CN104573794A - Frequency modulation return circuit for passive radio frequency card - Google Patents
Frequency modulation return circuit for passive radio frequency card Download PDFInfo
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- CN104573794A CN104573794A CN201410813843.3A CN201410813843A CN104573794A CN 104573794 A CN104573794 A CN 104573794A CN 201410813843 A CN201410813843 A CN 201410813843A CN 104573794 A CN104573794 A CN 104573794A
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Abstract
The invention discloses a frequency modulation return circuit for a passive radio frequency card, and belongs to the technical field of radio frequency circuits. The frequency modulation return circuit is used for enabling the passive radio frequency card to return voltage to an antenna loop so as to replenish power consumption when carrier waves are cut off from a card reader, and comprises an electricity storage capacitor for storing voltage, wherein the electricity storage capacitor is connected with the antenna loop through a simulation switch and is used for recharging the antenna loop after the simulation switch is turned on. A clock circuit module, a frequency-halving circuit module and a pulse generation circuit module are further integrated in the frequency modulation return circuit, the clock circuit module is used for extracting clock signals from two ends of an antenna, the frequency-halving circuit module is used for receiving the clock signals and outputting frequency-halving signals, the pulse generation circuit module is used for receiving the frequency-halving signals and used for generating time-delay pulse for turning on the simulation switch. The frequency modulation return circuit is adopted to provide power consumption for maintaining transmission of antenna signals, the defect that a conventional electronic tag is instable in chip property after the carrying waves are cut off from the card reader is overcome, and the passive radio frequency card can work stably.
Description
Technical field
The invention belongs to radio circuit technical field, be specially a kind of frequency modulation (PFM) return circuit for passive RF card.
Background technology
Passive radio-frequency identification labeled, being also passive RF card, is the transponder part of radio-frequency recognition system (RFID).RFID technique development is very rapid, passive RF jig has that volume is little, reading speed is fast, resistance to stained, be easy to realize automatic identification, the anti-interference plurality of advantages such as by force, in many fields such as logistics, gate inhibition, asset management, animal tag, vehicle identification, there is broad prospect of application.
Passive RF card relies on the carrier energy receiving card reader transmission to carry out work.Card reader sends carrier signal, antenna (or coil) in passive RF card and resonant capacitance form resonant tank and receive, carrier signal produces supply voltage, data-signal and system clock thus, data circuit is modulated on carrier wave after phase modulation coding, returns card reader through antenna.
Because base-band data signal has lower frequency component, should not be transmitted by wireless channel, therefore need to be delivered by a carrier wave, require that certain parameter of carrier wave changes with the rule of baseband signal.The method of passive RF card working load modulation transmits data to read write line.The antenna of passive RF card is the load of reading and writing device antenna, and radio-frequency card, by changing the parameter of antenna loop, makes read write line end modulated, thus realizes the data transmission snapping into card reader with faint energy from radio frequency.By regulating according to the beat of data stream the electrical quantity of resonant tank, the impedance magnitude that passive RF card signal is reflected and phase place change thereupon, thus complete the process of modulation.
Due to power consumption constraints, in the chip design of passive RF card, design one and the frequency modulation circuit of chip steady operation can be allowed always to be the difficult point of industry, adopt this circuit structure can solve the problem that on antenna, data-signal transmission is unstable well.
Summary of the invention
Technical matters to be solved by this invention is to provide a kind of frequency modulation (PFM) return circuit for passive RF card, be stuck in card reader for passive RF to disconnect after carrier wave and return the pulse voltage that matches with signal with supplementary power consumption to antenna loop, ensure that data send stable.Its technical scheme is as follows:
A kind of frequency modulation (PFM) return circuit for passive RF card, it is characterized in that, comprise accumulate electric capacity, it receives by antenna loop the voltage produced after card reader sends carrier wave for storing, and be connected with antenna loop by an analog switch, after described analog switch is opened, antenna loop is charged.
Frequency modulation (PFM) return circuit also comprises clock circuit module, and its antenna ends from passive RF card extracts clock signal; Clock signal is received and the two divided-frequency signal of clock signal by frequency-halving circuit module; Receive described two divided-frequency signal by pulse-generating circuit module, and produce delay pulse in order to open described analog switch along the peak value of two divided-frequency signal.
Further, described analog switch is composed in parallel by 3 pmos pipes, the grid of described pmos pipe connects described pulse-generating circuit module, and the source electrode of described pmos pipe connects described accumulate electric capacity, one end of the antenna of the drain electrode connected with passive radio-frequency card of described pmos pipe.
Further, described accumulate electric capacity is 220nF electric capacity.
Further, described pulse-generating circuit module comprises clock delay circuit module, and it exports rear end and described two divided-frequency signal accesses a Sheffer stroke gate, forms pulse-generating circuit module; Each periodic signal of described two divided-frequency signal produces negative level after clock delay circuit module and Sheffer stroke gate, and continues 100ns, obtains described delay pulse.
Further, described clock delay circuit module is made up of 3 inverter series, after first phase inverter and second phase inverter, connect filter capacitor respectively.
Frequency modulation (PFM) return circuit also comprises demodulator circuit module, its two ends in parallel and antenna, and connects described frequency-halving circuit module, to frequency-halving circuit module enable signal; When card reader sends carrier wave, described frequency-halving circuit module output enable signal is high level signal, frequency-halving circuit module attonity, and follow-up circuit does not enter duty; When carrier wave stops, described enable signal is low level signal, and frequency-halving circuit module is effective, exports described two divided-frequency signal.
Further, the antenna loop of frequency modulation (PFM) return circuit comprises antenna, and and the first resonant capacitance of sky line parallel and the second resonant capacitance, the front end of described second resonant capacitance is connected to the switch controlled by the data circuit of passive RF card; When data circuit output control signal is 0, described second resonant capacitance is inoperative, and signal return frequency is 134.2kHz; When data circuit output control signal is 1, described time second resonant capacitance adds resonance, and signal return frequency is 125kHz.
Control resonant capacitance by the break-make of switch to switch on and off, the resonance frequency of passive RF card is changed between two frequencies.The access of electric capacity makes the voltage drop on passive RF card antenna, reduces power consumption; Corresponding, card reader antenna voltage promotes, and strengthens resonance, ensures that stable signal transmission is continuous.
Signal return frequency changes, corresponding, the clock signal that described clock circuit module is extracted changes, and the frequency of the pulse voltage that subsequent conditioning circuit produces also changes simultaneously.
Compared with prior art, the present invention adopts novel circuit design method, adopts circuit of the present invention to solve well after card reader breaks carrier wave, and chip can be the stable power consumption self providing process and send needed for data.This frequency modulation circuit maintains chip and normally works, and sends data stabilization, and the Distance geometry performance that can read of passive RF the core of the card sheet is further promoted.Overcome the shortcoming of conditional electronic label chip performance instability after card reader breaks carrier wave, make the performance of chip be greatly improved and optimize.
Accompanying drawing explanation
Fig. 1 is the structural representation for the frequency modulation (PFM) return circuit of passive RF card in the present invention.
Fig. 2 is each signal waveform emulation schematic diagram in the present invention.
Embodiment
Below in conjunction with accompanying drawing, the present invention is further illustrated:
As shown in fig. 1, for the frequency modulation (PFM) return circuit of passive RF card, be integrated with accumulate electric capacity, analog switch and clock extracting circuit, demodulator circuit module, pulse (pluck) produce the circuit modules such as circuit module.
Accumulate electric capacity is 220nF, and it connects power circuit, receives and stores the voltage produced after card reader sends carrier wave.Clock extracting circuit is connected to two ends S1 and S2 of antenna and goes out clock signal clk from the carrier extract that antenna receives, the two ends parallel resonance electric capacity C of antenna
1, electric capacity C
2and demodulator circuit, electric capacity C2 open and the disconnected control signal mod exported by digital signal controls.
The output din of demodulator circuit and the output CLK of clock extracting circuit is connected to frequency-halving circuit.Din is the enable signal of two divided-frequency, and din exports as low level signal, and frequency-halving circuit module is effective; Din exports as high level signal, and frequency-halving circuit module is not imitated, and follow-up circuit does not all enter duty.
In conjunction with signal intensity each in circuit as shown in Figure 2, the two divided-frequency signal CLK2 of the output CLK of frequency-halving circuit, CLK2 receive the input end that pluck produces circuit module.Pluck produces circuit and comprises clock delay circuit, and it is by 3 inverter series, after first phase inverter and second phase inverter, connect filter capacitor respectively, and the 3rd phase inverter rear end and frequency-halving circuit access a Sheffer stroke gate.The each periodic signal of CLK2 is received after Sheffer stroke gate inputs through clock delay circuit and CLK2, produces a 100ns delay pulse Clkpuse.
The negative pulse of Clkpuse opens the analog switch MP0 that 3 pmos pipes are connected in parallel, and the source electrode of three pmos pipes in parallel meets accumulate capacitor high voltage end hv, and drain electrode meets antenna end S1.
Above-mentioned circuit constitutes the circuit structure of the present invention for the entirety of the frequency modulation (PFM) return circuit of passive RF card.Delay pulse Clkpuse opens MP0, extracts voltage charge to antenna loop by MP0 from accumulate electric capacity, the stable power consumption providing process and send needed for data.
The frequency of passive RF card return signal is determined by the coil (antenna) of chip exterior and internal capacitance.After matched coil, by the unlatching of gauge tap, determine whether electric capacity C2 connects people's chip input end, thus change signal return frequency.When control signal MOD=0 time, C2 is inoperative, and the frequency returned is 134.2k; When control signal MOD=1 time, C2 adds resonance, and the frequency returned is 125kHz.Corresponding, the CLK that clock circuit module is extracted changes, and the frequency of the pulse voltage that subsequent conditioning circuit produces also changes simultaneously.
This circuit can well solve after card reader breaks carrier wave, and chip can be the power consumption self providing reception and send needed for data, and performance is very stable.
Just the specific embodiment of the present invention is more than described; when not departing from the principle of circuit of the present invention; others skilled in the art still originally based on many distortion or the improvement made in ultimate principle of the circuit of invention, should may include within protection scope of the present invention.
Claims (7)
1., for a frequency modulation (PFM) return circuit for passive RF card, be stuck in card reader for passive RF and disconnect after carrier wave the pulse voltage that matches with signal is returned with supplementary power consumption to antenna loop, it is characterized in that, comprising:
Accumulate electric capacity, it receives by antenna loop the voltage produced after card reader sends carrier wave for storing, and is connected with antenna loop by an analog switch, charges after described analog switch is opened to antenna loop;
Clock circuit module, its antenna ends from passive RF card extracts clock signal;
Frequency-halving circuit module, it receives described clock signal and the two divided-frequency signal of clock signal;
Pulse-generating circuit module, it receives described two divided-frequency signal, and produces delay pulse in order to open described analog switch along the peak value of two divided-frequency signal.
2. as claimed in claim 1 for the frequency modulation (PFM) return circuit of passive RF card, it is characterized in that, described analog switch is composed in parallel by 3 pmos pipes, the grid of described pmos pipe connects described pulse-generating circuit module, the source electrode of described pmos pipe connects described accumulate electric capacity, one end of the antenna of the drain electrode connected with passive radio-frequency card of described pmos pipe.
3., as claimed in claim 1 for the frequency modulation (PFM) return circuit of passive RF card, it is characterized in that, described accumulate electric capacity is 220nF electric capacity.
4. as claimed in claim 1 for the frequency modulation (PFM) return circuit of passive RF card, it is characterized in that, described pulse-generating circuit module comprises clock delay circuit module, and it exports rear end and described two divided-frequency signal accesses a Sheffer stroke gate, forms pulse-generating circuit module;
Each periodic signal of described two divided-frequency signal produces delay pulse after clock delay circuit module and Sheffer stroke gate.
5., as claimed in claim 4 for the frequency modulation (PFM) return circuit of passive RF card, it is characterized in that, described clock delay circuit module is made up of 3 inverter series, after first phase inverter and second phase inverter, connect filter capacitor respectively.
6. as claimed in claim 1 for the frequency modulation (PFM) return circuit of passive RF card, it is characterized in that, also comprise demodulator circuit module, its two ends in parallel and antenna, and connect described frequency-halving circuit module, to frequency-halving circuit module enable signal;
When card reader sends carrier wave, described frequency-halving circuit module output enable signal is high level signal, frequency-halving circuit module attonity, and follow-up circuit does not enter duty; When carrier wave stops, described enable signal is low level signal, and frequency-halving circuit module is effective, exports described two divided-frequency signal.
7. as claimed in claim 1 for the frequency modulation (PFM) return circuit of passive RF card, it is characterized in that, described antenna loop comprises antenna, and and the first resonant capacitance of sky line parallel and the second resonant capacitance, the front end of described second resonant capacitance is connected to the switch controlled by the data circuit of passive RF card;
When data circuit output control signal is 0, described second resonant capacitance is inoperative, and signal return frequency is 134.2kHz; When data circuit output control signal is 1, described time second resonant capacitance adds resonance, and signal return frequency is 125kHz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410813843.3A CN104573794B (en) | 2014-12-23 | 2014-12-23 | A kind of frequency modulation(PFM) return circuit for passive RF card |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410813843.3A CN104573794B (en) | 2014-12-23 | 2014-12-23 | A kind of frequency modulation(PFM) return circuit for passive RF card |
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| CN104573794A true CN104573794A (en) | 2015-04-29 |
| CN104573794B CN104573794B (en) | 2017-07-28 |
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| CN201410813843.3A Expired - Fee Related CN104573794B (en) | 2014-12-23 | 2014-12-23 | A kind of frequency modulation(PFM) return circuit for passive RF card |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109662700A (en) * | 2017-10-17 | 2019-04-23 | 无锡闻心电子科技有限责任公司 | Wearable human life collection apparatus device, local server and its data analysis system, method |
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| CN1289188A (en) * | 1999-09-22 | 2001-03-28 | 松下电子工业株式会社 | Non-contact type IC card preventing data from error restoring while AM wave-carrier demodulation |
| US20050173542A1 (en) * | 2004-02-05 | 2005-08-11 | Kazuki Watanabe | Semiconductor integrated circuit device and contactless IC card |
| CN1703756A (en) * | 2002-10-11 | 2005-11-30 | 快捷半导体有限公司 | Current integrating sense amplifier for memory modules in RFID |
| WO2006025229A1 (en) * | 2004-09-02 | 2006-03-09 | Felica Networks, Inc. | Semiconductor integrated circuit and wireless communication device |
| CN101051359A (en) * | 2007-05-11 | 2007-10-10 | 清华大学 | Radio frequency label based on position information and anti-conflict method |
| 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 |
-
2014
- 2014-12-23 CN CN201410813843.3A patent/CN104573794B/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1289188A (en) * | 1999-09-22 | 2001-03-28 | 松下电子工业株式会社 | Non-contact type IC card preventing data from error restoring while AM wave-carrier demodulation |
| CN1703756A (en) * | 2002-10-11 | 2005-11-30 | 快捷半导体有限公司 | Current integrating sense amplifier for memory modules in RFID |
| US20050173542A1 (en) * | 2004-02-05 | 2005-08-11 | Kazuki Watanabe | Semiconductor integrated circuit device and contactless IC card |
| WO2006025229A1 (en) * | 2004-09-02 | 2006-03-09 | Felica Networks, Inc. | Semiconductor integrated circuit and wireless communication device |
| CN101051359A (en) * | 2007-05-11 | 2007-10-10 | 清华大学 | Radio frequency label based on position information and anti-conflict method |
| 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 |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109662700A (en) * | 2017-10-17 | 2019-04-23 | 无锡闻心电子科技有限责任公司 | Wearable human life collection apparatus device, local server and its data analysis system, method |
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| CB03 | Change of inventor or designer information | ||
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Inventor after: Zhou Qingfen Inventor before: Liu Jingshu Inventor before: Pan Mingyou Inventor before: Li Shenglong Inventor before: Liao Qiang |
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Effective date of registration: 20170627 Address after: 315012 Zhejiang Province, Ningbo city Haishu District Liyuan Road No. 755 room 1025 Applicant after: Ningbo Polygala cubic Energy Technology Co Ltd Address before: 536000, West 08A room, three floor, building A01, China Electronics Industrial Park, Beihai, the Guangxi Zhuang Autonomous Region Applicant before: BEIHAI YUNXIN ELECTRONIC TECHNOLOGY CO., LTD. |
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Inventor after: Liu Jingshu Inventor after: Pan Mingyou Inventor after: Li Shenglong Inventor after: Liao Qiang Inventor before: Zhou Qingfen |
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Effective date of registration: 20170906 Address after: 536000, West 08A room, three floor, building A01, China Electronics Industrial Park, Beihai, the Guangxi Zhuang Autonomous Region Patentee after: BEIHAI YUNXIN ELECTRONIC TECHNOLOGY CO., LTD. Address before: 315012 Zhejiang Province, Ningbo city Haishu District Liyuan Road No. 755 room 1025 Patentee before: Ningbo Polygala cubic Energy Technology Co Ltd |
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Granted publication date: 20170728 Termination date: 20171223 |