CN114361778A - NFC antenna circuit, NFC antenna module and electronic equipment - Google Patents

Abstract

The invention discloses an NFC antenna circuit, an NFC antenna assembly and electronic equipment, wherein the NFC antenna circuit comprises: an NFC antenna comprising a first antenna segment and a second antenna segment; the antenna matching circuit is connected with the first antenna section and used for realizing impedance matching with the NFC antenna; the receiving circuit is connected with the second antenna section of the NFC antenna and used for converting the wireless data signals received by the NFC antenna into electric signals; the first isolation device is arranged between the first antenna section and the second antenna section in series; and the second isolation device is arranged between the receiving circuit and the second antenna section in series. The method solves the problem of reduced yield of the PCB antenna caused by antenna short circuit in the PCB manufacturing process, and is beneficial to improving the manufacturing efficiency of the NFC antenna and the yield of the NFC antenna.

Description

NFC antenna circuit, NFC antenna assembly and electronic equipment

technical field

The present invention relates to the technical field of electronic circuits, in particular to an NFC antenna circuit, an NFC antenna assembly and an electronic device.

Background technique

In the PCB production process, due to the manufacturing process and other reasons, when the antenna set on the PCB has a relatively thin line width and a short line distance, there is a certain probability that some lines adjacent to the antenna will be short-circuited, causing the antenna to fail. Therefore, it is necessary to adjust the antenna. Perform a flying probe (short circuit) test. The antenna made on the printed board is because the matching circuit of the antenna belongs to the same network. After the antenna is made on the PCB, the flying probe test cannot be performed on the antenna. The electronic components of the NFC antenna assembly need to be placed on the PCB board, and Testing can only be performed after programming the program, which will cause unnecessary losses, serious material waste, complicated testing, and reduced manufacturing efficiency and yield of NFC antenna components.

SUMMARY OF THE INVENTION

The main purpose of the present invention is to propose an NFC antenna circuit, an NFC antenna assembly and an electronic device, aiming at solving the problem of the decrease in the yield rate of the PCB printed board antenna caused by the short circuit of the antenna caused in the PCB manufacturing process.

In order to achieve the above object, the present invention provides an NFC antenna circuit, the NFC antenna circuit includes:

an NFC antenna, including a first antenna segment and a second antenna segment;

an antenna matching circuit, connected to the first antenna segment, for realizing impedance matching with the NFC antenna;

a receiving circuit, connected to the second antenna segment of the NFC antenna, for converting the generated wireless data signal received by the NFC antenna into an electrical signal;

a first isolation device, arranged in series between the first antenna segment and the second antenna segment;

A second isolation device is arranged in series between the receiving circuit and the second antenna segment.

Optionally, the first isolation device has zero ohm resistance;

And/or, the second isolation device has zero ohmic resistance.

Optionally, the NFC antenna circuit further includes:

signal sender;

The EMC filter circuit is arranged in series between the signal transmitting end and the antenna matching circuit.

Optionally, the signal sending end includes a first signal sending end and a second signal sending end; the EMC filter circuit includes a first inductor, a second inductor, a first capacitor and a second capacitor, and the first inductor is One end of the inductance is connected to the first signal transmission end, the other end of the first inductance is connected to the antenna matching circuit; one end of the second inductance is connected to the second signal transmission end, and the second inductance is The other end is connected to the antenna matching circuit; the first capacitor is connected in series between the first inductor and the ground; the second capacitor is connected in series between the second inductor and the ground.

Optionally, the antenna matching circuit includes:

A third capacitor, a fourth capacitor, a fifth capacitor and a sixth capacitor, the third capacitor is arranged in series between the EMC filter circuit and the first antenna segment; the fourth capacitor is arranged in series between the EMC between the filter circuit and the second antenna segment; the fifth capacitor is connected in series between the third capacitor and the ground; the sixth capacitor is connected in series between the fourth capacitor and the ground.

Optionally, the NFC antenna circuit further includes a signal receiving terminal and a bias voltage input terminal;

The receiving circuit includes a first resistor, a second resistor and a seventh capacitor, one end of the first resistor is connected to the bias voltage input end, and the other end of the first resistor is connected to the signal receiving end and the other end. One end of the second resistor is interconnected, the other end of the second resistor is connected to one end of the seventh capacitor, and the other end of the seventh capacitor is connected to the second isolation device.

Optionally, the working frequency of the NFC antenna circuit is 13.56MHZ.

The present invention also provides an NFC antenna assembly, comprising an NFC chip and the above-mentioned NFC antenna circuit, wherein the NFC chip is electrically connected to the NFC antenna circuit.

Optionally, the NFC antenna assembly further includes:

A PCB circuit board, the NFC antenna circuit and the NFC chip are arranged on the PCB circuit board.

The present invention also provides an electronic device including the NFC antenna circuit as described above, or the NFC antenna assembly as described above.

In the present invention, the NFC antenna is divided into a first antenna segment and a second antenna segment, so that the first antenna segment is connected to an antenna matching circuit for realizing impedance matching with the NFC antenna, and the second antenna segment is connected to an antenna matching circuit used for impedance matching with the NFC antenna. A receiving circuit that converts the generated wireless data signal received by the NFC antenna into an electrical signal, the present invention is also provided with a first isolation device arranged in series between the first antenna segment and the second antenna segment, and a first isolation device arranged in series between the Under the isolation of the second isolation device between the receiving circuit and the second antenna segment, the first antenna segment is connected to the network formed with the antenna matching circuit, and the second antenna segment is connected to the network formed with the receiving circuit. The network means that the first antenna segment and the second antenna segment belong to two different networks. After the NFC antenna is formed on the PCB, or after the NFC antenna is fabricated, the short-circuit test device can be connected to complete the short-circuit test of the NFC antenna. The invention solves the problem of PCB printing caused by the short-circuit of the antenna caused by the PCB fabrication process. The problem of the decrease in the yield of the board antenna is conducive to improving the production efficiency of the NFC antenna and improving the yield of the NFC antenna.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the structures shown in these drawings without creative efforts.

1 is a schematic diagram of a circuit structure of an embodiment of an NFC antenna circuit according to the present invention;

FIG. 2 is a schematic structural diagram of an embodiment of an NFC antenna assembly of the present invention;

FIG. 3 is a schematic diagram of functional modules of an embodiment of an NFC antenna assembly of the present invention.

Description of reference numbers:

label name label name 100 PCB circuit board 50 Antenna matching circuit 200 NFC Antenna Circuit 60 EMC filter circuit 10 NFC antenna R1 first resistor 11 first antenna segment R2 second resistor 12 second antenna segment C1～C7 The first capacitor to the seventh capacitor 20 first isolation device L1 first inductance 30 second isolation device L2 second inductance 40 receiver circuit U1 NFC chip

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a 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 those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that if there are directional indications (such as up, down, left, right, front, back, etc.) involved in the embodiments of the present invention, the directional indications are only used to explain a certain posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly.

In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for the purpose of description, and should not be construed as indicating or implying Its relative importance or implicitly indicates the number of technical features indicated. Thus, a feature delimited with "first", "second" may expressly or implicitly include at least one of that feature. In addition, the technical solutions between the various embodiments can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of such technical solutions does not exist. , is not within the scope of protection required by the present invention.

The term "and/or" in this article is only an association relationship to describe the associated objects, indicating that there can be three kinds of relationships, for example, A and/or B, it can mean that A exists alone, A and B exist at the same time, and A and B exist independently B these three cases. In addition, the character "/" in this document generally indicates that the related objects are an "or" relationship.

The present invention provides an NFC antenna circuit.

1 to 3 , in an embodiment of the present invention, the NFC antenna circuit 200 includes:

The NFC antenna 10 includes a first antenna segment 11 (represented by a dotted line in the figure) and a second antenna segment 12 (represented by a solid line in the figure);

an antenna matching circuit 50, connected to the first antenna segment 11, for realizing impedance matching with the NFC antenna 10;

The receiving circuit 40, the second antenna segment 12 connected to the NFC antenna 10, is used for converting the generated wireless data signal received by the NFC antenna 10 into an electrical signal;

The first isolation device 20 is arranged in series between the first antenna segment 11 and the second antenna segment 12;

The second isolation device 30 is arranged in series between the receiving circuit 40 and the second antenna segment 12 .

In this embodiment, the NFC antenna circuit 200 is connected to the NFC chip U1, and transmits data from the NFC chip U1 through the electromagnetic field of radio frequency, so as to automatically identify the information stored in the NFC chip U1. The NFC antenna circuit 200 may be of passive topology, and the NFC chip U1 can obtain energy from the electromagnetic field emitted by the external device during identification, without consuming the energy of the electronic device applied by the antenna circuit. The electronic device to which the NFC antenna circuit 200 of this embodiment is applied can be used as a transponder or a reader. When used as a transponder, it can have a unique electronic code, and the unique electronic code can be recognized by an external device, thereby realizing card swiping. , access control, mobile payment, etc. When used as a reader, it can read the data of other external devices to realize short-range data transmission, such as the transmission of audio, images, etc. Among them, the main operating frequency of the NFC device can be a high frequency of 13.56MHZ.

The antenna matching circuit 50 is configured to perform impedance matching with the NFC antenna 10 when the frequency of the NFC antenna 10 is within the operating frequency range, thereby increasing the effective bandwidth of the NFC antenna 10 . The antenna matching circuit 50 is connected between the NFC antenna 10 and the NFC chip U1. The antenna matching circuit 50 can adjust the resonant frequency of the antenna and match the impedance in the direction toward the NFC chip U1 with the impedance in the direction toward the antenna, so as to increase the communication efficiency of the NFC antenna assembly. The operating frequency range may be the operating frequency range where the NFC antenna 10 is located, such as about 13 MHz, when performing NFC sensing (such as payment, door lock, etc.). The receiving circuit 40 is used to convert the wireless data signal into an electrical signal

The NFC antenna 10 is used to transmit the wireless data signal with an external NFC device through near-field coupling. The NFC antenna 10 receives the wireless data signal from the outside and converts it into an electrical signal, and transmits the electrical signal to the receiving circuit 40, and then the receiving circuit 40 transmits the electrical signal. 40 is transmitted to the NFC chip U1, establishes a connection with an external NFC device through near-field coupling, and performs signal transmission. The NFC antenna 10 transmits electromagnetic signals with external NFC devices such as mobile terminals and smart cards through near-field coupling. The NFC antenna circuit 200 transmits and receives wireless data signals, and performs corresponding conditioning, such as impedance matching.

The NFC antenna 10 in this embodiment can be optionally a planar antenna, which can be specifically prepared by using one of a physical vapor deposition process, a chemical vapor deposition process, an evaporation process, a sputtering process, an electroplating process or an electroless plating process. The NFC antenna 10 can be formed on the PCB circuit board 100 through a printed circuit wiring process, and the NFC antenna 10 can be directly formed on the PCB circuit board 100 through processes such as copper cladding, etching, etc. The NFC antenna 10 can also use The FPC antenna is realized. The FPC antenna can be pasted on the PCB circuit board 100 through adhesive materials, or the FPC antenna can be embedded in the PCB circuit board 100 in a pre-embedded manner, or the antenna pattern of the NFC antenna 10 can be pressed by other processes. combined to the PCB circuit board 100 . When the NFC antenna 10 is arranged on the electric control board, it can be realized by forming the wiring of the antenna on the PCB circuit board 100 in the form of PCB circuit wiring. The thickness, size and shape of the PCB circuit board 100 can be set according to the actual application product and application environment, etc., to meet different application requirements. In a specific embodiment, the shape of the PCB circuit board 100 may be square, for example, a rectangle or a square. The NFC antenna 10 can also be made of ferrite material with anti-interference ability.

In this embodiment, the NFC antenna 10 is divided into two antenna segments, that is, the first antenna segment 11 and the second antenna segment 12 are spaced apart from each other, and there is no direct connection between the two antenna segments. The two antenna segments respectively have two ends, respectively denoted as the first end and the second end, wherein the first end of the first antenna segment 11 is connected to the antenna matching circuit 50, and the second end of the first antenna is connected to the first isolation device. 20 is connected to one end; the first end of the second antenna segment 12 is connected to the receiving circuit 40, the second end of the second antenna is connected to the other end of the first isolation device 20, and the other end of the first isolation device 20 is also connected to the NFC The ground end of the antenna circuit 200 is connected, that is, the second end of the second antenna segment 12 is electrically connected to the first antenna under the isolation effect of the first isolation device 20 .

When the NFC antenna circuit 200 is working, for example, the NFC antenna circuit 200 receives an externally input wireless data signal through the NFC antenna 10 . Specifically, the second antenna segment 12 receives electromagnetic energy, and the second antenna segment 12 and the second isolation device 30 receive electromagnetic energy. It is output to the receiving circuit 40, and the receiving circuit 40 converts the wireless data signal into an electrical signal and outputs it to the NFC chip U1. When the NFC antenna circuit 200 sends a wireless data signal to the outside through the NFC antenna 10, the first antenna segment 11 and the second antenna segment 12 convert the electrical signal into a wireless data signal, radiate electromagnetic energy to the outside, and under the action of the NFC antenna 10 , the electromagnetic energy is radiated. Specifically, the electrical signal is output to the first antenna segment 11 through the antenna matching circuit 50 and the first isolation device 20 , and then radiated by the first antenna segment 11 .

Under the isolation of the first isolation device 20 and the second isolation device 30 , the first antenna segment 11 is connected to the network formed with the antenna matching circuit 50 , and the second antenna segment 12 is connected to the network formed by the receiving circuit 40 . , and the receiving circuit 40 and the antenna matching circuit 50 belong to two different networks. When fabricating the NFC antenna 10, the first antenna segment 11 and the second antenna segment 12 are separated from each other when fabricating the antenna wiring, so as to be physically isolated, and the first isolation device 20 and the second isolation device are separated from each other. Under the isolation of 30, the flying probe test during PCB production, that is, the short circuit test, can test whether there is a short circuit between adjacent antennas.

In practical applications, the first antenna segment 11 and the second antenna segment 12 can be tested respectively by using a test device for short-circuit testing. Specifically, the first antenna segment 11 can be connected to the power supply circuit constructed in the short-circuit test device to provide current for the first antenna segment 11, and a current loop is formed between the first antenna segment 11 and the short-circuit test device, and then a current loop is formed between the first antenna segment 11 and the short circuit test device. Connect two test points, such as test probes, to the first antenna segment 11 and the second antenna segment 12. It can be understood that the second antenna segment 12 is not connected to the power supply constructed in the short-circuit test device In the circuit, a current loop cannot be formed between the second antenna segment 12 and the short-circuit test device. Therefore, under normal circumstances, the first antenna segment 11 and the second antenna segment 12 are equivalent to an open circuit. If the short-circuit test device detects the first When an electrical signal exists between the first antenna segment 11 and the second antenna segment 12, it can be determined that adhesion occurs between the first antenna segment 11 and the second antenna segment 12, and there is a short-circuit point. Conversely, if the short-circuit test device detects that there is no electrical signal between the first antenna segment 11 and the second antenna segment 12, it can be determined that there is no adhesion between the first antenna segment 11 and the second antenna segment 12, and there is no short-circuit point. . Similarly, the second antenna segment 12 can be connected to the power supply circuit constructed in the short-circuit test device to provide current for the first antenna segment 11, and a current loop is formed between the second antenna segment 12 and the short-circuit test device, and then the Two test points, such as test probes, etc., are connected to the first antenna segment 11 and the second antenna segment 12. If the short-circuit test device detects that there are electrical signals in the first antenna segment 11 and the second antenna segment 12, then It can be determined that adhesion occurs between the first antenna segment 11 and the second antenna segment 12, and there is a short-circuit point. Conversely, if the short-circuit test device detects that there is no electrical signal between the first antenna segment 11 and the second antenna segment 12, it can be determined that there is no adhesion between the first antenna segment 11 and the second antenna segment 12, and there is no short-circuit point. .

In the present invention, the NFC antenna 10 is divided into a first antenna segment 11 and a second antenna segment 12, so that the first antenna segment 11 is connected to the antenna matching circuit 50 for realizing impedance matching with the NFC antenna 10, and the next day The line segment 12 is connected to the receiving circuit 40 for converting the generated wireless data signal received by the NFC antenna 10 into an electrical signal. The present invention also provides that the line segment 12 is connected in series between the first antenna segment 11 and the second antenna segment 12. The first isolation device 20 and the second isolation device 30 arranged in series between the receiving circuit 40 and the second antenna segment 12 are isolated, so that the first antenna segment 11 is connected to the antenna matching circuit 50 In the network formed, the second antenna segment 12 is connected to the network formed with the receiving circuit 40, that is, the first antenna segment 11 and the second antenna segment 12 belong to two different networks. After the NFC antenna 10 is formed on the PCB, or after the NFC antenna 10 is fabricated, the short-circuit test device can be connected to complete the short-circuit test of the NFC antenna 10. The present invention solves the problem caused by the short-circuit of the antenna caused by the PCB fabrication process. The problem of the decrease in the antenna yield of the PCB printed board is beneficial to improve the manufacturing efficiency of the NFC antenna 10 and improve the yield of the NFC antenna 10 .

1 to 3, in one embodiment, the first isolation device 20 has zero ohm resistance;

And/or, the second isolation device 30 has zero ohm resistance.

In this embodiment, both the first isolation device 20 and the second isolation device 30 can be implemented by using zero-ohm resistors, and the two zero-ohm resistors can isolate the first antenna segment 11 and the second antenna segment 12 into two different nets Therefore, it is physically isolated, so that the flying probe test can be carried out during PCB production, that is, the short circuit test can be used to test whether there is a short circuit between adjacent antennas.

1 to 3 , in an embodiment, the signal transmitting end includes a first signal transmitting end TX1 and a second signal transmitting end TX2; the EMC filter circuit 60 includes a first inductance L1, a second inductance L2, A first capacitor C1 and a second capacitor C2, one end of the first inductance L1 is connected to the first signal transmission end TX1, and the other end of the first inductance L1 is connected to the antenna matching circuit 50; the first One end of the second inductor L2 is connected to the second signal transmitting end TX2, and the other end of the second inductor L2 is connected to the antenna matching circuit 50; the first capacitor C1 is connected in series with the first inductor L1 and the antenna matching circuit 50. between the ground; the second capacitor C2 is connected in series between the second inductor L2 and the ground.

In this embodiment, the first signal transmitting end TX1 and the second signal transmitting end TX2 may be connected to two transmitting ends of the NFC chip U1, and the two transmitting ends output differential signals of equal amplitude and opposite phase to drive the antenna to work. The first inductor L1 and the first capacitor C1 form a low-pass filter circuit, and the second inductor L2 and the second capacitor C2 form another low-pass filter circuit.

1 to 3, in one embodiment, the antenna matching circuit 50 includes:

The third capacitor C3, the fourth capacitor C4, the fifth capacitor C5 and the sixth capacitor C6, the third capacitor C3 is arranged in series between the EMC filter circuit 60 and the first antenna segment 11; the fourth capacitor C3 The capacitor C4 is arranged in series between the EMC filter circuit 60 and the second antenna segment 12; the fifth capacitor C5 is arranged in series between the third capacitor C3 and the ground; the sixth capacitor C6 is arranged in series between the fourth capacitor C4 and the ground.

In this embodiment, the third capacitor C3 and the fourth capacitor C4 are series capacitors, and the fifth capacitor C5 and the sixth capacitor C6 are parallel capacitors. In practical applications, the internal resistance of the NFC receiving antenna can be measured by impedance, and the network analysis method can be used to measure the internal resistance of the NFC receiving antenna. The instrument measures the capacitive reactance and phase deviation of the antenna matching circuit 50, designs and adjusts the capacitance values of the third capacitor C3, the fourth capacitor C4, the fifth capacitor C5 and the sixth capacitor C6, so that the internal resistance of the NFC antenna and the antenna matching circuit 50 The impedance of the antenna matching circuit 50 is consistent, so that the impedance provided by the antenna matching circuit 50 can match the NFC antenna.

1 to 3, in one embodiment, the NFC antenna assembly further includes a signal receiving end RX and a bias voltage input end VMID;

The receiving circuit 40 includes a first resistor R1, a second resistor R2 and a seventh capacitor C7. One end of the first resistor R1 is connected to the bias voltage input terminal VMID, and the other end of the first resistor R1 is connected to the bias voltage input terminal VMID. The signal receiving end RX and one end of the second resistor R2 are interconnected, the other end of the second resistor R2 is connected to one end of the seventh capacitor C7, and the other end of the seventh capacitor C7 is connected to the The second isolation device 30 is connected.

In this embodiment, the first resistor R1 is used as a voltage divider and is arranged between the signal receiving terminal RX and the bias voltage input terminal VMID, and the bias voltage connected by the first resistor R1 from the bias voltage input terminal VMID can be increased and improved The voltage of the signal receiving terminal RX is driven. The NFC antenna can convert wireless data signals and interference signals received from the outside into electrical signals, and output the electrical signals to the seventh capacitor C7 and the second resistor R2 of the receiving circuit 40, under the coupling and filtering action of the seventh capacitor C7 , and transmitted to the NFC chip U1 through the second resistor R2.

The present invention also provides an NFC antenna assembly, which includes an NFC chip U1 and the above-mentioned NFC antenna circuit 200 , and the NFC chip U1 is electrically connected to the NFC antenna circuit 200 .

For the detailed structure of the NFC antenna circuit 200, reference may be made to the above-mentioned embodiments, which will not be repeated here; It includes all the technical solutions of all the above embodiments of the NFC antenna circuit, and the technical effects achieved are also the same, which will not be repeated here.

Referring to FIG. 1 to FIG. 3 , in this embodiment, the NFC antenna circuit 200 can perform impedance matching and filtering on the wireless data signal, and adjust the resonant frequency and input impedance of the antenna. The NFC chip U1 is a chip with a mutual communication function and a computing function, and can complete corresponding NFC function services according to the NFC chip U1. When the NFC chip U1 is applied to the electronic device, it can exchange information with the target device through the NFC antenna circuit 200 . The NFC chip U1 can be used to implement the function of executing the card mode, for example, when replacing the functions of bus card, shopping mall card swiping, and access control, the target device in the present invention is a card reader. When the target device is a card reader, the NFC chip U1 sends authentication information to the card reader through the communication link, and receives the authentication result response sent by the card reader, so as to execute the corresponding card function after the authentication is passed. The NFC chip U1 can also be used for point-to-point data transmission between electronic devices to realize short-distance data transmission with the target device, such as data or exchange of music files between two electronic devices, etc. It can also be applied to NFC Bluetooth devices, such as Bluetooth headsets , smart bracelet, etc.

The NFC chip U1 integrates a main control chip and an NFC read-write chip. The main control chip is preset with an NFC algorithm. The main control chip communicates with the NFC read-write chip. The NFC read-write chip is connected to the external NFC device through the NFC antenna circuit 20010. When the NFC read-write chip outputs a connection signal to the main control chip, so that the main control chip can control and respond according to the received information, and the main control chip can also output a control signal to the NFC read-write chip according to the connection signal fed back by the NFC read-write chip. The chip performs information processing, such as outputting a reset signal, an initialization signal, a read-write signal, a switch signal, etc. Based on the NFC antenna circuit 200, the working modes that the NFC chip U1 can perform with external NFC devices may include but are not limited to read-write mode, point-to-point transfer mode and smart card mode. Specifically, the NFC antenna circuit 200 realizes wireless data signal communication between the NFC chip U1 and an external NFC device. The connection signal fed back by the NFC read-write chip corresponds to the output control signal to the NFC read-write chip, so as to control the NFC read-write chip to read and write the wireless data signal, thereby realizing the NFC function between the NFC circuit and the external device.

The NFC chip U1 has two signal transmitting terminals TX1 and TX2, a signal receiving terminal RX and a bias voltage output terminal VMIND, and a ground terminal TVSS, two signal transmitting terminals TX1 and TX2 and the EMC filter circuit in the NFC antenna circuit 200. The two input terminals of 60 are connected in one-to-one correspondence, the signal receiving terminal RX and the bias voltage output terminal VMIND are connected to the signal receiving terminal RX and the bias voltage output terminal VMIND of the receiving circuit 40, and the ground terminal TVSS is used for grounding. The NFC chip U1 is connected to the NFC antenna circuit 200 through two signal transmitting ends TX1 and TX2 and a signal receiving end RX, and exchanges wireless data signals to realize wireless data signal transmission or stop transmission.

In some embodiments, the NFC antenna assembly also has a crystal oscillator (not shown) to provide a clock reference for the NFC chip U1, while the chip has high output power, making the DC/DC booster an unnecessary external component , the above advantages all contribute to saving component cost and board space.

1 to 3, in one embodiment, the NFC antenna assembly further includes:

The PCB circuit board 100 , the NFC antenna circuit 200 and the NFC chip U1 are disposed on the PCB circuit board 100 .

In this embodiment, the NFC chip U1 and the NFC antenna circuit 200 are both disposed on the PCB circuit board 100 . Specifically, the PCB circuit board 100 is formed with an antenna installation area and a circuit installation area, and the antenna installation area is wound around the Outside the circuit installation area; the NFC antenna 10 in the NFC antenna circuit 200 is implemented by a loop antenna, and the first loop antenna segment and the second loop antenna segment in the loop NFC antenna 10 are arranged on the antenna using a double-wire parallel winding process. Installation area; the antenna matching circuit 50 , the receiving circuit 40 , the NFC chip U1 , the first isolation device 20 and the second isolation device 30 in the NFC antenna circuit 200 are all disposed on the circuit installation area. The first antenna segment 11 and the second antenna segment 12 are annularly arranged on the peripheral side of the PCB circuit board 100, and the annular area formed by the annular NFC antenna 10 can be used as the circuit installation area of the NFC antenna assembly, that is, the electronic components of the NFC antenna assembly. The components are installed in the annular area formed by the annular NFC antenna 10, and PCB printing is performed in the annular area to form the circuit wiring for installing the antenna matching circuit 50, the receiving circuit 40, the first isolation device 20 and the second isolation device 30 The current loop of the antenna matching circuit 50 , the receiving circuit 40 , the first isolation device 20 and the second isolation device 30 can be formed by pasting the electronic components on the corresponding pads of the circuit wiring layer using a placement machine.

A plurality of conductive vias are provided on the PCB circuit board 100 to electrically connect the first antenna segment 11 to the first isolation device 20 and the antenna matching circuit 50 through the conductive vias; and,

The second antenna segment 12 and the second isolation device 30 are electrically connected through the conductive via.

In this embodiment, the PCB circuit board 100 has opposite side surfaces, which are a first side surface and a second side surface, respectively. The receiving circuit 40 , the antenna matching circuit 50 , the EMC filter circuit 60 and the NFC chip in the NFC antenna circuit U1 and the like may be arranged on one side surface of the PCB circuit board 100 , or may be arranged on the opposite side surfaces of the PCB circuit board 100 . In order to reduce the use of binding wires and flying wires, in this embodiment, a plurality of conductive via holes are arranged on the PCB circuit board 100 , so that the first antenna segment 11 and the second antenna segment 12 in the loop NFC antenna 10 belong to two different After the network, the electrical connection with the electronic components arranged in the annular mounting area can be achieved through conductive vias and circuit wiring.

It can be understood that after setting the NFC chip U1 on the PCB circuit board 100, it is necessary to program the NFC chip U1, and then the product function test of the NFC antenna assembly can be performed. The matching circuit of the NFC antenna and the antenna belong to the same network physically. If there is a short circuit, the flying probe test cannot be performed directly after the NFC antenna on the PCB printed board, that is, the internal short circuit in the antenna cannot be tested. Test the product during functional testing. At this time, the PCB has undergone SMT patching and software programming, which will cause unnecessary losses. The present invention can detect whether there is a short circuit during the flying probe test. At this time, the PCB with bad antenna can be removed, so that the PCB with normal antenna can enter the steps of electronic component patch and program programming. The optimized PCB printed board antenna of the present invention greatly reduces the resource waste of component mounting and the complexity of testing that may be caused during processing, and can also reduce the testing of the antenna.

The present invention also provides an electronic device including the NFC antenna circuit described above, or the NFC antenna assembly described above. For the detailed structure of the NFC antenna circuit and the NFC antenna assembly, reference may be made to the above-mentioned embodiments, which will not be repeated here; The embodiment of the electronic device includes all the technical solutions of the above-mentioned NFC antenna circuit and all the embodiments of the NFC antenna assembly, and the technical effects achieved are also the same, which will not be repeated here.

The mobile terminal may be a smart phone, a computer, a multimedia player, an electronic reader, a wearable device, and the like.

The above descriptions are only optional embodiments of the present invention, and are not intended to limit the scope of the present invention. Under the inventive concept of the present invention, any equivalent structural transformations made by using the contents of the description and drawings of the present invention, or direct/indirect Applications in other related technical fields are included in the scope of patent protection of the present invention.

Claims (10)

1. An NFC antenna circuit, characterized in that the NFC antenna circuit comprises: an NFC antenna, including a first antenna segment and a second antenna segment; an antenna matching circuit, connected to the first antenna segment, for realizing impedance matching with the NFC antenna; a receiving circuit, connected to the second antenna segment of the NFC antenna, for converting the generated wireless data signal received by the NFC antenna into an electrical signal; a first isolation device, arranged in series between the first antenna segment and the second antenna segment; A second isolation device is arranged in series between the receiving circuit and the second antenna segment. 2. The NFC antenna circuit according to claim 1, wherein the first isolation device has a zero ohm resistance; And/or, the second isolation device has zero ohmic resistance. 3. The NFC antenna circuit of claim 1, wherein the NFC antenna circuit further comprises: signal sender; The EMC filter circuit is arranged in series between the signal transmitting end and the antenna matching circuit. 4. The NFC antenna circuit according to claim 3, wherein the signal transmitting end comprises a first signal transmitting end and a second signal transmitting end; the EMC filter circuit comprises a first inductance, a second inductance, a first a capacitor and a second capacitor, one end of the first inductor is connected to the first signal transmitting end, the other end of the first inductor is connected to the antenna matching circuit; one end of the second inductor is connected to the The second signal sending end is connected, and the other end of the second inductor is connected to the antenna matching circuit; the first capacitor is connected in series between the first inductor and the ground; the second capacitor is connected in series with the between the second inductor and ground. 5. The NFC antenna circuit of claim 3, wherein the antenna matching circuit comprises: A third capacitor, a fourth capacitor, a fifth capacitor and a sixth capacitor, the third capacitor is arranged in series between the EMC filter circuit and the first antenna segment; the fourth capacitor is arranged in series between the EMC between the filter circuit and the second antenna segment; the fifth capacitor is connected in series between the third capacitor and the ground; the sixth capacitor is connected in series between the fourth capacitor and the ground. 6. The NFC antenna circuit according to claim 1, wherein the NFC antenna circuit further comprises a signal receiving terminal and a bias voltage input terminal; The receiving circuit includes a first resistor, a second resistor and a seventh capacitor, one end of the first resistor is connected to the bias voltage input end, and the other end of the first resistor is connected to the signal receiving end and the other end. One end of the second resistor is interconnected, the other end of the second resistor is connected to one end of the seventh capacitor, and the other end of the seventh capacitor is connected to the second isolation device. 7. The NFC antenna circuit according to any one of claims 1 to 6, wherein the operating frequency of the NFC antenna circuit is 13.56MHZ. 8. An NFC antenna assembly, comprising an NFC chip and the NFC antenna circuit according to any one of claims 1 to 7, wherein the NFC chip is electrically connected to the NFC antenna circuit. 9. The NFC antenna assembly of claim 8, wherein the NFC antenna assembly further comprises: A PCB circuit board, the NFC antenna circuit and the NFC chip are arranged on the PCB circuit board. 10. An electronic device, comprising the NFC antenna circuit according to any one of claims 1 to 7, or the NFC antenna assembly according to any one of claims 8 or 9.

Images