CN104113352B - Have and offset the transformer of self-interference signal function and the ultrahigh frequency RFID receiver front end based on this transformer - Google Patents
Have and offset the transformer of self-interference signal function and the ultrahigh frequency RFID receiver front end based on this transformer Download PDFInfo
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Abstract
The invention provides a kind of the have transformer of counteracting self-interference signal function and the ultrahigh frequency RFID receiver front end based on this transformer, transformer comprises positive coupling coil and coupled in reverse wi coil and three ports; Receiver front end comprises change-over switch, low-noise amplifier, transformer, active Ba Lun, the first frequency mixer, the second frequency mixer, first outer filter, second outer filter, the first trans-impedance amplifier, the second trans-impedance amplifier, phaselocked loop. Change-over switch makes receiver front end change in high-gain and low gain mode of operation; High-gain mode of operation is that change-over switch is connected to low-noise amplifier, makes signal pass to active Ba Lun and subsequent module through low-noise amplifier; Low gain mode of operation is that change-over switch is connected to transformer, makes signal pass to active Ba Lun and subsequent module through transformer. The present invention not only separates two mode of operations, and under low gain mode of operation, adopts based on transformer self-interference signal cancellation technology, effectively processes the problem of high-power leakage carrier signal.
Description
Technical field
The invention belongs to wireless telecommunications electronic system, be specifically related to a kind of have offset the transformer of self-interference signal function and based onThe ultrahigh frequency RFID receiver front end of this transformer. The present invention is especially applied to ultrahigh frequency radio frequency identification (RFID) reader system.
Background technology
Developing rapidly and the rapid growth of application demand of integrated circuit technique, makes RF identification (RFID) technology in the field of studyObtain paying close attention to widely with industrial quarters. With respect to traditional automatic identification technology such as bar code, smart card, REIDThere is the features such as noncontact, low cost, remote, two-forty, large capacity, can obtain identifying object more convenientlyInformation, there is demand and application prospect widely in identification, item tracing, the field such as false proof.
Ultrahigh frequency RFID system is a passive half-duplex recognition system, and read write line transmitting terminal produces and outwards launches carrier wave and believeNumber and modulation signal, passive RF label reception carrier signal change into energy for its power supply, simultaneously by receive modulation signal afterTo being scattered back read write line receiving terminal. According to EPC bis-generations agreement, in rfid system communication each time, read write line all will connectReceive and launch carrier signal when scattered signal and provide energy for passive RF label. The reception of signal shares the same antenna, gesture with transmittingThe carrier signal (self-interference signal) of transmitting must be leaked to receiving terminal. The signal returning due to passive label is that read write line is sent outPenetrate the part being reflected in signal, read write line transmitter and receiver uses same frequency. This with frequently and work simultaneouslyCharacteristic makes the isolation between Receiver And Transmitter become very difficult. Transmitting-receiving isolation is used circulator or directional coupler conventionally,Its leakage signal power can be greater than 0dBm conventionally. Therefore require read write line receiving front-end to there is the very high linearity or signal cancellationFunction, can process the large-signal of leakage, avoids the saturated of receiver subsequent module.
Commercial read write line chip on market is general adopt higher supply voltage (as 5V) or the less technique of noise (asSiGe), ensure noise and the linearity performance of read write line receiver front end. At bibliography [1] (I.Kipnis, S.Chiu, M.Loyer,J.Carrigan,J.Rapp,P.Johansson,D.Westberg,andJ.Johansson,“A900MHzUHFRFIDReadertransceiverIC, " inIEEEISSCCDig.Tech.Papers, Jan.2007, pp.214 – 215.) in, read write line existsIn 180nm-SiGe advanced technologies, realize, receiver front end does not adopt the traditional structure taking low-noise amplifier as the first order,But the active mixer that directly adopts Class-AB is input stage, its receiver front end has higher line degree. Although activeFrequency mixer has very high flicker noise under zero intermediate frequency, but the transistor noise of SiGe technique is less, also makes receiverNoiseproof feature unaffected. Read write line receiving front-end based on SiGe technique designs, and has not only increased the power consumption of system, andAnd improve the cost of design.
At bibliography [2] (P.B.Khannur, X.Chen, D.L.Yan, D.Shen, B.Zhao, M.K.Raja, Y.Wu, R.Sindunata,W.G.Yeoh,andR.Singh,“AuniversalUHFRFIDreaderICin0.18-μmCMOSTechnology, " IEEEJ.Solid-StateCircuits, vol.43, pp.1146 – 1154, May2008.) in, read write line existsIn 180nm-CMOS technique, realize. In order to process leakage carrier wave, receiver front end has adopted π type resistor network on sheet to declineSubtract device, the power of carrier signal is reduced, meanwhile also reduced the power of useful signal. On standard CMOS processRealize the design of receiver, reduced the cost of design, but it has sacrificed the sensitivity of receiver.
At bibliography [3] (LeYe, HuailinLiao, FeiSong, JiangChen, ChenLi, JinshuZhao, RuiqiangLiu,ChuanWang,CongyinShi,JunhuaLiu,RuHuang,andYangyuanWang,“ASingle-ChipCMOSUHFRFIDReaderTransceiverforChineseMobileApplications,”IEEEJ.Solid-StateCircuits, vol.45, pp.1316 – 1329, JULY2010.) in, the structure of read write line and bibliography [1] are similar, differencePart is all to have radio frequency amplifier on two paths of orthogonal IQ. For convenient design, directly mix active by passive Ba LunFrequently the input of device is divided into IQ two-way. Adopt the switching tube of parasitic vertical NPN bipolar transistor as frequency mixer, reducedThe impact of flicker noise on receiver noiseproof feature. But be subject to the restriction of supply voltage, this design can not be processed very largeReveal carrier signal.
Therefore, need a kind of high performance receiver front end, in the situation that not being subject to supply voltage and advanced technologies restriction, canProcess very large leakage carrier signal, do not affect the demodulation quality of useful signal.
On bibliography [1] basis, Ying Pinjie company develops read write line chip R2000, has adopted a kind of self-interference to supportExcept technology, as Fig. 1, process the problem of high-power carrier wave leakage, reduced the requirement to the receiver front end linearity simultaneously.
Summary of the invention
The invention provides a kind of the have transformer of counteracting self-interference signal function and the ultrahigh frequency RFID reception based on this transformerMachine front end, reduces the power of self-interference signal, avoids read write line receiver subsequent module to occur saturated compression, does not affect and has simultaneouslyBy the demodulation quality of signal.
The technology of the present invention solution:
Technical scheme 1: a kind of transformer 3 with counteracting self-interference signal function, comprises positive coupling coil and coupled in reverse wiCoil and P1, P2, tri-ports of P3. Port P1 and port P2 are respectively the input of two coils, and port P3 isThe output of two coils. Described positive coupling coil is made up of L1 and L2, and the coefficient of coup is K1, and insertion loss is less than 1dB,One end of L1 connects P1, and the other end is connected to and holds, and one end of L2 connects P3, and the other end connects L4; Described coupled in reverse wiCoil is made up of L3 and L4, and the coefficient of coup is K2, and insertion loss is less than 1dB, and one end of L3 connects P2, and the other end connectsTo ground end, L4 one end is connected to and holds, and the other end is connected with L2. Three port Impedance of transformer are 50 ohm, justIn port match.
Technical scheme 2: a kind of ultrahigh frequency RFID receiver front end based on transformer self-interference signal cancellation technology, comprises and turningChange switch, low-noise amplifier, transformer, active Ba Lun, the first frequency mixer, the second frequency mixer, first outer filter,Second outer filter, the first trans-impedance amplifier, the second trans-impedance amplifier, phaselocked loop. Described change-over switch by transistor MN1,MN2, MN3 and MN4 composition, can make receiver front end change in high-gain and two mode of operations of low gain; EndMouth T1 is input, and port T2 is connected with input and the output of low-noise amplifier respectively with port T3, port T4Be connected with active Ba Lun, its control signal represents by HGM, and this mode of operation is high-gain mode of operation (HGM, highgainMode); Port T5 is connected with port P1 and the P3 of transformer respectively with port T6, and control signal represents by LGM, thisMode of operation is low gain mode of operation (LGM, lowgainmode). Described low-noise amplifier have higher gain andLower noise coefficient, by the useful signal of reception and self-interference signal undistorted amplify, and improve the noise of receiver front endPerformance; It is connected with the input of active Ba Lun. Described transformer is as technical scheme 1, and port P2 receives read write line emitterThe self-interference signal providing, port P3 is connected with the input of active Ba Lun, and the signal and the port P2 that receive as port P1 connectThe signal amplitude of receiving is identical, and when phase place is identical, port P3 is output as zero. It is poor that described active Ba Lun converts one-channel signal toSub-signal, its output connects respectively the input of the first frequency mixer and the second frequency mixer. Described the first frequency mixer and the second mixingDevice is the passive frequency mixer with low flash noise, by useful signal and the unmatched self-interference signal down coversion of possibility, hasBe transformed into zero intermediate frequency with signal, and self-interference signal frequency and local frequency be with frequently, after mixing, it becomes direct current, and by theA slice outer filter and second outer filter filtering self-interference direct current signal. Described the first trans-impedance amplifier and second amplifies across resistanceUseful prime current signal is changed into voltage signal by device, for follow-up intermediate frequency and digital module processing. Described phaselocked loop is receiverFront end provides the local oscillation signal of pair of orthogonal.
The principle of the technology of the present invention:
According to EPCGen-2Protocol, ultrahigh frequency radio frequency identification (RFID) reader need to have LBT (ListenbeforeTalk) and TalkTwo kinds of patterns. For compatibility standard agreement, the present invention realizes high-gain and low gain two by the control voltage that changes change-over switchPlant the switching of mode of operation. Under LBT pattern, whether read write line is monitored some channel and is taken by other read write lines, read write lineDo not launch carrier signal, the signal of its reception is very faint, and this just requires read write line receiver front end to have higher gain andLow noise coefficient, is now switched to change-over switch high-gain mode of operation. Under Talk pattern, read write line receiving terminal receivesThe modulation signal that passive RF label scattering is returned, receives transmitting terminal simultaneously and is coupled to the carrier signal of receiving terminal. Self-interference signalPower much larger than the power of useful signal, be conventionally greater than 0dBm. This just requires read write line receiver front end to have higher lineProperty degree or there is the ability of large-signal revealed of processing. Now change-over switch is switched to low gain mode of operation by receiver front end.
Under LBT mode of operation, change-over switch switches to low-noise amplifier. The gain of supposing low-noise amplifier is G1,Noise coefficient is NF1, and the gain of subsequent module is G2, and noise coefficient is NF2. The noise coefficient NF of receiver front end soCalculate according to Friis formula:
Know according to above formula, when the gain of low-noise amplifier enough high, when noise coefficient is enough low, the noise system of receiver front endNumber will be lower, and according to following formula, the sensitivity of receiver front end will be higher, and therefore, receiver can have the function of monitoring.
Ssen＝-174+NF+10logBW+CNRmin
Under Talk mode of operation, change-over switch switches to transformer. On the one hand, the port P1 of transformer receives and contains leakageThe modulation signal of carrier wave, port P2 receives and offsets the erasure signal of revealing carrier wave, and both realize the algorithm subtracting each other at port P3,Finally export useful modulation signal. On the other hand, active Ba Lun amplifies single channel input voltage signal and is converted into difference currentSignal, drives passive frequency mixer from current field, then is converted into voltage signal through trans-impedance amplifier. Defeated due to trans-impedance amplifierEnter impedance very little, approximately have several ohm and tens ohm, the voltage signal of input is very little, can improve the line of receiver front endProperty degree, this be also for fear of reveal carrier wave may not be completely eliminated the saturated compression that causes front-end circuit by transformer.
The present invention's advantage is compared with prior art: the present invention not only separates high-gain and two mode of operations of low gainCome, and under low gain mode of operation, adopt based on transformer self-interference signal cancellation technology, can effectively process high-powerReveal the problem of carrier signal. The present invention can be applied to the circuit design based on standard CMOS process, does not need to use firstThe SiGe technique of entering, does not affect in guarantee under the demodulation quality of read write line reception signal, has reduced the cost of chip.
Brief description of the drawings
Fig. 1 supports the ultrahigh frequency RFID receiver front end except technology based on self-interference in prior art;
Fig. 2 is the way of realization of the ultrahigh frequency RFID receiver front end high-gain mode of operation that proposes of the present invention;
Fig. 3 is the way of realization of the ultrahigh frequency RFID receiver front end low gain mode of operation that proposes of the present invention;
Fig. 4 is the way of realization of transformer in the present invention;
Fig. 5 is the way of realization of change-over switch in the present invention.
Detailed description of the invention
Describe the specific embodiment of the present invention in detail referring to accompanying drawing.
As shown in Figures 2 and 3, ultrahigh frequency RFID receiver front end of the present invention comprise change-over switch 1, low-noise amplifier 2,Transformer 3, active Ba Lun 4, the first frequency mixer 5, the second frequency mixer 6, first outer filter 7, second outer filter8, the first trans-impedance amplifier 9, the second trans-impedance amplifier 10, phaselocked loop 11. Receiver front end operating frequency 840MHz～Within the scope of 960MHz, realize at standard CMOS process.
In Fig. 2, in the time that ultrahigh frequency reader-writer is worked, need to open LBT mode of operation, whether occupiedly detect a certain channelWith, now receive signal and only have useful signal f (t). Finding after idle channel, read write line could be launched modulation signal and carryRipple signal. Under LBT mode of operation, change-over switch 1 is connected to low-noise amplifier 2, and low-noise amplifier 2 has high increasingThe feature of benefit and low-noise factor, it can improve the noiseproof feature of receiver front end. Signal is undistorted by low-noise amplifier 2Ground is input to active Ba Lun 4 after amplifying. One-channel signal is converted into differential signal by active Ba Lun 4, offers of next stageOne frequency mixer 5 and the second frequency mixer 6. Differential signal amplitude difference and the phase difference of active Ba Lun 4 are enough little, and guarantee is notImpact receives the quality of signal. The first frequency mixer 5 and the second frequency mixer 6 adopt two balanced passive mixers of difference form, increaseBenefit is directly provided by 2/ π, compares and single balanced passive mixers, although gain does not change, it can eliminate local oscillator endTo the feedthrough of output. In addition, passive frequency mixer also can be avoided the impact of active mixer low frequency flicker noise. After down coversionSignal be current signal, through first outer filter 7 and first outer filter 8, respectively at the first trans-impedance amplifier 9Be converted to voltage signal with the input of the second trans-impedance amplifier 10, last output voltage offers other follow-up intermediate frequency mouldPiece. Phaselocked loop 11 provides the local oscillation signal of pair of orthogonal for double balanced mixer. Under LBT mode of operation, realize high increasingThe receiver front end performance of benefit and low-noise factor.
In Fig. 3, in the time that ultrahigh frequency reader-writer is read and write passive label, read write line need to be launched modulation signal and carrier signal.Now receive signal and both contained useful signal f (t), contain again self-interference signal s (t). Under Talk mode of operation, change-over switch 1Be connected to the port P1 of transformer 3. The port P2 of transformer 2 receives offseting signal s (t), and two paths of signals is through coil couplingRealize and subtract each other function at port P3 place. Its output signal still needs active Ba Lun 4, the first frequency mixer 5 and the second frequency mixer 6,Useful signal f (t) and the unmatched self-interference signal s (t) of possibility are down-converted to zero intermediate frequency. Because self-interference signal is by read-writeThe directional coupler of device chip or circulator are revealed and are come, and therefore self-interference signal and local oscillation signal are with frequently. First outer filter7 and second outer filter 8 by the filtering of self-interference DC terms.
In Fig. 4, transformer is by positive coupling coil 12 and coupled in reverse wi coil 13 and P1, P2, tri-port structures of P3Become. Described positive coupling coil 12 is made up of L1 and L2, and the coefficient of coup is K1, and insertion loss is less than 1dB, one of L1End connects P1, and the other end is connected to and holds, and one end of L2 connects P3, and the other end connects L4; Described coupled in reverse wi coil 13Be made up of L3 and L4, the coefficient of coup is K2, and insertion loss is less than 1dB, and one end of L3 connects P2, and the other end is connected to groundEnd, L4 one end is connected to and holds, and the other end is connected with L2. Three port Impedance of transformer are 50 ohm, are convenient to endMouth coupling.
In Fig. 5, the change-over switch of receiver front end is a kind of mature technology, can have different ways of realization, here onlyAdopt N-type transistor to illustrate. Change-over switch is made up of transistor MN1, MN2, MN3 and MN4, can make to connectReceipts machine front end is changed in high-gain and two mode of operations of low gain; Port T1 is input, port T2 and port T3Be connected with input and the output of low-noise amplifier respectively, port T4 is connected with active Ba Lun, and its control signal is by HGMRepresent, this mode of operation is high-gain mode of operation (HGM); Port T5 and port T6 respectively with the port P1 of transformerBe connected with P3, its control signal represents by LGM, and this mode of operation is low gain mode of operation (LGM).
Non-elaborated part of the present invention belongs to techniques well known. Be noted that and the foregoing is only preferably tool of the present inventionBody embodiment, but protection scope of the present invention is not limited to this. As long as realize the reception of signal cancellation function by transformerMachine front end, within all should being encompassed in protection scope of the present invention.
Claims (2)
1. one kind has the transformer (3) of offsetting self-interference signal function, it is characterized in that, comprises positive coupling coil and anti-Be coupled coil and P1, P2, tri-ports of P3, port P1 and port P2 are respectively the input of two coils, portP3 is the output of two coils, and described positive coupling coil is made up of L1 and L2, and the coefficient of coup is K1, and insertion loss is littleIn 1dB, one end of L1 connects P1, and the other end of L1 is connected to and holds, and one end of L2 connects P3, and the other end of L2 connectsL4; Described coupled in reverse wi coil is made up of L3 and L4, and the coefficient of coup is K2, and insertion loss is less than 1dB, and one end of L3 connectsMeet P2, the other end of L3 is connected to and holds, and one end of L4 is connected to and holds, and the other end of L4 is connected with L2, transformerThree port Impedance are 50 ohm, are convenient to port match.
2. the ultrahigh frequency RFID receiver front end based on transformer self-interference signal cancellation technology, is characterized in that, comprisesChange-over switch, low-noise amplifier, transformer, active Ba Lun, the first frequency mixer, the second frequency mixer, first outer filter,Second outer filter, the first trans-impedance amplifier, the second trans-impedance amplifier, phaselocked loop; Described change-over switch makes receiver front endChange in high-gain and two mode of operations of low gain, the mode of operation that is connected to the input of low-noise amplifier increases for highBenefit mode of operation; The mode of operation that is connected to the port P1 of transformer is low gain mode of operation; Described low noise amplification utensilThere are higher gain and lower noise coefficient, amplify undistorted the useful signal of reception, and improve making an uproar of receiver front endAcoustic performance; Described low-noise amplifier is connected with the input of active Ba Lun; Described transformer is claimed in claim 1ly to haveOffset the transformer of self-interference signal function, port P2 receives the self-interference signal that read write line emitter provides, port P3 with haveThe input of source Ba Lun is connected, and the signal receiving as port P1 is identical with the signal amplitude that port P2 receives, when phase place is identical,Port P3 is output as zero; Described active Ba Lun converts one-channel signal to differential signal, and described active Ba Lun output respectivelyConnect the input of the first frequency mixer and the second frequency mixer; The first frequency mixer connects first outer filter, first outer filterConnect the first trans-impedance amplifier; The second frequency mixer connects second outer filter, and second outer filter connects second and amplify across resistanceDevice; Described the first frequency mixer and the second frequency mixer are the passive frequency mixer with low flash noise, by useful signal and do not supportThe self-interference signal down coversion disappearing, useful signal is transformed into zero intermediate frequency, and self-interference signal frequency and local frequency are with frequently, through mixedFrequently after, it becomes direct current, and respectively by first outer filter and second outer filter filtering self-interference direct current signal; DescribedThe first trans-impedance amplifier and the second trans-impedance amplifier change into voltage signal by useful prime current signal respectively, for follow-up intermediate frequency andDigital module processing; Described phaselocked loop provides the local oscillation signal of pair of orthogonal for receiver front end.
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| CN104506209B (en) * | 2014-12-15 | 2017-02-22 | 北京邮电大学 | Method and system for eliminating full duplex self-interference signals based on coupling line tight coupler |
| US10034258B2 (en) * | 2016-06-29 | 2018-07-24 | Infineon Technologies Ag | Signal detector device and method |
| CN106168660A (en) | 2016-07-05 | 2016-11-30 | 合肥华凌股份有限公司 | Refrigerator and the positioner of refrigerator |
| CN106339732A (en) * | 2016-08-23 | 2017-01-18 | 池州睿成微电子有限公司 | UHF RFID reader-writer receiver |
| CN106778413B (en) * | 2016-12-05 | 2019-04-26 | 中国科学技术大学 | A kind of integrated simulation self-interference cancellation circuit applied to ultrahigh frequency RFID |
| CN106599754B (en) * | 2017-01-16 | 2023-08-11 | 深圳市傲科光电子有限公司 | LID reader-writer and transimpedance amplifying circuit thereof |
| CN107229886B (en) * | 2017-06-26 | 2020-05-19 | 深圳市远望谷信息技术股份有限公司 | Method and device for eliminating dynamic self-interference in RFID reader-writer |
| CN108512559B (en) * | 2018-01-18 | 2024-01-30 | 加特兰微电子科技(上海)有限公司 | Transformer, radio frequency receiving device and control method thereof |
| CN112949328A (en) * | 2019-12-11 | 2021-06-11 | 上海烨煊信息技术有限公司 | Industrial ultrahigh frequency RFID read-write device and RFID radio frequency identification system |
| CN118131137A (en) * | 2024-05-10 | 2024-06-04 | 中国电子科技集团公司第十四研究所 | Zero intermediate frequency circuit based on SFC technology |
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