CN104113352A - Transformer with self interference signal offsetting function and ultrahigh frequency radio frequency identification device (RFID) receiver front end based on same - Google Patents
Transformer with self interference signal offsetting function and ultrahigh frequency radio frequency identification device (RFID) receiver front end based on same Download PDFInfo
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Abstract
The invention provides a transformer with a self interference signal offsetting function and an ultrahigh frequency radio frequency identification device (RFID) receiver front end based on the same. The transformer comprises a normal phase coupling coil, a reverse phase coupling coil and three ports. The receiver front end comprises a conversion switch, a low noise amplifier, the transformer, an active balun, a first mixer, a second mixer, a first outer filter, a second outer filer, a first trans-impedance amplifier, a second trans-impedance amplifier and a phase-locked loop. The conversion switch enables the receiver front end to be converted between a high gain working mode and a low gain working mode. The high gain working mode is that the conversion switch is connected with the low noise amplifier to enable signals to be transmitted to the active balun and a follow-up module through the low noise amplifier. The low gain working mode is that the conversion switch is connected with the transformer to enable the signals to be transmitted to the active balun and the follow-up module through the transformer. The two working modes are separated, in the low gain working mode, a self interference signal offsetting technology based on the transformer is adopted, and the problem of high power carrier signal leakage can be effectively solved.
Description
Technical field
The invention belongs to wireless telecommunications electronic system, be specifically related to a kind of the have transformer of counteracting self-interference signal function and the ultrahigh frequency RFID receiver front end based on this transformer.The present invention is especially applied to ultrahigh frequency radio frequency identification (RFID) reader system.
Background technology
Integrated circuit technique develop the rapid growth with application demand rapidly, make radio-frequency (RF) identification (RFID) technology obtain paying close attention to widely with industrial quarters in the field of study.With respect to automatic identification technologies such as traditional bar code, smart cards, REID has the features such as noncontact, low cost, remote, two-forty, large capacity, can obtain the information of identifying object more conveniently, in identification, item tracing, the field such as false proof, there is demand and application prospect widely.
Ultrahigh frequency RFID system is a passive half-duplex recognition system, read write line transmitting terminal produces and outside transmitting carrier signal and modulation signal, passive RF label reception carrier signal changes into energy for its power supply, the modulation signal back scattering of reception is returned to read write line receiving terminal simultaneously.According to EPC bis-generations agreement, in the communication of rfid system each time, read write line all will be launched carrier signal when receiving scattered signal provides energy for passive RF label.The reception of signal shares the same antenna with transmitting, the carrier signal (self-interference signal) of transmitting will certainly be leaked to receiving terminal.The signal returning due to passive label is the part being reflected during read write line transmits, and read write line transmitter and receiver is used same frequency.This characteristic frequently same and that simultaneously work makes the isolation between Receiver And Transmitter become very difficult.Circulator or directional coupler are used in transmitting-receiving isolation conventionally, and 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 cancellation function, can process the large-signal of leakage, avoid the saturated of receiver subsequent module.
General higher supply voltage (as 5V) or the less technique (as SiGe) of noise, noise and the linearity performance of assurance read write line receiver front end of adopting of commercial read write line chip on market.At list of references [1] (I.Kipnis, S.Chiu, M.Loyer, J.Carrigan, J.Rapp, P.Johansson, D.Westberg, and J.Johansson, " A900MHz UHF RFID reader transceiver IC, " in IEEE ISSCC Dig.Tech.Papers, Jan.2007, pp.214 – 215.) in, read write line is realized in 180nm-SiGe advanced technologies, receiver front end does not have to adopt take the traditional structure that low noise amplifier is the first order, but the active mixer that directly adopts Class-AB is input stage, its receiver front end has higher line degree.Although active mixer has very high flicker noise under zero intermediate frequency, the transistor noise of SiGe technique is less, also makes the noiseproof feature of receiver unaffected.Read write line receiving front-end design based on SiGe technique, has not only increased the power consumption of system, and has improved the cost of design.
At list of references [2] (P.B.Khannur, X.Chen, D.L.Yan, D.Shen, B.Zhao, M.K.Raja, Y.Wu, R.Sindunata, W.G.Yeoh, and R.Singh, " A universal UHF RFID reader IC in0.18-μ m CMOS technology, " IEEE J.Solid-State Circuits, vol.43, pp.1146 – 1154, May2008.) in, read write line is realized in 180nm-CMOS technique.In order to process leakage carrier wave, receiver front end has adopted π type resistor network attenuator on sheet, and the power of carrier signal is reduced, and has meanwhile also reduced the power of useful signal.On standard CMOS process, realize the design of receiver, reduced the cost of design, but it has sacrificed the sensitivity of receiver.
At list of references [3] (Le Ye, Huailin Liao, Fei Song, Jiang Chen, Chen Li, Jinshu Zhao, Ruiqiang Liu, Chuan Wang, Congyin Shi, Junhua Liu, Ru Huang, and Yangyuan Wang, " A Single-Chip CMOS UHF RFID Reader Transceiver for Chinese Mobile Applications, " IEEE J.Solid-State Circuits, vol.45, pp.1316 – 1329, JULY2010.) in, the structure of read write line and list of references [1] are similar, difference is all to have radio frequency amplifier on two paths of quadrature IQ.For convenient design, by passive Ba Lun, directly at the input of active mixer, be divided into IQ two-way.Adopt parasitic vertical NPN bipolar transistor as the switching tube of frequency mixer, reduced the impact of flicker noise on receiver noiseproof feature.But be subject to the restriction of supply voltage, this design can not be processed very large leakage 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, can process very large leakage carrier signal, do not affect the demodulation quality of useful signal.
On list of references [1] basis, Ying Pinjie company develops read write line chip R2000, has adopted a kind of self-interference to support except technology, as Fig. 1, has processed the problem of high-power carrier wave leakage, has 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 receiver front end based on this transformer, reduce the power of self-interference signal, avoid read write line receiver subsequent module to occur saturated compression, do not affect the demodulation quality of useful signal simultaneously.
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 wi coil and P1, P2, tri-ports of P3.Port P1 and port P2 are respectively the input of two coils, and port P3 is the output of two coils.Described positive coupling coil consists of L1 and L2, and coupling coefficient is K1, and insertion loss is less than 1dB, and 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 wi coil consists of L3 and L4, and coupling coefficient is K2, and insertion loss is less than 1dB, and one end of L3 connects P2, and the other end is connected to and holds, and 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 port match.
Technical scheme 2: a kind of ultrahigh frequency RFID receiver front end based on transformer self-interference signal cancellation technology, 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, phase-locked loop.Described change over switch is comprised of transistor MN1, MN2, MN3 and MN4, can make receiver front end change in high-gain and two mode of operations of low gain; Port T1 is input, port T2 is connected with output with the input of low noise amplifier respectively with port T3, and port T4 is connected with active Ba Lun, and its control signal is represented by HGM, this mode of operation is high-gain mode of operation (HGM, high gain mode); Port T5 is connected with P3 with the port P1 of transformer respectively with port T6, and control signal represents by LGM, and this mode of operation is low gain mode of operation (LGM, low gain mode).Described low noise amplifier has higher gain and lower noise factor, by the useful signal of reception and self-interference signal undistorted amplify, and improve the noiseproof feature of receiver front end; It is connected with the input of active Ba Lun.Described transformer is as technical scheme 1, port P2 receives the self-interference signal that read write line transmitter provides, and port P3 is connected with the input of active Ba Lun, 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 its output connects respectively the input of the first frequency mixer and the second frequency mixer.Described the first frequency mixer and the second frequency mixer are the passive frequency mixer with low flash noise, by useful signal and the unmatched self-interference signal down-conversion of possibility, useful signal is transformed into zero intermediate frequency, and self-interference signal frequency and local frequency are with frequently, after mixing, it becomes direct current, and by first outer filter and second outer filter filtering self-interference direct current signal.Described the first trans-impedance amplifier and the second trans-impedance amplifier change into voltage signal by the useful current signal of prime, for follow-up intermediate frequency and digital module, process.Described phase-locked loop provides the local oscillation signal of pair of orthogonal for receiver front end.
The principle of the technology of the present invention:
According to EPC Gen-2Protocol, ultrahigh frequency radio frequency identification (RFID) reader need to have LBT (Listen before Talk) and two kinds of patterns of Talk.For compatibility standard agreement, the present invention realizes the switching of high-gain and two kinds of mode of operations of low gain by changing the control voltage of change over switch.Under LBT pattern, whether read write line is monitored some channel and by other read write lines, is taken, read write line is not launched carrier signal, the signal of its reception is very faint, this just requires read write line receiver front end to have higher gain and lower noise factor, now change over switch is switched to high-gain mode of operation.Under Talk pattern, read write line receiving terminal receives the modulation signal that passive RF label scattering is returned, and receives the carrier signal that transmitting terminal is coupled to receiving terminal simultaneously.The power of self-interference signal, much larger than the power of useful signal, is greater than 0dBm conventionally.This just requires read write line receiver front end to have the higher linearity or has the ability of revealing large-signal of processing.Now receiver front end is switched to low gain mode of operation by change over switch.
Under LBT mode of operation, change over switch switches to low noise amplifier.The gain of supposing low noise amplifier is G1, and noise factor is NF1, and the gain of subsequent module is G2, and noise factor is NF2.The noise factor NF of receiver front end calculates according to Friis formula so:
According to above formula, know, enough high when the gain of low noise amplifier, when noise factor is enough low, the noise factor of receiver front end 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.
S
sen＝-174+NF+10logBW+CNR
min
Under Talk mode of operation, change over switch switches to transformer.On the one hand, the port P1 of transformer receives and contains the modulation signal of revealing carrier wave, and 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 differential current signal, drives passive frequency mixer, then be converted into voltage signal through trans-impedance amplifier from current field.Because the input impedance of trans-impedance amplifier is very little, approximately there are several ohm and tens ohm, the voltage signal of input is very little, can improve the linearity of receiver front end, and this is also by transformer, may not to be completely eliminated the saturated compression that causes front-end circuit for fear of revealing carrier wave.
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 gain, and under low gain mode of operation, employing, based on transformer self-interference signal cancellation technology, can effectively be processed the problem of high-power leakage carrier signal.The present invention can be applied to the circuit design based on standard CMOS process, does not need to use advanced SiGe technique, does not affect under the demodulation quality of read write line reception signal in assurance, has reduced the cost of chip.
Accompanying drawing explanation
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.
Embodiment
Referring to accompanying drawing, describe the specific embodiment of the present invention in detail.
As shown in Figures 2 and 3, ultrahigh frequency RFID receiver front end of the present invention comprises 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 filter 8, the first trans-impedance amplifier 9, the second trans-impedance amplifier 10, phase-locked loop 11.Receiver front end operating frequency, within the scope of 840MHz～960MHz, realizes at standard CMOS process.
In Fig. 2, when ultrahigh frequency reader-writer is worked, need to open LBT mode of operation, whether occupiedly detect a certain channel, now receive signal and only have useful signal f (t).After finding idle channel, read write line could be launched modulation signal and carrier signal.Under LBT mode of operation, change over switch 1 is connected to low noise amplifier 2, and low noise amplifier 2 has the feature of high-gain and low-noise factor, and it can improve the noiseproof feature of receiver front end.Signal by low noise amplifier 2 undistorted amplify after, be input to active Ba Lun 4.Active Ba Lun 4 is converted into differential signal by one-channel signal, offers the first frequency mixer 5 and second frequency mixer 6 of next stage.Differential signal amplitude difference and the phase difference of active Ba Lun 4 are enough little, and guarantee does not affect the quality that receives signal.The first frequency mixer 5 and the second frequency mixer 6 adopt two balanced passive mixers of difference form, and gain is directly provided by 2/ π, compares and single balanced passive mixers, although gain does not change, it can eliminate local oscillator end to the feedthrough of output.In addition, passive frequency mixer also can be avoided the impact of active mixer low frequency flicker noise.Signal after down-conversion is current signal, through first outer filter 7 and first outer filter 8, input at the first trans-impedance amplifier 9 and the second trans-impedance amplifier 10 is converted to voltage signal respectively, and last output voltage offers other follow-up ifd module.Phase-locked loop 11 provides the local oscillation signal of pair of orthogonal for double balanced mixer.Under LBT mode of operation, realized the receiver front end performance of high-gain and low-noise factor.
In Fig. 3, when 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 1 is 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 realized and subtracted each other function at port P3 place through coil coupling.Its output signal still needs active Ba Lun 4, the first frequency mixer 5 and the second frequency mixer 6, and 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 to come by directional coupler or the circulator leakage of read write line chip, so self-interference signal and the same frequency of local oscillation signal.First outer filter 7 and second outer filter 8 are by the filtering of self-interference DC terms.
In Fig. 4, transformer consists of positive coupling coil 12 and coupled in reverse wi coil 13 and P1, P2, tri-ports of P3.Described positive coupling coil 12 consists of L1 and L2, and coupling coefficient is K1, and insertion loss is less than 1dB, and 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 wi coil 13 consists of L3 and L4, and coupling coefficient is K2, and insertion loss is less than 1dB, and one end of L3 connects P2, and the other end is connected to and holds, and 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 port match.
In Fig. 5, the change over switch of receiver front end is a kind of mature technology, can have different ways of realization, only adopts N-type transistor to illustrate here.Change over switch is comprised of transistor MN1, MN2, MN3 and MN4, can make receiver front end change in high-gain and two mode of operations of low gain; Port T1 is input, and port T2 is connected with output with the input of low noise amplifier respectively with port T3, and port T4 is connected with active Ba Lun, and its control signal represents by HGM, and this mode of operation is high-gain mode of operation (HGM); Port T5 is connected with P3 with the port P1 of transformer respectively with port T6, and 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 embodiment of the present invention, but protection scope of the present invention is not limited to this.As long as realize the receiver front end of signal cancellation function by transformer, 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, comprise positive coupling coil and coupled in reverse wi coil and P1, P2, tri-ports of P3, port P1 and port P2 are respectively the input of two coils, port P3 is the output of two coils, described positive coupling coil consists of L1 and L2, and coupling coefficient is K1, and insertion loss is less than 1dB, one end of L1 connects P1, 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 consists of L3 and L4, and coupling coefficient is K2, and insertion loss is less than 1dB, one end of L3 connects P2, and the other end is connected to and holds, and L4 one end is connected to and holds, the other end is connected with L2, and three port Impedance of transformer are 50 ohm, are convenient to port match.
2. the ultrahigh frequency RFID receiver front end based on transformer self-interference signal cancellation technology, it is characterized in that, comprise 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, phase-locked loop; Described change over switch can make receiver front end change in high-gain and two mode of operations of low gain, and the mode of operation that is connected to the input of low noise amplifier is high-gain 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 amplifier has higher gain and lower noise factor, by the useful signal of reception undistorted amplify, and improve the noiseproof feature of receiver front end; It is connected with the input of active Ba Lun; Described transformer is the transformer of offsetting self-interference signal function that has claimed in claim 1, port P2 receives the self-interference signal that read write line transmitter provides, port P3 is connected with the input of active Ba Lun, 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 its output connects respectively the input of the first frequency mixer and the second frequency mixer; Described the first frequency mixer and the second frequency mixer are the passive frequency mixer with low flash noise, by useful signal and the unmatched self-interference signal down-conversion of possibility, useful signal is transformed into zero intermediate frequency, and self-interference signal frequency and local frequency are with frequently, after mixing, it becomes direct current, and by first outer filter and second outer filter filtering self-interference direct current signal; Described the first trans-impedance amplifier and the second trans-impedance amplifier change into voltage signal by the useful current signal of prime, for follow-up intermediate frequency and digital module, process.Described phase-locked 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 |
| CN104506209A (en) * | 2014-12-15 | 2015-04-08 | 北京邮电大学 | Method and system for eliminating full duplex self-interference signals based on coupling line tight coupler |
| CN107547147B (en) * | 2016-06-29 | 2021-04-13 | 英飞凌科技股份有限公司 | Signal detector apparatus and method and corresponding system |
| CN107547147A (en) * | 2016-06-29 | 2018-01-05 | 英飞凌科技股份有限公司 | Signal detector apparatus and method |
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| CN106339732A (en) * | 2016-08-23 | 2017-01-18 | 池州睿成微电子有限公司 | UHF RFID reader-writer receiver |
| CN106778413A (en) * | 2016-12-05 | 2017-05-31 | 中国科学技术大学 | A kind of integrated simulation self-interference cancellation circuit for being applied to ultrahigh frequency RFID |
| 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 |
| CN106599754A (en) * | 2017-01-16 | 2017-04-26 | 深圳市傲科微创有限公司 | LID reader-writer and transresistance amplifier circuit thereof |
| 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 |
| CN107229886A (en) * | 2017-06-26 | 2017-10-03 | 深圳市远望谷信息技术股份有限公司 | The method and device of dynamic self-interference in a kind of elimination RFID reader |
| CN108512559A (en) * | 2018-01-18 | 2018-09-07 | 加特兰微电子科技(上海)有限公司 | Transformer, RF Receiving Device and its control method |
| 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 |
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