CN202694385U

CN202694385U - RFID tag

Info

Publication number: CN202694385U
Application number: CN 201220226799
Authority: CN
Inventors: 管超
Original assignee: Core Technology (beijing) Electronic Technology Co Ltd
Current assignee: Core Technology (beijing) Electronic Technology Co Ltd
Priority date: 2012-05-18
Filing date: 2012-05-18
Publication date: 2013-01-23
Anticipated expiration: 2022-05-18

Abstract

The utility model provides an RFID (Radio Frequency Identification) tag. The RFID tag comprises an energy recovery unit, a modulation unit, a demodulation unit, a protocol control circuit, a memory, a clock oscillator and a clock frequency calibration control unit, wherein the energy recovery unit is used for supply power to the tag; the demodulation unit processes a frequency signal and sends the processed frequency signal to the protocol control circuit; the protocol control circuit sequentially sends the signal to the clock frequency calibration control unit and the clock oscillator; the modulation unit emits the signal to a reader-writer through an antenna by utilizing clock modulation command and data which are output by the clock oscillator; and the memory is connected with the protocol control circuit. According to the utility model, the multiple relationship between discrete frequencies is uniquely determined by the multiple relationship between device parameters of the circuit to generate various return frequencies with fractional frequency division characteristic, so that the application range of a device is expanded, and the anti-interference ability of the device is improved. The clock oscillator can select a lower reference frequency to reduce the power consumption of the tag and improve the maximum identification distance of a system.

Description

A kind of label for radio-frequency (RF) identification

Technical field

The utility model relates to the REID field, is specifically related to a kind of label for radio-frequency (RF) identification.

Background technology

Radio-frequency (RF) identification (RFID) technology is a kind of contactless automatic identification technology.In radio-frequency recognition system, read write line sends radiofrequency signal and activates radio-frequency (RF) tag, and receives the radiofrequency signal of returning from label, thereby reaches the purpose of identification.

In passive ultrahigh frequency radio frequency identification, label self is charged not, therefore need to reduce as far as possible self circuit power consumption.In present ultrahigh frequency RFID circuit is realized, because the generation of return signal speed is subject to read write line to the adjusting of label communication procedure parameter, produce the requirement with certain precision and the continuous adjustable return signal speed of certain limit in order to satisfy, oscillator frequency has brought adverse effect for the reduction power consumption as reference clock signal on the sheet that need to be higher.

In the prior art, the frequency signal that label produces is the adjustable frequency that produces by counter and digital frequency division, and its frequency can only be the frequency of oscillator output frequency integral multiple, and in the application of prior art, some return frequencies can be subject to fixing the interference, have affected the recognition function of read write line.

The utility model content

For the deficiencies in the prior art, the utility model provides a kind of label for radio-frequency (RF) identification, and it not only can reduce the frequency of oscillator on the passive label sheet, reduces chip power-consumption, and can effectively produce multiple return frequency with fractional frequency division feature.

A kind of label for radio-frequency (RF) identification that the utility model provides, its improvements are, the internal circuit of described label comprises energy recovering unit, modulating unit, demodulating unit, agreement control circuit, storer, clock oscillator and clock frequency calibration control unit;

Described energy recovering unit provides power supply for described label; Described demodulating unit is passed to described agreement control circuit after the radiofrequency signal that receives is processed; Described agreement control circuit is passed to described clock frequency calibration control unit and described clock oscillator successively with signal, and described modulating unit is processed the signal of described clock oscillator output rear by the transceiver module of antenna transmission to read write line; Described storer is connected with described agreement control circuit.

Wherein, the selection of frequency return signal is by the setting parameter of read write line requirement.

Wherein, the signal of described clock oscillator output is the discrete frequency of decimal precision.

Wherein, described clock oscillator comprises electric capacity, return difference comparer and the current source of at least one; Electric capacity one end is connected other end ground connection with the reverse input end of return difference comparer; The in the same way input end of return difference comparer connects reference voltage source; The return difference comparator output terminal is connected with reset circuit;

Each current source arranges a relative coefficient; Described current source is made of transistor; The transistorized grid of at least one is connected with described agreement control circuit, and its drain electrode is connected with the reverse input end of the comparer of described clock oscillator according to corresponding relative coefficient.

Wherein, described clock frequency calibration control unit comprises the frequency calibration circuit.

Wherein, the reference frequency of described clock oscillator is determined by its device parameters.

Wherein, the reference frequency of described clock oscillator and read write line are synchronous to the traffic rate of label.

Wherein, the relation of the multiple between the described discrete point in frequency is to determine according to the relative coefficient that the current source of described clock oscillator is set; The frequency values of discrete point in frequency is the product of described reference frequency and relative coefficient.

Wherein, return between the speed each other prime number.

Compared with the prior art, the beneficial effects of the utility model are:

The utility model adopts current source to realize a plurality of frequencies with decimal precision, and it is simple in structure, is easy to realize, cost is low.

The multiple relation of the utility model discrete point in frequency is determined by the relation of the multiple between the device parameters on the circuit structure is unique, does not need to adopt the method for frequency division/frequency multiplication to produce different frequencies.Can produce so multiple return frequency with fractional frequency division feature, enlarge the range of application of device, improve the antijamming capability of device.

The utility model has been avoided a lot of undesired signals, thereby has been improved the recognition function of rfid device by adjusting frequency return signal.

The utility model has reduced the power consumption of label to the selection of the reference frequency of clock oscillator, and the power consumption of label is the important performance indexes of passive radio frequency identification system, reduces the maximum decipherment distance that power consumption can improve system.

Description of drawings

The existing rfid device schematic diagram that Fig. 1 provides for the utility model.

The circuit structure diagram of the label of the rfid device that Fig. 2 provides for the utility model.

The structural representation of the clock oscillator that Fig. 3 provides for the utility model.

Embodiment

Below in conjunction with accompanying drawing embodiment of the present utility model is described in further detail.

As shown in Figure 1, the RFID technology for prior art comprises read write line, antenna and label; To the label transmit frequency signal, described label produces corresponding signal according to the radiofrequency signal of emission to read write line, is back to the transceiver module of read write line by antenna by antenna.The present embodiment is changed the label internal circuit on this basis, and the optional discrete Frequency point that allows its signal frequency of returning can be to have the decimal precision makes its range of application that has enlarged device, has improved the antijamming capability of device.

The label internal circuit comprises energy recovering unit, modulating unit, demodulating unit, reset signal generation unit, agreement control circuit, storer, clock oscillator, clock frequency calibration control unit and encrypting module as shown in Figure 2; Described energy recovering unit receives the radiofrequency signal of described antenna, for described label provides power supply (can equivalence be a direct supply); Described demodulating unit is passed to described agreement control circuit with the radiofrequency signal that receives with the square wave that its digital signal converts simulation to; Signal is passed to described clock frequency calibration control unit successively with described agreement control circuit and described clock oscillator produces discrete Frequency point, gives the transceiver module of described read write line by described modulating unit and described antenna transmission; Unique setting parameter that the selection of frequency return signal requires by read write line; Described storer is used for the data of storing received and transmission; The voltage that described reset signal generation unit provides in described energy recovering unit resets when being lower than normal voltage.When the present embodiment needs the user, can be encrypted setting to label, encrypting module is connected with the agreement control circuit, when the user needs, module can back-up system realizes authentication and encryption to communication process and data, the security that improves radio-frequency recognition system by encrypting module.The agreement control circuit of the present embodiment is to be made of state machine and combinational logic circuit, finishes following functions: (1) decoding: demodulate corresponding control command according to the serial digital signal that receives.(2) tag state control: do the agreement abstract factory deferred to the control command that receives according to system according to current tag state and transfer to next state.(3) access data: according to the data in the current state access storage unit of the order that receives.(4) return data generates: according to the content of the order control return data that receives.(5) other: the work of control enciphering/deciphering module, the work of control clock frequency calibration circuit.

The frequency of the return signal of the present embodiment is the discrete point in frequency with decimal precision.Multiple relation between its discrete point in frequency is determined by the relation of the multiple between the parameter of label internal circuit.Concrete is to determine according to the relative coefficient that the current source of described clock oscillator is set.The frequency values of discrete point in frequency is the product of described reference frequency and relative coefficient.

Clock oscillator comprises electric capacity, return difference comparer and the current source of at least one as shown in Figure 3.Electric capacity one end is connected other end ground connection with the reverse input end of return difference comparer.The in the same way input end of return difference comparer connects an extra reference voltage source (voltage of its output is as reference voltage), and the return difference comparer is controlled simultaneously reset circuit and is used for the reset capacitance both end voltage.The reference frequency of clock oscillator is determined by its device parameters.Each current source is set a relative coefficient; Described current source is made of transistor; The transistorized grid of at least one is connected with described agreement control circuit, and its drain electrode is connected with the reverse input end of the comparer of described clock oscillator according to corresponding relative coefficient.The present embodiment is established transistor and is had 8, can set 8 relative coefficients.8 transistorized grids link together, and it becomes common port, are connected with described agreement control circuit, and 8 transistorized source electrodes are connected to label general supply positive pole jointly.8 transistorized drain electrodes are exported different electric currents and are connected to electric capacity one end by MUX.According to the order request that read write line sends, a reverse input end with the return difference comparer of clock oscillator of selecting accordingly to meet in 8 transistors is connected.Determined output current relation between them by physical size between transistor corresponding to 8 current sources.By with the product of reference frequency, obtain frequency values, the 64KHz that the present embodiment requires take reader is as example, as requested, choose suitable transistor, be connected with the return difference comparer by MUX, modulating unit emission modulation rate is that the return signal of 64KHz is to the transceiver module of read write line.If have undesired signal in this back-modulation speed and integer harmonics frequency thereof, then can select another back-modulation speed, for example, 320 * 3/7KHz, in the implementation, at commonly used return in the speed range (64KHz～640KHz), selected distribution uniform, and a preferred version of discrete frequency point selection in having a class frequency of minimum common divisor the utility model being implemented the most.

Described clock frequency calibration control unit comprises the frequency feedback calibration circuit, during fabrication in the process of clock oscillator, there is certain error between the reference frequency of being determined by the actual parameter of device and the reference frequency of setting, so, when label receives radiofrequency signal, by receiving the specific modulation speed of read write line signal transmitted, relatively receive the relation of signal and clock oscillator output signal, the frequency of progressive fine setting oscillator so that the output frequency of oscillator synchronously and read write line to the traffic rate of label.

The label of the rfid device of the present embodiment has been realized following function:

(1) frequency return signal is a series of optional discrete point in frequency with decimal precision.

(2) multiple of these discrete point in frequency relation is determined by the relation of the multiple between the device parameters on the circuit structure is unique, does not need to adopt the method for frequency division/frequency multiplication to produce different frequencies.

(3) reference frequency of oscillator can be chosen lower value on the sheet, to reduce power consumption.

(4) oscillator reference frequency can be synchronized with read write line to the traffic rate of label by the clock frequency calibration process on the sheet, has obtained to return accurately speed.

(5) selection of frequency return signal can directly be specified by read write line to the communication process parameter of label.

Should be noted that at last: above embodiment is only in order to illustrate that the technical solution of the utility model is not intended to limit, although with reference to above-described embodiment the utility model is had been described in detail, those of ordinary skill in the field are to be understood that: still can make amendment or be equal to replacement embodiment of the present utility model, and do not break away from any modification of the utility model spirit and scope or be equal to replacement, it all should be encompassed in the middle of the claim scope of the present utility model.

Claims

1. a label that is used for radio-frequency (RF) identification is characterized in that, the internal circuit of described label comprises energy recovering unit, modulating unit, demodulating unit, agreement control circuit, storer, clock oscillator and clock frequency calibration control unit;

2. rfid device as claimed in claim 1 is characterized in that, the setting parameter that the selection of frequency return signal requires by read write line.

3. rfid device as claimed in claim 1 is characterized in that, the signal of described clock oscillator output is the discrete frequency of decimal precision.

4. such as claim 1 or 3 arbitrary described rfid devices, it is characterized in that, described clock oscillator comprises electric capacity, return difference comparer and the current source of at least one; Electric capacity one end is connected other end ground connection with the reverse input end of return difference comparer; The in the same way input end of return difference comparer connects reference voltage source; The return difference comparator output terminal is connected with reset circuit;

5. rfid device as claimed in claim 1 is characterized in that, described clock frequency calibration control unit comprises the frequency calibration circuit.

6. such as claim 1,3 or 4 arbitrary described rfid devices, it is characterized in that, the reference frequency of described clock oscillator is determined by its device parameters.

7. such as claim 1,3,4 or 6 arbitrary described rfid devices, it is characterized in that, the reference frequency of described clock oscillator and read write line are synchronous to the traffic rate of label.

8. rfid device as claimed in claim 3 is characterized in that, the multiple relation between the described discrete point in frequency is to determine according to the relative coefficient that the current source of described clock oscillator is set; The frequency values of discrete point in frequency is the product of described reference frequency and relative coefficient.

9. rfid device as claimed in claim 1 is characterized in that, returns between the speed each other prime number.