CN103714374A - Demodulation circuit of A-type non-contact IC card - Google Patents
Demodulation circuit of A-type non-contact IC card Download PDFInfo
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- CN103714374A CN103714374A CN201210376881.8A CN201210376881A CN103714374A CN 103714374 A CN103714374 A CN 103714374A CN 201210376881 A CN201210376881 A CN 201210376881A CN 103714374 A CN103714374 A CN 103714374A
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Abstract
The invention discloses a demodulation circuit of an A-type non-contact IC card. The demodulation circuit comprises a demodulation module and a fixed pulse width circuit, wherein the fixed pulse width circuit is capable of outputting a second pause signal of which pulse width fluctuation is smaller than that of a first pause signal output by the demodulation module. The pulse width of a pause signal output by the demodulation circuit is enabled to be decreased and fixed, the fluctuation of pulse width of the pause signal output by the demodulation circuit is enabled to be minimized, and the requirement of digital decoding on the fluctuation of pulse width of the pause signal output by the demodulation circuit is met. The pulse width of the second pause signal can be directly determined by a current source and a capacitor; the influence of manufacturing process conditions of the A-type non-contact IC card, working temperature conditions of the A-type non-contact IC card, power voltages, sensed through magnetic fields of different magnitudes, of the A-type non-contact IC card and different types of card readers to the pulse width of the pause signals can be greatly reduced; and the fluctuation of pulse width of the pause signals can be further reduced.
Description
Technical field
The present invention relates to a kind of SIC (semiconductor integrated circuit), particularly relate to a kind of demodulator circuit of A type contactless IC card.
Background technology
Between A type (type) contactless IC card and card reader, by radiofrequency signal, do carrier wave and carry out transmission information.A type contactless IC card itself does not have power supply, and electric energy during its work provides by the radiofrequency signal of card reader, and wherein the radiofrequency signal of card reader is 13.56MHz.When card reader and A type contactless IC card pass data mutually, the radio-frequency carrier that carrier wave is 13.56MHz, signal transmission rate has respectively 106kbits/s, 212kbits/s, 424kbits/s, tetra-kinds of 848kbits/s.
Wherein, while transmitting data from card reader to A type contactless IC card, be to adopt amplitude-shift keying (ASK) method to modulate signal, coded system is synchronous, improved Miller (miller) coding.It is 0 that card reader and contactless ic calorie requirement carry out digital communication, during 1 communication, the digital signal modulated of card reader can form the modulation signal that includes groove (pause) signal after on described radio-frequency carrier signal, the amplitude of groove (pause) signal is less than the amplitude of radio-frequency carrier, and the amplitude of groove when signal transmission rate is 106kbits/s (pause) signal is 0.Position difference according to pause signal in the sequential of modulation signal is come representative digit signal 0 or 1, so groove signal is the expression way of data.Modulation signal is input in contactless IC card by wireless transmission, contactless IC card carries out demodulation by demodulator circuit to this modulation signal after by this modulation signal of antenna reception, demodulating process is divided into analog demodulator and digital demodulation two steps, analog demodulator by demodulator circuit is demodulated into digital signaling zero or 1 by the pause signal in modulation signal, digital signal after demodulation is carried out to digital decoding, and digital decoding is data 0 or 1 according to what transmit in the different confirmation in the position card reader of 0 in the digital signal of input.
As shown in Figure 1, it is the sequential existing three kinds of analog codecs from card reader to A type contactless IC card, after the analog demodulator of the demodulator circuit by A type contactless IC card is demodulated into digital signaling zero or 1 by the pause signal in modulation signal, comprise three sequential, each sequential is corresponding to the transmission cycle of a data bit, and three sequential are defined as follows respectively:
1, sequential X, this sequential X will be in (1/2) * (fc/ transfer rate) * (1/fc) locate to produce a groove signal, at t
xit is t that place starts to produce a width
agroove signal.
2, sequential Y, this sequential Y is t during whole position
bdo not modulate.
3, sequential Z, during beginning during this sequential Z is in place, producing a width is t
agroove signal.
During for the transfer rate of 848kbits/s, 424kbits/s, 212kbits/s and 106kbits/s, the transmission time Tbit of a data position, be respectively 16,32,64 and 128 clock period (clk), 1clk=1/13.56MHz=73.746nS wherein, the transmission time, Tbit was shown as t at Fig. 1
b.
Changing of the pulse width of the groove signal of exporting after the decoding circuit analog codec of existing A type contactless IC card, and due to the limitation of digital decoding (miller signal being decoded) algorithm, under any transfer rate, maximal value and minimum value for the pulse width of groove signal, require Tmax-Tmin<(1/2) * Tbit, wherein Tmax represents the maximal value of the pulse width of groove signal, and Tmin represents the minimum value of the pulse width of groove signal.
The influence factor of the pulse width of the groove signal of existing A type contactless IC card output comprises: the operational temperature conditions of the fabrication process condition of A type contactless IC card, A type contactless IC card, A type contactless IC card are by magnetic field the vary in size supply voltage sensing, the many factors such as card reader that different vendor provides, these influence factors can make the pulse width variation of groove signal too large, when the variation range of pulse width exceeds formula Tmax-Tmin<(1/2) the defined scope of * Tbit is can not meet decoding algorithm requirement.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of demodulator circuit of A type contactless IC card, can make the pulse width of the groove signal of demodulator circuit output reduce and fix, make the fluctuation of pulse width of the groove signal of demodulator circuit output reduce to minimum, meet the requirement of digital decoding to the fluctuation of the pulse width of the groove signal of demodulator circuit output.
For solving the problems of the technologies described above, the demodulator circuit of A type contactless IC card provided by the invention comprises:
Demodulation module, this demodulation module carries out demodulation for the input signal that amplitude-shift keying is modulated, and can export the first groove pulse signal of a numeral; Be positioned at described input signal not in the same time the pulse width of described first groove signal of position can change.
Fixed pulse width circuit, the input end of this fixed pulse width circuit connects the output terminal of described demodulation module, for the second groove signal is processed and exported to described the first groove signal, make the fluctuation of the pulse width of described the second groove signal be less than the fluctuation of the pulse width of described the first groove signal.
Further improving is that the carrier frequency of A type contactless IC card is 13.56MHZ.
Further improving is that the influence factor that pulse width of described first groove signal of position does not change in the same time that is positioned at described input signal comprises: the operational temperature conditions of the fabrication process condition of A type contactless IC card, A type contactless IC card, A type contactless IC card by magnetic field the vary in size supply voltage sensing, different types of card reader.
Further improving is that described fixed pulse width circuit comprises a current source and an electric capacity, is determined the pulse width of described the second groove signal by described current source to the charging delay time of described electric capacity.
Further improving is that described fixed pulse width circuit also comprises:
Nmos pass transistor, the grid of this nmos pass transistor is connected with the output terminal of described demodulation module, the source ground of described nmos pass transistor, the drain electrode of described nmos pass transistor connects described current source, and the two ends of described electric capacity are connected with drain electrode with the source electrode of described NMOS crystal respectively.
The first phase inverter, the input end of this first phase inverter connects the drain electrode of described nmos pass transistor.
The second phase inverter, the input end of this second phase inverter connects the output terminal of described demodulation module.
Sheffer stroke gate, two input ends of this Sheffer stroke gate connect respectively the output terminal of described the first phase inverter and the output terminal of described the second phase inverter, and the output terminal of described Sheffer stroke gate is exported described the second groove signal.
The present invention by arranging fixed pulse width circuit in demodulator circuit, can export than the second less and fixing groove signal of pulse width of the pulse width of the first groove signal of demodulation module output, with respect to existing demodulator circuit, the present invention can make the pulse width of the groove signal of demodulator circuit output reduce and be fixing, make the fluctuation of pulse width of the groove signal of demodulator circuit output reduce to minimum, meet the requirement of digital decoding to the fluctuation of the pulse width of the groove signal of demodulator circuit output.And the pulse width of the second groove signal of the present invention can directly be determined by current source and electric capacity, can greatly reduce the fabrication process condition of A type contactless IC card, the impact of the supply voltage of the read write line of the operational temperature conditions of A type contactless IC card, A type contactless IC card on the pulse width of groove signal further reduces the fluctuation of the pulse width of groove signal.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:
Fig. 1 is the sequential existing three kinds of analog codecs from card reader to A type contactless IC card;
Fig. 2 is embodiment of the present invention electrical block diagram;
Fig. 3 is each node oscillogram when mode transfer piece is exported the first groove signal in Fig. 2.
Embodiment
As shown in Figure 2, be embodiment of the present invention electrical block diagram; The carrier wave of the demodulator circuit from card reader to A type contactless IC card of the embodiment of the present invention for the frequency being provided by card reader be 13.56MHZ radiofrequency signal, data-signal in card reader is modulated in radiofrequency signal and is input in the demodulator circuit of A type contactless IC card through amplitude-shift keying (ASK) method, input signal through ASK method modulation comprises by groove signal, and the amplitude of groove signal is less than the amplitude of radio-frequency carrier.Position difference according to groove signal signal in the sequential of input signal is come representative digit signal 0 or 1.The demodulator circuit of embodiment of the present invention A type contactless IC card is for carrying out analog demodulator to the groove signal of the input signal of ASK modulation, groove signal is demodulated into digital signaling zero or 1, wherein digital signaling zero is a groove, the digital signaling zero of analog demodulator or 1 comprises three sequential as shown in Figure 1, the digital signaling zero of analog demodulator or 1 is carried out can obtaining after digital demodulation to the data-signal of the original input in card reader.
The demodulator circuit of embodiment of the present invention A type contactless IC card comprises:
Demodulation module 1, this demodulation module 1 is for carrying out demodulation to the input signal of amplitude-shift keying modulation, the output terminal of demodulation module 1 is exported an output signal CMPOUT, this output signal CMPOUT is digital signal, output signal CMPOUT comprises the first groove signal, and this first groove signal is numeral 0 signal obtaining after the groove signal in input signal is decoded.Be positioned at described input signal not in the same time the pulse width of described first groove signal of position can change, the influence factor that produces this variation comprises: the operational temperature conditions of the fabrication process condition of A type contactless IC card, A type contactless IC card, A type contactless IC card by the magnetic field card reader that the supply voltage sensing, different types of card reader provide as different vendor that varies in size.
Fixed pulse width circuit 10, the input end of this fixed pulse width circuit 10 connects the output terminal of described demodulation module 1, for the second groove signal DEMOUT is processed and exported to described the first groove signal, make the fluctuation of the pulse width of described the second groove signal DEMOUT be less than the fluctuation of the pulse width of corresponding described the first groove signal.
Described fixed pulse width circuit 10 comprises:
One current source 2, one end of this current source 2 is connected with power vd D.
One electric capacity 3, one end of this electric capacity 3 is connected with the other end of described current source 2, the other end ground connection of described electric capacity 3.By described current source 2, to the charging delay time of described electric capacity 3, determined the pulse width of described the second groove signal DEMOUT.
The first phase inverter 5, the input end of this first phase inverter 5 connects the drain electrode of described nmos pass transistor 4, and the input one input signal NETA of the input end of described the first phase inverter 5, output terminal are exported an output signal NETB.
The second phase inverter 6, the input end of this second phase inverter 6 connects the output terminal of described demodulation module 1.The output terminal output signal NETC of described the second phase inverter 6.
As shown in Figure 3, be each node oscillogram when mode transfer piece is exported the first groove signal in Fig. 2.Wherein when output signal CMPOUT decline be produced as amplitude be 0 be the first groove signal time, described nmos pass transistor 4 is closed, thereby 2 pairs of described electric capacity 3 chargings of described current source are slowly risen the input end signal NETA of described the first phase inverter 5, until input end signal NETA is while rising to the overturn point of described the first phase inverter 5, output signal NETB produces upset.Output signal NETC is the negate of output signal CMPOUT, the output signal DEMOUT that output signal NETB and output signal NETC obtain burst pulse after negate is the second groove signal, can find out, the pulse width of the second groove signal is determined by current source and electric capacity, and the second groove signal is less and fixing than the pulse width of the pulse width of the first groove signal, can greatly reduce the fabrication process condition of A type contactless IC card, the operational temperature conditions of A type contactless IC card, the impact of the supply voltage of the read write line of A type contactless IC card on the pulse width of groove signal, make the fluctuation of pulse width of the groove signal of demodulator circuit output reduce to minimum, meet the requirement of digital decoding to the fluctuation of the pulse width of the groove signal of demodulator circuit output.
By specific embodiment, the present invention is had been described in detail above, but these are not construed as limiting the invention.Without departing from the principles of the present invention, those skilled in the art also can make many distortion and improvement, and these also should be considered as protection scope of the present invention.
Claims (5)
1. a demodulator circuit for A type contactless IC card, is characterized in that, comprising:
Demodulation module, this demodulation module carries out demodulation for the input signal that amplitude-shift keying is modulated, and can export the first groove pulse signal of a numeral; Be positioned at described input signal not in the same time the pulse width of described first groove signal of position can change;
Fixed pulse width circuit, the input end of this fixed pulse width circuit connects the output terminal of described demodulation module, for the second groove signal is processed and exported to described the first groove signal, make the fluctuation of the pulse width of described the second groove signal be less than the fluctuation of the pulse width of described the first groove signal.
2. the demodulator circuit of A type contactless IC card as claimed in claim 1, is characterized in that: the carrier frequency of A type contactless IC card is 13.56MHZ.
3. the demodulator circuit of A type contactless IC card as claimed in claim 1, is characterized in that: the influence factor that pulse width of described first groove signal of position does not change in the same time that is positioned at described input signal comprises: the operational temperature conditions of the fabrication process condition of A type contactless IC card, A type contactless IC card, A type contactless IC card by magnetic field the vary in size supply voltage sensing, different types of card reader.
4. the demodulator circuit of A type contactless IC card as claimed in claim 1, it is characterized in that: described fixed pulse width circuit comprises a current source and an electric capacity, by described current source, to the charging delay time of described electric capacity, determined the pulse width of described the second groove signal.
5. the demodulator circuit of A type contactless IC card as claimed in claim 4, is characterized in that: described fixed pulse width circuit also comprises:
Nmos pass transistor, the grid of this nmos pass transistor is connected with the output terminal of described demodulation module, the source ground of described nmos pass transistor, the drain electrode of described nmos pass transistor connects described current source, and the two ends of described electric capacity are connected with drain electrode with the source electrode of described NMOS crystal respectively;
The first phase inverter, the input end of this first phase inverter connects the drain electrode of described nmos pass transistor;
The second phase inverter, the input end of this second phase inverter connects the output terminal of described demodulation module;
Sheffer stroke gate, two input ends of this Sheffer stroke gate connect respectively the output terminal of described the first phase inverter and the output terminal of described the second phase inverter, and the output terminal of described Sheffer stroke gate is exported described the second groove signal.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210376881.8A CN103714374B (en) | 2012-09-28 | 2012-09-28 | The demodulator circuit of A type contactless IC card |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210376881.8A CN103714374B (en) | 2012-09-28 | 2012-09-28 | The demodulator circuit of A type contactless IC card |
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| CN103714374A true CN103714374A (en) | 2014-04-09 |
| CN103714374B CN103714374B (en) | 2016-08-17 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105577149A (en) * | 2014-10-09 | 2016-05-11 | 上海华虹集成电路有限责任公司 | Waveform shaping circuit after card communication demodulation in ISO/IEC 14443 protocol |
| CN105738002A (en) * | 2014-12-24 | 2016-07-06 | 精工半导体有限公司 | Overheat detection circuit and semiconductor device |
| CN106228095A (en) * | 2016-07-19 | 2016-12-14 | 天津市炳华节能技术有限公司 | A kind of implementation method of the automatic card seeking of radio-frequency card |
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| CN1805416A (en) * | 2006-01-20 | 2006-07-19 | 清华大学 | Comparison and decision circuit in amplitude keying signal demodulation circuit module |
| CN101615260A (en) * | 2008-06-27 | 2009-12-30 | 株式会社瑞萨科技 | SIC (semiconductor integrated circuit), the IC-card that this circuit is installed and this IC-card method of operating |
| US20110310520A1 (en) * | 2010-06-22 | 2011-12-22 | Oticon A/S | High voltage swing input/output enabled in a standard ic process using passive impedance transformation |
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Patent Citations (4)
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| JPH0991072A (en) * | 1995-09-22 | 1997-04-04 | Canon Inc | Data processor and its controlling method |
| CN1805416A (en) * | 2006-01-20 | 2006-07-19 | 清华大学 | Comparison and decision circuit in amplitude keying signal demodulation circuit module |
| CN101615260A (en) * | 2008-06-27 | 2009-12-30 | 株式会社瑞萨科技 | SIC (semiconductor integrated circuit), the IC-card that this circuit is installed and this IC-card method of operating |
| US20110310520A1 (en) * | 2010-06-22 | 2011-12-22 | Oticon A/S | High voltage swing input/output enabled in a standard ic process using passive impedance transformation |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105577149A (en) * | 2014-10-09 | 2016-05-11 | 上海华虹集成电路有限责任公司 | Waveform shaping circuit after card communication demodulation in ISO/IEC 14443 protocol |
| CN105577149B (en) * | 2014-10-09 | 2018-08-14 | 上海华虹集成电路有限责任公司 | Waveform shaping circuit after card communication demodulation in 14443 agreements of ISO/IEC |
| CN105738002A (en) * | 2014-12-24 | 2016-07-06 | 精工半导体有限公司 | Overheat detection circuit and semiconductor device |
| CN105738002B (en) * | 2014-12-24 | 2020-03-03 | 艾普凌科有限公司 | Overheat detection circuit and semiconductor device |
| CN106228095A (en) * | 2016-07-19 | 2016-12-14 | 天津市炳华节能技术有限公司 | A kind of implementation method of the automatic card seeking of radio-frequency card |
| CN106228095B (en) * | 2016-07-19 | 2019-03-29 | 天津市炳华节能技术有限公司 | A kind of implementation method of the automatic card seeking of radio-frequency card |
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| CN103714374B (en) | 2016-08-17 |
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