WO2015176438A1 - 一种射频收发方法及系统 - Google Patents

一种射频收发方法及系统 Download PDF

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Publication number
WO2015176438A1
WO2015176438A1 PCT/CN2014/087122 CN2014087122W WO2015176438A1 WO 2015176438 A1 WO2015176438 A1 WO 2015176438A1 CN 2014087122 W CN2014087122 W CN 2014087122W WO 2015176438 A1 WO2015176438 A1 WO 2015176438A1
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radio frequency
transceiver system
switch
antenna
frequency transceiver
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PCT/CN2014/087122
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English (en)
French (fr)
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丁斐
张成赞
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中兴通讯股份有限公司
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Publication of WO2015176438A1 publication Critical patent/WO2015176438A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving

Definitions

  • the invention relates to a radio frequency transmitting and receiving method and system applicable to a mobile terminal.
  • LTE long-term evolution
  • 4G next-generation
  • Mobile terminal products for users such as Feature Phone/Smart Phone/Datacard/HotSpot, have been widely popularized and promoted.
  • the current fourth-generation mobile communication technology standard (4G) is the third-generation mobile communication technology standard (3G) long-term evolution (LTE) standard customized by the 3rd Generation Partnership Project (3GPP).
  • 3G third-generation mobile communication technology standard
  • LTE long-term evolution
  • the technical feature is the introduction of Orthogonal Frequency Division Multiplexing (OFDM) and Multiple-Input Multiple-Output (MIMO) antennas, which effectively increase the spectrum efficiency and data.
  • OFDM Orthogonal Frequency Division Multiplexing
  • MIMO Multiple-Input Multiple-Output
  • the transmission rate supports multiple bandwidth allocations, making spectrum allocation more flexible and system capacity and coverage significantly improved.
  • the LTE wireless network architecture is flatter, reduces system latency, reduces network construction costs and maintenance costs, and supports interoperability with other 3GPP systems.
  • the fourth generation mobile communication technology standard includes two branches: Time Division-Long Term Evolution (TD-LTE) and Frequency Division Duplexing-Long Term Evolution (FDD-LTE).
  • TD-LTE Time Division-Long Term Evolution
  • FDD-LTE Frequency Division Duplexing-Long Term Evolution
  • the uplink and downlink functions of the frequency division duplex long-term evolution (FDD-LTE) work in different pairs of symmetric frequency bands.
  • the uplink and downlink functions of TD-LTE share the same frequency band, and the uplink and downlink frame structures are adjusted according to actual needs of users in actual use. Proportioning, to improve the utilization of LTE network and system resources, with greater flexibility.
  • OTA over-the-air
  • TRP total radiant power
  • Total Isotropic total omnidirectional sensitivity
  • TRP total isotropic radiated power
  • TIS total omnidirectional sensitivity
  • the power amplifiers (PAs) used in mobile communication terminals are mostly monolithic integrated amplifiers, which integrate the input and output matching network, DC bias circuit and amplifier tube die into a small GaAs.
  • the chip on the substrate has the characteristics of small size, light weight, high reliability, low cost, and the like, and the user's redesign of the input and output matching network and the static working point can be eliminated, thereby saving design time.
  • the maximum output power of such PA is about 28 ⁇ 30dBm. Combined with the influence of 1dB compression point, the actual available output power of the power amplifier is about 27 ⁇ 29dBm, which is difficult to reach a higher level.
  • the traditional RF link design layout will be connected to a high power transmission filter (High Power Tx Filter) after the power amplifier, and then through the RF switch and RF test socket (RF). Coaxial Connector), then transmit the signal to the antenna contact reed.
  • the signal is sent by the RF transceiver chip, filtered by the filter and then enters the power amplifier, and then the amplified signal is transmitted to the antenna feed spring through the filter, the RF switch, and the RF test socket.
  • Insertion losses Insertion losses (Insertion Loss, IL) are introduced in the RF devices after the power amplifier.
  • these devices will introduce 1.8-3.3dB insertion loss into the RF link, and the insertion loss introduced by the RF switch. It is roughly 0.6-1.5dB, considering that the maximum available output power of the power amplifier (PA) is 27 ⁇ 29dBm, and the power reaching the antenna feeding shrapnel is only 23.7 ⁇ 27.2dBm, plus the radiation loss of the antenna, the actual OTA index. It is difficult to meet the requirements of some operators, and at the same time increase the difficulty of debugging the antenna, which is not conducive to improving the reliability of product design.
  • PA power amplifier
  • Embodiments of the present invention provide a radio frequency transceiver method and system, which can improve the transmission performance of a radio frequency link.
  • a radio frequency transceiver method including:
  • the power amplifier of the radio frequency transceiver system transmits the transmission signal to the antenna without insertion loss
  • the antenna form of the radio frequency transceiver system is transformed into a compensation type antenna to compensate the received signal performance of the radio frequency transceiver system.
  • a radio frequency switch is set in a receiving link of the radio frequency transceiver system, and the radio frequency transceiver system is switched to a transmitting mode or a receiving mode by controlling the radio frequency switch.
  • the radio frequency switch comprises a first radio frequency switch and a second radio frequency switch, and the first radio frequency switch and the second radio frequency switch are respectively connected to the transmitting link.
  • the radio frequency transceiver system is switched to the transmitting mode by switching both the first radio frequency switch and the second radio frequency switch to the floating end.
  • the radio frequency transceiver system is switched to the receiving mode by switching the first radio frequency switch to a receiving link and switching the second radio frequency switch to a ground terminal.
  • a radio frequency transceiver system including:
  • a baseband unit configured to switch the radio frequency transceiver system to a transmit mode or a receive mode
  • a power amplifier configured to transmit the transmitted signal that has undergone power amplification processing to the antenna without insertion loss when the radio frequency transceiver system is switched to the transmission mode
  • the antenna form is converted into a compensation type antenna to compensate the received signal performance of the radio frequency transceiver system.
  • the method further comprises:
  • a radio frequency switch disposed in a receiving link of the radio frequency transceiver system is configured to switch the radio frequency transceiver system to a transmitting mode or a receiving mode under the control of the baseband unit.
  • the radio frequency switch comprises a first radio frequency switch and a second radio frequency switch, and the first radio frequency switch and the second radio frequency switch are respectively connected to the transmitting link.
  • the baseband unit switches the radio frequency transceiver system to a transmitting mode by switching both the first radio frequency switch and the second radio frequency switch to a floating end.
  • the baseband unit switches the radio frequency transceiver system to a receiving mode by switching the first radio frequency switch to a receiving link and switching the second radio frequency switch to a ground end.
  • the invention avoids the insertion loss caused by setting the RF switch in the transmitting path, thereby improving the transmitting performance of the RF link, especially the RF transmitting power indicator.
  • FIG. 1 is a schematic block diagram of a method for improving radio frequency link transmission performance of a radio frequency transceiver system according to the present invention
  • FIG. 2 is a block diagram of a radio frequency transceiver system provided by the present invention.
  • FIG. 3 is a schematic diagram of a TD-LTE radio link layout scheme and a schematic diagram thereof according to an embodiment of the present invention
  • FIG. 4 is a schematic diagram of an example of antenna performance simulation of a radio frequency transceiver system in a transmitting mode according to an embodiment of the present invention
  • FIG. 5 is a schematic diagram of simulation results of antenna performance of a radio frequency transceiver system in a transmitting mode according to an embodiment of the present invention
  • FIG. 6 is a schematic diagram of an example of antenna performance simulation of a radio frequency transceiver system in a receiving mode according to an embodiment of the present invention
  • FIG. 7 is a schematic diagram of simulation results of antenna performance of a radio frequency transceiver system in a receiving mode according to an embodiment of the present invention.
  • FIG. 1 is a schematic block diagram of a first method for improving radio frequency link transmission performance of a radio frequency transceiver system according to the present invention. As shown in FIG. 1, the steps include:
  • Step S101 directly connect the output of the power amplifier of the radio frequency transceiver system to the antenna of the radio frequency transceiver system.
  • Step S102 When the radio frequency transceiver system switches to the transmission mode, the power amplifier of the radio frequency transceiver system transmits the transmission signal to the antenna without insertion loss.
  • the power amplifier of the radio frequency transceiver system transmits the transmission signal directly to the antenna, and the insertion loss introduced by the radio frequency switch does not exist in the transmission link, thereby effectively improving the quality of the transmission signal.
  • Step S103 When the radio frequency transceiver system switches to the receiving mode, convert the antenna form of the radio frequency transceiver system into a compensation type antenna to compensate the received signal performance of the radio frequency transceiver system.
  • a radio frequency switch is set in a receiving link of the radio frequency transceiver system, and the radio frequency transceiver system is switched to a transmitting mode or a receiving mode by controlling the radio frequency switch.
  • the radio frequency switch includes a first radio frequency switch and a second radio frequency switch, and the first radio frequency switch and the second radio frequency switch are respectively connected to the transmit link.
  • the radio frequency transceiver system is switched to the transmitting mode by switching both the first radio frequency switch and the second radio frequency switch to the floating end; by switching the first radio frequency switch to the receiving link and
  • the second RF switch is switched to the ground, and the RF transceiver system is switched to the receiving mode, thereby converting the antenna of the RF transceiver system into a compensation antenna.
  • FIG. 2 is a block diagram of a radio frequency transceiver system provided by the present invention, as shown in FIG. 2, including:
  • the baseband unit 15 is configured to switch the radio frequency transceiver system to a transmitting mode or a receiving mode;
  • the power amplifier 12 is configured to transmit the transmit signal that has undergone power amplification processing to the antenna 11 without insertion loss when the radio frequency transceiver system is switched to the transmit mode;
  • the antenna form is converted into a compensation type antenna to compensate the received signal performance of the radio frequency transceiver system.
  • the system also includes a radio frequency switch disposed in a receive link of the radio frequency transceiver system, configured to switch the radio frequency transceiver system to a transmit mode or a receive mode under control of the baseband unit.
  • the radio frequency switch includes a first radio frequency switch and a second radio frequency switch, and the first radio frequency switch and the second radio frequency switch are respectively connected to the transmitting link.
  • the baseband unit 15 switches the radio frequency transceiver system to a transmission mode or a reception mode by controlling the first radio frequency switch 13 and the second radio frequency switch 14.
  • the baseband unit 15 switches the radio frequency transceiver system to a transmitting mode by switching both the first radio frequency switch 13 and the second radio frequency switch 14 to a floating end; by switching the first radio frequency switch 13
  • the radio frequency transceiver system is switched to the receiving mode by going to the receiving link and switching the second radio frequency switch 14 to the ground.
  • the above RF link can be used for wireless communication products such as a Feature Phone/Smart Phone/Datacard/HotSpot.
  • the invention is applicable not only to TD-LTE, but also to 2G (GSM) and 3G (eg TDS-CDMA) systems.
  • GSM 2G
  • 3G eg TDS-CDMA
  • the invention is not affected by the form of the antenna and can be used in conjunction with a variety of mainstream terminal antenna forms.
  • a mobile terminal radio frequency transmitting system to which the present invention is applied includes a PCB board having completed patches, a radio frequency transceiver control chip (RFIC), a baseband chip (BBIC), a power amplifier (PA), a transmission filter (Tx Filter), A receiving filter (Rx Filter), a radio frequency switch (RF Switch), an RF Coaxial Connector (RF Coaxial Connector), a 50 Ohm resistor, and an antenna include these components, which are the basic components of the present invention, but are not limited thereto.
  • RFIC radio frequency transceiver control chip
  • BBIC baseband chip
  • PA power amplifier
  • Tx Filter transmission filter
  • Rx Filter A receiving filter
  • RF Switch radio frequency switch
  • RF Coaxial Connector RF Coaxial Connector
  • 50 Ohm resistor and an antenna
  • the receiving link and the transmitting link of the present invention are in two different working modes, and switching between the two modes may cause a change in the structure of the radio frequency link, thereby affecting the radiation performance of the terminal antenna.
  • the present invention introduces a new antenna supplement. Structure to accommodate changes in the structure of such RF links;
  • the mobile terminal designed by the invention has a radio frequency transmitting link sent by a radio frequency transceiver chip, filtered by a transmitting filter, and then amplified by a power amplifier, and the obtained high power signal is transmitted to the antenna feeding shrapnel, from the power amplifier to the antenna.
  • the antenna switch is omitted between the feeding shrapnel, which reduces the link insertion loss and effectively improves the RF output power of the transmitting link.
  • the mobile terminal designed by the present invention has a radio frequency receiving link received by the antenna, and a radio frequency switch connected to the transmitting link flows to the receiving filter, and the signal is filtered to enter the radio frequency transceiver chip; the other is coupled to the transmitting link.
  • the parallel switch is connected in series with a 50 Ohm resistor and grounded to form a grounding branch of the antenna in the RF link.
  • the length of the grounding branch is one quarter of the resonant wavelength of the antenna.
  • two RF switches connected in the output link of the power amplifier are controlled by the logic of the baseband chip, and the switching of the transmitting and receiving links is realized by controlling the two switches; in the connection state, the RF switch A For the 2T switch, one end of the output is connected to the receiving filter, and the other end is suspended; the RF switch B is also a 2T switch, one end of which is connected to a 50 Ohm resistor and grounded, and the other end is suspended.
  • the working mode is implemented as follows:
  • the baseband chip When testing the emission index, the baseband chip controls the RF switch A to switch to the floating end, and the RF switch B switches to the floating end.
  • the RF signal is directly sent to the RF test socket after being sent by the power amplifier, and the transmitting link works, and the emission index test can be performed. There is no insertion loss introduced by the switch, which effectively improves the quality of the RF transmission signal; when testing the reception index, the baseband signal controls the RF switch A to switch to the end connected to the receiving filter, and the RF switch B switches to the 50 Ohm series and grounded end.
  • the receiving link works, and the receiving indicator test can be performed. At this time, the structure of the receiving link changes, and the original antenna forms a new IFA (Inverted-F Antenna) antenna, which is equivalent. If an inductor is connected in parallel with the original antenna, if the proper grounding microstrip line length is selected or the antenna is debugged in advance, the negative effect of the grounding branch on the antenna will be offset or avoided.
  • corresponding matching circuits or other circuit components are arranged around the switch to adjust the impedance characteristics of the branch circuit in which the switch is located, so that the RF performance index of the transceiver is optimal, and the index is optimized.
  • the role of regulation is arranged around the switch to adjust the impedance characteristics of the branch circuit in which the switch is located, so that the RF performance index of the transceiver is optimal, and the index is optimized.
  • the conventional TD-LTE radio frequency layout scheme the detailed radio frequency layout scheme provided by the embodiment of the present invention, the antenna structure in the receiving link working mode of the present invention, and the board of the present invention are respectively applied to FIG.
  • the actual test method is described in detail in the form of a schematic diagram or a schematic diagram.
  • the baseband signal output from the baseband chip is modulated, the out-of-band clutter processing, and the power amplification processing are suppressed, and then transmitted to the antenna through the RF switch and the RF test socket, and radiated to the antenna. free space. It can be seen that the signal will be attenuated in the transmitting link due to the insertion loss caused by the RF switch, and the signal power is seriously reduced.
  • the present invention improves signal quality by eliminating RF switches in the transmit path.
  • FIG. 3 is a schematic diagram of a TD-LTE radio link layout scheme and a schematic diagram thereof according to an embodiment of the present invention.
  • a baseband chip (BBIC) 211 when the system transmits a transmit path, a baseband chip (BBIC) 211 outputs a baseband signal to a radio frequency transceiver chip (RFIC). 210.
  • the RF transceiver chip modulates the signal, and outputs a low-power RF signal to a transmit filter (Tx Filter) 209. After the filter suppresses the out-of-band clutter, the signal is transmitted to the power amplifier (PA) 208 for power. After amplification, the finally amplified signal is directly transmitted to the antenna 201 via the RF test socket 212, and radiated to the free space.
  • Tx Filter transmit filter
  • PA power amplifier
  • the RF switch 207 When the receiving path of the system works, the RF switch 207 is turned to the 50 ohm ground 205 side, and the antenna 201 captures the microwave signal from the free space, and is transmitted to the RF switch 202 through the RF test socket 212, and the signal is controlled by the switch.
  • the transmission to the receive filter (RX Filter) 203 performs out-of-band interference signal suppression, and the filtered signal is transmitted to a radio frequency transceiver chip (RFIC) 210 for demodulation processing, and finally transmitted to a baseband chip (BBIC) 211 for related information processing.
  • RFIC radio frequency transceiver chip
  • BBIC baseband chip
  • the RF transceiver working mode switching is implemented by controlling the logic control of the RF switches 202, 207.
  • the RF switch 202 switches to the side of the floating 204, the RF switch 207 switches to the side of the floating 206, and the two switching paths are open;
  • the RF switch ( The RF Switch) 202 is switched to the side of the receive filter (RX Filter) 203, and the RF switch 207 is switched to the 50 ohm ground 205 side.
  • the signal only needs to pass the RF switch in the receiving link, and is directly transmitted to the antenna 201 through the power amplifier (PA) 208 when the transmitting link is working, thereby eliminating the switch setting of the transmitting path and avoiding the RF switch.
  • the insertion loss is brought about to effectively improve the RF emission performance index.
  • the radio frequency transceiver system provided by the invention is not limited by the antenna type, and can be used in combination with various antenna forms widely used in current terminal products.
  • the antenna structure thereof changes due to the switching of the radio frequency link switch.
  • the simulation examples in FIG. 4 to FIG. 7 show the antenna in the transmitting and receiving working mode. Different working structures and explain how to eliminate the negative effects of structural changes on antenna performance.
  • FIG. 4 is a schematic diagram of an example of antenna performance simulation of a radio frequency transceiver system in a transmitting mode according to an embodiment of the present invention.
  • the main radiating structure of the antenna is a PCB antenna 301 with a resonant frequency of 2.4 GHz and a WiFi operating band.
  • the RF signal is directly transmitted to the PCB antenna 301 through the antenna feeding point 302, and the signal is radiated to the free space by the antenna 301; in the figure, 303 is a simulated analog bypass RF link, and 304 is a medium surface reference ground.
  • 301 is a PCB antenna with a working frequency of 2.4 Hz WiFi band
  • a gray substrate is a dielectric substrate having a dielectric constant of 4.4
  • 302 is an antenna feeding point.
  • FIG. 5 is a schematic diagram of simulation results of antenna performance of a radio frequency transceiver system in a transmitting mode according to an embodiment of the present invention.
  • the antenna model simulation example shows that the simulated S11 parameter and the reference radiation efficiency are 2.4.
  • the GHz WiFi operating band meets antenna performance requirements.
  • FIG. 6 is a schematic diagram of an example of antenna performance simulation of a radio frequency transceiver system in a receiving mode according to an embodiment of the present invention.
  • the antenna structure is different from the transmitting mode, and is affected by the grounding effect of the RF switch, and the main antenna is
  • the front end of the radiator 401 and the feeding point 402 is equivalently loaded with a radio frequency link grounding branch 403.
  • the front end of the grounding branch 403 may also include a suspended microstrip line 404, which is equivalent to paralleling a capacitive or inductive in the antenna matching network.
  • the specific attribute of the device depends on the position of the loading grounding branch, that is, the length of the grounding branch; it has been confirmed by practice that selecting a suitable grounding position, that is, the grounding position of the RF switch can avoid the short radiating section to the main radiator of the antenna The radiation performance of 401 is affected. Therefore, this additional structure of the antenna that is short-circuited to ground in the RF link can achieve zero impact on the antenna performance by optimizing the layout, and even better performance.
  • FIG. 7 is a schematic diagram of simulation results of antenna performance of a radio frequency transceiver system in a receiving mode according to an embodiment of the present invention.
  • the antenna model simulation example shows that the simulated S11 parameter and the reference radiation efficiency are compared.
  • the performance of the antenna in the transmit mode has not deteriorated, even better than the performance of the antenna in the transmit mode.
  • the present invention has the following technical effects:
  • the radio frequency transceiver system of the present invention comprises a new RF link design layout and an antenna form suitable for the design layout, which can reduce the insertion loss in the conventional RF transmission link, improve the RF transmission power, and improve the mobile terminal. TRP indicator.
  • the radio frequency transceiver method and system provided by the embodiments of the present invention have the following beneficial effects: the insertion loss in the conventional radio frequency transmission link can be reduced, the radio frequency transmission power can be improved, and the TRP index of the mobile terminal can be improved.

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Abstract

本发明公开了一种射频收发方法及系统，所述方法包括：将射频收发系统的功率放大器的输出直接接入射频收发系统的天线；当所述射频收发系统切换到发射模式时，所述射频收发系统的功率放大器将发射信号无插入损耗地传送给天线；当所述射频收发系统切换到接收模式时，将所述射频收发系统的天线形式变换成一种补偿型天线，补偿所述射频收发系统的接收信号性能。本发明具有改善射频链路发射性能的作用，尤其是提升射频发射功率。

Description

一种射频收发方法及系统 技术领域
本发明涉及一种可应用于移动终端的射频收发方法及系统。
背景技术
随着无线通信技术的高速发展和深入普及，用户已经能够深入感受到新技术具有的高速和便捷所带来的无线移动生活方式。当前，欧美日等发达国家和地区的长期演进(Long Term Evolution，LTE)网络已全面普及，中国、中亚、拉美等发展中国家和地区已经展开规模化网络建设。LTE作为新一代(4G)移动通信的标准技术，已经进入了实际应用和高速发展时期。面向用户使用的移动终端产品，如功能手机(Feature Phone)/智能手机(Smart Phone)/数据卡(Datacard)/便携WiFi热点(HotSpot)等产品得到了广泛的普及和推广。
目前的第四代移动通信技术标准(4G)是第三代合作伙伴计划组织(The 3rd Generation Partnership Project，3GPP)定制的第三代移动通信技术标准(3G)的长期演进(LTE)标准，其技术特点是引入了正交频分复用技术(Orthogonal Frequency Division Multiplexing，OFDM)和多输入多输出(Multiple-Input Multiple-Out-put，MIMO)天线等关键传输技术，有效增加了频谱效率和数据传输速率，同时支持多种带宽分配，使得频谱分配更加灵活，系统容量和覆盖显著提升。LTE无线网络架构更加扁平化，减小了系统时延，降低了建网成本和维护成本，并支持与其他3GPP系统的互操作。第四代移动通信技术标准包含两个分支：时分长期演进(Time Division-Long Term Evolution，TD-LTE)和频分双工长期演进(Frequency Division Duplexing-Long Term Evolution，FDD-LTE)。与频分双工长期演进(FDD-LTE)上行和下行功能工作在成对的对称频段不同，TD-LTE的上行和下行功能共用同一频段，在实际使用中根据用户实际需求调整上下行帧结构配比，提高LTE网络和系统资源的利用率，具有更强的灵活性。
在4G网络已经建成或者在建的国家和地区中，运营商对于移动终端的具体要求，除了参考3GPP定制标准规范外，还结合本国或地区的网络部署特点及实际用户需求等多方面因素，制定了相关的标准规范，其中很重要的一条就是移动终端的屏蔽暗室的空中下载(Over The Air，OTA)指标，包括总全向辐射功率(Total Radiated Power，TRP)和总全向灵敏度(Total Isotropic Sensitivity，TIS)，该指标直接关系到用户切身 体验，是运营商选择移动终端产品的重要的标准。在达到3GPP规定的传导功率和接收灵敏度的前提下，具有更高的总全向辐射功率(TRP)和总全向灵敏度(TIS)的产品更具竞争力，这意味着在离网络基站天线更远的地方，移动终端产品仍然能保持良好的上下行服务功能。对无线移动终端产品而言，搭载一个高辐射效率的终端天线，辅以一个低链路损耗的射频通路，无疑可以为用户提供更优质的用户体验。
然而，目前移动通信终端所使用的功率放大器(Power Amplifier，PA)大多为单片集成放大器，它是将输入输出匹配网络、直流偏置电路以及放大管管芯等度集成在一块很小的GaAs为衬底的芯片上面，具有体积小、重量轻、可靠性高、成本低等特点，同时可免去使用者对输入输出匹配网络和静态工作点的重设计，从而节省了设计时间。但受当前技术及工艺水平限制，此类PA最大输出功率约为28～30dBm，加之1dB压缩点的影响，功率放大器实际可用的输出功率约为27～29dBm，难以达到更高的水平。
与此同时，对于TD-LTE制式，传统的射频链路设计布局会在功率放大器后连接一个高功率发射滤波器(High Power Tx Filter)，再经过射频开关(RF Switch)及射频测试座(RF Coaxial Connector)，然后将信号传输到天线触点簧片。对于信号发射通路，信号由射频收发芯片发出，经过滤波器滤波后进入功率放大器，随后被放大的信号再经过滤波器、射频开关、射频测试座传输到天线馈电弹片。而功率放大器后的射频器件均会引入插入损耗(Insertion Loss，IL)，根据目前器件应用情况，这些器件大概会给射频链路中引入1.8～3.3dB的插入损耗，其中射频开关引入的插入损耗大致在0.6～1.5dB，考虑到功率放大器(PA)的最大可用输出功率为27～29dBm，而到达天线馈电弹片的功率仅为23.7～27.2dBm，加上天线的辐射损耗，实际的OTA指标难以满足某些运营商的要求，同时增大了天线的调试难度，不利于提高产品设计的可靠性。
发明内容
本发明实施例提供了一种射频收发方法及系统，能够改善射频链路的发射性能。
根据本发明的一个方面，提供了一种射频收发方法，包括：
将射频收发系统的功率放大器的输出直接接入射频收发系统的天线；
当所述射频收发系统切换到发射模式时，所述射频收发系统的功率放大器将发射信号无插入损耗地传送给天线；
当所述射频收发系统切换到接收模式时，将所述射频收发系统的天线形式变换成一种补偿型天线，补偿所述射频收发系统的接收信号性能。
优选地，在射频收发系统的接收链路中设置射频开关，通过控制所述射频开关，将所述射频收发系统切换到发射模式或接收模式。
优选地，所述射频开关包括第一射频开关和第二射频开关，所述第一射频开关和第二射频开关分别与发射链路并接。
优选地，通过把所述第一射频开关和第二射频开关均切换到悬空端，将所述射频收发系统切换到发射模式。
优选地，通过把所述第一射频开关切换到接收链路且把所述第二射频开关切换到接地端，将所述射频收发系统切换到接收模式。
根据本发明的另一方面，提供了一种射频收发系统，包括：
天线；
基带单元，设置为将所述射频收发系统切换到发射模式或接收模式；
功率放大器，设置为在所述射频收发系统切换到发射模式时，将已进行功率放大处理的发射信号无插入损耗地直接传送给天线；
其中，在所述射频收发系统切换到接收模式时，所述天线形式变换为一种补偿型天线，补偿所述射频收发系统的接收信号性能。
优选地，还包括：
设置在射频收发系统的接收链路中的射频开关，设置为在所述基带单元的控制下，将所述射频收发系统切换到发射模式或接收模式。
优选地，所述射频开关包括第一射频开关和第二射频开关，所述第一射频开关和第二射频开关分别与发射链路并接。
优选地，所述基带单元通过把所述第一射频开关和第二射频开关均切换到悬空端，将所述射频收发系统切换到发射模式。
优选地，所述基带单元通过把所述第一射频开关切换到接收链路且把所述第二射频开关切换到接地端，将所述射频收发系统切换到接收模式。
与现有技术相比较，本发明的有益效果在于：
本发明通过将功率放大器的输出直接接入天线，避免了在发射通路中设置射频开关带来的插入损耗，从而具有改善射频链路发射性能的作用，尤其是提升射频发射功率指标。
附图说明
图1是本发明提供的改善射频收发系统的射频链路发射性能的方法原理框图；
图2是本发明提供的射频收发系统框图；
图3是本发明实施例提供的TD-LTE射频链路布局方案及原理示意图；
图4是本发明实施例提供的射频收发系统在发射工作模式下的天线性能仿真实例示意图；
图5是本发明实施例提供的射频收发系统在发射工作模式下的天线性能仿真结果示意图；
图6是本发明实施例提供的射频收发系统在接收工作模式下的天线性能仿真实例示意图；
图7是本发明实施例提供的射频收发系统在接收工作模式下的天线性能仿真结果示意图。
具体实施方式
以下结合附图对本发明的优选实施例进行详细说明，应当理解，以下所说明的优选实施例仅用于说明和解释本发明，并不用于限定本发明。
图1是本发明提供的改善射频收发系统的射频链路发射性能的第一方法原理框图，如图1所示，步骤包括：
步骤S101：将射频收发系统的功率放大器的输出直接接入射频收发系统的天线。
步骤S102：当所述射频收发系统切换到发射模式时，所述射频收发系统的功率放大器将发射信号无插入损耗地传送给天线。
也就是说，所述射频收发系统的功率放大器将发射信号直接传送给天线，发射链路中不存在射频开关引入的插入损耗，从而有效地改善发射信号的质量。
步骤S103：当所述射频收发系统切换到接收模式时，将射频收发系统的天线形式变换成一种补偿型天线，补偿所述射频收发系统的接收信号性能。
进一步地，在射频收发系统的接收链路中设置射频开关，通过控制所述射频开关，将所述射频收发系统切换到发射模式或接收模式。其中，所述射频开关包括第一射频开关和第二射频开关，所述第一射频开关和第二射频开关分别与发射链路并接。具体地说，通过把所述第一射频开关和第二射频开关均切换到悬空端，将所述射频收发系统切换到发射模式；通过把所述第一射频开关切换到接收链路且把所述第二射频开关切换到接地端，将所述射频收发系统切换到接收模式，从而将射频收发系统的天线变换成一种补偿型天线。
图2是本发明提供的射频收发系统框图，如图2所示，包括：
天线11；
基带单元15，设置为将所述射频收发系统切换到发射模式或接收模式；
功率放大器12，设置为在所述射频收发系统切换到发射模式时，将已进行功率放大处理的所述发射信号无插入损耗地直接传送给天线11；
其中，在所述射频收发系统切换到接收模式时，所述天线形式变换成一种补偿型天线，补偿所述射频收发系统的接收信号性能。
所述系统还包括：设置在射频收发系统的接收链路中的射频开关，设置为在所述基带单元的控制下，将所述射频收发系统切换到发射模式或接收模式。进一步说，所述射频开关包括第一射频开关和第二射频开关，所述第一射频开关和第二射频开关分别与发射链路并接。所述基带单元15通过控制所述第一射频开关13和第二射频开关14，将所述射频收发系统切换到发射模式或接收模式。进一步地，所述基带单元15通过把所述第一射频开关13和第二射频开关14均切换到悬空端，将所述射频收发系统切换到发射模式；通过把所述第一射频开关13切换到接收链路且把所述第二射频开关14切换到接地端，将所述射频收发系统切换到接收模式。
上述射频链路可用于功能手机(Feature Phone)/智能手机(Smart Phone)/数据卡(Datacard)/便携WiFi热点(HotSpot)等无线通信产品。
本发明不仅适用于TD-LTE，同样也适用于2G制式(GSM)和3G(例如TDS-CDMA)制式。
本发明不受天线形式的影响，可与多种主流终端天线形式配合使用。
例如，应用本发明技术的移动终端射频发射系统，包括已完成贴片的PCB板、射频收发控制芯片(RFIC)、基带芯片(BBIC)、功率放大器(PA)、发射滤波器(Tx Filter)、接收滤波器(Rx Filter)、射频开关(RF Switch)、射频测试座(RF Coaxial Connector)、50Ohm电阻及天线，包含这些构成本发明的基本元器件，但不局限于这些元器件。
本发明接收链路与发射链路处于两种不同的工作模式下，两种模式间的切换会导致射频链路结构发生变化，进而影响终端天线辐射性能，本发明引入了一种新的天线补充结构来适应这种射频链路结构上的变化；
应用本发明设计的移动终端，其射频发射链路由射频收发芯片发出信号，经过发射滤波器滤波，再通过功率放大器放大后，得到的高功率信号传输到天线馈电弹片，从功率放大器到天线馈电弹片间省去了天线开关，降低了链路插入损耗，有效提升了发射链路射频输出功率。
应用本发明设计的移动终端，其射频接收链路由天线接收到耦合信号，经与发射链路并接的一个射频开关流向接收滤波器，信号滤波后进入射频收发芯片；另一与发射链路并接的开关串接50Ohm电阻后接地，构成射频链路中天线的一个接地枝节，接地枝节长度为天线谐振波长的四分之一。
本发明设计中在功率放大器输出链路中并接的两个射频开关均受基带芯片的逻辑控制，通过对两个开关的控制实现发射和接收链路工作的切换；连接状态上，射频开关A为2T开关，其输出一端连接到接收滤波器，另一端做悬空处理；射频开关B亦为2T开关，其输出一端连接一个50Ohm电阻并接地，另一端做悬空处理。
工作模式实现如下：
测试发射指标时，基带芯片控制射频开关A切换到悬空端，射频开关B切换到悬空端，射频信号由功率放大器发出后直接进入射频测试座，发射链路工作，可以进行发射指标测试，此时不存在开关引入的插入损耗，有效地改善了射频发射信号质量；测试接收指标时，基带信号控制射频开关A切换到与接收滤波器连接一端，射频开关B切换到与50Ohm串接并接地一端，接收链路工作，可以进行接收指标测试，此时接收链路结构发生变化，与原天线构成一个新的IFA(Inverted-F Antenna)天线，等效 于给原天线并联一个电感，若选择合适的接地微带线长或预先对天线进行调试，则会抵消或避免该接地枝节对天线造成的负面影响。
发射与接收状态的射频链路中，开关周边会设置相应的匹配电路或其他电路元件，用以调节开关所在枝节电路的阻抗特性，以使收发状态下射频性能指标达到最佳，起到指标优化调节的作用。
以下结合图3-图7分别对传统TD-LTE射频布局方案、本发明实施例所提供的详细射频布局方案、本发明中接收链路工作模式下的天线结构、以及例举应用本发明单板的实际测试方法以示意图或原理图的方式进行详细描述。
传统TD-LTE射频布局中，系统发射通路工作时，对基带芯片输出的基带信号进行调制处理、抑制带外杂波处理、功率放大处理后，经由射频开关和射频测试座传输到天线，辐射到自由空间。由此可知，信号在发射链路中将因射频开关带来的插入损耗而衰减，信号功率降低比较严重。本发明通过在发射通路中省去射频开关改善信号质量。
图3是本发明实施例提供的TD-LTE射频链路布局方案及原理示意图，如图3所示，该系统发射通路工作时，基带芯片(BBIC)211输出基带信号到射频收发芯片(RFIC)210，射频收发芯片对此信号进行调制处理，输出一个低功率的射频信号到发射滤波器(Tx Filter)209，经过滤波器抑制带外杂波后将信号传输至功率放大器(PA)208进行功率放大，最后被放大后的信号经射频测试座212直接传输到天线201，辐射到自由空间。
该系统接收通路工作时，射频开关(RF Switch)207打至50ohm接地205一侧，天线201从自由空间捕获微波信号，经过射频测试座212传输到射频开关(RF Switch)202，信号受开关控制传输到接收滤波器(RX Filter)203进行带外干扰信号抑制，滤波后的信号再传输到射频收发芯片(RFIC)210进行解调处理，最后传输到基带芯片(BBIC)211进行相关信息处理。
射频收发工作模式切换通过控制射频开关(RF Switch)202、207的逻辑控制实现。当发射通路工作时，射频开关(RF Switch)202切换至悬空204一侧，射频开关(RF Switch)207切换至悬空206一侧，及两条开关通路开路；当接收通路工作时，射频开关(RF Switch)202切换至接收滤波器(RX Filter)203一侧，射频开关(RF Switch)207切换至50ohm接地205一侧。
在图3系统中，信号仅在接收链路中需要经过射频开关，在发射链路工作时通过功率放大器(PA)208直接传输到天线201，省去了发射通路的开关设置，避免了射频开关带来的插入损耗，从而有效改善射频发射性能指标。
本发明所提供的射频收发系统不受天线类型限制，可与目前终端产品中广泛应用的多种天线形式配合使用。
本发明所提供的射频收发系统工作在发射和接收模式下时，其天线结构会因射频链路开关切换发生变化，图4至图7已仿真实例的形式给出了收发工作模式下，天线的不同工作结构，并解释了如何消除结构变化对天线性能造成的负面影响。
图4是本发明实施例提供的射频收发系统在发射工作模式下的天线性能仿真实例示意图，当系统工作在发射模式下时，天线主要辐射结构为谐振频率为2.4GHz WiFi工作频段的PCB天线301；此时，射频信号通过天线馈电点302直接传输到的PCB天线301，在由天线301将信号辐射到自由空间；图中303为仿真模拟的旁路射频链路，304为介质表面参考地设置，301为工作频率为2.4Hz WiFi频段的PCB天线，灰色衬底为介电常数为4.4的介质基板，302为天线馈电点。
图5是本发明实施例提供的射频收发系统在发射工作模式下的天线性能仿真结果示意图，当系统工作在发射模式下时，天线模型仿真实例结果显示，其仿真S11参数及参考辐射效率在2.4GHz WiFi工作频段满足天线性能要求。
图6是本发明实施例提供的射频收发系统在接收工作模式下的天线性能仿真实例示意图，当系统工作在接收模式下时，天线结构与发射模式不同，受到射频开关接地效果影响，天线的主要辐射体401及馈电点402前端等效加载了一个射频链路接地枝节403，接地枝节403前端还可能包括一段悬空的微带线404，这等同于在天线匹配网络中并联一个容性或感性器件，其具体属性取决于所述加载接地枝节的位置选取，亦即接地枝节的长度选取；经实践证实，选择合适的接地位置，即射频开关的接地位置可以避免该短路枝节对天线主要辐射体401的辐射性能影响，因此这种在射频链路中做短路接地的天线附加结构，可以通过优化布局实现对天线性能的零影响，甚至性能更好。
图7是本发明实施例提供的射频收发系统在接收工作模式下的天线性能仿真结果示意图，当系统工作在接收模式下时，天线模型仿真实例结果显示，其仿真S11参数及参考辐射效率相比于发射模式下的天线性能未见恶化，甚至优于发射模式下的天线性能。
综上所述，本发明具有以下技术效果：
本发明的射频收发系统，包含一种新的射频链路设计布局和一种适用于此设计布局的天线形式，能够降低传统射频发射链路中的插入损耗，提高射频发射功率，改善移动终端的TRP指标。
尽管上文对本发明进行了详细说明，但是本发明不限于此，本技术领域技术人员可以根据本发明的原理进行各种修改。因此，凡按照本发明原理所作的修改，都应当理解为落入本发明的保护范围。
工业实用性
如上所述，本发明实施例提供的一种射频收发方法及系统具有以下有益效果：能够降低传统射频发射链路中的插入损耗，提高射频发射功率，改善移动终端的TRP指标。

Claims (10)

  1. 一种射频收发方法，包括：
    将射频收发系统的功率放大器的输出直接接入射频收发系统的天线；
    当所述射频收发系统切换到发射模式时，所述射频收发系统的功率放大器将发射信号无插入损耗地传送给天线；
    当所述射频收发系统切换到接收模式时，将所述射频收发系统的天线形式变换成一种补偿型天线，补偿所述射频收发系统的接收信号性能。
  2. 根据权利要求1所述的方法，其中，在射频收发系统的接收链路中设置射频开关，通过控制所述射频开关，将所述射频收发系统切换到发射模式或接收模式。
  3. 根据权利要求2所述的方法，其中，所述射频开关包括第一射频开关和第二射频开关，所述第一射频开关和第二射频开关分别与发射链路并接。
  4. 根据权利要求3所述的方法，其中，通过把所述第一射频开关和第二射频开关均切换到悬空端，将所述射频收发系统切换到发射模式。
  5. 根据权利要求3所述的方法，其中，通过把所述第一射频开关切换到接收链路且把所述第二射频开关切换到接地端，将所述射频收发系统切换到接收模式。
  6. 一种射频收发系统，包括：
    天线；
    基带单元，设置为将所述射频收发系统切换到发射模式或接收模式；
    功率放大器，设置为在所述射频收发系统切换到发射模式时，将已进行功率放大处理的发射信号无插入损耗地直接传送给天线；
    其中，在所述射频收发系统切换到接收模式时，所述天线形式变换成一种补偿型天线，补偿所述射频收发系统的接收信号性能。
  7. 根据权利要求6所述的系统，其中，还包括：
    设置在射频收发系统的接收链路中的射频开关，设置为在所述基带单元的控制下，将所述射频收发系统切换到发射模式或接收模式。
  8. 根据权利要求7所述的系统，其中，所述射频开关包括第一射频开关和第二射频开关，所述第一射频开关和第二射频开关分别与发射链路并接。
  9. 根据权利要求8所述的系统，其中，所述基带单元通过把所述第一射频开关和第二射频开关均切换到悬空端，将所述射频收发系统切换到发射模式。
  10. 根据权利要求8所述的系统，其中，所述基带单元通过把所述第一射频开关切换到接收链路且把所述第二射频开关切换到接地端，将所述射频收发系统切换到接收模式。
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