WO2012139344A1

WO2012139344A1 - Nfc dual-mode mobile terminal and communication method thereof

Info

Publication number: WO2012139344A1
Application number: PCT/CN2011/077402
Authority: WO
Inventors: 朱大龙; 胡易木; 袁爱国; 徐金禄
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-04-11
Filing date: 2011-07-20
Publication date: 2012-10-18
Also published as: CN102158236A

Abstract

Disclosed are an NFC dual-mode mobile terminal and communication method thereof. The method comprises the following steps: when use of the frequency modulation (FM) function of a mobile terminal is required, the mobile terminal instructs the mobile terminal internal antenna via the mobile terminal control network to receive radio frequency signals from an FM transmitting station; when use of the NFC function of the mobile terminal is required, the mobile terminal instructs the internal antenna via the control network to conduct near field wireless communication with a reader or a tag via electromagnetic induction. The present invention reduces the number of antennas on a mobile terminal, enhances system performance and improves user experience.

Description

TECHNICAL FIELD The present invention relates to the field of communications, and in particular, to a Near Field Communication (NFC) dual-mode mobile terminal and a communication method thereof. BACKGROUND With the advent of The Third Generation Mobile Communications (3G) era, mobile communications has entered the 3G era. At present, there are three major 3G communication standards in the world, namely Wideband Code Division Multiple Access (WCDMA), Code Distribute Multiple Access (CDMA) 2000 and Time Division Synchronization Codes. Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) is a three-standard system. Among them, TD-SCDMA is an international standard proposed by China and recognized by the International Telecommunication Standardization Organization. China has core independent intellectual property rights. At present, China Mobile's TD-SCDMA network has accumulated 85MHz frequencies, which are 20MHz (1880-1900MHz) in the F-band, 15MHz (2010-2025MHz) in the A-band and 50MHz (2320-2370MHz;) in the E-band, among which The E band is now only allowed for indoor coverage. However, due to the fact that the current TD-SCDMA network is not fully mature, it has to face the problem that the network coverage is not comprehensive enough. In order to solve this problem, consider improving the coverage problem through other networks, and the Global System for Mobile Communications (GSM) network is the best cost-effective supplement. Therefore, TD-SCDMA and GSM are currently available. The application of analog mobile terminals has become very common.

NFC is a contactless identification and interconnection technology jointly developed by Philips and Sony. It can be used in mobile devices, consumer electronics, personal computers (PCs) and smart control tools. Wireless communication. The NFC operates in the frequency range of 13.56 MHz and has a working distance of about 10 cm. NFC technology is developed by the International Organization for Standardization (ISO) 18092, the European Computer Manufacturers Association (ECMA) 340, and the European Telecommunication Standards Institute (ETSI). Technical Specification (TS) 102 190 4 Standardization of 4 gallops under the truss, and also compatible with the widely used ISO14443 Type-A, B and Felica standard contactless smart card infrastructure. Take the NFC dual-mode mobile terminal of TD-SCDMA/GSM communication system as an example. In addition to the TD-SCDMA/GSM dual-mode wireless communication module, the built-in NFC chip can be used as a label to pay the fee, or as a fee. The reader is used as a data exchange and collection. NFC technology supports a wide range of applications, including mobile payments and transactions, peer-to-peer communications, and mobile information access. For example, people can use NFC phones to connect to any other device, anytime, any entertainment device and transaction they want, to complete payments, get information, and more.

The NFC antenna is the main unit for realizing the NFC near-field communication function. It is implemented by the transformer principle and generally consists of a set of turns and two antenna contacts. Therefore, the NFC antenna is generally a loop antenna. The NFC reader generates a magnetic flux through the current of the antenna coil, and a portion of the magnetic flux passes through the antenna loop of the tag, and a voltage is induced on the coil of the NFC tag to supply power to the NFC tag. With the continuous advancement of technology, electronic components are becoming more and more integrated, which greatly stimulates the diversification and miniaturization of portable products. Frequency Modulation (FM) The use of radio functions in portable products has become very common, especially in mobile phone terminal products. For example, the operating frequency band of the FM function of a mobile phone is generally 88 MHz to 108 MHz. In general, FM antennas for such FM-enabled mobile terminal products are mostly implemented by FM antennas through the ground wire of the earplugs. But in fact, people have a shortcoming in the use of the earplug antenna is very inconvenient to carry, so many people are reluctant to carry, so that the benefits of FM can not be fully utilized. At the same time, the number of antennas for mobile phones that tend to be multi-functional and multi-service applications is increasing. For example, Wireless Fidelity (WiFi), Bluetooth (Blue Tooth, BT for short), China Mobile Multimedia Broadcasting (CMMB), NFC, Global Position System (Global Position System, Referred to as GPS, FM and other multi-functional mobile phones, plus the main antenna, its number of antennas has exceeded 5, densely distributed on the edge of the mobile phone, making the design of mobile phone antenna more and more difficult. SUMMARY OF THE INVENTION A primary object of the present invention is to provide a communication scheme for an NFC dual-mode mobile terminal, so as to at least solve the above-mentioned related art, which is difficult to expand the FM function due to the external FM antenna of the mobile terminal, and the antenna design is difficult. High problem. In order to achieve the above object, according to an aspect of the present invention, an NFC dual mode mobile terminal is provided. An NFC dual-mode mobile terminal according to the present invention includes: an internal antenna configured to receive a radio frequency signal of an FM transmitting station to implement an FM function, and an NFC function between a reader or a tag by electromagnetic induction; and a control network, Set to control the built-in antenna to switch between the NFC function and the FM function, so that the FM function and the NFC function share the built-in antenna. Preferably, the mobile terminal further includes a matching network, where the matching network includes: an FM matching unit configured to perform FM impedance matching according to physical properties of the built-in antenna, wherein the physical attribute includes an NFC ring winding mode of the built-in antenna and The length of the built-in antenna determined by the FM band resonance point; the NFC matching unit is set to perform NFC inter-stage impedance matching according to the impedance of the built-in antenna to adjust the resonance point and quality factor of the built-in antenna corresponding to different NFC ring winding modes. Preferably, the FM matching unit is an LC or RC network; the NFC matching unit is a differential RC network. Preferably, the mobile terminal further comprises an FM processing network, the FM processing network comprising: a signal protection unit configured to suppress the radio frequency signals of the two communication systems of the mobile terminal by the multi-stage series-parallel LC resonance circuit; and/or the power amplifying unit, It is arranged to suppress link noise of the FM receiving system of the mobile terminal according to a control signal of the control network and to amplify the FM radio wave signal. Preferably, the mobile terminal further comprises: an NFC filtering network, configured to filter out higher harmonics outside the NFC frequency range. Preferably, the NFC filtering network is an LC differential pair network, and the type of the network is one of the following: L type, T type, π type. Preferably, the built-in antenna receives the FM radio antenna and/or CMMB antenna of the broadcast station for the mobile terminal. Preferably, the position of the built-in antenna fixed to the mobile terminal is one of the following: around the battery, on the rear of the battery, around the outer frame. Preferably, the internal antenna is a loop antenna made of wire or FPC. In order to achieve the above object, according to another aspect of the present invention, a communication method of an NFC dual mode mobile terminal is also provided. The communication method of the NFC dual-mode mobile terminal according to the present invention includes the following steps: when the FM function of the mobile terminal is required to be used, the mobile terminal instructs the internal antenna of the mobile terminal to receive the radio frequency signal of the FM transmitting station through its control network; When using the mobile terminal's NFC function, move The terminal instructs the built-in antenna to perform short-range wireless communication with the reader or tag through electromagnetic induction through the control network. The present invention solves the problem that the antenna design is difficult due to the limited expansion of the FM function caused by the external FM antenna of the mobile terminal and the difficulty in designing the antenna due to the internal antenna shared by the NFC and the FM in the related art, and the mobility is reduced. The number of antennas in the terminal enhances the performance of the system and improves the user experience. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are set to illustrate,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the structure of an NFC dual-mode mobile terminal according to an embodiment of the present invention; FIG. 2 is a block diagram showing the structure of an NFC dual-mode mobile terminal according to a preferred embodiment of the present invention; A flowchart of a communication method of an NFC dual-mode mobile terminal according to an embodiment of the present invention; FIG. 4 is a schematic diagram of a mobile terminal sharing an internal antenna with NFC and FM according to Embodiment 1 of the present invention; FIG. 6 is a schematic diagram of a built-in antenna shared by an NFC and an FM according to Embodiment 2 of the present invention; FIG. 7 is an FM protection according to Embodiment 2 of the present invention; FIG. 8 is a schematic diagram of a circuit of a low noise amplifier network according to a second embodiment of the present invention; FIG. 9 is a schematic diagram of a built-in antenna according to Embodiment 2 of the present invention as an NFC antenna; FIG. FIG. 11 is a circuit diagram of an NFC EMC filter network according to Embodiment 2 of the present invention; and FIG. 11 is a circuit diagram of an NFC EMC filter network according to Embodiment 2 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict. According to an embodiment of the present invention, an NFC dual mode mobile terminal is provided. 1 is a structural block diagram of an NFC dual-mode mobile terminal according to an embodiment of the present invention. As shown in FIG. 1, the mobile terminal 10 includes: an internal antenna 12 configured to receive a radio frequency signal of an FM transmitting station to implement an FM function, and Implementing an NFC function with the reader or tag by electromagnetic induction; and a control network 14 coupled to the internal antenna 12, configured to control the internal antenna 12 to switch between the NFC function and the FM function to implement the FM function and The NFC function shares the internal antenna. Through the above-mentioned NFC dual-mode mobile terminal 10, the internal antenna 12 is shared by the NFC and the FM, which solves the problem that the antenna design is difficult due to the limited expansion of the FM function and the increase of the mobile terminal service due to the external FM antenna of the mobile terminal in the related art. The problem is that the number of antennas of the mobile terminal is reduced, the performance of the system is enhanced, and the user experience is improved. 2 is a structural block diagram of an NFC dual-mode mobile terminal according to a preferred embodiment of the present invention. As shown in FIG. 2, the mobile terminal 10 further includes a matching network 22 coupled to the control network 14, wherein the matching network 22 includes: FM matching. The unit 222 is configured to perform FM impedance matching according to the physical attributes of the built-in antenna 12, wherein the physical attributes include the NFC ring winding mode of the built-in antenna 12 and the length of the built-in antenna 12 determined by the FM band resonance point; NFC matching unit 224. Set the impedance matching between the NFC stages according to the impedance of the built-in antenna 12 to adjust the resonance point and the quality factor of the built-in antenna corresponding to different NFC ring winding modes. For example, the NFC matching unit 224 can be configured to adjust the resonance point of different antenna forms and to adjust the quality factor Q (ie, quality factor) of the NFC antenna. The method can perform impedance matching through the matching network 22 to maximize the communication quality of the mobile terminal. Preferably, the FM matching unit 222 is an LC or RC network; the NFC matching unit 224 is a differential

RC network. The method is simple and practical, and has high operability. Preferably, the mobile terminal 10 further includes an FM processing network 24 coupled to the FM matching unit 222.

The FM processing network 24 includes: a signal protection unit 242 configured to suppress radio frequency signals of two communication systems of the mobile terminal 10 through a multi-stage series-parallel LC resonance circuit; and/or a power amplification unit 244 configured to be in accordance with the control network 14 The control signal suppresses the link noise of the FM receiving system of the mobile terminal 10 and amplifies the FM radio wave signal. The method can reduce the frequency between the two communication systems and the frequency band in which the FM is located, and improve the reception quality of the FM radio frequency signal. For example, if the two communication systems of the mobile terminal 10 are WCDMA and GSM, the radio frequency signals of the WCDMA and GSM communication bands can be suppressed by the resonance circuit of the signal protection unit 242. Preferably, the mobile terminal 10 further comprises: an NFC filtering network 26 arranged to filter out higher harmonics outside the NFC frequency range. This method can improve the performance of NFC. For example, in general, the operating frequency of NFC is 13.56 MHz. In this case, in addition to the function of filtering harmonics, the NFC filter network 26 can also perform impedance change to reduce the amplitude rise time after the modulation phase and expand the NFC receive bandwidth. . Preferably, the NFC filtering network 26 is an LC differential pair network, and the type of the network is one of the following: L type, T type, π type. The method is simple and practical, and has high operability. Preferably, the built-in antenna 12 receives the FM radio antenna of the broadcast station for the mobile terminal 10 and/or

CMMB antenna. For example, the NFC antenna of an NFC dual-mode mobile terminal can also perform FM radio reception as well as watching mobile TV. Preferably, the position of the built-in antenna 12 fixed to the mobile terminal 10 is one of the following: around the battery, on the rear of the battery, around the outer frame. For example, the built-in antenna 12 is placed around the outer frame of the phone. The method is simple and practical, and has high operability. Preferably, the built-in antenna 12 is a loop antenna made of a wire or a flexible printed circuit (FPC). For example, the built-in antenna 12 is an NFC antenna of the mobile terminal 10. The method can effectively reduce the number of antennas in the mobile terminal, and simplifies the complexity of the hardware design of the mobile terminal. Corresponding to the NFC dual-mode mobile terminal 10, the embodiment of the present invention further provides a communication method of an NFC dual-mode mobile terminal. 3 is a flowchart of a communication method of an NFC dual-mode mobile terminal according to an embodiment of the present invention. As shown in FIG. 3, the method includes the following steps: Step S302, when a FM FM function of a mobile terminal is required, the mobile terminal Receiving, by the control network, the radio frequency signal of the FM transmitting station by the built-in antenna of the mobile terminal; Step S304, when the NFC function of the mobile terminal is needed, the mobile terminal instructs the built-in antenna to perform near-reading with the reader or the label through electromagnetic induction through the control network. Distance wireless communication. Through the above steps, the method of sharing the built-in antenna by using the NFC and the FM solves the limitation of the FM function expansion and the increase of the mobile terminal service due to the external FM antenna of the mobile terminal in the related art. The problem that the antenna design is difficult is high, the number of antennas of the mobile terminal is reduced, the performance of the system is enhanced, and the user experience is improved. For example, when the FM function of the mobile terminal is used to listen to the radio station, the built-in antenna of the mobile terminal is used as the FM antenna to receive the radio frequency signal. If the NFC function is used for consumption during the listening period, the mobile terminal can be used. The control network switches the built-in antenna to the NFC function. After the switch, the built-in antenna of the mobile terminal functions as an NFC antenna to exchange data with the reader or the tag through electromagnetic induction. It should be noted that the dual mode mobile terminal involved in the embodiment of the present invention may be a combination of any two communication systems, and is not limited to TD-SCDMA/GSM. For example, it may be WCDMA/GSM, or CDMA2000/GSM or the like. Moreover, the function antenna shared by the mobile terminal referred to in the embodiment of the present invention is not limited to the NFC and FM antenna sharing, and may be applied to other forms, for example, the NFC and the CMMB antenna are shared. The implementation process of the above embodiment will be described in detail below in conjunction with the preferred embodiments and the accompanying drawings. Embodiment 1 This embodiment provides a method for sharing an internal antenna between an NFC and an FM under the premise of ensuring the function of the mobile terminal, and multiplexing the NFC antenna and the FM antenna on the mobile terminal product. Specifically, the NFC and the FM share a built-in antenna, an antenna switch control network, an antenna matching network, an FM protection network, an FM 氐 noise amplification network, and an NFC electromagnetic compatibility (EMC) filter network, and the like, The built-in FM antenna can be built in to improve the performance of the built-in FM antenna. Moreover, the FM built-in antenna has the same performance, better appearance characteristics, and is more robust than the external one. 4 is a schematic diagram of a mobile terminal that shares an internal antenna with an NFC and an FM according to the first embodiment of the present invention. As shown in FIG. 4, the mobile terminal may include:

(1) NFC and FM share a built-in antenna, which is set to receive wireless RF signals from the FM transmitter in the air, and achieve near-field communication between the NFC mobile terminal and the reader or tag.

Preferably, the internal antenna shared by the NFC and the FM is a loop antenna wound by a wire, a loop antenna made of FPC, or a loop antenna made of other forms of metal conductor. It has two antenna feed points, connected to NFC and FM for NFC and FM communication. The antenna The number of winding turns varies depending on the winding method used, the winding area, and the like. In the implementation process, the built-in antenna of the NFC mobile terminal can use a flexible circuit board, and is embedded in the battery case or around the casing of the mobile terminal. For example, the built-in antenna may be fixed around the battery of the mobile terminal, or on the rear case of the battery, or may be fixed around the outside of the mobile terminal. (2) The antenna switch control network is set to realize switching between the NFC communication and the FM communication channel, and realizes the purpose of sharing the antenna by the NFC and the FM. The control network also includes a control signal from the baseband chip, which can control the operation of the Low Noise Amplifier (LNA) only when the user uses the FM, reduce the power consumption of the mobile phone, and extend the battery usage. life. Preferably, the antenna switch control network can include a single pole single throw switch, a single pole double throw switch, and a baseband control signal interface. The single-pole single-throw switch is configured to connect the NFC and the FM to share the internal antenna as the NFC antenna signal path when performing NFC near-field communication on the mobile terminal; and when the user listens to the FM broadcast, disconnect the path, so that the NFC and the FM share the built-in The antenna acts as an FM antenna. The single-pole double-throw switch is configured to connect one of its two paths as an NFC signal path when the mobile terminal performs NFC near-field communication; the other path connects the NFC/FM antenna feed point only when the user listens to the FM using the mobile terminal, When NFC and FM share the built-in antenna as an FM antenna. When the user uses FM, the antenna switch control network will also send a control signal to enable the low noise amplifier to work. When the user does not use FM, the low noise amplifier is turned off through the control network to reduce power consumption and protect the LNA. purpose. (3) Antenna matching network, including FM antenna matching network and NFC antenna matching network. According to different forms of antennas (for example, NFC winding method), the best antenna port input standing wave is achieved, and power transmission is realized. Preferably, the antenna matching network may comprise an FM antenna zone network and an NFC antenna matching network. The FM antenna matching network can match the FM according to different forms of the antenna pattern (Pattern;) to achieve the optimal antenna port input standing wave, and realize power efficient transmission. In the implementation process, the matching circuit can be a The LC network or the RC network may also be a T-type network or a π-type network, or may be an L-type network; and the NFC antenna matching network may be composed of a differential RC network, which may be L-shaped or Τ-type or The π-type is designed to perform impedance matching between NFC stages to achieve optimal transmission efficiency between NFC and FM internal antenna and EMC filter network.

(4) FM protection network, taking TD-SCDMA/GSM dual-mode mobile phone as an example, considering that the mobile phone works in GSM900, Data Communication System (Digital Cellular System, DCS) 1800, Personal Communication Service (PCS) 1900 and TD1.9G, TD2.1G and other five frequency bands, through multi-stage series-parallel resonance and low-pass filter, effectively suppress the above multi-band RF The signal, thus avoiding blocking, achieves the purpose of protecting the LNA of the latter stage. Preferably, the FM protection network can be implemented with four LC series-parallel circuits, namely two parallel LC circuits and two series LC circuits. Taking the TD-SCDMA/GSM dual-mode mobile phone as an example, the two-stage resonance in parallel is in the GSM transmission frequency band, and the two stages in series are respectively resonated in the DCS 1800 transmission and the TD transmission frequency band. Through the four-stage series-parallel resonant circuit, the TD-SCDMA and GSM signals of the TD-SCDMA/GSM dual-mode mobile phone are effectively suppressed to avoid blocking, and the LNA of the latter stage is protected from large signal damage.

(5 M氐 noise amplifier network, in order to solve the poor sensitivity of the built-in CMMB antenna itself, affecting the sensitivity of the entire FM receiving system, reduce the system noise figure by increasing the LNA method, and improve the receiving sensitivity of the whole system. Considering the difference between the built-in antenna and the external antenna environment, the noise can be suppressed and amplified by the low-noise amplifier network, and the noise of the entire FM system can be reduced, thereby improving the receiving sensitivity of the built-in FM antenna.

(6) The NFC EMC filter network is set to filter out high-order harmonics other than 13.56MHz near-field communication, and simultaneously perform impedance change to reduce the amplitude rise time after the modulation phase, and expand the NFC receiving bandwidth. Preferably, the NFC EMC filter network can also be configured to perform impedance changes to reduce the amplitude rise time after the modulation phase and extend the NFC receive bandwidth. In the implementation process, it can be composed of an LC differential pair network, which can be L-type or T-type or π-type LC network. It can be seen that, by the above embodiment, the method of sharing the built-in antenna by using NFC and FM is realized.

The built-in FM antenna reduces the number of antennas in the mobile terminal and reduces the hardware design complexity of the mobile terminal. Embodiment 2 This embodiment provides a mobile terminal with NFC and FM functions and supports TD-SCDMA/GSM dual-mode communication. The composition of the mobile terminal is as shown in FIG. 1 , and the NFC and FM multiplexed internal antennas have two Signal feed point, through a single-pole single-throw switch, a single-pole double-throw switch and an antenna switch control network composed of control signals from the baseband chip to complete the multiplexing of NFC and FM antennas, through the antenna matching network, FM protection network, low Noise amplifier network, NFC EMC filter network, etc. reduce the interference between multiple antennas and improve antenna performance. FIG. 5 is a schematic diagram of the built-in antenna according to the second embodiment of the present invention as an FM antenna. As shown in FIG. 5, when the user listens to the FM broadcast, the baseband control chip controls the switch control network to switch the single-pole single-throw switches 4 and 7. Disconnect, make the NFC and FM share the antenna signal feed point 1 open circuit, disconnect the single-pole double-throw switch 3 and 6, and connect 3 and 5. At this time, the NFC and FM shared antenna signal feed point 2 is connected to the FM path, at this time NFC The FM shared signal is shared with the FM as an FM antenna to receive FM radio signals from the air. It should be noted that, as an antenna shared by the NFC and the FM, the antenna pattern must satisfy the requirements of the NFC loop antenna, and also consider the requirement of the resonance point of the antenna of the FM frequency band of 88 MHz to 108 MHz. For example, FIG. 6 is a schematic diagram of a built-in antenna shared by an NFC and an FM according to Embodiment 2 of the present invention. As shown in FIG. 6, FIG. 6 is a Pattern of an NFC/FM shared antenna used in the implementation process. When the NFC and the FM shared antenna are used as the FM antenna, the radio wave signals received from the air interface are matched by the FM antenna matching sub-network of the antenna matching network. According to different antenna patterns, to achieve a good antenna port input standing wave, the matching circuit may be different. For example, the matching network may be T-type, L-shaped, or a π-type LC circuit. In the implementation process, considering the practical application of multi-antenna of TD-SCDMA/GSM dual-mode mobile terminal, in order to effectively TD-SCDMA and GSM signals of TD-SCDMA/GSM dual-mode mobile phones, avoid blocking, protect the rear-stage circuit, FM The protection network is implemented by a multi-stage series-parallel LC resonant circuit. FIG. 7 is a circuit diagram of an FM protection network according to Embodiment 2 of the present invention. As shown in FIG. 7, it is composed of a four-stage LC series-parallel resonant circuit: two parallel LC circuits and two series LC circuits. Among them, the parallel two-stage resonance is in the DCS 1800 emission and TD transmission frequency bands, and the two-stage resonance in series is in the GSM transmission frequency band. In order to achieve a better effect, the CMMB protection network insertion loss is not required to exceed 3dB, and the standing wave is less than 2dB. The suppression requirement is greater than 25dB in the GSM900 band, greater than 20dB in the DCS 1800 band, greater than 17dB in the TD1.9G band, and greater than 25dB in the TD2.1G band. In order to reduce the link noise of the entire FM receiving system and improve the receiving sensitivity of the NFC antenna, this embodiment uses an LNA application circuit. Figure 8 is a circuit diagram of a low noise amplifier network in accordance with a second embodiment of the present invention. As shown in Figure 8, it is comprised of an LNA, a power supply, and associated damper components. It amplifies the received weak FM radio wave signal, which can reduce the noise of the entire FM receiver system and improve the receiving sensitivity of the FM internal antenna. At the same time, the control signals sent by the control network formed by the baseband processor of the mobile phone are used to control V and V. When the user uses the FM function, V and V _3⁄43⁄4 are enabled to control the LNA operation, and at other times, the user uses the NFC near field. When the communication is being consumed, the LNA is turned off and the FM signal path is disconnected. FIG. 9 is a schematic diagram of the built-in antenna according to the second embodiment of the present invention as an NFC antenna. As shown in FIG. 9, when the user uses NFC near field communication for consumption, the baseband control chip controls the switch control network to single-pole and single-throw. The switch connects 4 and 7, so that the NFC and FM share the antenna signal feed point 1 and one of the two paths of the NFC differential signal; at the same time, the single-pole double-throw switches 3 and 5 are disconnected, 3 and 6 are connected, and the NFC and the FM are shared at this time. The antenna signal feed point 2 is connected to the other of the two paths of the NFC differential signal, and the NFC/FM shared antenna is used as the NFC antenna at the time of jt. When the mobile terminal is used for reading, the current through the antenna coil generates a magnetic flux, and the portion of the magnetic flux passes through the antenna coil of the tag, and a voltage is induced on the coil of the NFC tag to supply power to the NFC tag; When used as a card emulation, a voltage is induced through the antenna line, power is supplied to the NFC module of the mobile terminal, and data transfer between the card and the reader is completed. When the NFC and the FM shared antenna are used as the NFC antenna, the corresponding NFC antenna matching network is required to perform the impedance change between the antenna port and the subsequent EMC filtering network. FIG. 10 is a schematic circuit diagram of an NFC antenna matching network according to Embodiment 2 of the present invention. As shown in FIG. 10, the matching network is a differential RC network, and the network is generally an L-type network. Among them, in order to make the NFC antenna have an ideal quality factor (generally about 35), the R value can be calculated according to the corresponding formula. It is related to the impedance, inductance, and capacitance of the antenna itself, which in turn is related to the number of turns of the antenna. In general, the sense of the antenna body is generally not more than 3uH, the capacitance is generally not more than 30pF, and the resistance is generally not more than 8ohm. In order to suppress the NFC near field communication more reliable, it is necessary to suppress the harmonics of the NFC. 11 is a circuit diagram of an NFC EMC filter network according to Embodiment 2 of the present invention. As shown in FIG. 11, a differential L-type LC filter network can filter not only the i-waves other than 13.56 MHz but also the impedance. Transforming, to reduce the signal amplitude rise time after phase modulation, and correspondingly increase the NFC receive bandwidth. In summary, according to the embodiment of the present invention, the method of multiplexing the NFC and the FM antenna is adopted, and the number of antennas in the mobile terminal is reduced, and the hardware design of the mobile terminal is reduced, while maintaining the function of the mobile terminal unchanged. Complexity, improving the user experience. Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device so that they may be stored in the storage device by the computing device, or they may be separately fabricated into individual integrated circuit modules, or Multiple modules or steps are made into a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the scope of the present invention are intended to be included within the scope of the present invention.

Claims

Claim

1. A near-major wireless communication NFC dual-mode mobile terminal, including:

a built-in antenna, configured to receive a radio frequency signal of the FM FM transmitter to implement an FM function, and an NFC function between the reader or the tag by electromagnetic induction; and a control network configured to control the built-in antenna at the NFC Switching between the function and the FM function to implement sharing of the built-in antenna by the FM function and the NFC function.

The mobile terminal according to claim 1, wherein the mobile terminal further includes a matching network, where the matching network includes:

An FM matching unit configured to perform FM impedance matching according to physical properties of the built-in antenna, wherein the physical attribute includes an NFC ring winding manner of the built-in antenna and a length of the built-in antenna determined by an FM band resonance point ;

The NFC matching unit is configured to perform NFC-stage impedance matching according to the impedance of the built-in antenna to adjust the i-vibration point and the quality factor of the built-in antenna corresponding to different NFC ring winding modes.

The mobile terminal according to claim 2, wherein the FM matching unit is an LC or RC network; and the NFC matching unit is a differential RC network.

4. The mobile terminal according to claim 1, wherein the mobile terminal further comprises an FM processing network, and the FM processing network comprises:

a signal protection unit configured to suppress RF signals of the two communication systems of the mobile terminal by a multi-stage series-parallel LC resonant circuit; and/or

And a power amplifying unit configured to suppress link noise of the FM receiving system of the mobile terminal and to amplify the FM radio wave signal according to a control signal of the control network.

The mobile terminal according to claim 1, wherein the mobile terminal further comprises:

The NFC filter network is set to filter out higher harmonics outside the NFC frequency range.

The mobile terminal according to claim 5, wherein the NFC filtering network is an LC differential pair network, and the type of the network is one of the following: L type, T type, π type.

7. The mobile terminal according to claim 1, wherein the built-in antenna is an FM radio antenna for receiving a broadcast station of the mobile terminal and/or a China Mobile Multimedia Broadcast CMMB antenna.

The mobile terminal according to claim 1, wherein the position of the built-in antenna fixed to the mobile terminal is one of the following: around the battery, on the battery rear case, around the outer frame.

The mobile terminal according to any one of claims 1 to 8, wherein the internal antenna is a loop antenna made of a wire or a flexible wiring board FPC.

10. A communication method for a wireless communication NFC dual mode mobile terminal, comprising the following steps: when the FM FM function of the mobile terminal is required to be used, the mobile terminal indicates the mobile through its control network The built-in antenna of the terminal receives the radio frequency signal of the FM transmitting station;

When it is required to use the NFC function of the mobile terminal, the mobile terminal instructs the built-in antenna to perform short-range wireless communication with a reader or a tag through electromagnetic induction through the control network.