CN101038616B - Limiting amplitude protection circuit used in non-contact IC card and radio frequency identification label - Google Patents
Limiting amplitude protection circuit used in non-contact IC card and radio frequency identification label Download PDFInfo
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- CN101038616B CN101038616B CN200610024814A CN200610024814A CN101038616B CN 101038616 B CN101038616 B CN 101038616B CN 200610024814 A CN200610024814 A CN 200610024814A CN 200610024814 A CN200610024814 A CN 200610024814A CN 101038616 B CN101038616 B CN 101038616B
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Abstract
The invention discloses an amplitude-limiting circuit used for the non-contact type IC card and the radio frequency identified tag chip comprising a bypass grounding transistor being paralleled to the rectified filter circuit of the chip radio frequency interface, a high voltage and a low voltage detection circuits for detecting the output signal from the rectified filter circuit, wherein the high voltage and low voltage circuit controls the opening of a charging current source for charging a capacitor and a discharging current source, the capacitor forms an amplitude-limiting signal by discharging, and the amplitude-limiting signal controls the opening of the bypass grounding transistor. The invention can implement amplitude-limiting function without affecting the posterior demodulation, voltage stabilization, and normal operation of the clock and the reset circuit.
Description
Technical field
The present invention relates to a kind of limiter protection circuit, particularly relate to a kind of limiter protection circuit that is used for non-contact IC card and radio frequency identification label chip.
Background technology
At present, non-contact IC card or the RFID tag generally used in industries such as subway, public transport, authentication, logistics just progressively replace traditional paper ticket, have application more and more widely.
The theory diagram of non-contact IC card or radio frequency identification label system, as shown in Figure 1, it comprises read write line and non-contact IC card or radio frequency identification label chip two parts.
The data load that read write line will send behind high frequency carrier to spatial emission, be in non-contact IC card or the RFID tag that read write line effectively launches in the field strength range and receive this signal by inside antenna, and therefrom obtain internal work voltage and clock, recover read write line and send data, and then carry out inter-process.
Data in non-contact IC card or the RFID tag by to the load-modulate of inside antenna to the spatial emission modulation signal.The read write line internal antenna is caught this modulation signal by the space, and by inner correlation demodulation circuit reduction non-contact IC card or data that RFID tag sends.So far, finish communicating by letter between read write line and non-contact IC card or the RFID tag.
Non-contact IC card or RFID tag need can both send instruction to read write line in read write line sends the certain limit of field intensity make correct response.Fig. 2 shows to finishing normal communication between read write line and non-contact IC card or the RFID tag, non-contact IC card or the needed functional circuit of RFID tag internal radio frequency interface.Wherein, the AC signal that rectification and limit filtration circuit are come the antenna end coupling on the one hand changes the direct current signal through limit filtration into, send into follow-up mu balanced circuit and demodulator circuit then and handle, by the mode of load-modulate logical signal d_in is launched on the other hand.Clock generation circuit generates synchronous clock clk.Mu balanced circuit produces burning voltage vdd and powers to internal circuit.Reset circuit produces reset signal por according to the height of voltage vdd.Demodulator circuit recovers read write line transmission data d_out by the detection to envelope signal.
As previously mentioned, non-contact IC card or RFID tag need and can respond the signal that read write line sends in certain field strength range, therefore the amplitude limiter circuit energy limited wanting non-contact IC card or RFID tag coupling to be obtained can not influence the operate as normal of subsequent demodulation, voltage stabilizing, clock, reset circuit simultaneously again within the acceptable scope.If but use the amplitude limiter circuit that does not have bandwidth control, will have influence on the envelope of modulation signal, thereby have influence on the operate as normal of subsequent demodulation, voltage stabilizing, reset circuit.
Summary of the invention
The technical problem to be solved in the present invention provides a kind of limiter protection circuit that is used for non-contact IC card and radio frequency identification label chip; the energy limited that it can be in certain field strength range will obtain by the antenna coupling can not influence the operate as normal of chip internal subsequent demodulation, voltage stabilizing, clock, reset circuit simultaneously in the acceptable scope.
For solving the problems of the technologies described above, the limiter protection circuit that the present invention is used for non-contact IC card and radio frequency identification label chip comprises: the bypass earial drainage transistor that is connected in parallel on described chip radio frequency interface current rectifying and wave filtering circuit, detect the high-voltage detecting circuit and the low-voltage testing circuit of described current rectifying and wave filtering circuit output signal, described high-voltage detecting circuit is by the charging of the transistorized switch control of control one PMOS charging current source to electric capacity; Described low-voltage testing circuit is controlled the discharge current source to described capacitance discharges by the switch of control one nmos pass transistor; Described capacitor charge and discharge forms the amplitude limit control signal, and this amplitude limit control signal is controlled the transistorized unlatching of described bypass earial drainage.
Further improve as the present invention, described limiter protection circuit also comprises the amplitude limit branch road that is connected in parallel on described current rectifying and wave filtering circuit, and the unlatching of this amplitude limit branch road is by described amplitude limit control signal and the control of described chip radio frequency interface demodulator circuit output signal.
Owing to adopt circuit of the present invention; utilize the high-low pressure testing circuit that the current rectifying and wave filtering circuit output signal is carried out voltage detecting respectively; and capacitor charge and discharge controlled; the amplitude limit control signal control bypass earial drainage transistor that utilizes electric capacity to form then carries out earial drainage; thereby finish limited amplitude protection effect, and avoided influence subsequent demodulation, voltage stabilizing, reset circuit to IC-card or label.
In addition, utilize the unlatching of demodulator circuit output signal control amplitude limit branch road, when read write line send be the carrier signal of not passing through amplitude modulation(PAM) the time amplitude limit branch road conducting earial drainage, strengthen discharge capacity; When read write line send be carrier signal through amplitude modulation(PAM) the time amplitude limit branch road close, weaken discharge capacity.The chip internal problem of electricity down easily in the time of can avoiding under the very high situation of field intensity antenna through amplitude modulation(PAM) has like this been expanded the scope that IC-card and label can operate as normal.
Description of drawings
The present invention is further detailed explanation below in conjunction with accompanying drawing and embodiment:
Fig. 1 is the system chart of non-contact IC card or RFID tag;
Fig. 2 is the radio-frequency interface circuit theory diagram of non-contact IC card or radio frequency identification label chip;
Fig. 3 is the schematic diagram that the present invention is used for the limiter protection circuit embodiment of non-contact IC card and RFID tag.
Embodiment
As shown in Figure 3, the interchange carrier signal that sends to the space when read write line produces output signal by the coupling of the antenna end of non-contact IC card or RFID tag and after sending into current rectifying and wave filtering circuit, i.e. direct current envelope signal rec_out.The height of this envelope signal rec_out is directly relevant with non-contact IC card or RFID tag field intensity of living in.Field intensity of living in is high more, and envelope signal rec_out is high more, and field intensity of living in is low more, and envelope signal rec_out is low more.Described envelope signal rec_out is as the input of high pressure and low-voltage testing circuit.
After described envelope signal rec_out is higher than certain value Vhigh (input voltage when high-voltage detecting circuit produces effectively output), the output terminal output low level vctrl1 of high-voltage detecting circuit, PMOS transistor M1 as the charging current source gauge tap opens, and charging current source I1 begins to charge to capacitor C through PMOS transistor M1.The amplitude limit control signal vshunt level that capacitor C discharges and recharges formation begins to raise, when being elevated to bypass earial drainage transistor Mshunt1 and can opening, and this bypass earial drainage transistor Mshunt1 conducting cascading water.
After described envelope signal rec_out is lower than certain value Vlow (input voltage when low-voltage testing circuit produces effectively output) (Vlow＜Vhigh), the output terminal output high level vctrl2 of low-voltage testing circuit, nmos pass transistor M2 as discharge current source gauge tap opens, and discharge current source I2 begins to discharge to capacitor C through nmos pass transistor M2.Amplitude limit control signal vshunt begins to descend, and when dropping to when bypass earial drainage transistor Mshunt1 can be turn-offed, bypass earial drainage transistor Mshunt1 ends, and cascading water finishes.
Need to prove in the present embodiment: the input voltage Vhigh when the input voltage Vlow when 1, low-voltage testing circuit produces effectively output must produce effectively output less than high-voltage detecting circuit, the output vctrl1 that so just can guarantee at certain intermediate range inner high voltage testing circuit of described envelope signal rec_out is for high, the output vctrl2 of low-voltage testing circuit is low, it is constant relatively that the amplitude limit control signal vshunt that capacitor C forms keeps, thereby keep described envelope signal rec_out relatively stable in some fixed values.The purpose of doing like this is in order to guarantee non-contact IC card or RFID tag certain to be shaken in than the low field intensity scope near amplitude limit begins effect, and limiter protection circuit can not opened or be closed continually, in order to avoid have influence on the quality of envelope signal rec_out.2, capacitor C discharged and recharged the rise and fall edge of time constant much larger than the envelope signal rec_out envelope of current rectifying and wave filtering circuit output, thereby can not make normal envelope signal rec_out modulation amplitude shoal, in order to avoid have influence on the operate as normal of demodulator circuit, this just need rationally be provided with the size of capacitor C and charging and discharging currents source I1 and I2.
Also have a problem, the cascading water ability of amplitude limiter circuit was suitable when promptly the discharge capacity of amplitude limiter circuit and read write line sent the carrier signal of not passing through amplitude modulation(PAM) when read write line sends the carrier signal of process amplitude modulation(PAM).This can cause carrier signal amplitude limit during amplitude modulation(PAM) excessive, thereby makes the voltage stabilizing output voltage cross low and then make non-contact IC card or the inner electricity down that produces of radio frequency identification label chip, causes non-contact IC card or the RFID tag can't operate as normal.In order to address this problem, need be at the other amplitude limit branch road in parallel of described current rectifying and wave filtering circuit, this amplitude limit props up the second bypass earial drainage transistor Mshunt2 and the switching transistor Mswitch composition that route is connected in series.The unlatching of the described second bypass earial drainage transistor Mshunt2 is by amplitude limit control signal vshunt control, and the unlatching of described switching transistor Mswitch is controlled by demodulator circuit output signal d_out.As demodulator circuit output signal d_out when being high, be that read write line sends when not passing through the carrier signal of amplitude modulation(PAM), arrive to a certain degree as long as non-contact IC card or RFID tag field intensity of living in is high, two-way bypass cascading water transistor Mshunt1, Mshunt2 all open, and the cascading water ability is relatively large.When demodulator circuit output signal d_out when low, when being the carrier signal of read write line transmission process amplitude modulation(PAM), arrive to a certain degree bypass cascading water transistor Mshunt1 unlatching as long as field intensity is high, and bypass cascading water transistor Mshunt2 still closes, the cascading water ability relatively a little less than.So just solved under the amplitude limit situation the following electric problem that when read write line sends am signals non-contact IC card or radio frequency identification label chip inside may exist well.
As mentioned above; the present invention is by the amplitude limiter circuit of utilized bandwidth control signal control; and cooperation is with the control action of demodulator circuit output signal; finished the limited amplitude protection effect under high field intensity well, can not have influence on normal data communication between non-contact IC card or RFID tag and the read write line simultaneously again non-contact IC card or RFID tag.
Claims (5)
1. limiter protection circuit that is used for non-contact IC card and radio frequency identification label chip, it is characterized in that, described limiter protection circuit comprises the bypass earial drainage transistor that is connected in parallel on described chip radio frequency interface current rectifying and wave filtering circuit, detect the high-voltage detecting circuit and the low-voltage testing circuit of described current rectifying and wave filtering circuit output signal, described high-voltage detecting circuit is by the charging of the transistorized switch control of control one PMOS charging current source to electric capacity; Described low-voltage testing circuit is controlled the discharge current source to described capacitance discharges by the switch of control one nmos pass transistor; Described capacitor charge and discharge forms the amplitude limit control signal, and this amplitude limit control signal is controlled the transistorized unlatching of described bypass earial drainage.
2. the limiter protection circuit that is used for non-contact IC card and radio frequency identification label chip as claimed in claim 1; it is characterized in that: also comprise the amplitude limit branch road that is connected in parallel on described current rectifying and wave filtering circuit, the unlatching of this amplitude limit branch road is by described amplitude limit control signal and the control of described chip radio frequency interface demodulator circuit output signal.
3. the limiter protection circuit that is used for non-contact IC card and radio frequency identification label chip as claimed in claim 1 or 2 is characterized in that: described electric capacity discharge and recharge the rise and fall edge of time constant much larger than described current rectifying and wave filtering circuit output signal envelope.
4. the limiter protection circuit that is used for non-contact IC card and radio frequency identification label chip as claimed in claim 1 or 2 is characterized in that: the input voltage the when input voltage when described high-voltage detecting circuit produces effectively output produces effectively output greater than described low-voltage testing circuit.
5. the limiter protection circuit that is used for non-contact IC card and radio frequency identification label chip as claimed in claim 2, it is characterized in that: described amplitude limit props up the second bypass earial drainage transistor and the switching transistor composition that route is connected in series, the transistorized unlatching of the described second bypass earial drainage is controlled by described amplitude limit control signal, and the unlatching of described switching transistor is controlled by described demodulator circuit output signal; When described demodulator circuit output signal is high, and described amplitude limit control signal is during greater than the transistorized cut-in voltage of the second bypass earial drainage, this second bypass earial drainage transistor turns; When described demodulator circuit output signal when low, this second bypass earial drainage transistor is closed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200610024814A CN101038616B (en) | 2006-03-17 | 2006-03-17 | Limiting amplitude protection circuit used in non-contact IC card and radio frequency identification label |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200610024814A CN101038616B (en) | 2006-03-17 | 2006-03-17 | Limiting amplitude protection circuit used in non-contact IC card and radio frequency identification label |
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| Publication Number | Publication Date |
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| CN101038616A CN101038616A (en) | 2007-09-19 |
| CN101038616B true CN101038616B (en) | 2010-05-12 |
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| CN200610024814A Active CN101038616B (en) | 2006-03-17 | 2006-03-17 | Limiting amplitude protection circuit used in non-contact IC card and radio frequency identification label |
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Families Citing this family (18)
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| CN102103679B (en) * | 2009-12-18 | 2014-10-15 | 上海华虹集成电路有限责任公司 | A/B mode detection circuit adaptive to variation of field intensity |
| CN102122368A (en) * | 2010-01-07 | 2011-07-13 | 上海华虹集成电路有限责任公司 | Non-contact type intelligent card with prompting function |
| CN102456153B (en) * | 2010-11-02 | 2013-10-23 | 上海华虹Nec电子有限公司 | Power-on reset circuit of electronic label of RFID (radio frequency identification device) system |
| CN102244502A (en) * | 2011-04-25 | 2011-11-16 | 胡建国 | Automatic Q value adjustment amplitude limiting circuit |
| CN103199814B (en) * | 2012-01-06 | 2017-03-15 | 上海华虹集成电路有限责任公司 | Amplitude limiter circuit in RF identification |
| CN103034827B (en) * | 2012-12-10 | 2015-07-15 | 杭州昂润科技有限公司 | Radio frequency tag detecting device and detecting method thereof |
| CN104065385B (en) * | 2013-03-20 | 2017-11-17 | 凌通科技股份有限公司 | Applied to wireless charging or the signal decoding circuit of radio-frequency recognition system |
| CN103413168B (en) * | 2013-08-19 | 2016-06-08 | 电子科技大学 | The rectification amplitude limiter circuit of radio electronic label |
| CN104516381B (en) * | 2013-09-26 | 2016-04-27 | 上海华虹集成电路有限责任公司 | Regulator rectifier circuit in radio-frequency (RF) identification |
| CN103699928B (en) * | 2014-01-08 | 2017-01-04 | 卓捷创芯科技（深圳）有限公司 | A kind of amplitude limiter circuit and passive RF label that can adjust rectified signal amplitude continuously |
| CN103714378B (en) * | 2014-01-08 | 2016-09-07 | 卓捷创芯科技（深圳）有限公司 | The intelligent EMS of a kind of passive RF label and energy management method |
| CN103679259B (en) * | 2014-01-08 | 2016-08-17 | 卓捷创芯科技（深圳）有限公司 | A kind of rectification amplitude limiter circuit with multiple time constant and passive RF label |
| CN104866791A (en) * | 2015-06-12 | 2015-08-26 | 安徽朗坤物联网有限公司 | High-frequency semi-active RFID (Radio Frequency Identification) radiofrequency analog front-end circuit |
| CN105651282A (en) * | 2015-12-22 | 2016-06-08 | 无锡信大气象传感网科技有限公司 | Radio frequency identification based system for detecting trajectory of motion of carrier |
| SG10201607275YA (en) * | 2016-09-01 | 2018-04-27 | Huawei Int Pte Ltd | Method and device for radio frequency voltage limiting |
| CN108133247A (en) * | 2016-11-30 | 2018-06-08 | 北京同方微电子有限公司 | A kind of area-optimized non-contact card analog front circuit |
| CN108334926A (en) * | 2018-04-13 | 2018-07-27 | 捷德（中国）信息科技有限公司 | Fingerprint fiscard and fingerprint financial system |
| CN112288068B (en) * | 2020-10-24 | 2024-02-27 | 卓捷创芯科技（深圳）有限公司 | Positive feedback latch amplitude limiting control circuit and method for passive radio frequency identification tag |
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| Publication number | Publication date |
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| CN101038616A (en) | 2007-09-19 |
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