CN1987900B - Resonant frequency regulating circuit and method for radio frequency identifying chip capacity - Google Patents

Abstract

This invention is about a kind of adjustment electric circuit and method for resonance frequency to identify the capacitor of the chip through the radio frequency of it. The following are included by the method: the separation step: the capacitor inside the clip identified through resonance frequency will be divides in two parts. One part is the fixed capacitor (CA) less than the resonance capacitor (CO), and the other part are number of the trimming disposition capacitor (CB), the value of which are different, and paralleled to CA; the controlling step: the pass and the off of the switch arecontrolled by the binary data, and the adjustment for the resonance frequency of the capacitor. This invention has provided a method to adjust the capacitor of the chip by data controlling rather than physical processing, and it borrow the fragment of the unique sequence number(UID) of the chip as controlling data, the detection area and cost are not needed to be increased. This invention has resolved the adjustment problem for the resonance frequency in the large scale production of the chip identified by ratio frequency. The compatibility of it to the previous method is perfect, the detection time is short, and the structure of it is simple. It doesn't need expensive special equipment, and can reduce the detection cost for the RFID production, and the large scale production of the RFID will become possible according to it.

Description

A kind of resonant frequency regulating circuit of radio frequency identifying chip capacity and method

Technical field

The present invention relates to a kind of electronics device that utilizes electromagnetic coupling effect to carry out work, especially refer to the tuned circuit and the method for radio-frequency (RF) identification chip.

Background technology

Radio-frequency (RF) identification (RFID) chip is a kind of electron device that utilizes electromagnetic coupling effect to carry out work, generally requires the resonance frequency of chip itself and read-write equipment accurately to mate, and chip could operate as normal like this.In general, the inherent feature that the resonance frequency of radio-frequency (RF) identification chip is is established the chip internal capacitor C, the external antenna inductance L, and then the resonance frequency of RFID chip is determined by following formula:

$f_{\mathrm{res}}=\frac{1}{2\mathrm{\π}\sqrt{\mathrm{LC}}}$

When the RFID device production, generally adopt the external antenna of standard, its inductance value L generally has higher precision and good consistance, and chip capacity generally is exactly the internal capacitance of chip, be subjected to the influence of manufacture of semiconductor, this parameter generally has bigger dispersiveness, is difficult to accurate control.For the resonance frequency that makes chip equals fixed value f ₀, in the RFID production run, generally all to add last procedure, physical means such as employing laser cut electric capacity on the sheet of chip, make capacitance adjust to standard value C0, make

$f_0=\frac{1}{2\mathrm{\π}\sqrt{{\mathrm{LC}}_0}}$

But adjust electric capacity in process of production by this method and can bring following problem: at first be this specialized equipment of going up the action need costliness of micro-dimension, next all different needs of each chip capacity device are one by one adjusted, waste time and energy, can not satisfy the needs of large-scale production, and the cost increase that brings thus allows the user be difficult to accept.

Summary of the invention

Problem at above-mentioned tuning methods existence, the object of the present invention is to provide a kind of resonant frequency regulating circuit and method of radio frequency identifying chip capacity, have the test duration weak point, simple in structure, need not expensive specialized equipment, can reduce RFID production test cost.

The resonance frequency method of adjustment of a kind of radio frequency identifying chip capacity provided by the present invention comprises: separating step: the radio-frequency (RF) identification chip internal capacitance is divided into two parts, and a part is less than resonant capacitance C ₀Fixed capacity C _A, another part be some appearance values do not wait and respectively by a switch in parallel to C _AFine setting configuration capacitor C _BControlled step: the employing binary data comes the turn-on and turn-off of gauge tap, the resonance frequency adjustment of reaching electric capacity.

In the resonance frequency method of adjustment of above-mentioned radio frequency identifying chip capacity, the segment in the unique sequence number of use radio-frequency (RF) identification chip is come the turn-on and turn-off of gauge tap as control data.

In the resonance frequency method of adjustment of above-mentioned radio frequency identifying chip capacity, before the radio-frequency (RF) identification chip writing sequence number, test result calculations according to chip capacity goes out the control corresponding data, to reach the resonance frequency adjustment of finishing chip in writing sequence number.

The present invention also provides a kind of resonant frequency regulating circuit of radio frequency identifying chip capacity, it is characterized in that: comprise one less than resonant capacitance C ₀Fixed capacity C _ADo not wait with some appearance values and respectively by a switch in parallel to C _AFine setting configuration capacitor C _B, and a control module that is used to be provided with some on off states.

In the resonant frequency regulating circuit of above-mentioned radio frequency identifying chip capacity, control module is controlled the turn-on and turn-off of several switches by binary data.

In the resonant frequency regulating circuit of above-mentioned radio frequency identifying chip capacity, control module is to use the segment in the unique sequence number of radio-frequency (RF) identification chip to come the turn-on and turn-off of gauge tap as control data.

Above-mentioned technical solution proposes a kind of Physical Processing that need not and adjusts electric capacity on the sheet of chip with the method for Data Control, and uses segment in unique sequence number (UID) of chip as control data, and does not need to increase chip area or testing cost.The present invention solves the resonance frequency of radio-frequency (RF) identification chip when large-scale production and adjusts problem, it is good to have with original method of testing compatibility, test duration is short, and it is simple in structure, need not expensive specialized equipment, can reduce RFID production test cost, make the large-scale production of RFID device become possibility.

Description of drawings

Fig. 1 is the resonant frequency regulating circuit synoptic diagram of radio frequency identifying chip capacity of the present invention.

Embodiment

As shown in Figure 1, in design, the radio-frequency (RF) identification chip internal capacitance is divided into two parts, a part is fixed capacity C _A, C _ALess than resonant capacitance C ₀A part is a trimming capacitor C _B, the little electric capacity (be the convenience of narration, below hypothesis electric capacity number is 4) that is not waited by some appearance values constitutes, and each electric capacity is parallel to C by an independent switch _A

Among the figure with C _BBe divided into 4 capacitor C _B0～C _B4, respectively by 4 K switch ₁～K ₄Control, the present invention controls the turn-on and turn-off of 4 switches by 4 bit binary data BC.Suppose the chip resonance frequency is transferred to f ₀, the chip resonant capacitance that needs is 5pF, test now obtains C _AAdd with the chip stray capacitance is 4.3pF together, C _B0=0.1pF, C _B1=0.2pF, C _B2=0.4pF, C _B3=0.5pF as long as we make control data BC=1010 so, just makes K ₀, K ₂Disconnect K ₁, K ₃Conducting, the total capacitance of chip just just in time equals 5pF so at this moment, thereby has reached tuning purpose.

Consider if on chip, increase some storage unit, can increase area of chip first, after test process finishes, also will carry out programming operation to control bit separately in addition, increased testing cost for adjusting resonance frequency.

Therefore as improvement of the present invention and optimization, can adopt several the usefulness that are used as capacitance adjustment in global unique sequence number (UID) of chip.Because writing of sequence number is an operation must carrying out before chip testing is dispatched from the factory, therefore as long as the test result calculations according to the chip resonant capacitance goes out the control corresponding data before writing sequence number, just can in writing sequence number, finish the resonance frequency adjustment of chip.Because the sequence number of radio-frequency (RF) identification chip is generally 64, so the configuration data of enough data bit as resonant capacitance generally arranged.

Though the present invention is described with reference to current instantiation, but those skilled in the art should be realized that, above example only is to be used for illustrating the present invention, also can make the variation and the modification of various equivalences under the situation that does not break away from spirit of the present invention.Therefore, if in connotation scope of the present invention to the variation of above-mentioned example, modification all will drop in the scope of claims of the present invention.

Claims (4)

1. the resonance frequency method of adjustment of a radio frequency identifying chip capacity comprises:

Separating step: the radio-frequency (RF) identification chip internal capacitance is divided into two parts, and a part is less than resonant capacitance (C ₀) fixed capacity (C _A), another part be some appearance values do not wait and respectively by a switch in parallel to fixed capacity (C _A) fine setting configuration electric capacity (C _B);

Controlled step: the employing binary data comes the turn-on and turn-off of gauge tap, the resonance frequency adjustment of reaching electric capacity; In described controlled step, the segment in the unique sequence number of use radio-frequency (RF) identification chip is come the turn-on and turn-off of gauge tap as control data.

2. the resonance frequency method of adjustment of radio frequency identifying chip capacity according to claim 1, it is characterized in that: before described radio-frequency (RF) identification chip writing sequence number, test result calculations according to chip capacity goes out the control corresponding data, to reach the resonance frequency adjustment of finishing chip in writing sequence number.

3. the resonant frequency regulating circuit of a radio frequency identifying chip capacity is characterized in that: comprise one less than resonant capacitance (C ₀) fixed capacity (C _A) and some appearance values do not wait and pass through a switch in parallel respectively to fixed capacity (C _A) fine setting configuration electric capacity (C _B), and a control module that is used to be provided with some on off states, described control module is to use the segment in the unique sequence number of radio-frequency (RF) identification chip to come the turn-on and turn-off of gauge tap as control data.

4. the resonant frequency regulating circuit of radio frequency identifying chip capacity according to claim 3, it is characterized in that: described control module is controlled the turn-on and turn-off of several switches by binary data.

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