CN102682327A

CN102682327A - Radio frequency identification device (RFID) chip and internal resonance capacitor setting method thereof

Info

Publication number: CN102682327A
Application number: CN2011100592528A
Authority: CN
Inventors: 徐俊花; 曹玉升
Original assignee: SHANGHAI FEIJU MICROELECTRONICS CO Ltd
Current assignee: SHANGHAI FEIJU MICROELECTRONICS CO Ltd
Priority date: 2011-03-11
Filing date: 2011-03-11
Publication date: 2012-09-19

Abstract

The invention provides a radio frequency identification device (RFID) chip and a corresponding internal resonance capacitor setting method. The RFID chip comprises a central capacitor, an electrically erasable programmable read-only memory (EEPROM), and one or more than one programmable capacitor. The programmable capacitors are connected with corresponding circuit control switches respectively, the circuit control switches are electrically connected with the EEPROM, and opening and closing of the circuit control switches are controlled by output information in the EEPROM. The RFID chip and the corresponding internal resonance capacitor setting method enable each RFID chip to have precise resonance capacitance value in programming of each RFID chip, therefore the RFID chip has the optimum resonance frequency, and an optimum read-write distance is achieved.

Description

A kind of RFID chip with and internal resonance electric capacity method to set up

Invention field

The present invention relates to the encapsulation of RFID chip, relate in particular to a kind of RFID chip with and internal resonance electric capacity method to set up.

Background technology

The RFID chip design is day by day towards low cost, and the direction of reading/writing distance far away develops, and particularly the low frequency RF ID chip of 125KHZ, 134KHz is particularly evident.A very crucial degree of accuracy that the technical parameter index is the resonant capacitance of chip internal of low frequency RF ID chip decision reading/writing distance.The degree of accuracy of resonant capacitance has determined the OWF of RFID electronic tag, and OWF has determined the distance of best read-write.Present low frequency RF ID electronic tag inside on the market has only a fixing capacitance, if revise this capacitance, realize through the MASK (illumination version) that revises chip manufacturing.But this method also can only be changed to the another one fixed value from a fixed value, for example makes 320pF into from 300pF, can not repair accent to the resonant capacitance of each electronic tag separately.And present chip processing factory is in processing chip internal resonant capacitance; All there is certain fluctuation in the value of electric capacity; Can't with capacitance do very accurate, and also there is certain fluctuation in the inductance value of the antenna of low frequency RF ID label, this resonance frequency deviation ratio that has just caused large batch of electronic tag to encapsulate is bigger; Consistance is very poor, and different electronic label read-writes is bigger apart from difference.

Summary of the invention

Problem to above-mentioned existence; The purpose of this invention is to provide a kind of RFID chip and corresponding internal resonance electric capacity method to set up; Thereby can make it have accurate resonant capacitance value to each RFID chip programming; And then make this RFID chip have best resonance frequency, reach best reading/writing distance.

The object of the invention is exactly in order to solve the problems of the technologies described above, and a kind of RFID chip is provided, and comprising:

Center electric capacity and eeprom memory

One or more programmable capacitor; Corresponding with the one respectively circuit controling switch of said programmable capacitor is connected; Said circuit controling switch is electrically connected with said eeprom memory, and the opening and closing of foregoing circuit CS are by the information Control of exporting in the said eeprom memory.

Preferably, said circuit controling switch comprises a PMOS transistor and nmos pass transistor that connects in order.

Preferably, the information of exporting in the said eeprom memory is the numerical value more than one that leaves the particular address in the eeprom memory in, said numerical value with the foregoing circuit CS that will control corresponding one by one.

Preferably, when said numerical value was " 1 ", its pairing circuit controling switch was closed, and when these numerical value were " 0 ", its pairing circuit controling switch was opened.

The present invention also provides a kind of RFID chip internal resonant capacitance method to set up, and it comprises:

-a kind of RFID chip is provided; It comprises a center electric capacity, eeprom memory and one or more programmable capacitor; Corresponding with the one respectively circuit controling switch of said programmable capacitor is connected; Said circuit controling switch is electrically connected with said eeprom memory, and the opening and closing of foregoing circuit CS are by the information Control of exporting in the said eeprom memory;

-test the resonance frequency fr of said RFID chip through the resonance frequency testing apparatus;

-according to calculating resonance frequency formula resonance frequency the value of the internal resonance capacitance of RFID chip is adjusted until the resonance frequency fr of RFID chip and to be reached the optimum resonant frequency value, thus pairing best internal resonance capacitance this moment obtained;

-according to said best internal resonance capacitance the output information content among the EEPROM is set.

By technique scheme, the advantage and the beneficial effect of apkin cover of the present invention are:

Through a kind of RFID chip and corresponding internal resonance electric capacity method to set up; Thereby can be provided with to each RFID chip makes it have accurate resonant capacitance value; And then make this RFID chip have best resonance frequency, reach best reading/writing distance.

Description of drawings

Accompanying drawing shows embodiments of the invention, and with instructions, is used for explaining principle of the present invention.Through the detailed description of doing below in conjunction with accompanying drawing, can more be expressly understood the object of the invention, advantage and characteristic, wherein:

Fig. 1 is the structural representation of the embodiment of the invention one.

Embodiment

Embodiment 1

As shown in Figure 1, the internal resonance electric capacity method to set up of RFID chip of the present invention at first is provided with a center electric capacity at the RFID chip internal, and for instance, its value can be 320pF.In the RFID chip, also be provided with a plurality of programmable capacitor; For instance; Its value can be 16p, 8p, 4p, 2p, 1p etc.; The above-mentioned electric capacity that is provided with is connected with the circuit controling switch that a nmos pass transistor constitutes with a PMOS transistor that is connected in order respectively, and when the foregoing circuit CS was opened, then its pairing capacitance that electric capacity is set was calculated in the total capacitance value of RFID chip; Otherwise when the foregoing circuit switch cut out, then its pairing capacitance that electric capacity is set was not calculated in the total capacitance value of RFID chip.The total capacitance value of RFID chip is that the capacitance of center electric capacity adds the pairing capacitance sum total of the on-off circuit of opening.

The value of opening and closing of foregoing circuit CS exists in the byte (byte) of the particular address in the eeprom memory of RFID chip internal; A byte has 8 (bit) numerical value, these position (bit) numerical value with the foregoing circuit CS that will control corresponding one by one.For example shown in Fig. 1 circuit diagram: Coil [0], Coil [1], Coil [2], Coil [3], these numerical value of Coil [4] are in the byte (byte) that leaves the particular address in the eeprom memory in; When these numerical value are " 1 "; Its pairing circuit controling switch is closed; When these numerical value were " 0 ", its pairing circuit controling switch was opened.

When the RFID label encapsulates at last, the resonance frequency that the equipment of user through the automatic test resonance frequency of periphery comes test chip.

can know according to calculating resonance frequency formula resonance frequency, and departing from of actual resonance frequency that causes owing to the fluctuation of the inductance value (L) of each label and optimum resonant frequency can remedy through the adjustment to the internal resonance capacitance of RFID chip.Specific practice is: if resonance frequency is too high, then reduce resonance frequency through the total capacitance value that increases the RFID chip; If resonance frequency is low excessively, then increase resonance frequency through the total capacitance value that reduces the RFID chip.Realize that through the numeral in the byte (byte) that the EEPROM particular address is set the repairing of resonant capacitance of different gears transfer to reach accurate resonance frequency.Afterwards the CR automated procedures will according to the internal resonance capacitance of the RFID chip under optimum resonant frequency that calculates to EEPROM in numerical value in the byte (byte) of particular address programme, make the optimum resonant frequency that reaches of RFID chip.

More than be merely the preferred embodiments of the present invention, be not limited to the present invention.In the above-described embodiments, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims

1. RFID chip comprises:

Center electric capacity and eeprom memory

It is characterized in that, also comprise:

2. RFID chip according to claim 1 is characterized in that, said circuit controling switch comprises a PMOS transistor and nmos pass transistor that connects in order.

3. RFID chip according to claim 1; It is characterized in that; The information of exporting in the said eeprom memory is the numerical value more than one that leaves the particular address in the eeprom memory in, said numerical value with the foregoing circuit CS that will control corresponding one by one.

4. RFID chip according to claim 3 is characterized in that, when said numerical value was " 1 ", its pairing circuit controling switch was closed, and when these numerical value were " 0 ", its pairing circuit controling switch was opened.

5. RFID chip internal resonant capacitance method to set up, it comprises:

-according to calculating resonance frequency formula resonance frequency

value of the internal resonance capacitance of RFID chip is adjusted until the resonance frequency fr of RFID chip and to be reached the optimum resonant frequency value, thus pairing best internal resonance capacitance this moment obtained;

6. according to the said RFID chip internal of claim 5 resonant capacitance method to set up, it is characterized in that said circuit controling switch comprises a PMOS transistor and nmos pass transistor that connects in order.

7. according to the said RFID chip internal of claim 5 resonant capacitance method to set up; It is characterized in that; The information of exporting in the said eeprom memory is the numerical value more than one that leaves the particular address in the eeprom memory in, said numerical value with the foregoing circuit CS that will control corresponding one by one.

8. want 7 said RFID chip internal resonant capacitance methods to set up according to right, it is characterized in that, when said numerical value was " 1 ", its pairing circuit controling switch was closed, and when these numerical value were " 0 ", its pairing circuit controling switch was opened.