CN104518735A - Load modulating module in radio-frequency identification (RFID) - Google Patents
Load modulating module in radio-frequency identification (RFID) Download PDFInfo
- Publication number
- CN104518735A CN104518735A CN201310447401.7A CN201310447401A CN104518735A CN 104518735 A CN104518735 A CN 104518735A CN 201310447401 A CN201310447401 A CN 201310447401A CN 104518735 A CN104518735 A CN 104518735A
- Authority
- CN
- China
- Prior art keywords
- nmos pass
- pass transistor
- load
- grid
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
The invention discloses a load modulating module in RFID. The load modulating module comprises a coupling circuit, which is used to couple the signals to the RFID card terminal or couple the load modulating signals of the RFID card terminal to the card reader terminal; and a load modulating circuit, which is connected to the output terminal of the coupling circuit and is used to return the data processed by the digital circuit to the card reader; and further comprises an amplitude limiting circuit, which is connected to the output terminal of the load modulating circuit and is used to limit the amplitude of the output of the load modulating circuit and provide a variable voltage to the load modulating circuit; wherein the variable voltage changes with the change of field strength: when the field strength increases, the variable voltage increases, when the field strength decreases, the variable voltage decreases too; and moreover, the amplitude limiting circuit can conduct the load modulating circuit under a large field strength to finish the load modulation. The provided load modulating module can improve the load modulation waveform and load modulation depth under a large field strength so as to improve the compatibility of RFID cards.
Description
Technical field
The present invention relates to load-modulate circuit field in analog integrated circuit, particularly relate to the load-modulate module in a kind of radio-frequency (RF) identification.
Background technology
In radio-frequency (RF) identification, the analog signal that radio-frequency (RF) identification card needs coupling card reader to send, and demodulate the data that card reader sends and give digital circuit process again, the data after process are returned to card reader through load-modulate circuit by digital circuit again, this completes whole communication process.Process data being returned to card reader is exactly load-modulate, and waveform and the load-modulate degree of depth of load-modulate are bad, and can affect the demodulation of card reader to data, therefore load-modulate circuit is extremely important and crucial.
See Fig. 1, in traditional load-modulate circuit, nmos pass transistor MN3 is just equivalent to a switch, and with regard to conducting when modulation, just close when not modulating, DIN is control signal, is provided and control by digital circuit.The conducting of MOS transistor and close the signal affected on antenna of closing, when MOS transistor conducting, signal on antenna will be pulled down, form the groove of, groove signal is one by one exactly load-modulate waveform, with data in these waveforms, out again by card reader demodulation finally.The advantage of this structure is simple, easily realizes, and under being operated in little field intensity, load-modulate waveform and the load-modulate degree of depth are all well; Shortcoming is under being operated in large field intensity, and load-modulate waveform and the load-modulate degree of depth are all deteriorated, and card reader is difficult to demodulation, or easily causes card reader demodulation mistake.If card reader demodulation makes mistakes, whole communication also just have failed.Therefore all there is good load-modulate waveform under each field intensity and the larger load-modulate degree of depth is all very important.
Summary of the invention
The technical problem to be solved in the present invention is to provide the load-modulate module in a kind of radio-frequency (RF) identification, can improve the load-modulate waveform under large field intensity and the load-modulate degree of depth preferably, strengthens the compatibility of radio-frequency (RF) identification card.
For solving the problems of the technologies described above, the load-modulate module in radio-frequency (RF) identification of the present invention, comprising:
One coupling circuit, for coupling a signal to radio-frequency (RF) identification card end, or is coupled to card reader end by the load modulation signal of radio-frequency (RF) identification card end;
One load-modulate circuit, is connected with the output of described coupling circuit, for the data after digital circuit process are returned to card reader; Wherein also comprising: an amplitude limiter circuit, be connected with the output of described load-modulate circuit, for carrying out amplitude limit to the output of described load-modulate circuit, and providing a variable voltage for this load-modulate circuit; This variable voltage is followed field intensity change and changes, and when field intensity increases, this variable voltage also increases, and when field intensity reduces, variable voltage also reduces; And the energy control load modulation circuit conducting when large field intensity, complete load-modulate.
Load-modulate module of the present invention, carrys out control load modulation circuit by a variable voltage with field intensity change, and when being operated in little field intensity, the magnitude of voltage of variable voltage is little, can well control the load-modulate with settling signal; When being operated in large field intensity, its magnitude of voltage is larger, antenna waveform can be pulled down, and can form good load-modulate waveform and the larger load-modulate degree of depth equally.Therefore the load-modulate waveform of load-modulate circuit of the present invention not only under little field intensity and the load-modulate degree of depth good, the load-modulate waveform under large field intensity and the load-modulate degree of depth also can better meet the demodulation of card reader very well; Radio-frequency (RF) identification card can good compatible various card reader, thus ensures the normal communication of radio-frequency (RF) identification card, enhances the compatibility of radio-frequency (RF) identification card.
Accompanying drawing explanation
Below in conjunction with accompanying drawing and embodiment, the present invention is further detailed explanation:
Fig. 1 is existing load-modulate circuit theory diagrams;
Fig. 2 is the load-modulate module one embodiment schematic diagram in described radio-frequency (RF) identification.
Embodiment
Fig. 2 is one embodiment of the invention, and the load-modulate module in described radio-frequency (RF) identification, comprising: a coupling circuit, the load-modulate circuit be connected with the output of described coupling circuit, the amplitude limiter circuit be connected with the output of described load-modulate circuit.In order to improve load-modulate waveform under large field intensity and the load-modulate degree of depth, strengthen the compatibility of radio-frequency (RF) identification card, described load-modulate circuit by a variable voltage, the unlatching of nmos pass transistor MN1 and MN2 in control load modulation circuit under large field intensity, thus realize load-modulate.
Described coupling circuit, by inductance L 1, inductance L 2 and electric capacity C1 form.Electric capacity C1 is connected in parallel on the two ends of inductance L 2.Input signal IN is coupled to radio-frequency (RF) identification card end by inductance L 1 and L2, with electric capacity C1, resonance occurs; Meanwhile, data-signal is inputed to radio circuit, radio circuit demodulates digital signal and sends digital circuit to, and the data after process are returned to card reader by digital circuit again.The data returned after digital circuit process return in the mode of load-modulate, and namely digital circuit realizes load-modulate by the magnitude of voltage of the load modulation signal DIN of the load modulation signal end of load-modulate circuit in control chart 2.Load modulation signal DIN is provided by digital circuit and controls.
Described load-modulate circuit is by nmos pass transistor MN1, MN2 and MN3, and PMOS transistor MP1, inverter INV1 and inverter INV2 form.
The drain electrode of nmos pass transistor MN1 is connected with one end of the inductance L 2 of coupling circuit, and the node of this connection is held as a link ANT1 of antenna; The drain electrode of nmos pass transistor MN2 is connected with the other end of the inductance L 2 of coupling circuit, and the node of this connection is held as another link ANT2 of antenna; The source electrode of nmos pass transistor MN1 and the source ground of nmos pass transistor MN2.The grid of nmos pass transistor MN1 is connected with the grid of nmos pass transistor MN2, and its node connected is set to A.
The output of inverter INV1 is connected with the input of inverter INV2, and the output of inverter INV2 is connected with the grid of PMOS transistor MP1; The input of inverter INV1 as the load modulation signal end input load modulation signal DIN of load-modulate circuit, and is connected with the grid of nmos pass transistor MN3; The source electrode of PMOS transistor MP1 is as input variable voltage end input variable voltage VLIM.The source ground of nmos pass transistor MN3.The drain electrode of PMOS transistor MP1 is connected with node A with the drain electrode of nmos pass transistor MN3.
Described amplitude limiter circuit by nmos pass transistor MN4, MN5, MN6, MN7, MN8, MN9 and MN10, and resistance R1 forms.
The grid of nmos pass transistor MN4 and drain electrode holds with described ANT1 and are connected, and the grid of nmos pass transistor MN5 is connected with draining to hold with described ANT2, and the source electrode of nmos pass transistor MN4 is connected with the source electrode of nmos pass transistor MN5, and node of its connection is set to B.
The source electrode of nmos pass transistor MN6, the source electrode of nmos pass transistor MN9 are connected with described B point with the drain electrode of nmos pass transistor MN10.The grid of nmos pass transistor MN6 is connected with the source electrode of nmos pass transistor MN7 with drain electrode, and the grid of nmos pass transistor MN7 is connected with the source electrode of nmos pass transistor MN8 with drain electrode, the grid of nmos pass transistor MN8 and grounded drain.
The grid of nmos pass transistor MN9 is connected with the grid of nmos pass transistor MN6, and the drain electrode of nmos pass transistor MN9 is connected with one end of resistance R1, the other end ground connection of resistance R1.The drain electrode of nmos pass transistor MN9 and the output of the node be connected of resistance R1 as variable voltage, export variable voltage VLIM.
The grid of nmos pass transistor MN10 is connected with the output of variable voltage, its source ground.
Described amplitude limiter circuit except there is the function of amplitude limit itself, also for load-modulate circuit provides a variable voltage VLIM.This variable voltage VLIM changes along with the change of field intensity.When the load-modulate module work in described radio-frequency (RF) identification is in little field intensity, the magnitude of voltage of variable voltage VLIM is also lower, along with the magnitude of voltage of the increase variable voltage VLIM of field intensity is also along with increase.When the load-modulate module work in described radio-frequency (RF) identification is under large field intensity, the magnitude of voltage of variable voltage VLIM is also larger.
When B point voltage raises and is greater than the threshold voltage sum of nmos pass transistor MN6, MN7 and MN8, the magnitude of voltage of variable voltage VLIM just raises, and open NMOS transistor MN10 releases unwanted currents gradually; B point voltage will reduce thereupon, finally be stabilized on the magnitude of voltage of threshold voltage sum of three nmos pass transistors MN6, MN7 and MN8.Therefore, the magnitude of voltage of variable voltage VLIM changes along with field intensity change, and field intensity is little, and variable voltage VLIM value is just little, and field intensity is large, and variable voltage VLIM value just becomes large.The present invention is by VLIM magnitude of voltage control load modulation waveform and the load-modulate degree of depth.
When load modulation signal DIN is low level, just mean that load-modulate circuit has been started working.First nmos pass transistor MN3 is closed, PMOS transistor MP1 pipe conducting variable voltage VLIM is transferred to A point thereupon, A point is once after having voltage, nmos pass transistor MN1 and MN2 is with regard to conducting, and the signal of antenna ends ANT1 and ANT2 end can be pulled down, form groove, also just realize and complete the load-modulate of signal.A point voltage size directly decides the opening degree of nmos pass transistor MN1 and MN2.Under little field intensity, antenna ends magnitude of voltage is less, and A point voltage is also little, and it is also little that nmos pass transistor MN1 and MN2 opens, and the waveform of antenna end also forms groove than being easier to be left behind, and therefore the effect of load-modulate waveform and the load-modulate degree of depth is all right.Along with the increase of field intensity, A point voltage also will raise, and nmos pass transistor MN1 and MN2 opening degree also increase, load-modulate waveform and the load-modulate degree of depth also not bad.Under large field intensity, although antenna ends voltage is larger, A point voltage is also higher, and the unlatching of nmos pass transistor MN1 and MN2 is just very abundant, therefore antenna ends waveform also easily forms groove, therefore under large field intensity load-modulate waveform and the load-modulate degree of depth also better.
Load-modulate completes primarily of nmos pass transistor MN1 and MN2, variable voltage VLIM is by inverter INV1, inverter INV2, PMOS transistor MP1 and nmos pass transistor MN3 are transferred to A point smoothly during load-modulate, coordinate nmos pass transistor MN1 and MN2 to complete load-modulate.
The work field intensity of radio-frequency (RF) identification card is generally 1.5A/m ~ 7.5A/m.For dissimilar radio-frequency (RF) identification card, the large field intensity possibility difference of its definition is very large, generally can think large field intensity when field intensity is more than 6A/m, or can think large field intensity when field intensity is more than 7A/m.
Similar to dissimilar radio-frequency (RF) identification card, little field intensity of its definition also may difference very large.
Although the present invention utilizes specific embodiment to be described, the explanation of embodiment is not limit the scope of the invention.One skilled in the art, by reference to explanation of the present invention, when not deviating from the spirit and scope of the present invention, easily carrying out various amendment or can combine embodiment.
Claims (5)
1. the load-modulate module in radio-frequency (RF) identification, comprising:
One coupling circuit, for coupling a signal to radio-frequency (RF) identification card end, or is coupled to card reader end by the load modulation signal of radio-frequency (RF) identification card end;
One load-modulate circuit, is connected with the output of described coupling circuit, for the data after digital circuit process are returned to card reader; It is characterized in that, also comprise:
One amplitude limiter circuit, is connected with the output of described load-modulate circuit, for carrying out amplitude limit to the output of described load-modulate circuit, and provides a variable voltage for this load-modulate circuit; This variable voltage is followed field intensity change and changes, and when field intensity increases, this variable voltage also increases, and when field intensity reduces, variable voltage also reduces; And the energy control load modulation circuit conducting when large field intensity, complete load-modulate.
2. load-modulate module as claimed in claim 1, is characterized in that:
Described coupling circuit, by the first inductance, the second inductance and electric capacity composition, described Capacitance parallel connection is at the two ends of the second inductance; Input signal is inductively coupled to radio-frequency (RF) identification card end by the first inductance and second, with described electric capacity generation resonance.
3. load-modulate module as claimed in claim 1 or 2, is characterized in that:
Described load-modulate circuit by the first nmos pass transistor, the second nmos pass transistor and the second nmos pass transistor, the first PMOS transistor, the first inverter and the second inverter composition;
The drain electrode of the first nmos pass transistor is connected with one end of the second inductance of coupling circuit, and the node of this connection is set to ANT1 end as a link of antenna; The drain electrode of the second nmos pass transistor is connected with the other end of the second inductance of coupling circuit, and the node of this connection is set to ANT2 end as another link of antenna; The source electrode of the first nmos pass transistor and the source ground of the second nmos pass transistor; The grid of the first nmos pass transistor is connected with the grid of the second nmos pass transistor, and its node connected is set to A;
The output of the first inverter is connected with the input of the second inverter, and the output of the second inverter is connected with the grid of the first PMOS transistor; The input of the first inverter as the load modulation signal end input load modulation signal DIN of load-modulate circuit, and is connected with the grid of the 3rd nmos pass transistor; The source electrode of the first PMOS transistor inputs variable voltage VLIM, the source ground of the 3rd nmos pass transistor as input variable voltage end; The drain electrode of the first PMOS transistor is connected with node A with the drain electrode of the 3rd nmos pass transistor.
4. load-modulate module as claimed in claim 3, is characterized in that:
Described amplitude limiter circuit is by the 4th nmos pass transistor ~ the tenth nmos pass transistor, and resistance composition;
The grid of the 4th nmos pass transistor and drain electrode holds with described ANT1 and are connected, and the grid of the 5th nmos pass transistor is connected with draining to hold with described ANT2, and the source electrode of the 4th nmos pass transistor is connected with the source electrode of the 5th nmos pass transistor, and node of its connection is set to B;
The source electrode of the 6th nmos pass transistor, the source electrode of the 9th nmos pass transistor are connected with described B point with the drain electrode of the tenth nmos pass transistor; The grid of the 6th nmos pass transistor is connected with the source electrode of the 7th nmos pass transistor with drain electrode, and the grid of the 7th nmos pass transistor is connected with the source electrode of the 8th nmos pass transistor with drain electrode, the grid of the 8th nmos pass transistor and grounded drain;
The grid of the 9th nmos pass transistor is connected with the grid of the 6th nmos pass transistor, and the drain electrode of the 9th nmos pass transistor is connected with one end of described resistance, the other end ground connection of this resistance; The node that the drain electrode of the 9th nmos pass transistor is connected with described resistance, as the output of variable voltage, exports variable voltage VLIM;
The grid of the tenth nmos pass transistor is connected with the output of variable voltage VLIM, its source ground.
5. load-modulate module as claimed in claim 1, is characterized in that:
Described amplitude limiter circuit is by the 4th nmos pass transistor ~ the tenth nmos pass transistor, and resistance composition;
The grid of the 4th nmos pass transistor and drain electrode holds with described ANT1 and are connected, and the grid of the 5th nmos pass transistor is connected with draining to hold with described ANT2, and the source electrode of the 4th nmos pass transistor is connected with the source electrode of the 5th nmos pass transistor, and node of its connection is set to B;
The source electrode of the 6th nmos pass transistor, the source electrode of the 9th nmos pass transistor are connected with described B point with the drain electrode of the tenth nmos pass transistor; The grid of the 6th nmos pass transistor is connected with the source electrode of the 7th nmos pass transistor with drain electrode, and the grid of the 7th nmos pass transistor is connected with the source electrode of the 8th nmos pass transistor with drain electrode, the grid of the 8th nmos pass transistor and grounded drain;
The grid of the 9th nmos pass transistor is connected with the grid of the 6th nmos pass transistor, and the drain electrode of the 9th nmos pass transistor is connected with one end of described resistance, the other end ground connection of this resistance; The node that the drain electrode of the 9th nmos pass transistor is connected with described resistance, as the output of variable voltage, exports variable voltage VLIM;
The grid of the tenth nmos pass transistor is connected with the output of variable voltage VLIM, its source ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310447401.7A CN104518735B (en) | 2013-09-26 | 2013-09-26 | Load modulation module in radio frequency identification |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310447401.7A CN104518735B (en) | 2013-09-26 | 2013-09-26 | Load modulation module in radio frequency identification |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104518735A true CN104518735A (en) | 2015-04-15 |
| CN104518735B CN104518735B (en) | 2017-09-15 |
Family
ID=52793574
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310447401.7A Active CN104518735B (en) | 2013-09-26 | 2013-09-26 | Load modulation module in radio frequency identification |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN104518735B (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070246546A1 (en) * | 2006-04-20 | 2007-10-25 | Yuko Yoshida | Information Processing Terminal, IC Card, Portable Communication Device, Wireless Communication Method, and Program |
| CN101145188A (en) * | 2006-09-12 | 2008-03-19 | 盛群半导体股份有限公司 | Wireless radio frequency identification responder |
| CN102244502A (en) * | 2011-04-25 | 2011-11-16 | 胡建国 | Automatic Q value adjustment amplitude limiting circuit |
-
2013
- 2013-09-26 CN CN201310447401.7A patent/CN104518735B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070246546A1 (en) * | 2006-04-20 | 2007-10-25 | Yuko Yoshida | Information Processing Terminal, IC Card, Portable Communication Device, Wireless Communication Method, and Program |
| CN101145188A (en) * | 2006-09-12 | 2008-03-19 | 盛群半导体股份有限公司 | Wireless radio frequency identification responder |
| CN102244502A (en) * | 2011-04-25 | 2011-11-16 | 胡建国 | Automatic Q value adjustment amplitude limiting circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| CN104518735B (en) | 2017-09-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105322813A (en) | Voltage converter | |
| CN101436855A (en) | Level shift circuit and method thereof | |
| US20160315554A1 (en) | Rectifier and limiter circuit having a plurality of time constants and passive radio frequency tag | |
| CN102244502A (en) | Automatic Q value adjustment amplitude limiting circuit | |
| CN112288068B (en) | Positive feedback latch amplitude limiting control circuit and method for passive radio frequency identification tag | |
| CN103413168A (en) | Rectification amplitude limiting circuit of RFID | |
| CN103795401A (en) | Output unit circuit with controllable output level | |
| CN105447547A (en) | Demodulation circuit with adjustable sensitivity | |
| CN102004939A (en) | Demodulator circuit for the UHF (Ultrahigh Frequency) radio frequency identification label chip | |
| CN101145207B (en) | Variable bandwidth filter circuit for RFID read-write equipment | |
| CN106815625A (en) | A kind of novel demodulation circuit of suitable ultralow Consumption | |
| CN104579175B (en) | Load modulation circuit in radio frequency identification | |
| CN104518735A (en) | Load modulating module in radio-frequency identification (RFID) | |
| CN106845600B (en) | A kind of demodulator circuit applied to ultrahigh-frequency tag | |
| CN102843121B (en) | Wideband radio-frequency switch CMOS (Complementary Metal Oxide Semiconductors) circuit | |
| CN106788369A (en) | With the radio-frequency switch circuit for improving biasing circuit | |
| CN101038617B (en) | Clock recovery circuit used in non-contact IC card and radio frequency identification label | |
| CN104850885A (en) | Low and intermediate-frequency electronic tag and signal transmitting method thereof | |
| CN104463311A (en) | Circuit for improving contactless card strong field modulation waveform and modulation length | |
| CN108809285A (en) | A kind of transmission gate circuit of isolation high input voltage | |
| CN102456151B (en) | Clamping circuit for electronic tag of RFID (radio frequency identification) system | |
| CN107404291A (en) | Biasing circuit and low-noise amplifier | |
| CN206292588U (en) | Radio frequency snaps into detection circuit | |
| CN101964065A (en) | Radio frequency integrated circuit for near-field communication | |
| CN207637180U (en) | A kind of near-field communication front end hardware circuit, safety chip, dynamic token and contact type intelligent card |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |