Nfc co-body antenna circuit and debugging method

Abstract

The NFC common antenna circuit and debugging method, comprising: NFC antenna connection circuit, diversity antenna connection circuit and debugging circuit; the NFC antenna connection circuit is equipped with first switch, the diversity antenna connection circuit is equipped with second switch respectively; by switching the working state of the first switch and the second switch, the working environment of the NFC antenna and the diversity antenna is changed; the debugging circuit is connected with the NFC antenna connection circuit, and the debugging circuit debugs the impedance and frequency matching of the NFC antenna and the diversity antenna. By changing the working state of the first switch and the second switch, the NFC antenna and the diversity antenna common body and the free switching of non-common body are realized, the small antenna space area and the read-write card coverage are improved, so that the induction speed and sensitivity in small area induction are improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of integrated circuits, and relates to an NFC common antenna circuit and a debugging method. BACKGROUND

[0002] NFC is near field communication, also called close-range wireless communication. Devices using NFC technology can exchange data when close to each other. NFC is derived from the integration and evolution of non-contact radio frequency identification and interconnection technology. By integrating an inductive card reader, an inductive card and a point-to-point communication function on a single chip, mobile terminals can be used to realize mobile payment, electronic ticketing, access control, mobile identity recognition and anti-counterfeiting applications. Please refer to Figure 1 and Figure 2 , which are respectively a circuit diagram of an NFC and diversity antenna design and a positional relationship diagram of an NFC and diversity antenna in a terminal device. In the prior art, an independent NFC antenna and diversity antenna are used, and the read-write card coverage area and the antenna space area are small, and the user experience is poor when a small area is inducted. SUMMARY

[0003] The application provides an NFC common antenna circuit and a debugging method, which improves the read-write card coverage area and the antenna space area, thereby improving the inductive speed and sensitivity.

[0004] The application provides an NFC common antenna circuit, which comprises an NFC antenna connection circuit, a diversity antenna connection circuit and a debugging circuit; an NFC antenna and a diversity antenna are respectively connected to the NFC antenna connection circuit and the diversity antenna connection circuit;

[0005] The diversity antenna connection circuit is connected to the NFC antenna connection circuit; and the NFC antenna connection circuit is connected to a chip.

[0006] A first switch is arranged on the NFC antenna connection circuit, and a second switch is arranged on the diversity antenna connection circuit; by changing the states of the first switch and the second switch, the working environment of the NFC antenna and the diversity antenna is switched.

[0007] The debugging circuit is connected to the NFC antenna connection circuit, and the debugging circuit adjusts the impedance and frequency matching of the NFC antenna and the diversity antenna.

[0008] Further, the NFC antenna comprises a first NFC antenna and a second NFC antenna, the diversity antenna comprises a first diversity antenna and a second diversity antenna, the diversity antenna connection circuit comprises a first diversity antenna connection circuit and a second diversity antenna connection circuit, and the NFC antenna connection circuit comprises a first NFC antenna connection circuit and a second NFC antenna connection circuit.

[0009] The first NFC antenna is connected with the debugging circuit through a first switch;

[0010] The first diversity antenna is connected with the first diversity antenna connection circuit, and is connected with the first NFC antenna connection circuit through a second switch in the first diversity antenna connection circuit, and is connected with the debugging circuit through the first switch;

[0011] The second diversity antenna is connected with the second diversity antenna connection circuit, and is connected with the debugging circuit and the first NFC antenna connection circuit through a second switch in the second diversity antenna connection circuit;

[0012] The second NFC antenna is connected with the debugging circuit.

[0013] Further, the first switch includes a first switch capacitor and a second switch capacitor, and the second switch includes a third switch capacitor and a fourth switch capacitor;

[0014] The first NFC antenna is connected with the debugging circuit through the third switch capacitor and the second switch capacitor;

[0015] The first diversity antenna is connected with the debugging circuit through the first switch capacitor and the second switch capacitor after being connected with the first NFC antenna connection circuit through the fourth switch capacitor;

[0016] The second diversity antenna is connected with the debugging circuit and the first NFC antenna connection circuit through the second switch capacitor.

[0017] Further, the first diversity antenna connection circuit includes a first inductor, a second inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor;

[0018] The first NFC antenna is connected with the first inductor and is connected with the debugging circuit through the first switch; the first inductor is also connected with the first capacitor and is grounded through the first capacitor;

[0019] The first NFC antenna is connected with the second capacitor, the third capacitor, and the fourth capacitor in series; the second capacitor is also connected with the second inductor and is grounded through the second inductor; the third capacitor is also connected with the fifth capacitor and is grounded through the fifth capacitor.

[0020] Further, the second diversity antenna connection circuit includes a sixth capacitor, a third inductor, and a seventh capacitor;

[0021] The second diversity antenna is connected with the debugging circuit through the sixth capacitor and the third inductor, and the sixth capacitor is also grounded through the seventh capacitor.

[0022] Further, the inductance values of the first inductor and the third inductor are 18 NH.

[0023] Further, the debugging circuit comprises a first frequency debugging circuit, the first frequency debugging circuit comprises an eighth capacitor, a ninth capacitor, a tenth capacitor and an eleventh capacitor.

[0024] The eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor are respectively connected in parallel across the first NFC antenna connection circuit and the second NFC antenna connection circuit; one end of the eighth capacitor is connected to the first switch, and the other end of the eighth capacitor is connected to the second NFC antenna receiving port.

[0025] Further, the debugging circuit further comprises a second frequency debugging circuit, the second frequency debugging circuit comprises a twelfth capacitor, a thirteenth capacitor, a fourteenth capacitor and a fifteenth capacitor.

[0026] One end of the twelfth capacitor is connected to one end of the eleventh capacitor, and one end of the thirteenth capacitor is connected to the other end of the eleventh capacitor.

[0027] One end of the twelfth capacitor and one end of the thirteenth capacitor are respectively connected to one end of the fourteenth capacitor and one end of the fifteenth capacitor.

[0028] The other end of the twelfth capacitor is connected to the other end of the thirteenth capacitor and then grounded.

[0029] The other end of the fourteenth capacitor is connected to the other end of the fifteenth capacitor, and then connected to the other end of the twelfth capacitor and the other end of the thirteenth capacitor and grounded.

[0030] Further, the debugging circuit further comprises an impedance debugging circuit; the impedance debugging circuit comprises a sixteenth capacitor, a seventeenth capacitor, an eighteenth capacitor and a nineteenth capacitor.

[0031] The sixteenth capacitor and the seventeenth capacitor are respectively arranged on the first NFC antenna connection circuit and the second NFC antenna connection circuit.

[0032] One end of the sixteenth capacitor is connected to one end of the fourteenth capacitor, and one end of the seventeenth capacitor is connected to one end of the fifteenth capacitor; the other ends of the sixteenth capacitor and the seventeenth capacitor are connected to the chip.

[0033] The eighteenth capacitor and the nineteenth capacitor are respectively connected in parallel across the sixteenth capacitor and the seventeenth capacitor.

[0034] Further, the debugging circuit further comprises a read-write card debugging circuit; the read-write card debugging circuit comprises a twentieth capacitor, a twenty-first capacitor, a first resistor and a second resistor;

[0035] The twentieth capacitor and the first resistor are connected in series and then connected in parallel across the first NFC antenna connection circuit;

[0036] One end of the first resistor is connected to one end of the sixteenth capacitor; one end of the twentieth capacitor is connected between the ninth capacitor and the tenth capacitor;

[0037] The twenty-first capacitor and the second resistor are connected in series and then connected in parallel across the second NFC antenna connection circuit;

[0038] One end of the second resistor is connected to one end of the seventeenth capacitor; the twenty-first capacitor is connected between the ninth capacitor and the tenth capacitor.

[0039] Further, the chip connection circuit comprises a twenty-second capacitor, a twenty-third capacitor, a twenty-fourth capacitor, a twenty-fifth capacitor, a fourth inductor and a fifth inductor;

[0040] One end of the twenty-second capacitor is connected to the first resistor and one end of the twenty-fourth capacitor, and one end of the twenty-third capacitor is connected to the second resistor and one end of the twenty-fifth capacitor,

[0041] The other end of the twenty-fourth capacitor is connected to the other end of the twenty-fifth capacitor and further connected to a chip;

[0042] The other end of the twenty-second capacitor is connected to the other end of the twenty-third capacitor and then grounded;

[0043] The other end of the twenty-fourth capacitor is connected to the other end of the twenty-fifth capacitor, and the other end of the twenty-second capacitor is connected to the other end of the twenty-third capacitor and then grounded;

[0044] The other end of the twenty-fourth capacitor is connected to the other end of the twenty-fifth capacitor and further connected to a chip through the fourth inductor and the fifth inductor respectively.

[0045] Further, the sum of the capacitance values of the twenty-second capacitor, the twenty-third capacitor, the twenty-fourth capacitor and the twenty-fifth capacitor ranges from 560pF to 680pF.

[0046] The application provides an NFC common-body antenna debugging method, which adopts the above NFC common-body antenna circuit, and the debugging method comprises the following steps:

[0047] When the first switch is closed and the second switch is opened, the antenna is in a non-common-body state;

[0048] When the first switch is closed and the second switch is also closed, the antenna is in the common body state.

[0049] Further, when the antenna is in the common body state, the capacitance values of the eighth capacitor, the ninth capacitor, the tenth capacitor and the eleventh capacitor in the first frequency debugging circuit and the twelfth capacitor, the thirteenth capacitor, the fourteenth capacitor and the fifteenth capacitor are increased, so that the frequency of the radio frequency signal is increased.

[0050] When the antenna is in the non-common body state, the capacitance values of the twelfth capacitor, the thirteenth capacitor, the fourteenth capacitor and the fifteenth capacitor in the second frequency debugging circuit are reduced, so that the frequency of the radio frequency signal is reduced.

[0051] The capacitance values of the sixteenth capacitor, the seventeenth capacitor, the eighteenth capacitor and the nineteenth capacitor in the impedance debugging circuit are reduced, so that the circuit impedance is reduced.

[0052] Further, the debugging circuit comprises a read-write card debugging circuit,

[0053] When it is necessary to improve the read card performance, the first resistor and the second resistor are debugged, and the twentieth capacitor and the twenty-first capacitor are disconnected.

[0054] When it is necessary to improve the analog performance, the twentieth capacitor and the twenty-first capacitor are debugged, and the first resistor and the second resistor are disconnected.

[0055] Compared with the prior art, the present application has at least the following technical effects:

[0056] The present application connects the NFC antenna connection circuit and the diversity antenna connection circuit, and changes the working state of the antenna through the first switch and the second switch, realizes the free switching of the common body and the non-common body of the NFC antenna and the diversity antenna, improves the small antenna space area and the read-write card coverage, and thus improves the induction speed and sensitivity in small area induction.

[0057] Further, by debugging the inductance and capacitance of the connection port of the diversity antenna connection circuit and the NFC antenna connection circuit, better compatibility of the NFC antenna and the diversity antenna is realized. The first frequency debugging circuit and the second frequency debugging circuit are set to realize the frequency debugging of the radio frequency signal when the antenna is in the common body and the non-common body. And by setting the impedance debugging circuit and the frequency debugging circuit, the matching of the circuit impedance and the radio frequency signal frequency is realized. Finally, the overall circuit takes into account the performance of the NFC and the diversity antenna, and successfully completes the debugging. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1The position relation diagram of NFC and diversity antenna in terminal equipment in prior art;

[0059] Figure 2 The circuit diagram of NFC antenna design in prior art;

[0060] Figure 3 The circuit diagram of NFC common antenna in embodiment one of the present application;

[0061] Figure 4 The circuit diagram of diversity antenna connection circuit in embodiment one of the present application;

[0062] Figure 5 The position relation diagram of NFC and diversity antenna in terminal equipment in embodiment two of the present application. DETAILED DESCRIPTION

[0063] The NFC common antenna circuit and debugging method of the present application will be described below in conjunction with the schematic diagram, in which the preferred embodiment of the present application is represented, and it should be understood that the present application described herein can be modified by those skilled in the art while still achieving the advantageous effects of the present application. Therefore, the following description should be understood as the extensive knowledge of those skilled in the art, and not as the limitation of the present application.

[0064] The present application will be described in more detail in the following paragraphs with reference to the accompanying drawings. The advantages and features of the present application will be more apparent according to the following description. It should be noted that the drawings are very simplified and all use non-precise proportions, only to facilitate, clearly assist the purpose of illustrating the embodiments of the present application.

[0065] Embodiment one

[0066] The present embodiment provides a NFC common antenna circuit, please refer to Figure 3 , comprising: NFC antenna connection circuit, diversity antenna connection circuit and debugging circuit; the NFC antenna connection circuit and the diversity antenna connection circuit are connected with the NFC antenna and the diversity antenna respectively.

[0067] The NFC antenna connection circuit is connected with the diversity antenna connection circuit; the NFC antenna connection circuit is connected into the chip 500. The first switch is arranged on the NFC antenna connection circuit, and the second switch is arranged on the diversity antenna connection circuit; by changing the state of the first switch and the second switch, the working environment of the NFC antenna and the diversity antenna is switched;

[0068] The debugging circuit is connected with the NFC antenna connection circuit, and the debugging circuit debugs the impedance and frequency matching of the NFC antenna and the diversity antenna.

[0069] In the present example, please refer toFigure 3 and Figure 4 The second switch in the first diversity antenna connection circuit connects the first switch in the first NFC antenna connection circuit with the NFC-ANT port.

[0070] In this embodiment, the first NFC antenna connection circuit, the second NFC antenna connection circuit, the first diversity antenna connection circuit and the second diversity antenna connection circuit are included.

[0071] The first diversity antenna 600 is connected with the first diversity antenna connection circuit, and after being connected with the first NFC antenna connection circuit through the second switch in the first diversity antenna connection circuit, the first diversity antenna 600 is connected with the debugging circuit through the first switch.

[0072] The second diversity antenna 601 is connected with the second diversity antenna connection circuit, and is connected with the debugging circuit and the first NFC antenna connection circuit through the second switch in the second diversity antenna connection circuit.

[0073] The first NFC antenna 700 is connected with the debugging circuit through the first switch.

[0074] The second NFC antenna 701 is connected with the debugging circuit.

[0075] Specifically, the first switch and the second switch are capacitors, the first switch includes a first switch capacitor C100 and a second switch capacitor C200, and the second switch includes a third switch capacitor C300 and a fourth switch capacitor C400.

[0076] The first NFC antenna connection circuit is connected with the chip 500 after being debugged by the debugging circuit through the first switch capacitor C100 and the second switch capacitor C200.

[0077] The first diversity antenna connection circuit is connected with the first switch capacitor C100 after being connected with the first NFC antenna connection circuit through the third switch capacitor C300.

[0078] The second diversity antenna connection circuit is connected with the debugging circuit and the first NFC antenna connection circuit through the fourth switch capacitor C400.

[0079] When the first switch capacitor C100 and the second switch capacitor C200 are connected, but the third switch capacitor C300 and the fourth switch capacitor C400 are disconnected, only the NFC antenna is connected in the circuit, and at this time, the antenna is a non-common-body type; when all the switch capacitors are connected, the NFC antenna and the diversity antenna are connected, and at this time, the antenna is a common-body antenna design.

[0080] The NFC antenna connection circuit and the diversity antenna connection circuit are connected, and the working state of the antenna is changed through the first switch and the second switch, so that the NFC antenna and the diversity antenna are freely switched between the common body and the non-common body, the small antenna space area and the card reading and writing coverage are improved, and the induction speed and sensitivity during small area induction are improved.

[0081] Preferably, the second switching capacitor C200 switch is also grounded through the first breakdown diode D1.

[0082] In this example, please refer to Figure 4 The first diversity antenna connection circuit includes a third switching capacitor C300, and also includes a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5.

[0083] The first diversity antenna 600 is connected to the first inductor L1 and connected to the debugging circuit through the first switch; the first inductor L1 is also connected to the first capacitor C1 and grounded through the first capacitor C1.

[0084] The first diversity antenna 600 is connected in series with the second capacitor C2, the third capacitor C3, and the fourth capacitor C4; the second capacitor C2 is also connected to the second inductor L2 and grounded through the second inductor L2; the third capacitor C3 is also connected to the fifth capacitor C5 and grounded through the fifth capacitor C5.

[0085] Preferably, the first diversity antenna is also grounded through the thirtieth capacitor 30.

[0086] The second diversity antenna 601 includes a sixth capacitor C6, a third inductor L3, and a seventh capacitor C7.

[0087] Specifically, the second diversity antenna 601 is connected to the debugging circuit through the sixth capacitor C6 and the third inductor L3, and the sixth capacitor C6 is also grounded through the seventh capacitor C7.

[0088] Preferably, the second NFC antenna 701 is grounded through the second breakdown diode D2, and the second NFC antenna 701 is also connected to the chip 500.

[0089] Specifically, the first inductor L1 and the third inductor L3 have the function of passing low frequency and blocking high frequency, and the second capacitor C2 has the function of passing high frequency and blocking low frequency. The inductance values of the first inductor L1 and the third inductor L3 are the same, for example, both can be 18NH, which is used to block non-NFC signals and realize compatibility of the NFC antenna and the diversity antenna.

[0090] Further, the debugging circuit includes a first frequency debugging circuit, the first frequency debugging circuit includes an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10 and an eleventh capacitor C11.

[0091] The eighth capacitor C8, the ninth capacitor C9, the tenth capacitor C10 and the eleventh capacitor C11 are connected in parallel across the first NFC antenna connection circuit and the second NFC antenna connection circuit respectively; and one end of the eighth capacitor C8 is connected with the first switch, and the other end of the eighth capacitor C8 is connected with the second NFC antenna receiving port.

[0092] In the present example, a twenty-eighth capacitor C28 and a twenty-ninth capacitor C29 are further included, and are connected in parallel across the first NFC antenna connection circuit and the second NFC antenna connection circuit respectively, two ends of the twenty-eighth capacitor C28 are connected with two ends of the eighth capacitor C8, and two ends of the twenty-ninth capacitor C29 are connected with two ends of the twenty-eighth capacitor C28.

[0093] The debugging circuit further includes a second frequency debugging circuit, the second frequency debugging circuit includes a twelfth capacitor C12, a thirteenth capacitor C13, a fourteenth capacitor C14 and a fifteenth capacitor C15.

[0094] One end of the twelfth capacitor C12 is connected with one end of the eleventh capacitor C11, and one end of the thirteenth capacitor C13 is connected with the other end of the eleventh capacitor C11.

[0095] One end of the twelfth capacitor C12 and one end of the thirteenth capacitor C13 are further connected with one end of the fourteenth capacitor C14 and one end of the fifteenth capacitor C15 respectively.

[0096] The other end of the twelfth capacitor C12 is connected with the other end of the thirteenth capacitor C13 and then grounded.

[0097] The other end of the fourteenth capacitor C14 is connected with the other end of the fifteenth capacitor C15, and then connected with the other end of the twelfth capacitor C12 and the other end of the thirteenth capacitor C13, and grounded.

[0098] In the present example, the first frequency debugging circuit and the second frequency debugging circuit jointly debug the frequency of the radio frequency signal when the antenna is in the non-corporate state. The second frequency debugging circuit alone debugs the frequency of the radio frequency signal when the antenna is in the corporate state.

[0099] Further, the debugging circuit further comprises an impedance debugging circuit; the impedance debugging circuit comprises a sixteenth capacitor C16, a seventeenth capacitor C17, an eighteenth capacitor C18 and a nineteenth capacitor C19. The sixteenth capacitor C16 and the seventeenth capacitor C17 are arranged on the first NFC antenna connection circuit and the second NFC antenna connection circuit respectively. One end of the sixteenth capacitor C16 is connected with one end of the fourteenth capacitor C14, and one end of the seventeenth capacitor C17 is connected with one end of the fifteenth capacitor C15; the other ends of the sixteenth capacitor C16 and the seventeenth capacitor C17 are connected to the chip 500. The eighteenth capacitor C18 and the nineteenth capacitor C19 are connected in parallel across the sixteenth capacitor C16 and the seventeenth capacitor C17 respectively.

[0100] In the present example, the sixteenth capacitor C16, the eighteenth capacitor C18 and the seventeenth capacitor C17, the nineteenth capacitor C19 are used to debug the impedance value of the debugging circuit.

[0101] In addition, the present embodiment further comprises a read-write card debugging circuit, the read-write card debugging circuit comprises a twentieth capacitor C20, a twenty-first capacitor C21, a first resistor R1 and a second resistor R2.

[0102] The twentieth capacitor C20 and the first resistor R1 are connected in series and then connected in parallel across the first NFC antenna connection circuit. One end of the first resistor R1 is connected with one end of the sixteenth capacitor C16; the other end of the twentieth capacitor C20 is connected between the ninth capacitor C9 and the tenth capacitor C10. The twenty-first capacitor C21 and the second resistor R2 are connected in series and then connected in parallel across the second NFC antenna connection circuit. One end of the second resistor R2 is connected with one end of the seventeenth capacitor C17; the other end of the twenty-first capacitor C21 is connected between the ninth capacitor C9 and the tenth capacitor C10.

[0103] In the present example, during the debugging process, the first resistor R1 and the second resistor R2 or the twentieth capacitor C20 and the twenty-first capacitor C21 are connected, and the other pair is disconnected. The first resistor R1 and the second resistor R2 close to the chip 500 end are better for the read card performance, and the twentieth capacitor C20 and the twenty-first capacitor C21 close to the antenna end are better for the card simulation performance.

[0104] In the present example, one end of the first resistor R1 is further connected with a twenty-sixth capacitor C26, and the other end of the twenty-sixth capacitor C26 is connected to the chip 500. One end of the second resistor R2 is further connected with a twenty-seventh capacitor C27, and the other end of the twenty-seventh capacitor C27 is connected to the chip 500.

[0105] Further, the debugging circuit further comprises a chip 500 connecting circuit, and the chip 500 connecting circuit comprises a twenty-second capacitor C22, a twenty-third capacitor C23, a twenty-fourth capacitor C24, a twenty-fifth capacitor C25, a fourth inductor L4 and a fifth inductor L5.

[0106] One end of the twenty-second capacitor C22 is connected with the first resistor R1 and one end of the twenty-fourth capacitor C24, and one end of the twenty-third capacitor C23 is connected with the second resistor R2 and one end of the twenty-fifth capacitor C25.

[0107] The other end of the twenty-fourth capacitor C24 is connected with the other end of the twenty-fifth capacitor C25 and the chip 500.

[0108] The other end of the twenty-second capacitor C22 is connected with the other end of the twenty-third capacitor C23 and grounded.

[0109] The other end of the twenty-fourth capacitor C24 is connected with the other end of the twenty-fifth capacitor C25, and the other end of the twenty-second capacitor C22 is connected with the other end of the twenty-third capacitor C23 and grounded.

[0110] The other end of the twenty-fourth capacitor C24 is connected with the other end of the twenty-fifth capacitor C25 through the fourth inductor L4 and the fifth inductor L5 respectively and the chip 500.

[0111] In the present example, the two pairs of capacitors, the twenty-second capacitor C22 and the twenty-third capacitor C23 and the twenty-fourth capacitor C24 and the twenty-fifth capacitor C25, can be connected at the same time, and the sum of the capacitance values of the two pairs of capacitors ranges from 560pF to 680pF, and the maximum is not more than 720PF.

[0112] It can be seen that, by adjusting the inductance and capacitance of the connecting port of the diversity antenna connecting circuit and the NFC antenna connecting circuit, the present embodiment realizes better compatibility of the NFC antenna and the diversity antenna. By setting the first frequency debugging circuit and the second frequency debugging circuit, the frequency of the radio frequency signal can be adjusted when the antenna is in the common body and the non-common body. By setting the impedance debugging circuit and the frequency debugging circuit, the matching of the circuit impedance and the radio frequency signal frequency is realized. Finally, the overall circuit takes into account the performance of the NFC and the diversity antenna, and the debugging is successfully completed.

[0113] Embodiment Two

[0114] The present embodiment provides a NFC common body antenna design debugging method, which adopts the NFC common body antenna circuit in embodiment one, and the debugging method comprises:

[0115] When the first switch is closed and the second switch is open, the antenna is in a non-corporate state. When the first switch is closed and the second switch is also closed, the antenna is in a corporate state.

[0116] In a specific example, the first diversity antenna connection circuit is connected to the first NFC antenna connection circuit through the third switching capacitor C300, and is connected to the first switching capacitor C100 and the second switching capacitor C200. The second diversity antenna connection circuit is connected to the debugging circuit and the first NFC antenna connection circuit through the fourth switching capacitor C400. When the first switching capacitor C100 and the second switching capacitor C200 are connected, but the third switching capacitor C300 and the fourth switching capacitor C400 are disconnected, only the NFC antenna is connected to the circuit, and at this time the antenna is a non-corporate type. When all the switching capacitors are connected, the NFC antenna and the diversity antenna are connected, and at this time the antenna is a corporate antenna design.

[0117] Further, the embodiment also provides a debugging circuit, which includes a first frequency debugging circuit, the first frequency debugging circuit including an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10 and an eleventh capacitor C11; and a second frequency debugging circuit, the second frequency debugging circuit including a twelfth capacitor C12, a thirteenth capacitor C13, a fourteenth capacitor C14 and a fifteenth capacitor C15.

[0118] When the antenna is in a corporate state, the capacitance values of the eighth capacitor C8, the ninth capacitor C9, the tenth capacitor C10 and the eleventh capacitor C11 and the twelfth capacitor C12, the thirteenth capacitor C13, the fourteenth capacitor C14 and the fifteenth capacitor C15 are increased, so that the frequency of the radio frequency signal is increased. When the antenna is in a non-corporate state, the capacitance values of the twelfth capacitor C12, the thirteenth capacitor C13, the fourteenth capacitor C14 and the fifteenth capacitor C15 are reduced, so that the frequency of the radio frequency signal is reduced.

[0119] The debugging circuit also includes an impedance debugging circuit, the impedance debugging circuit including a sixteenth capacitor C16, a seventeenth capacitor C17, an eighteenth capacitor C18 and a nineteenth capacitor C19.

[0120] Increasing the capacitance values of the sixteenth capacitor C16, the seventeenth capacitor C17, the eighteenth capacitor C18 and the nineteenth capacitor C19 increases the circuit impedance; reducing the capacitance values of the sixteenth capacitor C16, the seventeenth capacitor C17, the eighteenth capacitor C18 and the nineteenth capacitor C19 reduces the circuit impedance.

[0121] When the first frequency adjustment circuit, the second frequency adjustment circuit and the impedance adjustment circuit are adjusted, the first frequency adjustment circuit and the second frequency adjustment circuit are adjusted first, so that the frequency of the radio frequency signal is close to the target value, and then the impedance adjustment circuit is adjusted, so that the frequency and the impedance of the radio frequency signal reach the target value.

[0122] Further, the adjustment circuit comprises a read-write card adjustment circuit.

[0123] When it is necessary to improve the read card performance, the first resistor R1 and the second resistor R2 are adjusted, and the twentieth capacitor C20 and the twenty-first capacitor C21 are disconnected.

[0124] In addition, as Figure 5 shown, it is a position relation diagram of the NFC and the diversity antenna in the terminal device in the embodiment, when the common antenna is adjusted, due to the existence of the diversity antenna, the number of turns of the coil is one less than that of the conventional antenna, and the inductance of the coil is also a little smaller.

[0125] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and the equivalent technologies thereof, the present application also intends to include these modifications and variations.

Claims

1. An NFC common antenna circuit, characterized in that: include: NFC antenna connection circuit, diversity antenna connection circuit and debugging circuit; NFC antenna and diversity antenna are connected to the NFC antenna connection circuit and the diversity antenna connection circuit respectively; The NFC antenna connection circuit includes a first NFC antenna connection circuit and a second NFC antenna connection circuit; the NFC antenna includes a second NFC antenna; The diversity antenna connection circuit is connected to the NFC antenna connection circuit; the NFC antenna connection circuit is connected to the chip; The NFC antenna connection circuit is provided with a first switch, and the diversity antenna connection circuit is provided with a second switch; by changing the states of the first switch and the second switch, the working environment of the NFC antenna and the diversity antenna is switched; The debugging circuit is connected to the NFC antenna connection circuit, and the debugging circuit debugs the impedance and frequency matching of the NFC antenna and the diversity antenna; The debugging circuit includes a first frequency debugging circuit, and the first frequency debugging circuit includes an eighth capacitor, a ninth capacitor, a tenth capacitor, and an eleventh capacitor; The eighth capacitor, the ninth capacitor, the tenth capacitor, and the eleventh capacitor are respectively connected in parallel to the first NFC antenna connection circuit and the second NFC antenna connection circuit; one end of the eighth capacitor is connected to the first switch, and the other end of the eighth capacitor is connected to the second NFC antenna receiving port; The debugging circuit further includes a second frequency debugging circuit, and the second frequency debugging circuit includes a twelfth capacitor, a thirteenth capacitor, a fourteenth capacitor and a fifteenth capacitor; One end of the twelfth capacitor is connected to one end of the eleventh capacitor, and one end of the thirteenth capacitor is connected to the other end of the eleventh capacitor; One end of the twelfth capacitor and one end of the thirteenth capacitor are further connected to one end of the fourteenth capacitor and one end of the fifteenth capacitor respectively; The other end of the twelfth capacitor is connected to the other end of the thirteenth capacitor and then grounded; The other end of the fourteenth capacitor is connected to the other end of the fifteenth capacitor, and then connected to the other end of the twelfth capacitor and the other end of the thirteenth capacitor, and is grounded.

2. The NFC common antenna circuit according to claim 1, wherein: The NFC antenna includes a first NFC antenna, and the diversity antenna includes a first diversity antenna and a second diversity antenna; The diversity antenna connection circuit includes a first diversity antenna connection circuit and a second diversity antenna connection circuit, and the NFC antenna connection circuit includes a first NFC antenna connection circuit and a second NFC antenna connection circuit; The first NFC antenna is connected to the debugging circuit via a first switch; The first diversity antenna is connected to the first diversity antenna connection circuit, is connected to the first NFC antenna connection circuit through the second switch in the first diversity antenna connection circuit, and is then connected to the debugging circuit through the first switch; The second diversity antenna is connected to the second diversity antenna connection circuit, and is connected to the debugging circuit and the first NFC antenna connection circuit through a second switch in the second diversity antenna connection circuit; The second NFC antenna is connected to the debugging circuit.

3. The NFC common antenna circuit according to claim 2, wherein: The first switching switch includes a first switching capacitor and a second switching capacitor, and the second switching switch includes a third switching capacitor and a fourth switching capacitor; The first NFC antenna is connected to the debugging circuit through the first switching capacitor and the second switching capacitor; After the first diversity antenna is connected to the first NFC antenna connection circuit through the third switching capacitor, it is connected to the debugging circuit through the first switching capacitor and the second switching capacitor; The second diversity antenna is connected to the debugging circuit and the first NFC antenna connection circuit via a fourth switching capacitor.

4. The NFC diversity antenna circuit according to claim 2, wherein the first diversity antenna connection circuit further comprises a first inductor, a second inductor, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, and a fifth capacitor; The first diversity antenna is connected to the first inductor and then connected to the debugging circuit through a first switch; the first inductor is also connected to the first capacitor and grounded through the first capacitor; The first diversity antenna is connected in series with the second capacitor, the third capacitor, and the fourth capacitor; the second capacitor is also connected to the second inductor and grounded through the second inductor; the third capacitor is also connected to the fifth capacitor and grounded through the fifth capacitor.

5. The NFC common antenna circuit according to claim 4, characterized in that: The second diversity antenna connection circuit further includes a sixth capacitor, a third inductor, and a seventh capacitor; The second diversity antenna is connected to the debugging circuit through the sixth capacitor and the third inductor, and the sixth capacitor is also grounded through the seventh capacitor.

6. The NFC common antenna circuit according to claim 4 or 5, characterized in that: The inductance values ​​of the first inductor and the third inductor are 18NH.

7. The NFC common antenna circuit according to claim 6, characterized in that: The debugging circuit further includes an impedance debugging circuit; the impedance debugging circuit includes a sixteenth capacitor, a seventeenth capacitor, an eighteenth capacitor and a nineteenth capacitor; The sixteenth capacitor and the seventeenth capacitor are respectively provided on the first NFC antenna connection circuit and the second NFC antenna connection circuit; One end of the sixteenth capacitor is connected to one end of the fourteenth capacitor, and one end of the seventeenth capacitor is connected to one end of the fifteenth capacitor; the other ends of the sixteenth capacitor and the seventeenth capacitor are connected to the chip; The eighteenth capacitor and the nineteenth capacitor are connected in parallel at both ends of the sixteenth capacitor and the seventeenth capacitor respectively.

8. The NFC common antenna circuit according to claim 7, wherein: The debugging circuit further includes a card reader / writer debugging circuit; the card reader / writer debugging circuit includes a twentieth capacitor, a twenty-first capacitor, a first resistor, and a second resistor; The 20th capacitor and the first resistor are connected in series and then in parallel across the first NFC antenna connection circuit; One end of the first resistor is connected to one end of the sixteenth capacitor; one end of the 20th capacitor is connected between the ninth capacitor and the tenth capacitor; The twenty-first capacitor and the second resistor are connected in series and then in parallel across the second NFC antenna connection circuit; One end of the second resistor is connected to one end of the seventeenth capacitor; and the twenty-first capacitor is connected between the ninth capacitor and the tenth capacitor.

9. The NFC common antenna circuit according to claim 8, characterized in that: The debugging circuit further includes a chip connection circuit, wherein the chip connection circuit includes a twenty-second capacitor, a twenty-third capacitor, a twenty-fourth capacitor, a twenty-fifth capacitor, a fourth inductor, and a fifth inductor; One end of the twenty-second capacitor is connected to the first resistor and one end of the twenty-fourth capacitor, and one end of the twenty-third capacitor is connected to the second resistor and one end of the twenty-fifth capacitor. The other end of the twenty-fourth capacitor and the other end of the twenty-fifth capacitor are also connected to the chip; The other end of the twenty-second capacitor is connected to the other end of the twenty-third capacitor and then grounded; The other end of the twenty-fourth capacitor is connected to the other end of the twenty-fifth capacitor, and then connected to the other end of the twenty-second capacitor and the other end of the twenty-third capacitor, and grounded; The other end of the 24th capacitor and the other end of the 25th capacitor are further connected to the chip through the fourth inductor and the fifth inductor respectively.

10. The NFC common antenna circuit according to claim 9, wherein: The sum of the capacitance values ​​of the twenty-second capacitor, the twenty-third capacitor, the twenty-fourth capacitor, and the twenty-fifth capacitor ranges from 560 pF to 680 pF.

11. A method for debugging an NFC common antenna, using the NFC common antenna circuit according to any one of claims 8 to 10, characterized in that: The debugging method includes: When the first switch is closed and the second switch is open, the antenna is in a non-co-body state; When the first switch is closed and the second switch is also closed, the antenna is in a co-existing state; When the antenna is in the common state, the capacitances of the eighth capacitor, the ninth capacitor, the tenth capacitor, the eleventh capacitor, and the twelfth capacitor, the thirteenth capacitor, the fourteenth capacitor, and the fifteenth capacitor in the first frequency debugging circuit in the debugging circuit are increased, so that the frequency of the radio frequency signal increases; When the antenna is in a non-common state, the capacitances of the twelfth capacitor, the thirteenth capacitor, the fourteenth capacitor and the fifteenth capacitor in the second frequency debugging circuit in the debugging circuit are reduced, so that the frequency of the radio frequency signal is reduced.

12. The NFC common antenna debugging method according to claim 11, characterized in that: Adjusting the impedance in the debugging circuit: If the capacitance values ​​of the sixteenth capacitor, the seventeenth capacitor, the eighteenth capacitor, and the nineteenth capacitor in the debugging circuit increase, the circuit impedance increases; By adjusting the capacitances of the sixteenth capacitor, the seventeenth capacitor, the eighteenth capacitor, and the nineteenth capacitor in the impedance debugging circuit to decrease, the circuit impedance is reduced.

13. The NFC common antenna debugging method according to claim 12, characterized in that: The debugging circuit also includes a card reading and writing debugging circuit, When the card reading performance needs to be improved, the first resistor and the second resistor are debugged, and the twentieth capacitor and the twenty-first capacitor are disconnected; When the analog performance needs to be improved, the twentieth capacitor and the twenty-first capacitor are debugged, and the first resistor and the second resistor are disconnected.

Images