CN202583439U - Critical field intensity detection and protection circuit and radio frequency identification chip - Google Patents
Critical field intensity detection and protection circuit and radio frequency identification chip Download PDFInfo
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- CN202583439U CN202583439U CN 201120546932 CN201120546932U CN202583439U CN 202583439 U CN202583439 U CN 202583439U CN 201120546932 CN201120546932 CN 201120546932 CN 201120546932 U CN201120546932 U CN 201120546932U CN 202583439 U CN202583439 U CN 202583439U
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Abstract
The utility model relates to a critical field intensity detection and protection circuit and a radio frequency identification chip. The critical field intensity detection and protection circuit indirectly judges a current allowance available under the current working field intensity through detecting the magnitude of a current flowing through the bleeder of a rectifier and limiter circuit, so as to ensure the radio frequency recognition chip to be operated within a normal field intensity scope. Meanwhile, in order to meet the need of the practical application, a lowest detection threshold is set to ensure the radio frequency identification chip to be operated in a more reliable field intensity and prevent the unstable operation of the radio frequency identification chip in a critical field intensity. The critical field intensity detection and protection circuit is simple in structure and does not occupy excessive area of the chip or consumes excessive power.
Description
Technical field
The utility model relates to the magnetic field intensity detection range, is specifically related to a kind of critical field strength and detects holding circuit and the RF identification chip with critical field strength detection holding circuit.
Background technology
At present, non-contact IC card or RFID tag have effect more and more widely, and it generally uses in industries such as subway, public transport, authentication, logistics, admission ticket, just progressively replaces traditional paper ticket.Non-contact IC card is claimed radio-frequency identification card again, is made up of IC chip, induction antenna, is encapsulated in the PVC card of a standard, and chip and antenna do not have any exposed parts.Fig. 1 shows in order to accomplish the proper communication between card reader and the radio-frequency identification card; The logical organization functional circuit of present widely used radio-frequency identification card chip internal; As shown in Figure 1: said radio-frequency identification card chip internal comprises analog radio frequency front-end module 100 and processor 200; Wherein, said analog radio frequency front-end module 100 also comprises rectification amplitude limit unit 101, Clock Extraction unit 102, voltage regulation unit 103, modem module 104 and reset detection unit 105.Wherein rectification amplitude limit unit 101 changes AC signal ANTA, the ANTB that the antenna coupling is come into through amplitude limit direct current signal on the one hand, sends into follow-up voltage regulation unit 103 then and handles with modem module 104; Clock Extraction unit 102 generates synchronous clock clk and input processor 200; Producing burning voltage vdd by voltage regulation unit 103 supplies power to internal circuit; Reset detection unit 105 produces reset signal por and input processor 200 according to the height of vdd; When communicating with outside card reader, modem module 104 recovers card reader and transmits data d_out to processor 200 through the detection to envelope signal.
Radio-frequency identification card; Need in certain field strength range, can carry out proper communication with card reader; The data read-write operation with card reader is accomplished in its transmission through radiowave, and therefore, the residing field intensity of radio-frequency identification card is different; The energy that antenna is coupled to is also different, thereby the electric current that flows into chip is also different.Under low field intensity, the antenna of radio-frequency identification card can only be coupled to less energy, and the electric current that flows into chip is also less, causes the reliability and stability of chip operation to can not get guaranteeing; To the situation of present one card for multiple uses, in different application, used algorithm is also different simultaneously, so the chip maximum power dissipation is different, causes minimum field intensity demand different the most at last.
The utility model content
The utility model technical matters to be solved provides a kind of critical field strength and detects holding circuit and RF identification chip; The size of current of the bleeder pipe through detecting the rectification amplitude limiter circuit; Judge the electric current surplus that the work at present field intensity provides; Guarantee that with this radio-frequency identification card is operated in normal field strength range, avoids the unstable operation under critical field strength.
The utility model is in order to solve the problems of the technologies described above; Disclose a kind of critical field strength and detected holding circuit; Said critical field strength detects holding circuit and comprises that signal conversion module, field intensity detect judge module; Said signal conversion module receives the grid voltage control signal of outside rectification amplitude limiter circuit, and is converted into the output of load voltage value; Said field intensity detects the load voltage value that judge module receives signal conversion module, and itself and reference voltage level are compared, and output is to the judged result of field intensity.
Further, said signal conversion module comprises: the first transistor, transistor seconds, the 3rd transistor and load circuit, wherein,
The grid of said the first transistor is connected with outside rectification amplitude limiter circuit, receives the grid voltage control signal of rectification amplitude limiter circuit output, and its source electrode is connected with ground, and its drain electrode is connected with the drain electrode of said transistor seconds;
The source electrode of said transistor seconds is connected with power vd D, and its grid is connected with the drain electrode of the first transistor with drain electrode;
The said the 3rd transistorized source electrode is connected with power vd D, and its grid is connected with drain electrode with the grid of transistor seconds, and its drain electrode is connected with load circuit, and the output load magnitude of voltage.
Further, said load circuit is made up of the capacitor C and the resistance R of parallel connection, and an end of the capacitor C of said parallel connection and resistance R is connected with the said the 3rd a transistorized end, and the other end is connected with ground.
Further, said resistance R is an adjustable resistance, exports different load voltage values through regulating resistance R.
Further; Said field intensity detects judge module and comprises comparer; An input end of said comparer is connected with the 3rd transistor drain; Another input end receives reference voltage level, and said comparer compares load voltage value and reference voltage level, and the output terminal output of said comparer is to the judged result of field intensity.
Further, said the first transistor is the N transistor npn npn.
Further, said transistor seconds and the 3rd transistor are the P transistor npn npn.
The invention also discloses a kind of RF identification chip; Said RF identification chip comprises that above-described critical field strength detects holding circuit and rectification amplitude limiter circuit; Said critical magnetic field detects holding circuit and receives the grid voltage control signal of said rectification amplitude limiter circuit, and is converted into the output of load voltage value.
Further; Said rectification amplitude limiter circuit comprises voltage detecting circuit module and bleeder pipe; The source electrode of said bleeder pipe is connected with ground; Its grid is connected with said voltage detecting circuit module with drain electrode, and said voltage detecting circuit module output grid voltage control signal is with the grid of controlled discharge pipe, thus the leakage current size of regulating bleeder pipe.
Further, said bleeder pipe is the N transistor npn npn.
Adopt the beneficial effect of above-mentioned the utility model technical scheme to be: the critical field strength that the utility model provides detects holding circuit; Can be integrated in the inside of radio-frequency identification card chip; The size of current of the bleeder pipe through detecting amplitude limiter circuit; Judge the electric current surplus that the work at present field intensity provides, guarantee that with this radio-frequency identification card is operated in normal field strength range, avoids the unstable operation under critical field strength; Simultaneously, this circuit structure is simple, can not consume too much chip area and power consumption.
Description of drawings
Fig. 1 is the inner building-block of logic of RF identification chip that generally uses at present;
The equivalent circuit diagram that Fig. 2 communicates for card reader among the utility model embodiment and radio-frequency identification card;
Fig. 3 is the building-block of logic of radio-frequency identification card chip internal among the utility model embodiment;
Fig. 4 is the circuit diagram of field intensity testing circuit module among the utility model embodiment;
Fig. 5 is a kind of physical circuit project organization figure of adjustable resistance R among the utility model embodiment.
Embodiment
Below in conjunction with accompanying drawing the principle and the characteristic of the utility model are described, institute gives an actual example and only is used to explain the utility model, is not the scope that is used to limit the utility model.
The equivalent circuit diagram that Fig. 2 communicates for card reader among the utility model embodiment and radio-frequency identification card; The principle of the utility model is described below in conjunction with Fig. 2; As shown in Figure 2: L1 is the aerial coil of card reader; L2 is the resonance coil on the radio-frequency identification card, when radio-frequency identification card during near the antenna of card reader, on radio-frequency identification card, induces electric current I 2 and voltage VA (voltage of VA is by the decision of rectification amplitude limiter circuit in the present embodiment) through electromagnetic induction.The electric current that wherein flows through chip load R1 is I3, and the electric current that flows through rectification amplitude limiter circuit Lmt is I4, by knowing I2=I3+I4 among the figure.Therefore, when radio-frequency identification card near card reader, when perhaps the emissive power of card reader strengthens; The magnetic field that radio-frequency identification card is sensed is also just big more, and the electric current I 2 that induction produces also can become greatly thereupon, and I3 generally is a fixing value; So when field intensity becomes big, finally cause I4 to become big.
Hence one can see that; The field intensity that card reader produced is directly proportional with the size that flows through the electric current I 2 of radio-frequency identification card aerial coil, again because chip Finite Amplitude circuit Lmt can be stabilized to a fixed value with voltage VA; So can release: H ∝ W=P*t according to power P=IV; Wherein H is a magnetic field intensity, and P is a power, and W is that RF identification is stuck in the energy of being sensed in the time t; And the energy W that magnetic field intensity H and radio-frequency identification card are sensed also is directly proportional, and promptly magnetic field H is strong more, and the energy W that radio-frequency identification card obtained is just many more.Because P=VA*I2 adds the amplitude limit module, can keep the stable of VA again, so H ∝ I2, promptly field intensity H is strong more, and the electric current I 2 that the radio-frequency identification card induction obtains is just big more.And the electric current I 2=I3+I4 of radio-frequency identification card chip induction; Wherein I3 is the fixedly power consumption of chip, and I4 is the electric current that flows through the amplitude limit module, as I3 during less than I2; Unnecessary electric current flows away through I4; So the size of current of I4 can reflect the variation of I2 indirectly, can further release thus: H ∝ I2=I3+I4->H ∝ I4, promptly magnetic field intensity H is big more; The electric current I 4 that flows through amplitude limiter circuit Lmt is also just big more, so the utility model just is based on this principle is judged current field intensity through the size of the electric current I 4 of detection rectification amplitude limit module size.
Fig. 3 is the building-block of logic of radio-frequency identification card chip internal among the utility model embodiment; As shown in Figure 3: the radio-frequency identification card chip comprises rectification amplitude limiter circuit 300 and critical field strength detection module 400; Wherein, Rectification amplitude limiter circuit 300 comprises voltage detecting circuit module 301 and bleeder pipe N0 again, and the source electrode of said bleeder pipe N0 is connected with ground, and its grid is connected with said voltage detecting circuit module 301 with drain electrode; Said voltage detecting circuit module 301 output grid voltage control signal Lmt_ctrl, the grid of controlled discharge pipe N0; Voltage detecting circuit module 301 passes through to detect the size of voltage VA simultaneously, thereby changes the control voltage swing of bleeder pipe N0 grid, so that further regulate the size of the leakage current I4 of bleeder pipe N0.
In this embodiment, critical field strength detection module 400 also comprises field intensity testing circuit module 401 and detects configuration and judge module 402.Grid voltage control signal Lmt_ctrl with 301 outputs of voltage detecting circuit module is directly inputted in the field intensity testing circuit module 401 of critical field strength detection module 400 through rectification amplitude limiter circuit 300, detects back output testing result IDL and judges to detecting in configuration and the judge module 402.Said detection configuration and judge module 402, the applied environment that one side receiving processor 500 sends is selected signal, selects suitable configuration signal TR to export field intensity testing circuit module 401 to; Judge the output signal IDL of field intensity testing circuit module 401 on the other hand through sampling, and final testing result is exported in the processor 500.
In the above-mentioned embodiment, said field intensity testing circuit module 401 judges according to the configuration signal TR that detects configuration and judge module 402 outputs whether the electric current I 4 of bleeder pipe N0 reaches detection threshold, and output signal IDL is to detecting configuration and judge module 402.Detection configuration and judge module 402 are made as judging according to the result of the continuous sampling IDL in a period of time:
If the result of IDL is " 0 ", judge that then current field intensity does not meet demand, stop communication, proceed to detect by field intensity testing circuit module 401;
If the result of IDL is " 1 ", judge that then current field intensity meets demand, continue follow-up communication; When the result of said IDL was " 1 ", system can also automatically perform and close critical field strength detection module 400, according to the particular moment or the special scenes of configuration information, opened critical field strength detection module 400 again and detected.
Fig. 4 is the circuit diagram of field intensity testing circuit module among the utility model embodiment; The size of current of bleeder pipe N0 through detecting the rectification amplitude limiter circuit; Judge the electric current surplus that the work at present field intensity provides, to avoid the unstable operation of chip under critical field strength.As shown in Figure 4; Said field intensity detects holding circuit and comprises: the first transistor N1, transistor seconds P0, the 3rd transistor P1, load circuit and comparator C omp; Wherein, the grid of said the first transistor N1 is connected with outside rectification amplitude limiter circuit, receives the grid voltage control signal Lmt_ctrl of rectification amplitude limiter circuit output; Its source electrode is connected with ground, and its drain electrode is connected in the A point with the drain electrode of said transistor seconds P0; The source electrode of said transistor seconds P0 is connected with power vd D, and the drain electrode of its grid and drain electrode and the first transistor N1 and the grid of the 3rd transistor P1 are connected in the A point; The source electrode of said the 3rd transistor P1 is connected with power vd D, and its drain electrode is connected in the B point with an end of load circuit, and the other end of said load circuit is connected with ground; Wherein, the load circuit described in the present embodiment is made up of the capacitor C and the resistance R of parallel connection.In the utility model embodiment, flow through the electric current I 5 of the first transistor N1, its proportionate relationship according to the mirror image pipe can be known, I5=n*I4, wherein n is the scale-up factor of bleeder pipe N0 and the first transistor N1.And the image current of the 3rd transistor P1 is I6, and I6=m*I5=m*n*I4, wherein m is the scale-up factor of transistor seconds P0 and the 3rd transistor P1; I6 flows through resistance R and produces load voltage value VB, wherein VB=I6*R=m*n*I4*R.
Two input ends of comparator C omp receive load voltage value VB and reference voltage level Vref respectively, as Vref>during VB, promptly I4 Vref/ (m*n*R), comparator C omp exports IDL=" 0 ", the expression field intensity is lower than the minimum field strength detection threshold; As Vref < during VB, i.e. I4>Vref/ (m*n*R), comparator C omp exports IDL=" 1 ", and the expression field intensity is higher than the minimum field strength detection threshold.Certainly, it will be understood by those skilled in the art that as circuit design is carried out certain adjustment, also can be designed as at Vref during VB, the expression field intensity is higher than the minimum field strength detection threshold; < during VB, the expression field intensity is lower than the minimum field strength detection threshold, and modification of being made and change all should be in the protection domains of the utility model at Vref.
In the utility model embodiment, resistance R is an adjustable resistance, can carry out different samplings to load voltage value VB through regulating resistance R, thereby the different detection current point can be set.Fig. 5 is a kind of physical circuit project organization figure of adjustable resistance R among the utility model embodiment; As shown in Figure 5; Through select different sampling switch K0, K1 ..., Kn and from R_0, R_1 ... Choose different sampling spots on the R_n resistance; Thereby export different load voltage value VB, obtain different configuration signal TR_0, TR_0 ..., TR_n realizes the change for the current detecting thresholding.
The field intensity testing circuit that the utility model provides is the module that can join, can be integrated in the inside of radio-frequency identification card chip, can guarantee that chip operation is under reliable field intensity; And its circuit structure is simple, need not consume excessive chip area and power consumption, has also improved the compatibility of chip to a certain extent.
The above is merely the preferred embodiment of the utility model, and is in order to restriction the utility model, not all within the spirit and principle of the utility model, any modification of being done, is equal to replacement, improvement etc., all should be included within the protection domain of the utility model.
Claims (10)
1. a critical field strength detects holding circuit; It is characterized in that; Said critical field strength detects holding circuit and comprises that signal conversion module, field intensity detect judge module, and said signal conversion module receives the grid voltage control signal of outside rectification amplitude limiter circuit, and is converted into the output of load voltage value; Said field intensity detects the load voltage value that judge module receives signal conversion module, and itself and reference voltage level are compared, and output is to the judged result of field intensity.
2. critical field strength according to claim 1 detects holding circuit, it is characterized in that said signal conversion module comprises: the first transistor, transistor seconds, the 3rd transistor and load circuit, wherein,
The grid of said the first transistor is connected with outside rectification amplitude limiter circuit, receives the grid voltage control signal of rectification amplitude limiter circuit output, and its source electrode is connected with ground, and its drain electrode is connected with the drain electrode of said transistor seconds;
The source electrode of said transistor seconds is connected with power vd D, and its grid is connected with the drain electrode of the first transistor with drain electrode;
The said the 3rd transistorized source electrode is connected with power vd D, and its grid level is connected with drain electrode with the grid of transistor seconds, and its drain electrode is connected with load circuit, and the output load magnitude of voltage.
3. critical field strength according to claim 2 detects holding circuit; It is characterized in that; Said load circuit is made up of the capacitor C and the resistance R of parallel connection, and an end of the capacitor C of said parallel connection and resistance R is connected with the said the 3rd a transistorized end, and the other end is connected with ground.
4. critical field strength according to claim 3 detects holding circuit, it is characterized in that said resistance R is an adjustable resistance, exports different load voltage values through regulating resistance R.
5. critical field strength according to claim 4 detects holding circuit; It is characterized in that; Said field intensity detects judge module and comprises comparer, and an input end of said comparer is connected with the 3rd transistor drain, and another input end receives reference voltage level; Said comparer compares load voltage value and reference voltage level, and the output terminal output of said comparer is to the judged result of field intensity.
6. critical field strength according to claim 2 detects holding circuit, it is characterized in that said the first transistor is the N transistor npn npn.
7. critical field strength according to claim 2 detects holding circuit, it is characterized in that said transistor seconds and the 3rd transistor are the P transistor npn npn.
8. RF identification chip; It is characterized in that; Said RF identification chip comprises that each described critical field strength of claim 1 to 7 detects holding circuit and rectification amplitude limiter circuit; Said critical magnetic field detects holding circuit and receives the grid voltage control signal of said rectification amplitude limiter circuit, and is converted into the output of load voltage value.
9. chip according to claim 8; It is characterized in that; Said rectification amplitude limiter circuit comprises voltage detecting circuit module and bleeder pipe, and the source electrode of said bleeder pipe is connected with ground, and its grid is connected with said voltage detecting circuit module with drain electrode; Said voltage detecting circuit module output grid voltage control signal is with the grid of controlled discharge pipe, thus the leakage current size of regulating bleeder pipe.
10. chip according to claim 9 is characterized in that, said bleeder pipe is the N transistor npn npn.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN 201120546932 CN202583439U (en) | 2011-12-23 | 2011-12-23 | Critical field intensity detection and protection circuit and radio frequency identification chip |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201120546932 CN202583439U (en) | 2011-12-23 | 2011-12-23 | Critical field intensity detection and protection circuit and radio frequency identification chip |
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| CN202583439U true CN202583439U (en) | 2012-12-05 |
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| CN 201120546932 Expired - Lifetime CN202583439U (en) | 2011-12-23 | 2011-12-23 | Critical field intensity detection and protection circuit and radio frequency identification chip |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103926965A (en) * | 2013-01-16 | 2014-07-16 | 上海华虹集成电路有限责任公司 | Self-biased constant-current voltage stabilizing circuit |
| CN104516381A (en) * | 2013-09-26 | 2015-04-15 | 上海华虹集成电路有限责任公司 | Rectification and voltage stabilization circuit for radio frequency identification |
| WO2015103956A1 (en) * | 2014-01-08 | 2015-07-16 | 卓捷创芯科技（深圳）有限公司 | Dynamic rectification control circuit and passive rfid, and dynamic rectification control method |
| CN106610687A (en) * | 2015-10-23 | 2017-05-03 | 上海华虹集成电路有限责任公司 | Critical field intensity protection system in radio frequency identification |
-
2011
- 2011-12-23 CN CN 201120546932 patent/CN202583439U/en not_active Expired - Lifetime
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103926965A (en) * | 2013-01-16 | 2014-07-16 | 上海华虹集成电路有限责任公司 | Self-biased constant-current voltage stabilizing circuit |
| CN104516381A (en) * | 2013-09-26 | 2015-04-15 | 上海华虹集成电路有限责任公司 | Rectification and voltage stabilization circuit for radio frequency identification |
| 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 |
| WO2015103956A1 (en) * | 2014-01-08 | 2015-07-16 | 卓捷创芯科技（深圳）有限公司 | Dynamic rectification control circuit and passive rfid, and dynamic rectification control method |
| CN106610687A (en) * | 2015-10-23 | 2017-05-03 | 上海华虹集成电路有限责任公司 | Critical field intensity protection system in radio frequency identification |
| CN106610687B (en) * | 2015-10-23 | 2018-02-13 | 上海华虹集成电路有限责任公司 | Critical field strength protection system in radio frequency identification |
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Granted publication date: 20121205 |