CN108152604A - A kind of non-contact card field strength detection circuit - Google Patents
A kind of non-contact card field strength detection circuit Download PDFInfo
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- CN108152604A CN108152604A CN201611101646.4A CN201611101646A CN108152604A CN 108152604 A CN108152604 A CN 108152604A CN 201611101646 A CN201611101646 A CN 201611101646A CN 108152604 A CN108152604 A CN 108152604A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/12—Measuring electrostatic fields or voltage-potential
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Abstract
The present invention provides a kind of non-contact card field strength detection circuits.The field strength detection circuit includes current mirroring circuit, current-to-voltage converting circuit and adc circuit, wherein, the current signal that the current mirror that field strength size is characterized in amplitude limiter circuit is 20uA ~ 360uA by current mirror circuit, and it exports to current-to-voltage converting circuit, current signal is converted to voltage signal by current-to-voltage converting circuit, voltage signal is converted into digitized field strength indicating signal by adc circuit again so that external digital circuit makes running frequency real-time adjustment according to field strength indicating signal.Card designed by the invention identical Card Reader apart from the upper speed of service faster, and the speed of service is more linear with the variation of distance, and since digital circuit is made that adjustment in advance, big capacitance is not needed in the new circuit of electricity to ensure system not power down, so as to save chip area.
Description
Technical field
The present invention relates to contactless smart card technology field more particularly to a kind of non-contact card field strength detection circuits.
Background technology
In contactless smart card application, the magnetic field energy of card reader release is supplied to card by way of inductive coupling
Piece, card receives the size of energy and Card Reader distance is inversely proportional.Card Reader distance is more remote, and the reduction of energy, on the contrary then energy is got over
Greatly.It is big to adapt to different energy so as to change power consumption that this means that the running parameter of card must make corresponding adjustment
Small, these parameters include central processing unit（Central Processing Unit, English abbreviation CPU）Running frequency, association's processing
Device running frequency etc..The power consumption of chip and running frequency are proportional, and in long-range card reading, card needs rapid drop
Frequently, otherwise not enough it will lead to lower electricity because of energy.Therefore card how according to field strength size automatically adjust running frequency,
Reach balance between processing speed and power consumption as one of key technology of card design.
There is no the presence of field strength indicating circuit in traditional non-contact card design, i.e., card this can not find out week
The strong variation in enveloping field, this causes big inconvenience to system application.As shown in Figure 1, for existing non-contact card circuit system
Structure chart.Wherein, card antenna is sensed that AC signal is converted into 5V DC voltages VCC by rectification amplitude limiter circuit；Low voltage difference is steady
Volt circuit by VCC in the core voltage VDD for being converted into 1.6V, to supplying digital circuits；Voltage detecting circuit detects core voltage
VDD, detection threshold value 1.5V.As core voltage VDD>During 1.5V, digital circuit operates in high-frequencyf H, as core voltage VDD<
During 1.5V, digital circuit operates in low frequencyf L。
On the other hand in order to give the digital circuit for receiving alarm signal there are enough frequency regulating times, in core voltage
It under the voltage domain of VDD, needs to ensure not power down before frequency reducing with very big capacitance C1, this results in the expenses of chip area, increase
Cost is added.
Invention content
In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a kind of non-contact card field strength detection electricity
Road allows field strength detection circuit to provide field strength indicating signal, adjusts the digital signal real time execution of non-contact card system in correspondence
Power consumption frequency on.
In order to reach above-mentioned technical purpose, the technical solution adopted in the present invention is：
A kind of non-contact card field strength detection circuit, the field strength detection circuit include current mirroring circuit, current-voltage conversion circuit
And adc circuit, wherein, the electricity that the current mirror that field strength size is characterized in amplitude limiter circuit is 20uA ~ 360uA by current mirror circuit
Signal is flowed, and is exported to current-voltage conversion circuit, current signal is converted to voltage signal by current-voltage conversion circuit,
Voltage signal is converted into digitized field strength indicating signal by adc circuit again so that external digital circuit indicates to believe according to field strength
Number real-time adjustment is made to running frequency.
Preferably, the current mirroring circuit is 500 by size ratio:1 NMOS tube and amplifier composition, amplifier is by NMOS
The drain terminal voltage of pipe is forced to same voltage value.
The present invention is as a result of the composition field strength detection of above-mentioned current mirroring circuit, current-voltage conversion circuit and adc circuit
Circuit, the advantageous effect obtained are that, since field strength detection circuit provides field strength indicating signal, entire non-contact card system is adopted
With conventional feed forward design, i.e., operated in the frequency of corresponding power consumption according to the big minor adjustment digital circuit of field strength, such non-contact card
There is no need in high-frequency for system operation frequencyf HAnd low frequencyf LBetween saltus step, as long as the correspondence of frequency domain power consumption is done
It is good, it is possible to make full use of field strength energy so that system running speed reaches best, this and traditional circuit non-contact card system
Compare, card designed by the invention identical Card Reader apart from the upper speed of service faster, and the speed of service is with the change of distance
Change more linear, and since digital circuit is made that adjustment in advance, big capacitance is not needed in electric new circuit to ensure to be
System not power down, so as to save chip area.
The present invention will be further described with reference to the accompanying drawings and detailed description.
Description of the drawings
Fig. 1 is existing non-contact card circuit system structure figure.
Fig. 2 is the non-contact card circuit system structure figure with the present invention.
Fig. 3 is the non-contact card field strength detection circuit structure diagram of the present invention.
Fig. 4 is the non-contact card field strength detection circuit figure that the present invention is embodied.
Fig. 5 is the adc circuit output and the corresponding diagram of field strength that the present invention is embodied.
Fig. 6 is the chip that is embodied of the present invention and be averaged running frequency and field strength pair using the chip of traditional circuit framework
Answer relational graph.
Specific embodiment
As shown in Fig. 2, to have the non-contact card circuit system structure figure of the present invention.With traditional non-contact card system
Circuit framework ratio, inserts the field strength detection circuit of low-power consumption in rectification amplitude limiter circuit, and the power that non-contact card obtains is big
Small proportional with field strength, power multiplies electric current equal to voltage, as long as so ensure that rectification output DC voltage VCC is constant, it is defeated
It is more big to go out electric current I, represents that field strength is bigger, output current I is smaller to represent that field strength is smaller；Analog circuit is recycled by different electricity
Stream signal is converted to voltage signal and is achieved that detection of the card to external field strength size.It, will be whole in order to ensure detection sensitivity
Stream output DC voltage VCC is reset to 4V, exports 3 field strength indicating signals to digital circuit.Since the field strength detects electricity
Road provides field strength indicating signal, and entire non-contact card system uses conventional feed forward design, i.e., according to the big minor adjustment of field strength number electricity
Road is operated in corresponding power consumption frequency, in this way, there is no need in high-frequency for this non-contact card system operation frequencyf HWith it is low
Frequencyf LBetween saltus step, as long as the correspondence of frequency domain power consumption is carried out, it is possible to make full use of field strength energy so that entire
Non-contact card system running speed reaches best.
As shown in figure 3, the non-contact card field strength detection circuit structure diagram for the present invention.The non-contact card field strength detection circuit
Including current mirroring circuit, current-voltage conversion circuit and adc circuit（Analog-to-digital conversion circuit）, wherein, current mirror circuit
Current mirror by characterization field strength size in amplitude limiter circuit is smaller current signal, and export to current-voltage conversion circuit,
Current signal is converted to voltage signal by current-voltage conversion circuit, and voltage signal is converted into digitized field by adc circuit again
Strong indication signal so that external digital circuit makes running frequency real-time adjustment according to field strength indicating signal.In specific implementation,
In digital circuit idle phase, when DC voltage VCC is more than 4V, amplitude limiter circuit inflow current；When DC voltage VCC is less than 4V
When, amplitude limiter circuit outflow electric current finally controls DC voltage VCC to stablize in 4V, and the final size of electric current is directly proportional to field strength,
Representative value is in 1mA ~ 18mA.Since current value is larger, directly processing can bring larger additional power consumption to system, and the present invention is set
The current mirroring circuit of the highly attenuating degree of high-precision has been counted, high current has been converted into low current to lower power consumption, electric current passes through electric current-electricity
Voltage conversion circuit is converted into voltage, then exports digitized field strength indicating signal by adc circuit.
As shown in figure 4, the non-contact card field strength detection circuit figure being embodied for the present invention.Wherein, diode D1 ~ D4 and
Capacitance C1 constitutes traditional full-wave rectifying circuit, output voltage VCC, and resistance R1/R2, amplifier 1 and NMOS tube MN0 are constituted
Amplitude limiter circuit.Vref is 0.8V reference voltages.R1 and R2 is VCC voltage sample resistance, and R1 resistance values are 1.6M Ω, R2 0.4M
Ω.When VCC is more than 4V, 1 output voltage of amplifier increases, and MN0 gate source voltages increase, and the electric current I_PASS of extraction increases, from
And VCC declines；When VCC is less than 4V, I_PASS reduces.Final VCC stablizes in 4V.MN0 ~ MN2, amplifier 2 constitute 500:1
Accurately current mirroring circuit.MN0 is 500 with MN1 size ratios:1；The drain terminal voltage of MN0 and MN1 is forced to together by amplifier 2
One voltage value, current mirror deviation caused by eliminating channel modulation effect, ensure that detection accuracy.The typical value of I_PASS
In 1mA ~ 18mA, then the electric current of MN1 suckings is 20uA ~ 360uA.MP0 ~ MP1 and resistance R3 constitutes current-voltage conversion electricity
Road, MP0 are 1 with MP1 dimension scales:1, R1 resistance value is 100K Ω.Output voltage VO UT ranging from 0.2V ~ 3.6V are can be calculated,
VOUT is converted to 3 position digital signals and inputs to digital circuit by ADC.
As shown in figure 5, the corresponding diagram with field strength is exported for the adc circuit that the present invention is embodied.It is using the present invention non-
Contact card circuit completes field strength detection function well.
The running frequency as shown in fig. 6, chip for the chip of the invention being embodied and use traditional circuit framework is averaged
With field strength correspondence figure.As can be seen that can be worked using the chip of new departure under 2A/m field strength in the specific embodiment
In 4MHz, and the chip of traditional scheme is used to can only operate in 2MHz；Use the chip of new departure can be under 3.7A/m field strength
9MHz is operated in, and 6MHz can only operate in using traditional scheme chip.In 2.5A/m ~ 3.5A/m field strength ranges, using new
The working frequency of chip of scheme shows linear increase, and uses the working frequency of traditional scheme chip then constant.Comparison can be with
It was found that in the case where running same Typical commands condition, the running frequency of card using the present invention at a specific distance obtains
It improves, and more steady with the variation of Card Reader distance.
The present invention is not limited to embodiment discussed above, more than the description of specific embodiment is intended to retouch
It states and illustrates technical solution of the present invention.The obvious transformation or replacement enlightened based on the present invention should also be as being considered
Fall into protection scope of the present invention；Above specific embodiment is used for disclosing the best implementation of the present invention, so that this
The those of ordinary skill in field can apply numerous embodiments of the invention and a variety of alternatives to reach the present invention's
Purpose.
Claims (2)
1. a kind of non-contact card field strength detection circuit, which is characterized in that the field strength detection circuit includes current mirroring circuit, electricity
Stream-voltage conversion circuit and adc circuit, wherein, current mirror circuit will characterize field strength size current mirror in amplitude limiter circuit
It for the current signal of 20uA ~ 360uA, and exports to current-voltage conversion circuit, current-voltage conversion circuit is by current signal
Voltage signal is converted to, voltage signal is converted into digitized field strength indicating signal by adc circuit again so that external digital circuit
Real-time adjustment makes running frequency according to field strength indicating signal.
2. current mirroring circuit as described in claim 1, which is characterized in that the current mirroring circuit is 500 by size ratio:1
The drain terminal voltage of NMOS tube is forced to same voltage value by NMOS tube and amplifier composition, amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611101646.4A CN108152604A (en) | 2016-12-05 | 2016-12-05 | A kind of non-contact card field strength detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611101646.4A CN108152604A (en) | 2016-12-05 | 2016-12-05 | A kind of non-contact card field strength detection circuit |
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| Publication Number | Publication Date |
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| CN108152604A true CN108152604A (en) | 2018-06-12 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CN201611101646.4A Pending CN108152604A (en) | 2016-12-05 | 2016-12-05 | A kind of non-contact card field strength detection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109917180A (en) * | 2019-04-03 | 2019-06-21 | 杭州安脉盛智能技术有限公司 | Direct current signal non-contact detecting sensor based on current transformer |
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| JP2005191961A (en) * | 2003-12-25 | 2005-07-14 | Sharp Corp | Noncontact ic card, electronic information apparatus, portable electronic information apparatus, open-type system, method for controling electric power consumption, control program, and readable recording medium |
| JP2005237166A (en) * | 2004-02-23 | 2005-09-02 | Nippon Telegr & Teleph Corp <Ntt> | Electric power suppressing method for non-contact device, and non-contact device |
| CN102968655A (en) * | 2011-08-31 | 2013-03-13 | 北京中电华大电子设计有限责任公司 | Operating frequency adjusting method and circuit for contactless card chip |
| CN103065182A (en) * | 2011-10-19 | 2013-04-24 | 国民技术股份有限公司 | Module and method for field intensity self-adaption and non-contact integrated circuit (IC) card |
| CN103731046A (en) * | 2014-01-08 | 2014-04-16 | 卓捷创芯科技（深圳）有限公司 | Dynamic rectifying control circuit, passive radio frequency identification (RFID) and dynamic rectifying control method |
| CN104063674A (en) * | 2013-03-22 | 2014-09-24 | 国民技术股份有限公司 | Field intensity self-adaption circuit and method and smart card |
| CN104063954A (en) * | 2013-03-22 | 2014-09-24 | 国民技术股份有限公司 | Non-contact type power supply self-adaptive adjustment system and adjustment method thereof |
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2016
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005191961A (en) * | 2003-12-25 | 2005-07-14 | Sharp Corp | Noncontact ic card, electronic information apparatus, portable electronic information apparatus, open-type system, method for controling electric power consumption, control program, and readable recording medium |
| JP2005237166A (en) * | 2004-02-23 | 2005-09-02 | Nippon Telegr & Teleph Corp <Ntt> | Electric power suppressing method for non-contact device, and non-contact device |
| CN102968655A (en) * | 2011-08-31 | 2013-03-13 | 北京中电华大电子设计有限责任公司 | Operating frequency adjusting method and circuit for contactless card chip |
| CN103065182A (en) * | 2011-10-19 | 2013-04-24 | 国民技术股份有限公司 | Module and method for field intensity self-adaption and non-contact integrated circuit (IC) card |
| CN104063674A (en) * | 2013-03-22 | 2014-09-24 | 国民技术股份有限公司 | Field intensity self-adaption circuit and method and smart card |
| CN104063954A (en) * | 2013-03-22 | 2014-09-24 | 国民技术股份有限公司 | Non-contact type power supply self-adaptive adjustment system and adjustment method thereof |
| CN103731046A (en) * | 2014-01-08 | 2014-04-16 | 卓捷创芯科技（深圳）有限公司 | Dynamic rectifying control circuit, passive radio frequency identification (RFID) and dynamic rectifying control method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109917180A (en) * | 2019-04-03 | 2019-06-21 | 杭州安脉盛智能技术有限公司 | Direct current signal non-contact detecting sensor based on current transformer |
| CN109917180B (en) * | 2019-04-03 | 2021-01-15 | 杭州安脉盛智能技术有限公司 | Direct current signal non-contact detection sensor based on current transformer |
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| PB01 | Publication | ||
| PB01 | Publication | ||
| CB02 | Change of applicant information |
Address after: 100083 18 floor, West Tower, block D, Tongfang science and Technology Plaza, 1 Wang Zhuang Road, Wudaokou, Haidian District, Beijing. Applicant after: Purple light co core Microelectronics Co., Ltd. Address before: 100083 18 floor, West Tower, block D, Tongfang science and Technology Plaza, 1 Wang Zhuang Road, Wudaokou, Haidian District, Beijing. Applicant before: Beijing Tongfang Microelectronics Company |
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| CB02 | Change of applicant information | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| WD01 | Invention patent application deemed withdrawn after publication |
Application publication date: 20180612 |
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| WD01 | Invention patent application deemed withdrawn after publication |