CN1996352A - Semi-active RFID tag supporting wireless charging - Google Patents

The semi-active RFID tag of the support wireless charging that the present invention proposes is formed by the part system that changes passive label, and increases modules such as battery, energy measuring, energy selection and battery protection therein.Fig. 2 has provided structured flowchart of the present invention.It comprises

antenna

5,

battery

6, rectification and load-modulate

module

7,

battery protection module

8,

energy detection module

9,

energy selection module

10 and carries out

circuit

11 these seven parts of functions such as data storage, processing and signal generation.Modules such as core of the present invention is that energy provides in the system, energy measuring and energy selection.Rectification and load-modulate

module

7 are recovered out with the radiofrequency signal that obtains in the

antenna

5, form galvanic current and press.When the RFID tag range reader is near, the energy height that

antenna

5 receives, thereby the voltage height that rectification goes out; When the radio-frequency (RF) tag range reader was distant, the voltage that rectification goes out was low.

Energy detection module

9 is according to rectification and load-modulate

module

7 output voltage V _RHeight judge the size that receives energy on the

antenna

5, control energy selects

module

10 to select V _RPerhaps

battery

6 power supply V _BBe used as in the tag system power supply V in order to the

circuit

11 of functions such as storage, deal with data and signal generation _DD

Fig. 3 has provided the structural diagrams of

energy detection module

9 and energy selection module 10.Owing to carry out accurate voltage detecting and need use the bigger circuit of power consumption such as reference voltage source and voltage comparator,, can shorten the maximum reading/writing distance of radio-frequency recognition system if the energy that receives with

antenna

5 is powered to this part circuit fully.Therefore, the mode that the present invention proposes a kind of two-stage energy measuring solves this problem.Be that

energy detection module

9 comprises

elementary detection module

14 and

accurate detection module

15,

elementary testing circuit

14 uses the radio-frequency (RF) energy power supply, it adopts the minimum electrify restoration circuit of quiescent dissipation to carry out preliminary energy measuring, when it detects energy on the

antenna

5 when enough strong, export a wake-up signal V _WakeWith

K switch

₃16 conductings.At this moment, use

battery

6 power supply V _B

Accurate testing circuit

15 once more to V _RSize detect, the result of detection will be by control line K ₁C and K ₂C is sent to energy and selects

module

10

gauge tap K

₁12 and K ₂13 conducting or shutoff, thus carry out the switch and the switching of energy.If the energy that receives on the

antenna

5 also has outside the operate as normal of tag system is provided when more than needed, this part energy more than needed will be used for

battery

6 is charged, thereby make label to reuse for a long time and need not often change

battery

6.

Battery protection module

8 is in order to detecting the voltage and current of

battery

6 in charge and discharge process, in case stopcock K immediately occurred overcharging, after mistake is put or electric current the is excessive situation ₂13,

protection battery

6 is not damaged, and simultaneously, label sends alerting signal to read write line.

Fig. 3 is the structural diagrams that

energy detection module

9 and energy are selected

module

10.

Fig. 5 is the structural diagrams of

accurate testing circuit

15 in the

energy detection module

9.

Number in the figure: 1 is read write line, and 2 is reading and writing device antenna, and 3 is transponder antenna; 4 is transponder, and 5 is antenna, and 6 is battery; 7 are rectification and load-modulate module, and 8 is the battery protection module, and 9 is energy detection module; 10 are energy selection module, and 11 is data storage; functional circuit module such as processing and signal generation, 12 is gauge tap K1; 13 is gauge tap K2, and 14 is elementary detection module, and 15 is accurate detection module; 16 is

K switch

3; 17 is reference voltage source, and 18 are voltage stabilizing and filtering circuit, and 19 is bleeder circuit; 20 is voltage comparator; 21 is logical circuit, and 22 is wave detector, and 23 is biasing circuit; 24 is low dropout voltage regulator; 25 is ring oscillator, and 26 is level shift and driving circuit, and 27 is electrify restoration circuit; 28 is non-volatility memorizer and control circuit thereof, and 29 is digital baseband.

Fig. 4 has provided the system construction drawing of a complete semi-active label.Wherein,

functional circuit

11 is connected to form through circuit by

ring oscillator amount

25, level shift and

driving circuit

26,

electrify restoration circuit

27, non-volatility memorizer and the

control circuit

28 thereof of

biasing circuit

23, low dropout

voltage regulator amount

24, belt current biasing and digital baseband 29.When label entered into the on-site of read write line electromagnetic field, rectification and load-modulate

module

7 reverted to a DC voltage V with the radio-frequency (RF) energy on the

antenna

5 _R, the

elementary testing circuit

14 in the

energy detection module

9 is subjected to this voltage V _RExcitation after, export a wake-up signal V _WakeWith

K switch

₃16 conductings, accurately

testing circuit

15 is started working.As shown in Figure 5, accurately

testing circuit

15 is connected to form by filter circuit of pressure-stabilizing 18, reference voltage source 17, bleeder circuit 19, voltage comparator 20 and logical circuit 21 circuit successively.Wherein, bleeder circuit 19 comprises several divider resistances (being R1-R3 among the figure).

Accurately testing circuit

15 is at first used voltage stabilizing and 18 couples of V of filtering circuit _RStablize, get wherein two specific intermediate level V with bleeder circuit 19 then ₁And V ₂Fixed reference level V with reference voltage source 17 outputs _CmpCompare.Distance between read write line and label is far, the radio-frequency (RF) energy that

antenna

5 receives very hour, the DC level V of rectification and 7 outputs of load-modulate module _RVery low, V ₁And V ₂All less than V _CmpSo, the output V of voltage comparator 20 _XAnd V _YBe low level, after logical circuit 21 is handled this comparative result, export two signal K ₁C and K ₂C stopcock energy is selected the K in the

module

10 ₁12 and K ₂13, control K simultaneously ₃C turn-offs the supply access of himself, and provides the unlatching threshold that feedback signal Logic_Back requires to improve elementary testing circuit 14.When the energy that receives on the

antenna

5 is enough to keep communication between read write line and the label and needs, V _RRaise, cause V ₁Less than V _CmpAnd V ₂Greater than V _CmpSo, the output V of voltage comparator 20 _XBe low level, and V _YBe high level, after logical circuit 21 is handled this comparative result, with K switch ₂13 open, and power in 6 pairs of tag systems of battery.Further shorten the distance between read write line and the label, when the energy that receives on the

antenna

5 is enough to provide whole tag system to be worked, the output V of bleeder circuit 19 ₁And V ₂All greater than V _CmpSo, the output V of voltage comparator _XAnd V _YBe high level, after logical circuit 21 is handled this comparative result, export two

signals K switch

₁12 and K ₂13 all conductings, this moment, the energy of tag system was provided by the radio-frequency (RF) energy that obtains on the

antenna

5, and label enters passive

mode.In K switch

₁12 and K ₂13 all under the situation of conducting, if the distance between read write line and the label is very short, when the energy that receives on the

antenna

5 was very strong, the output of rectification and load-

modulate module

7 will also be charged to

battery

6 with unnecessary energy when providing energy for tag system.

In tag system shown in Figure 4, as long as energy selects

module

10 to select V _RAnd V _BIn any one export V as it _DD, label promptly enters duty.The envelope signal that

wave detector

22 takes out on the

antenna

5 converts thereof into digital signal Data; Biasing

circuit

23 and low

dropout voltage regulator

24 provide current reference I for the

ring oscillator

25 of belt current biasing _RefWith voltage reference V _RefThereby, obtain the signal of frequency stabilization, after handling through level shift and

driving circuit

26, this signal becomes the clock signal C lock of system;

Electrify restoration circuit

27 provides a power-on reset signal POR.In addition,

biasing circuit

23 also provides a current offset signal I for

non-volatility memorizer

28 _Bias

Digital baseband

29 is handled above-mentioned Data, Clock, POR according to the regulation of communication protocol, simultaneously, finish communication with non-volatility memorizer by control bus and data bus, final signal processing results coding back (Mod) is transferred to rectification and load-modulate

module

7, change the input impedance of tag system with it, the mode that adopts the electromagnetism back scattering to be coupled realizes the communication between label and the read write line.

In the above-mentioned course of work of tag system, in case energy is selected the K switch in the

module

10 ₂13 conductings,

battery

6 enters charging and discharging circuit, and

battery protection module

8 promptly is waken up, and begins to detect the voltage and current of

battery

6 in charge and discharge process.If abnormal conditions have appearred in the work of

battery

6, stopcock K at once ₂13;

battery

6 is protected, exported the alerting signal that a

battery

6 is made mistakes simultaneously, give the

digital baseband

29 in the label together with the state (voltage, electric current, dump energy etc.) of

battery

6;

digital baseband

29 is transferred to read write line with alerting signal after this signal is encoded.