

[0047] In one embodiment, step S3, i.e., when the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, debugging the matching impedance from the input end to the ground of the impedance matching circuit 12, and determining the target element parameters of the impedance matching circuit 12 when the matching impedance of the impedance matching circuit 12 satisfies the first condition and the second condition at the same time, includes: S31: When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the matching impedance from the input end to the ground of the impedance matching circuit 12 is debugged, and when the matching impedance of the impedance matching circuit 12 satisfies the first condition and the second condition at the same time, the standard component parameters of the impedance matching circuit 12 are determined; S32: When the resonant circuit 11 and the impedance matching circuit 12 are in a connected state, a performance test is performed on the NFC matching circuit 1 to obtain a first test result of the NFC matching circuit 1; S33: Based on the first test result of the NFC matching circuit 1 , the standard component parameters of the matching unit 122 are debugged to determine the target component parameters of the matching unit 122 .

[0048] As an example, when the resonance circuit 11 and the impedance matching circuit 12 are in a disconnected state, for example, the control Figure 3Point C of the NFC matching circuit 1 shown is disconnected. At this time, the impedance matching circuit 12 and the NFC antenna 3 are connected, and the circuit formed by the impedance matching circuit 12 and the NFC antenna 3 is debugged, specifically including: debugging the matching impedance from the input end of the impedance matching circuit 12 to the ground, so that the matching impedance of the impedance matching circuit 12 measured in real time satisfies the first condition and the second condition at the same time by adjusting the component parameters in the impedance matching circuit 12. At this time, the component parameters of the impedance matching circuit 12 determined after debugging are determined as standard component parameters of the impedance matching circuit 12. The standard component parameters here can be understood as the component parameters debugged when the matching impedance of the impedance matching circuit 12 satisfies the first condition and the second condition.

[0049] As an example, after the standard component parameters of the impedance matching circuit 12 are determined, the resonant circuit 11 and the impedance matching circuit 12 need to be connected so as to perform a performance test on the NFC matching circuit 1 to obtain a first test result of the NFC matching circuit 1. In this example, the NFC matching circuit 1 is debugged, and specifically, the NFC controller 2 can control the NFC antenna 3 to transmit a signal, and a measuring device is used to collect measured indicators during the signal transmission process and measured indicators during the signal reception process, and determine them as the first test result of the NFC matching circuit 1.

[0050] As an example, after determining the first test result of the NFC matching circuit 1, it is necessary to further determine whether the first test result of the NFC matching circuit 1 meets the preset performance test standard. The performance test standard here can be to determine the performance standard that needs to be controlled and achieved according to the actual situation. If the first test result of the NFC matching circuit 1 meets the performance test standard, there is no need to debug the standard component parameters of the impedance matching circuit 12, and the standard component parameters are directly determined as the target component parameters of the impedance matching circuit 12. If the first test result of the NFC matching circuit 1 does not meet the performance test standard, the standard component parameters of the impedance matching circuit 12 are debugged, and the performance test is performed again until the first test result meets the performance test standard, and the target component parameters of the impedance matching circuit 12 are determined, so that the target component parameters of the impedance matching circuit 12 meet the debugging success standard corresponding to the impedance matching circuit 12 and meet the preset performance test standard to ensure the overall performance of the NFC matching circuit 1. In this example, based on the first test result corresponding to the performance test, the standard component parameters in the impedance matching circuit 12 are debugged, so that the component parameters that need to be adjusted during the adjustment process are less, the debugging process is simpler, and it helps to improve the debugging efficiency.

[0051] In one embodiment, the impedance matching circuit 12 includes an EMC filter 121 and a matching unit 122, wherein a first end of the EMC filter 121 is used to connect to the resonant circuit 11, a second end of the EMC filter 121 is connected to a first end of the matching unit 122, and a second end of the matching unit 122 is used to connect to the NFC antenna 3; Step S32, i.e., when the resonant circuit 11 and the impedance matching circuit 12 are in a connected state, a performance test is performed on the NFC matching circuit 1 to obtain a first test result of the NFC matching circuit 1, including: Connecting a first end of the receiving circuit 13 to a receiving end RXP of the NFC controller 2, connecting a second end of the receiving circuit 13 to the NFC antenna 3 or connecting to the NFC antenna 3 through the matching unit 122, and performing a performance test on the NFC matching circuit 1 when the resonant circuit 11 and the EMC filter 121 are in a connected state, and obtaining a first test result of the NFC matching circuit 1, wherein the first test result includes a measured transmission magnetic field strength and a measured receiving load modulation amplitude; Step S33, i.e., debugging the standard component parameters of the matching unit 122 based on the first test result of the NFC matching circuit 1 to determine the target component parameters of the matching unit 122, includes: S331: If the measured transmit magnetic field strength is greater than the preset magnetic field strength threshold, and the measured receive load modulation amplitude is greater than the preset load modulation amplitude threshold, the standard component parameters of the EMC filter 121 are determined as the target component parameters of the EMC filter 121, and the standard component parameters of the matching unit 122 are determined as the target component parameters of the matching unit 122; S332: If the measured transmitting magnetic field strength is not greater than the preset magnetic field strength threshold, or the measured receiving load modulation amplitude is not greater than the preset load modulation amplitude threshold, the standard component parameters of the EMC filter 121 are determined as the target component parameters of the EMC filter 121, and the standard component parameters of the matching unit 122 are biased to determine the target component parameters of the matching unit 122.

[0052] Among them, the measured transmission magnetic field strength is the transmission magnetic field strength collected during the signal transmission process. The preset magnetic field strength threshold is the magnetic field strength threshold determined in advance according to the transmission performance to be achieved. The measured receiving load modulation amplitude is the receiving load modulation amplitude (load modulation amplitude, referred to as LMA) collected during the signal reception process. The preset load modulation amplitude threshold is the threshold corresponding to the load modulation amplitude determined in advance according to the receiving performance to be achieved.

[0053] As an example, in step S32, it is necessary to first connect the first end of the receiving circuit 13 to the receiving end RXP of the NFC controller 2, and connect the second end of the receiving circuit 13 to the NFC antenna 3 or to the NFC antenna 3 through the matching unit 122, so that the NFC controller 2 can receive the signal of the NFC antenna 3 through the receiving circuit 13. Then, when the resonant circuit 11 and the EMC filter 121 are in a connected state, the NFC matching circuit 1 is subjected to a performance test to obtain a first test result of the NFC matching circuit 1, wherein the first test result includes the measured transmission magnetic field strength and the measured receiving load modulation amplitude. In this example, the performance test of the NFC matching circuit 1 specifically includes: enabling the NFC controller 2 to emit a signal outward, so that the signal is transmitted to the NFC antenna 3 through the resonant circuit 11, the EMC filter 121 and the matching unit 122 in sequence, and the signal is emitted outward through the NFC antenna 3 to obtain the measured emission magnetic field strength of the signal emission process; and receiving the signal through the NFC antenna 3, so that the received signal is sent to the NFC controller 2 through the receiving circuit 13. In this process, the measured receiving load modulation amplitude is monitored, and the measured emission magnetic field strength and the measured receiving load modulation amplitude are determined as the first test result of the NFC matching circuit 1.

[0054] As an example, after determining the measured transmission magnetic field strength and the measured receiving load modulation amplitude of the NFC matching circuit 1, it is also necessary to compare the measured transmission magnetic field strength with the preset magnetic field strength threshold, and compare the measured receiving load modulation amplitude with the preset load modulation amplitude threshold, so as to determine whether it is necessary to adjust the standard component parameters of the impedance matching circuit 12 according to the ratio results of the two, specifically including the following two situations: In the first case, when the measured transmission magnetic field intensity is greater than the preset magnetic field intensity threshold, and the measured receiving load modulation amplitude is greater than the preset load modulation amplitude threshold, it is determined that the transmission performance and receiving performance of the circuit where the NFC matching circuit 1 is located have reached the expected goals. At this time, the standard component parameters of the EMC filter 121 are determined as the target component parameters of the EMC filter 121, and the standard component parameters of the matching unit 122 are determined as the target component parameters of the matching unit 122. That is, when the transmission performance and receiving performance of the NFC matching circuit 1 have reached the expected goals, there is no need to further adjust the standard component parameters of the impedance matching circuit 12, and they can be directly determined as the target component parameters.

[0055] The second case: when the measured transmission magnetic field strength is not greater than the preset magnetic field strength threshold, or the measured receiving load modulation amplitude is not greater than the preset load modulation amplitude threshold, it is determined that at least one of the transmission performance and the receiving performance of the circuit where the NFC matching circuit 1 is located has not reached the expected target, and the standard component parameters of the EMC filter 121 are determined as the target component parameters of the EMC filter 121, and the standard component parameters of the matching unit 122 are biased to determine the target component parameters of the matching unit 122. That is, when at least one of the transmission performance and the receiving performance of the NFC matching circuit 1 has not reached the expected target, there is no need to adjust the standard component parameters of the EMC filter 121, but only adjust the standard component parameters of the matching unit 122 to improve the transmission performance and the receiving performance of the circuit where the NFC matching circuit 1 is located, so that it reaches the expected target, and the debugging process is simple to operate, which helps to ensure the debugging efficiency.

[0056] In one embodiment, the matching unit 122 includes a first matching capacitor C1 and a second matching capacitor C2; a first end of the first matching capacitor C1 is connected to the EMC filter 121, and a second end of the first matching capacitor C1 is connected to the NFC antenna 3; a first end of the second matching capacitor C2 is connected to a connection node between the EMC filter 121 and the NFC antenna 3, and a second end of the second matching capacitor C2 is grounded; In step S332, the standard component parameters of the matching unit 122 are subjected to a deviation process to determine the target component parameters of the matching unit 122, including: The standard capacitance value of the first matching capacitor C1 is determined as the target capacitance value of the first matching capacitor C1 , and the difference between the standard capacitance value of the second matching capacitor C2 and the preset variation is determined as the target capacitance value of the second matching capacitor C2 .

[0057] As an example, when at least one of the transmission performance and the receiving performance of the NFC matching circuit 1 does not reach the expected target, the standard capacitance value of the first matching capacitor C1 is determined as the target capacitance value of the first matching capacitor C1, and the second matching capacitor C2 is subjected to a pull-off process to determine the difference between the standard capacitance value of the second matching capacitor C2 and the preset change amount as the target capacitance value of the second matching capacitor C2, so that the capacitance value of the second matching capacitor C2 is reduced, thereby increasing the resonant frequency of the overall circuit, thereby ensuring that the imaginary part of the matching impedance of the operating frequency (13.56MHz) of the NFC antenna 3 is a positive number, so as to improve the transmission performance and receiving performance of the circuit in which the NFC matching circuit 1 is located, so that it reaches the expected target. For example, when the matching impedance from the input end of the EMC filter 121 to the ground is 10ohm, the standard capacitance value of the second matching capacitor C2 can be reduced by 100pF to determine the target capacitance value of the second matching capacitor C2, so as to ensure the transmission performance and receiving performance of the NFC matching circuit 1. In this example, by debugging the standard component parameters of the second matching capacitor C2, the imaginary part of the matching impedance of the operating frequency of the NFC antenna 3 measured is a positive number. This debugging process is simple to operate and helps to ensure debugging efficiency.

[0058] In one embodiment, the preset variation ranges from 0.025 times to 0.25 times the standard capacitance value of the second matching capacitor.

[0059] As an example, when the matching conditions of the impedance matching circuit 12 simultaneously meet the first condition and the second condition, the standard capacitance value of the debugged second matching capacitor C2 is Cs, and the corresponding preset change amount can be determined as (0.025~0.25)*Cs according to the standard capacitance value Cs, and the difference between the standard capacitance value of the second matching capacitor C2 and the preset change amount is determined as the target capacitance value of the second matching capacitor C2, thereby determining the range of its target capacitance value to be (0.75~0.975)*Cs, so as to lower the target capacitance value of the second matching capacitor C2, thereby increasing the resonant frequency of the overall circuit, thereby ensuring that the imaginary part of the matching impedance of the operating frequency (13.56MHz) of the NFC antenna 3 is a positive number, so as to improve the transmission performance and receiving performance of the circuit where the NFC matching circuit 1 is located, so that it achieves the expected goal.

[0060] In one embodiment, the EMC filter 121 includes a filter inductor L0 and a filter capacitor C0; a first end of the filter inductor L0 is connected to the resonant circuit 11, and a second end of the filter inductor L0 is connected to the matching unit 122; a first end of the filter capacitor C0 is connected to a connection node between the filter inductor L0 and the matching unit 122, and a second end of the filter capacitor C0 is grounded; The target impedance is configured to be positively correlated with the target inductance value of the filter inductor L0.

[0061] As an example, the EMC filter 121 includes a filter inductor L0 and a filter capacitor C0, the two ends of the filter inductor L0 are arranged between the resonant circuit 11 and the matching unit 122, one end of the filter capacitor C0 is arranged between the connection node between the filter inductor L0 and the matching unit 122, and the other end of the filter capacitor C0 is grounded; during the operation of the matching unit 122, the matching impedance corresponding to the operating frequency (such as 13.56MHz) of the NFC antenna 3 needs to be configured to be equal to the target impedance, and the target impedance is positively correlated with the target inductance value of the filter inductor L0. That is, during the debugging and design process of the NFC matching circuit 1, it is necessary to first determine the target impedance corresponding to the resonant inductor Ltx according to the target inductance value of the resonant inductor Ltx, and then, through the operation of the NFC matching circuit 1, the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance corresponding to the filter inductor L0, so as to ensure that the active power of the NFC antenna 3 is achieved.

[0062] In one embodiment, the debugging method of the NFC matching circuit 1 further includes: S41: When the resonant circuit 11 and the impedance matching circuit 12 are in a connected state, the first end of the receiving circuit 13 is connected to the receiving end RXP of the NFC controller 2, and the second end of the receiving circuit 13 is connected to the connection node between the EMC filter 121 and the matching unit 122, and the NFC matching circuit 1 is tested for performance to obtain a first receiving load modulation amplitude; S42: When the resonant circuit 11 and the impedance matching circuit 12 are in a connected state, the first end of the receiving circuit 13 is connected to the receiving end RXP of the NFC controller 2, and the second end of the receiving circuit 13 is connected to the connection node between the matching unit 122 and the NFC antenna 3, and the performance test of the NFC matching circuit 1 is performed to obtain the second receiving load modulation amplitude; S43: If the larger value of the first receiving load modulation amplitude and the second receiving load modulation amplitude is greater than the preset load modulation amplitude threshold, determine the target component parameters of the receiving circuit 13, and determine that the second end of the receiving circuit 13 is connected to the connection node corresponding to the larger value.

[0063] As an example, in step S41, when the resonant circuit 11 and the impedance matching circuit 12 are in a connected state, the first end of the receiving circuit 13 is connected to the receiving end RXP of the NFC controller 2, and the second end of the receiving circuit 13 is connected to the connection node between the EMC filter 121 and the matching unit 122, and the performance test of the NFC matching circuit 1 is performed, that is, the signal is received through the NFC antenna 3, and the received signal is sent to the NFC controller 2 through the receiving circuit 13, and the receiving load modulation amplitude of this process is obtained, and the receiving load modulation amplitude is determined as the first receiving load modulation amplitude. In other words, the first receiving load modulation amplitude is the receiving load modulation amplitude detected when the second end of the receiving circuit 13 is set at the connection node between the EMC filter 121 and the matching unit 122.

[0064] As an example, in step S42, when the resonant circuit 11 and the EMC filter 121 are in a connected state, the first end of the receiving circuit 13 is connected to the receiving end RXP of the NFC controller 2, and the second end of the receiving circuit 13 is connected to the connection node between the matching unit 122 and the NFC antenna 3, and the performance test of the NFC matching circuit 1 is performed, that is, the signal is received through the NFC antenna 3, and the received signal is sent to the NFC controller 2 through the receiving circuit 13, and the receiving load modulation amplitude of this process is obtained, and the receiving load modulation amplitude is determined as the second receiving load modulation amplitude. In other words, the second receiving load modulation amplitude is the receiving load modulation amplitude detected when the second end of the receiving circuit 13 is set at the connection node between the matching unit 122 and the NFC antenna 3.

[0065] The preset load modulation amplitude threshold is a load modulation amplitude threshold determined in advance according to the receiving performance that needs to be achieved.

[0066] As an example, in step S43, after obtaining the first receiving load modulation amplitude and the second receiving load modulation amplitude, the first receiving load modulation amplitude and the second receiving load modulation amplitude need to be compared to determine the larger value of the two, and then the larger value is compared with the preset load modulation amplitude threshold. If the larger value is greater than the preset load modulation amplitude threshold, it is determined that when the second end of the receiving circuit 13 is connected to the connection node corresponding to the larger value, the receiving performance of the NFC matching circuit 1 meets the preset requirements, and it is determined that the debugging of the receiving circuit 13 is completed, and the component parameters of the completed debugging are determined as the target component parameters of the receiving circuit 13, and the connection node corresponding to the larger value is determined as the node to be connected to the second end of the receiving circuit 13. For example, when the first receiving load modulation amplitude is greater than the second receiving load modulation amplitude, and the first receiving load modulation amplitude is greater than the preset load modulation amplitude threshold, it can be determined that the receiving performance of the second end of the receiving circuit 13 connected to the connection node between the EMC filter 121 and the matching unit 122 is better than the receiving performance of the second end of the receiving circuit 13 connected to the connection node between the matching unit 122 and the NFC antenna 3, and the receiving performance of the NFC matching circuit 1 meets the preset requirements. On the contrary, when the second receiving load modulation amplitude is greater than the first receiving load modulation amplitude, and the second receiving load modulation amplitude is greater than the preset load modulation amplitude threshold, it can be determined that the receiving performance of the connection node between the second end of the receiving circuit 13 connected to the matching unit 122 and the NFC antenna 3 is better than the receiving performance of the connection node between the second end of the receiving circuit 13 connected to the EMC filter 121 and the matching unit 122, and the receiving performance of the NFC matching circuit 1 meets the preset requirements. When the larger value of the first receiving load modulation amplitude and the second receiving load modulation amplitude is not greater than the preset load modulation amplitude threshold, it is determined that the receiving performance of the NFC matching circuit 1 does not meet the preset requirements, and the component parameters of the receiving circuit 13 need to be adjusted until it is detected that the larger value of the first receiving load modulation amplitude and the second receiving load modulation amplitude is greater than the preset load modulation amplitude threshold, and then it is determined that the debugging of the receiving circuit 13 is completed and the target component parameters of the receiving circuit 13 are determined.

[0067] In one embodiment, the debugging method of the NFC matching circuit 1 further includes: S51: Obtain target performance indicators corresponding to the target application scenario; S52: Perform a performance test on the NFC matching circuit 1 to obtain a measured performance indicator of the NFC matching circuit 1; S53: When the measured performance index of the NFC matching circuit 1 does not meet the target performance index, adjust the target element parameters of the resonant circuit 11 .

[0068] The target application scenario refers to the scenario in which the NFC matching circuit 1 needs to be applied. The target performance index corresponding to the target application scenario refers to the performance requirement that needs to be controlled to be achieved by the NFC matching circuit 1 in the target application scenario.

[0069] As an example, the debugging device can also obtain the target application scenario input by the user and the target performance index corresponding to the target application scenario. Then, according to the target application scenario, the test strategy corresponding to the target application scenario is called to perform a performance test on the pre-debugging NFC matching circuit 1, and the measured performance index of the NFC matching circuit 1 is collected in real time. The measured performance index can be the measured data collected in real time during the performance test of the NFC matching circuit 1 to reflect its performance. Next, the measured performance index of the NFC matching circuit 1 is compared with the target performance index to be achieved. When the measured performance index of the NFC matching circuit 1 does not meet the target performance index, the target element parameters of the NFC matching circuit 1 need to be further debugged until the measured performance index meets the target performance index. The NFC matching circuit 1 with the adjusted target element parameters can be applied to the NFC device corresponding to the target application scenario, so that it can adapt to the performance requirements of the target application scenario. In this example, after the debugging of the NFC matching circuit 1 is completed, the corresponding performance test can be performed based on the target performance index of the target application scenario to achieve the target performance index of different target application scenarios, and adaptively adjust its target element parameters to ensure that it can adapt to the needs of different application scenarios.

[0070] In one embodiment, a debugging method of the NFC matching circuit 1 includes: A51: Obtain the target transmit power corresponding to the target application scenario; A52: Perform a performance test on the NFC matching circuit 1 to obtain the measured transmission power of the NFC matching circuit 1; A53: When the measured transmission power of the NFC matching circuit 1 is less than the target transmission power, the target inductance value of the resonant inductor Ltx is increased and / or the target capacitance value of the resonant capacitor Ctx is increased.

[0071] Among them, step A51 is a specific implementation of step S51, step A52 is a specific implementation of step S52, and step A53 is a specific implementation of step S53.

[0072] The target transmission power refers to the transmission power that needs to be achieved. The measured transmission power refers to the transmission power detected in real time during the performance test of the NFC matching circuit 1.

[0073] As an example, when the NFC matching circuit 1 needs to be applied to a card that is limited by the transmission power of the NFC controller 2, at this time, the target transmission power corresponding to the target application scenario input by the user can be obtained. Then, the NFC matching circuit 1 is subjected to a performance test to obtain the measured transmission power of the NFC matching circuit 1 collected by the measuring device; the measured transmission power is compared with the target transmission power. When the measured transmission power is less than the target transmission power, it is determined that its transmission performance does not meet the performance requirements of the target application scenario. At this time, the target inductance value of the resonant inductor Ltx and / or the target capacitance value of the resonant capacitor Ctx can be increased to improve the transmission performance of the NFC matching circuit 1. The card that is limited by the transmission power of the NFC controller 2 here means that the reading distance of the card is only affected by the transmission power of the NFC controller 2. The greater the transmission power, the longer the reading distance. Common cards include T3T and T5T types defined by the NFC forum.

[0074] In one embodiment, a debugging method of the NFC matching circuit 1 includes: B51: Obtain the target receiving load modulation amplitude corresponding to the target application scenario; B52: Perform a performance test on the NFC matching circuit 1 to obtain the measured receiving load modulation amplitude of the NFC matching circuit 1; B53: When the measured receiving load modulation amplitude of the NFC matching circuit 1 is less than the target receiving load modulation amplitude, the target inductance value of the resonant inductor Ltx is reduced and / or the target capacitance value of the resonant capacitor Ctx is reduced.

[0075] Among them, step B51 is a specific implementation of step S51, step B52 is a specific implementation of step S52, and step B53 is a specific implementation of step S53.

[0076] The target receiving load modulation amplitude refers to the receiving load modulation amplitude that needs to be achieved. The measured receiving load modulation amplitude refers to the receiving load modulation amplitude detected in real time during the performance test of the NFC matching circuit 1.

[0077] As an example, when the NFC matching circuit 1 needs to be applied to a card that is limited by the receiving load modulation amplitude of the NFC controller 2, the target receiving load modulation amplitude corresponding to the target application scenario input by the user can be obtained. Then, the NFC matching circuit 1 is subjected to a performance test to obtain the measured receiving load modulation amplitude of the NFC matching circuit 1 collected by the measuring device; the measured receiving load modulation amplitude is compared with the target receiving load modulation amplitude. When the measured receiving load modulation amplitude is less than the target receiving load modulation amplitude, it is determined that its receiving performance does not meet the performance requirements of the target application scenario. At this time, the target inductance value of the resonant inductor Ltx and / or the target capacitance value of the resonant capacitor Ctx can be reduced to improve the receiving performance of the NFC matching circuit 1. The card that is limited by the receiving load modulation amplitude of the NFC controller 2 here means that the reading distance of the card is only affected by the receiving load modulation amplitude of the NFC controller 2. The higher the receiving load modulation amplitude, the longer the reading distance. Common cards include the T4T type defined by the NFC forum.

[0078] An embodiment of the present invention provides an NFC matching circuit 1, such as Figure 3 As shown, the NFC matching circuit 1 includes a resonant circuit 11 and an impedance matching circuit 12; The resonant circuit 11 is connected to two transmitting terminals of the NFC controller 2 and is used to resonate the differential output of the NFC controller 2 and output a single-ended signal; A first end of the impedance matching circuit 12 is connected to the resonant circuit 11, and a second end of the impedance matching circuit 12 is used to connect to the NFC antenna 3; When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the measured resonant frequency of the resonant circuit 11 is configured to be equal to the target resonant frequency, and the target resonant frequency is greater than or equal to the operating frequency of the NFC antenna 3; When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the matching impedance from the input end of the impedance matching circuit 12 to the ground satisfies both the first condition and the second condition; The first condition is that the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna 3; The second condition is that the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance.

[0079] As an example, the NFC matching circuit 1 includes a resonant circuit 11, which is connected to the two transmitting terminals TXP / TXN of the NFC controller 2, and is used to resonate the differential output of the two transmitting terminals TXP / TXN of the NFC controller 2. For example, the voltage of the transmitting terminal TXP of the NFC controller 2 to the ground is 3.3V, and the voltage of the transmitting terminal TXN of the NFC controller 2 to the ground is -3.3V, so that the NFC controller 2 can output a differential signal with an amplitude range of -3.3V to 3.3V; the resonant circuit 11 is connected to the two transmitting terminals TXP / TXN of the NFC controller 2, and the characteristics of the resonant circuit 11 and the bidirectional current control technology are used to enable the resonant circuit 11 to convert the differential signal into a single-ended output. In this example, the resonant circuit 11 realizes single-ended matching, and converts the two transmitting terminals TXP / TXN of the differential output of the NFC controller 2 into a single-ended output through the resonant circuit 11. Because it does not contain a balun, the cost is low, the path loss is small, and the single-ended output active power of the resonant circuit 11 is large.

[0080] As an example, the NFC matching circuit 1 further includes an impedance matching circuit 12 connected to the resonant circuit 11 , and the impedance matching circuit 12 is used to connect to the NFC antenna 3 and to adjust the matching impedance from the input end of the impedance matching circuit 12 to the ground.

[0081] In this example, the NFC matching circuit 1 is a pre-debugged circuit, that is, the target component parameters in the resonant circuit 11 and the impedance matching circuit 12 are debugged parameters, and the debugging process meets the following conditions to ensure the transceiver performance of the NFC matching circuit 1.

[0082] When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the measured resonant frequency of the resonant circuit 11 is configured to be equal to the target resonant frequency, and the target resonant frequency is greater than or equal to the operating frequency of the NFC antenna 3. That is, when the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the resonant circuit 11 is debugged, and the measured resonant frequency corresponding to the resonant circuit 11 is collected by a measuring device; then, the measured resonant frequency corresponding to the resonant circuit 11 is analyzed to evaluate whether the resonant circuit 11 reaches its corresponding target resonant frequency; if the measured resonant frequency reaches the target resonant frequency corresponding to the resonant circuit 11, the component parameters determined after debugging are determined as the target component parameters of the resonant circuit 11, so that the impedance of the resonant circuit 11 at the target resonant frequency is small, which helps to ensure the effective transmission of the signal and reduce signal attenuation.

[0083] When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the matching impedance from the input end of the impedance matching circuit 12 to the ground must meet the condition that "the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna 3". For example, Figure 2 As shown, the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point and a third resonance point with increasing frequencies in the Smith chart, the second resonance point in the middle is the matching impedance corresponding to the operating frequency (i.e., 13.56 MHz) of the NFC antenna 3, the first resonance point coincides with the third resonance point, that is, the matching impedance of the first resonance point and the third resonance point is the same or nearly the same (i.e., the difference between the matching impedance of the first resonance point and the second resonance point is less than the preset threshold value), at this time, the impedance curve of the impedance matching circuit 12 is symmetrical based on the real axis of the Smith chart in the area close to the operating frequency of the NFC antenna 3, in this case, the matching impedance from the input end of the impedance matching circuit 12 to the ground is a pure resistance, so that the signal can be transmitted based on a larger power and reduce signal reflection.

[0084] When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the matching impedance from the input end of the impedance matching circuit 12 to the ground must meet the condition that "the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance", which helps to ensure the efficiency and performance of the signal transmission through the impedance matching circuit 12.

[0085] In this example, single-ended matching is achieved through the resonant circuit 11, which converts the two transmitter ends TXP / TXN of the differential output of the NFC controller 2 into single-ended outputs through the resonant circuit 11. Since it does not contain a balun, the cost is low and the path loss is small, so that the single-ended output active power of the resonant circuit 11 is large; during the impedance matching process, the impedance matching circuit 12 must meet the requirement that the impedance curve of the impedance matching circuit 12 has a first resonance point, a second resonance point and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as the impedance of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna 3, so as to ensure that the matching impedance from the input end of the impedance matching circuit 12 to the ground is pure resistance, so that the signal can be transmitted based on a larger power and reduce signal reflection; and it must be satisfied that the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance, so as to ensure the efficiency and performance of signal transmission.

[0086] In one embodiment, the resonant circuit 11 includes a resonant inductor Ltx and a resonant capacitor Ctx; a first end of the resonant inductor Ltx is connected to a transmitting end TXP of the NFC controller 2, and a second end of the resonant inductor Ltx is connected to the impedance matching circuit 12; A first end of the resonant capacitor Ctx is connected to another transmitting end TXN of the NFC controller 2, and a second end of the resonant capacitor Ctx is connected to the impedance matching circuit 12; When the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, the measured resonant frequency of the series circuit formed by the resonant inductor Ltx and the resonant capacitor Ctx is configured to be equal to the target resonant frequency, and the target resonant frequency is 15 MHz.

[0087] As an example, the resonant circuit 11 includes a resonant inductor Ltx and a resonant capacitor Ctx; the two ends of the resonant inductor Ltx are respectively connected between a transmitting end TXP of the NFC controller 2 and the impedance matching circuit 12, and the two ends of the resonant capacitor Ctx are respectively connected between another transmitting end TXN of the NFC controller 2 and the impedance matching circuit 12, and the resonant circuit 11 formed by the resonant inductor Ltx and the resonant capacitor Ctx performs resonant processing on the output signal of the NFC controller 2. For example, in Figure 3 When point C of the NFC matching circuit 1 shown is disconnected, the measured resonant frequency of the series circuit formed by the resonant inductor Ltx and the resonant capacitor Ctx is configured to be equal to 15 MHz, so that the impedance of the resonant circuit 11 at the target resonant frequency is small, which helps to ensure effective transmission of the signal and reduce signal attenuation.

[0088] In one embodiment, the impedance matching circuit 12 includes an EMC filter 121 and a matching unit 122; The EMC filter 121 includes a filter inductor L0 and a filter capacitor C0; a first end of the filter inductor L0 is connected to the resonant circuit 11, and a second end of the filter inductor L0 is connected to the matching unit 122; a first end of the filter capacitor C0 is connected to a connection node between the filter inductor L0 and the matching unit 122, and a second end of the filter capacitor C0 is grounded; a target impedance is configured to be positively correlated with a target inductance value of the filter inductor L0; In one embodiment, the matching unit 122 includes a first matching capacitor C1 and a second matching capacitor C2; a first end of the first matching capacitor C1 is connected to the EMC filter 121, and a second end of the first matching capacitor C1 is connected to the NFC antenna 3; a first end of the second matching capacitor C2 is connected to a connection node between the EMC filter 121 and the NFC antenna 3, and a second end of the second matching capacitor C2 is grounded; The target capacitance value of the second matching capacitor C2 is configured to be equal to the difference between the standard capacitance value and the preset variation; The standard capacitance value is the capacitance value of the second matching capacitor C2 adjusted when the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state and the matching impedance from the input end of the impedance matching circuit 12 to the ground satisfies the first condition and the second condition at the same time; The preset variation value ranges from 0.025 times to 0.25 times the standard capacitance value of the second matching capacitor.

[0089] As an example, the EMC filter 121 includes a filter inductor L0 and a filter capacitor C0, the two ends of the filter inductor L0 are arranged between the resonant circuit 11 and the matching unit 122, one end of the filter capacitor C0 is arranged between the connection node between the filter inductor L0 and the matching unit 122, and the other end of the filter capacitor C0 is grounded; during the operation of the matching unit 122, the matching impedance corresponding to the operating frequency (such as 13.56MHz) of the NFC antenna 3 (i.e., the matching impedance corresponding to 13.56MHz) needs to be configured to be equal to the target impedance, and the target impedance is configured to be positively correlated with the target inductance value of the filter inductor L0 to ensure the efficiency and performance of signal transmission. That is, during the debugging and design process of the NFC matching circuit 1, it is necessary to first determine the target impedance corresponding to the resonant inductor Ltx according to the resonant inductor Ltx, and then, through the operation of the NFC matching circuit 1, the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance corresponding to the filter inductor L0 to ensure that the active power of the NFC antenna 3 is achieved. The filter inductor L0 is arranged between the resonant circuit 11 and the matching unit 122. The larger the target inductance value of the filter inductor L0 is, the larger the series resistance equivalent to being arranged between the resonant circuit 11 and the matching unit 122 is, and the greater the loss in the signal transmission process is. Only by making the matching impedance from the input end of the EMC filter 121 to the ground larger can the active power of the NFC antenna 3 be ensured to be large enough to ensure the transmission performance of the NFC antenna 3. The target impedance needs to be configured to be positively correlated with the target inductance value of the filter inductor L0.

[0090] As an example, after determining the elements of the matching unit 122 and their connection relationship, the resonant circuit 11 and the impedance matching circuit 12 are in a disconnected state, and the matching impedance from the input end of the impedance matching circuit 12 to the ground is debugged. When the matching impedance from the input end of the impedance matching circuit 12 to the ground satisfies both the first condition and the second condition, the standard capacitance value of the second matching capacitor C2 is debugged; then, the difference between the standard capacitance value and the preset change amount is determined as the target capacitance value of the second matching capacitor C2, so that the capacitance value of the second matching capacitor C2 is reduced, thereby increasing the resonant frequency of the overall circuit, thereby ensuring that the imaginary part of the matching impedance of the operating frequency (13.56 MHz) of the NFC antenna 3 is a positive number, so that the signal can be transmitted based on a larger power and reduce signal reflection, thereby improving the transmission performance and receiving performance of the circuit where the NFC matching circuit 1 is located, so that it achieves the expected goal. In this example, the standard capacitance value is the capacitance value of the second matching capacitor C2 debugged when the matching condition of the impedance matching circuit 12 is debugged to meet the first condition and the second condition at the same time; the target capacitance value of the second matching capacitor C2 is determined as the difference between its standard capacitance value and the preset change amount, so as to lower the target capacitance value of the second matching capacitor C2, thereby increasing the resonant frequency of the overall circuit, thereby ensuring that the imaginary part of the matching impedance of the operating frequency (13.56MHz) of the NFC antenna 3 is a positive number, so as to improve the transmission performance and receiving performance of the circuit where the NFC matching circuit 1 is located, so that it can achieve the expected goal.

[0091] In one embodiment, the NFC matching circuit 1 further includes a receiving circuit 13, a first end of the receiving circuit 13 is connected to a receiving end RXP of the NFC controller 2, a second end of the receiving circuit 13 is connected to a connection node between the EMC filter 121 and the matching unit 122, or a second end of the receiving circuit 13 is connected to a connection node between the matching unit 122 and the NFC antenna 3.

[0092] As an example, the NFC matching circuit 1 also includes a receiving circuit 13, which is a circuit for implementing signal reception processing. The first end of the receiving circuit 13 is connected to the receiving end RXP of the NFC controller 2, and the second end of the receiving circuit 13 is connected to the NFC antenna 3, that is, the second end of the receiving circuit 13 is connected to the connection node between the matching unit 122 and the NFC antenna 3, so that the radio frequency signal received by the NFC antenna 3 can be directly sent to the NFC controller 2 through the receiving circuit 13 to ensure its receiving performance. Alternatively, the first end of the receiving circuit 13 is connected to the receiving end RXP of the NFC controller 2, and the second end of the receiving circuit 13 is connected to the NFC antenna 3 through the matching unit 122, that is, the second end of the receiving circuit 13 is connected to the connection node between the EMC filter 121 and the matching unit 122, so that the radio frequency signal received by the NFC antenna 3 is sent to the NFC controller 2 through the matching unit 122 and the receiving circuit 13 to ensure its receiving performance. The first end of the receiving circuit 13 is connected to the receiving end of the NFC controller, and the second end of the receiving circuit 13 is connected to the NFC antenna, or is connected to the NFC antenna through the matching unit 122. Specifically, the performance test of the NFC matching circuit 1 during the debugging process can be performed, and the connection relationship of the receiving circuit 13 can be determined based on the position with better performance test results to ensure effective reception of the signal.

[0093] In one embodiment, the NFC matching circuit 1 further includes an impedance resistor Rq, a first end of the impedance resistor Rq is connected to the impedance matching circuit 12, and a second end of the impedance resistor Rq is connected to the NFC antenna 3, for reducing the Q value of the NFC antenna.

[0094] Among them, the Q value is the main parameter for measuring inductance devices, which indicates the ratio of the inductive reactance presented by the inductor to its equivalent loss resistance when the inductor works under an AC voltage of a certain frequency. As an example, the NFC matching circuit 1 also includes an impedance resistor Rq, an impedance resistor Rq, a first end of which is connected to the impedance matching circuit 12 (specifically, the second end of the matching circuit 122), and a second end of the impedance resistor Rq is connected to the NFC antenna 3, which is used to reduce the Q value of the NFC antenna 3 when necessary. When the Q value of the NFC antenna 3 is low (such as a mobile phone and watch antenna), the impedance resistor Rq can be short-circuited to make the NFC antenna more selective in certain situations and more effectively receive or transmit signals.

[0095] An embodiment of the present invention provides an NFC device, including an NFC controller 2, an NFC antenna 3 and the NFC matching circuit 1 in the above embodiment; the NFC matching circuit 1 is connected to the NFC controller 2 and the NFC antenna 3.

[0096] In the NFC device provided in this example, the resonant circuit 11 of the NFC matching circuit 1 is connected to the two transmitting terminals TXP / TXN of the NFC controller 2, the EMC filter 121 is connected to the resonant circuit 11, and the matching unit 122 is connected to the EMC filter 121 and the NFC antenna 3, so that the resonant circuit 11 can convert the two transmitting terminals TXP / TXN of the differential output of the NFC controller 2 into single-ended output. Since it does not contain a balun, the cost is low, the path loss is small, and the output active power is large; the EMC filter 121 can effectively suppress high-order resonance during signal transmission and avoid electromagnetic interference during signal transmission between the NFC controller 2 and the NFC antenna 3; during the impedance matching process of the matching unit 122, the overall impedance curve of the circuit composed of the EMC filter 121, the matching unit 122 and the NFC antenna 3 needs to be symmetrical based on the real axis to ensure that the matching impedance from the input end of the EMC filter 121 to the ground is pure resistance, so that the signal can be transmitted based on a larger power and reduce signal reflection; and the matching impedance corresponding to the operating frequency of the NFC antenna 3 is configured to be equal to the target impedance to ensure the efficiency and performance of signal transmission.

[0097] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A debugging method for an NFC matching circuit, characterized in that: include: Connect the resonant circuit to the two transmitting terminals of the NFC controller, and connect the impedance matching circuit to the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the resonant circuit, and determining target element parameters of the resonant circuit when a measured resonant frequency of the resonant circuit is configured to be equal to a target resonant frequency, wherein the target resonant frequency is greater than or equal to an operating frequency of the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the matching impedance from the input end of the impedance matching circuit to the ground, and when the matching impedance of the impedance matching circuit satisfies the first condition and the second condition at the same time, determining the target element parameter of the impedance matching circuit; The first condition is that the impedance curve of the impedance matching circuit has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna; The second condition is that the matching impedance corresponding to the operating frequency of the NFC antenna is configured to be equal to the target impedance.

2. The debugging method of the NFC matching circuit according to claim 1, characterized in that: The resonant circuit includes a resonant inductor and a resonant capacitor; a first end of the resonant inductor is connected to a transmitting end of the NFC controller, and a second end of the resonant inductor is used to be connected to the impedance matching circuit; a first end of the resonant capacitor is connected to another transmitting end of the NFC controller, and a second end of the resonant capacitor is used to be connected to the impedance matching circuit; The step of debugging the resonant circuit when the resonant circuit and the impedance matching circuit are in a disconnected state, and determining a target component parameter of the resonant circuit when the measured resonant frequency of the resonant circuit is configured to be equal to a target resonant frequency, comprises: Controlling the resonant circuit and the impedance matching circuit to be in a disconnected state, debugging the resonant circuit, and obtaining a measured resonant frequency of a series circuit formed by the resonant inductor and the resonant capacitor; If the measured resonant frequency is greater than the target resonant frequency, increasing the initial inductance value of the resonant inductor and / or the initial capacitance value of the resonant capacitor; If the measured resonant frequency is less than the target resonant frequency, reducing the initial inductance value of the resonant inductor and / or the initial capacitance value of the resonant capacitor; If the measured resonant frequency is equal to the target resonant frequency, the initial inductance value of the resonant inductor and the initial capacitance value of the resonant capacitor are respectively determined as the target inductance value of the resonant inductor and the target capacitance value of the resonant capacitor.

3. The debugging method of the NFC matching circuit according to claim 2, characterized in that: When the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the matching impedance from the input end of the impedance matching circuit to the ground, and when the first condition and the second condition are simultaneously met, determining the target element parameters of the impedance matching circuit, comprises: When the resonant circuit and the impedance matching circuit are in a disconnected state, debugging the matching impedance from the input end of the impedance matching circuit to the ground, and when the first condition and the second condition are met at the same time, determining the standard component parameters of the impedance matching circuit; When the resonant circuit and the impedance matching circuit are in a connected state, performing a performance test on the NFC matching circuit to obtain a first test result of the NFC matching circuit; Based on the first test result of the NFC matching circuit, standard component parameters of the impedance matching circuit are debugged to determine target component parameters of the impedance matching circuit.

4. The debugging method of the NFC matching circuit according to claim 3, characterized in that: The impedance matching circuit comprises an EMC filter and a matching unit, wherein a first end of the EMC filter is used to connect to the resonant circuit, a second end of the EMC filter is connected to a first end of the matching unit, and a second end of the matching unit is used to connect to the NFC antenna; The step of performing a performance test on the NFC matching circuit to obtain a first test result of the NFC matching circuit when the resonant circuit and the impedance matching circuit are in a connected state includes: Connecting a first end of the receiving circuit to a receiving end of the NFC controller, connecting a second end of the receiving circuit to an NFC antenna or to the NFC antenna through the matching unit, and performing a performance test on the NFC matching circuit when the resonant circuit and the EMC filter are in a connected state to obtain a first test result of the NFC matching circuit; wherein the first test result includes a measured transmission magnetic field strength and a measured receiving load modulation amplitude; The step of debugging the standard component parameters of the impedance matching circuit based on the first test result of the NFC matching circuit to determine the target component parameters of the impedance matching circuit includes: If the measured transmit magnetic field strength is greater than a preset magnetic field strength threshold, and the measured receive load modulation amplitude is greater than a preset load modulation amplitude threshold, the standard component parameters of the EMC filter are determined as target component parameters of the EMC filter, and the standard component parameters of the matching unit are determined as target component parameters of the matching unit; If the measured transmitted magnetic field strength is not greater than the preset magnetic field strength threshold, or the measured received load modulation amplitude is not greater than the preset load modulation amplitude threshold, the standard component parameters of the EMC filter are determined as the target component parameters of the EMC filter, and the standard component parameters of the matching unit are biased to determine the target component parameters of the matching unit.

5. The debugging method of the NFC matching circuit according to claim 4, characterized in that: The impedance matching circuit includes a first matching capacitor and a second matching capacitor; a first end of the first matching capacitor is connected to the EMC filter, and a second end of the first matching capacitor is connected to the NFC antenna; a first end of the second matching capacitor is connected to a connection node between the EMC filter and the NFC antenna, and a second end of the second matching capacitor is grounded; The step of performing a deviation process on the standard component parameters of the matching unit to determine the target component parameters of the matching unit includes: The standard capacitance value of the first matching capacitor is determined as the target capacitance value of the first matching capacitor, and the difference between the standard capacitance value of the second matching capacitor and the preset change amount is determined as the target capacitance value of the second matching capacitor.

6. The debugging method of the NFC matching circuit according to claim 5, characterized in that: The preset change amount has a value range of 0.025 to 0.25 times the standard capacitance value of the second matching capacitor.

7. The debugging method of the NFC matching circuit according to claim 4, characterized in that: The EMC filter comprises a filter inductor and a filter capacitor; a first end of the filter inductor is connected to the resonant circuit, and a second end of the filter inductor is connected to the impedance matching circuit; a first end of the filter capacitor is connected to a connection node between the filter inductor and the impedance matching circuit, and a second end of the filter capacitor is grounded; The target impedance is configured to be positively correlated with a target inductance value of the filter inductor.

8. The debugging method of the NFC matching circuit according to claim 4, characterized in that: The debugging method of the NFC matching circuit also includes: When the resonant circuit and the impedance matching circuit are in a connected state, connecting a first end of the receiving circuit to a receiving end of the NFC controller, connecting a second end of the receiving circuit to a connection node between the EMC filter and the matching unit, performing a performance test on the NFC matching circuit, and obtaining a first receiving load modulation amplitude; When the resonant circuit and the impedance matching circuit are in a connected state, connecting a first end of the receiving circuit to a receiving end of the NFC controller, connecting a second end of the receiving circuit to a connection node between the matching unit and the NFC antenna, performing a performance test on the NFC matching circuit, and obtaining a second receiving load modulation amplitude; If the larger value of the first receiving load modulation amplitude and the second receiving load modulation amplitude is greater than a preset load modulation amplitude threshold, the target component parameters of the receiving circuit are determined, and the second end of the receiving circuit is determined to be connected to a connection node corresponding to the larger value.

9. The debugging method of the NFC matching circuit according to claim 1, characterized in that: The target resonant frequency is 15 MHz.

10. The debugging method of the NFC matching circuit according to any one of claims 1 to 9, characterized in that: The debugging method of the NFC matching circuit also includes: Obtain target performance indicators corresponding to target application scenarios; Performing a performance test on the NFC matching circuit to obtain a measured performance indicator of the NFC matching circuit; When the measured performance index of the NFC matching circuit does not meet the target performance index, the target element parameter of the resonant circuit is adjusted.

11. The debugging method of the NFC matching circuit according to claim 10, characterized in that: The obtaining of the target performance indicator corresponding to the target application scenario includes: Obtain the target transmit power corresponding to the target application scenario; The performing a performance test on the NFC matching circuit to obtain a measured performance index of the NFC matching circuit includes: Performing a performance test on the NFC matching circuit to obtain a measured transmission power of the NFC matching circuit; When the measured performance index of the NFC matching circuit does not meet the target performance index, adjusting the target component parameters of the resonant circuit includes: When the measured transmission power of the NFC matching circuit is less than the target transmission power, the target inductance value of the resonant inductor is increased and / or the target capacitance value of the resonant capacitor is increased.

12. The debugging method of the NFC matching circuit according to claim 10, characterized in that: The obtaining of the target performance indicator corresponding to the target application scenario includes: Obtain the target receiving load modulation amplitude corresponding to the target application scenario; The performing a performance test on the NFC matching circuit to obtain a measured performance index of the NFC matching circuit includes: Performing a performance test on the NFC matching circuit to obtain a measured receiving load modulation amplitude of the NFC matching circuit; When the measured performance index of the NFC matching circuit does not meet the target performance index, adjusting the target component parameters of the resonant circuit includes: When the measured receiving load modulation amplitude of the NFC matching circuit is less than the target receiving load modulation amplitude, the target inductance value of the resonant inductor is reduced and / or the target capacitance value of the resonant capacitor is reduced.

13. An NFC matching circuit, characterized in that: including a resonant circuit and an impedance matching circuit; The resonant circuit is connected to two transmitting ends of the NFC controller and is used to perform resonance processing on the differential output of the NFC controller and output a single-ended signal; The first end of the impedance matching circuit is connected to the resonant circuit, and the second end of the impedance matching circuit is used to connect to the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, the measured resonant frequency of the resonant circuit is configured to be equal to a target resonant frequency, and the target resonant frequency is greater than or equal to an operating frequency of the NFC antenna; When the resonant circuit and the impedance matching circuit are in a disconnected state, the matching impedance from the input end of the impedance matching circuit to the ground satisfies the first condition and the second condition at the same time; The first condition is that the impedance curve of the impedance matching circuit has a first resonance point, a second resonance point, and a third resonance point with increasing frequencies in the Smith chart, the impedance of the first resonance point is the same as that of the third resonance point, and the frequency of the second resonance point is the operating frequency of the NFC antenna; The second condition is that the matching impedance corresponding to the operating frequency of the NFC antenna is configured to be equal to the target impedance.

14. The NFC matching circuit according to claim 13, characterized in that: The resonant circuit includes a resonant inductor and a resonant capacitor; a first end of the resonant inductor is connected to a transmitting end of the NFC controller, and a second end of the resonant inductor is connected to the impedance matching circuit; a first end of the resonant capacitor is connected to another transmitting end of the NFC controller, and a second end of the resonant capacitor is connected to the impedance matching circuit; When the resonant circuit and the impedance matching circuit are in a disconnected state, the measured resonant frequency of the series circuit formed by the resonant inductor and the resonant capacitor is configured to be equal to a target resonant frequency, and the target resonant frequency is 15 MHz.

15. The NFC matching circuit according to claim 13, characterized in that: The impedance matching circuit includes an EMC filter and a matching unit; The EMC filter comprises a filter inductor and a filter capacitor; a first end of the filter inductor is connected to the resonant circuit, and a second end of the filter inductor is connected to the matching unit; a first end of the filter capacitor is connected to a connection node between the filter inductor and the matching unit, and a second end of the filter capacitor is grounded; the target impedance is configured to be positively correlated with a target inductance value of the filter inductor; The matching unit includes a first matching capacitor and a second matching capacitor; a first end of the first matching capacitor is connected to the EMC filter, and a second end of the first matching capacitor is connected to the NFC antenna; a first end of the second matching capacitor is connected to a connection node between the EMC filter and the NFC antenna, and a second end of the second matching capacitor is grounded; The target capacitance value of the second matching capacitor is configured to be equal to the difference between the standard capacitance value and the preset variation; The standard capacitance value is the capacitance value of the second matching capacitor adjusted when the resonant circuit and the impedance matching circuit are in a disconnected state and the matching impedance from the input end of the impedance matching circuit to the ground satisfies the first condition and the second condition at the same time; The preset change amount has a value range of 0.025 to 0.25 times the standard capacitance value of the second matching capacitor.

16. The NFC matching circuit according to claim 15, characterized in that: The NFC matching circuit also includes a receiving circuit, a first end of the receiving circuit is connected to a receiving end of the NFC controller, a second end of the receiving circuit is connected to a connection node between the EMC filter and the matching unit, or a second end of the receiving circuit is connected to a connection node between the matching unit and the NFC antenna.

17. The NFC matching circuit according to claim 13, characterized in that: The NFC matching circuit further includes an impedance resistor, a first end of the impedance resistor is connected to the impedance matching circuit, and a second end of the impedance resistor is connected to the NFC antenna, for reducing the Q value of the NFC antenna.

18. An electronic device, characterized in that: Comprising an NFC controller, an NFC antenna and the NFC matching circuit according to any one of claims 13 to 17; The NFC matching circuit is connected to the NFC controller and the NFC antenna.

Images