KR101150523B1 - RFID device - Google Patents

Abstract

An embodiment of the present invention relates to an RFID device, and discloses a technology related to an RFID tag chip (Radio Frequency IDentification Tag Chip) that communicates with an RFID reader using a radio signal. Such an embodiment of the present invention includes a modulator for modulating a response signal inside the RFID and outputting the modulated response signal to an antenna, wherein the modulator is connected to a switching element controlled according to the response signal and a power supply voltage terminal of the antenna to turn on the switching element. It includes a driver for outputting a radio frequency signal as a signal below a specific level.

Description

RFID device {RFID device}

An embodiment of the present invention relates to an RFID device, and a technology related to an RFID tag chip (Radio Frequency IDentification Tag Chip) that communicates with an RFID reader using a radio signal.

RFID (Radio Frequency IDentification Tag Chip) is a contactless automatic identification method that communicates with an RFID reader by attaching an RFID tag to an object to be identified and automatically transmitting and receiving it by using a wireless signal. To provide technology. As RFID is used, it is possible to compensate for the disadvantages of the conventional automatic identification technology, barcode and optical character recognition technology.

Recently, RFID (Radio Frequency Identification) devices have been used in various cases, such as logistics management system, user authentication system, electronic money system, transportation system.

For example, in the logistics management system, cargo classification or inventory management is performed using an integrated circuit (IC) tag in which data is recorded instead of a delivery slip or a tag. On the other hand, in the user authentication system, entrance management and the like are performed using an IC card that records personal information and the like.

On the other hand, a nonvolatile ferroelectric memory is used as a memory used in an RFID device.

In general, nonvolatile ferroelectric memory, or ferroelectric random access memory (FeRAM), has a data processing speed of about dynamic random access memory (DRAM) and is attracting attention as a next-generation memory device because of its characteristic that data is preserved even when the power is turned off. have.

The FeRAM is a memory device having a structure almost similar to that of a DRAM, and uses a ferroelectric material as a capacitor material, and uses high residual polarization characteristic of the ferroelectric material. Due to this residual polarization characteristic, data is not erased even when the electric field is removed.

1 is a block diagram of a general RFID device.

The RFID device according to the related art includes an antenna unit 1, an analog unit 10, a digital unit 20, and a memory unit 30.

Here, the antenna unit 1 serves to receive a radio signal transmitted from an external RFID reader. The wireless signal received through the antenna unit 1 is input to the analog unit 10 through the antenna pads 11 and 12.

The analog unit 10 amplifies the input wireless signal to generate a power supply voltage VDD which is a driving voltage of the RFID tag. The operation command signal is detected from the input wireless signal, and the command signal RX is output to the digital unit 20. In addition, the analog unit 10 senses the output voltage VDD and outputs a power-on reset signal POR and a clock CLK to the digital unit 20 for controlling the reset operation.

The digital unit 20 receives the power supply voltage VDD, the power-on reset signal POR, the clock CLK, and the command signal RX from the analog unit 10, and outputs a response signal TX to the analog unit 10. The digital unit 20 also outputs the address ADD, input / output data I / O, control signal CTR, and clock CLK to the memory unit 30.

In addition, the memory unit 30 reads / writes data using a memory element and stores the data.

Here, the RFID device uses a frequency of several bands, the characteristics of which vary depending on the frequency band. In general, the lower the frequency band, the slower the recognition speed, the RFID device operates in a short distance, and is less affected by the environment. On the contrary, the higher the frequency band, the faster the recognition speed and the longer the distance is affected by the environment.

FIG. 2 is a circuit diagram of a modulator 11 included in the analog unit 10 in the RFID device of FIG. 1.

The RFID apparatus of the related art modulates a radio signal in a demodulator included in the analog unit 10 to output a command signal RX to the digital unit 20, and the modulator 11 responds to the digital unit 20. The signal TX is modulated and transmitted to the antenna unit 1.

Here, the modulator 11 includes a resistor R connected in series between a power supply voltage terminal and a ground voltage terminal, and an NMOS transistor N1. The resistor R is connected between the power supply voltage terminal of the antenna unit 1 and the NMOS transistor N1. The NMOS transistor N1 is connected between the resistor R and the ground voltage terminal, and the response signal TX is applied through the gate terminal.

3 is a view for explaining an operating area of the modulation unit 11 according to the prior art.

The modulation unit 11 according to the prior art emits an output to the antenna in proportion to the input voltage region of the antenna. That is, since the modulation unit 11 according to the prior art emits an output to the antenna unit 1 through the resistor element R, the input and output of the antenna show linear characteristics.

In the antenna output method of the passive RFID chip, the antenna output is controlled by controlling the output of the reflected wave as in the principle of a reader. However, if the strength of the antenna output is too strong, the input of the radio frequency supplied to the passive RFID chip is weakened, and the power generation is weak.

As shown in the graph of FIG. 3, the modulator 11 according to the prior art linearly increases the output of the antenna, so that the output intensity of the antenna is too strong, thereby weakening the power of the passive RFID chip.

An embodiment of the present invention is characterized by improving the structure of the modulator to control the output strength of the antenna so that the RFID device can operate stably at a long distance.

According to an embodiment of the present invention, an RFID device includes a modulator for modulating a response signal inside an RFID and outputting the modulated response signal to an antenna, wherein the modulator includes: a switching element controlled according to the response signal; And a driving unit connected to the power supply voltage terminal of the antenna and outputting a radio frequency signal as a signal below a specific level when the switching element is turned on.
According to another embodiment of the present invention, an RFID device includes a modulation unit for modulating a response signal inside an RFID signal and outputting the same to an antenna, wherein the modulation unit includes: a switching element controlled according to the response signal; And a driving unit connected to the power supply voltage terminal of the antenna and outputting a radio frequency signal as a signal of a predetermined level or higher when the switching element is turned on.

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In addition, the RFID device according to another embodiment of the present invention, the modulation unit for modulating the response signal in the RFID and output to the antenna, the modulation unit is a switching element controlled according to the response signal; And a driving unit connected to the power supply voltage terminal of the antenna and outputting a radio frequency signal only at a certain level above and below a period when the switching element is turned on.

The embodiment of the present invention improves the structure of the modulator to control the output strength of the antenna, thereby providing an effect of allowing the RFID device to operate stably at a long distance.

It will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible, and that various modifications, additions and substitutions are possible, within the spirit and scope of the appended claims. As shown in Fig.

1 is a block diagram of an RFID device according to the prior art.
FIG. 2 is a circuit diagram of a modulator in the RFID device of FIG. 1. FIG.
FIG. 3 is a diagram for describing an operation region of a modulator of FIG. 2. FIG.
4 is a block diagram of an RFID device according to an embodiment of the present invention.
5 to 12 are embodiments of the modulator of FIG.
FIG. 13 is a diagram for describing an operation region of a modulator of FIG. 4. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram of an RFID device according to an embodiment of the present invention.

According to an embodiment of the present invention, an RFID device includes a voltage multiplier (100), a modulator (110), a demodulator (120), a power on reset unit (130), and a clock. The generator includes a clock generator 140, a digital processor 200, and a memory 300.

Antenna ANT is a configuration for transmitting and receiving data with an external reader or lighter. The voltage multiplier 100 generates the power supply VDD of the RFID device by the transmission frequency applied from the antenna ANT.

In addition, the modulator 110 modulates the response signal TX applied from the digital processor 200 and transmits the modulated signal TX to the antenna ANT. The demodulator 120 detects an operation command signal at a transmission frequency applied from the antenna ANT according to the output voltage of the voltage multiplier 100 and outputs the command signal RX to the digital processor 200.

The power on reset unit 130 detects the output voltage VDD of the voltage multiplier 100 and outputs a power on reset signal POR for controlling the reset operation to the digital processing unit 200. The clock generator 140 supplies the clock CLK for controlling the operation of the digital processor 200 to the digital processor 200 according to the output voltage VDD of the voltage multiplier 100.

In addition, the above-described digital processor 200 receives a power supply voltage VDD, a power-on reset signal POR, a clock CLK, and a command signal RX, and outputs a response signal TX to the modulator 110. The digital processor 200 outputs the address ADD, input / output data I / O, control signal CTR, and clock CLK to the memory unit 300.

The memory unit 300 includes a plurality of memory cells, each memory cell writes data to a storage element and serves to read data stored in the storage element.

The memory unit 300 may use a nonvolatile ferroelectric memory (FeRAM). FeRAM has a data processing speed of about DRAM. In addition, FeRAM has a structure almost similar to DRAM, and has a high residual polarization characteristic of the ferroelectric by using a ferroelectric as the material of the capacitor. Due to this residual polarization characteristic, data is not erased even when the electric field is removed.

FIG. 5 is a detailed circuit diagram illustrating the modulator 110 of FIG. 4.

The modulator 110_1 includes an NMOS transistor N3 that operates as a driver and an NMOS transistor N2 that is a switching element.

Here, the NMOS transistor N3 and the NMOS transistor N2 are connected in series between the power supply voltage terminal and the ground voltage terminal of the antenna ANT.

The NMOS transistor N3 may be made of a diode type. The NMOS transistor N3 is connected between the power supply voltage terminal of the antenna ANT and the NMOS transistor N2. In addition, the gate terminal and the source terminal of the NMOS transistor N3 serving as a diode are commonly connected.

In addition, the NMOS transistor N2 is connected between the NMOS transistor N3 and the ground voltage terminal, and the response signal TX is applied through the gate terminal.

In the modulation unit 110_1 having this configuration, the NMOS transistor N3 has a -Vt (threshold voltage).

That is, when the response signal TX is applied to the high level and the NMOS transistor N2 is turned on, the ground voltage GND is applied to the gate terminal of the NMOS transistor N3, so that the NMOS transistor N3 is always turned off.

At this time, since the NMOS transistor N3 has a -Vt (threshold voltage), the signal is emitted through the antenna ANT only when the radio frequency signal RF output to the power voltage terminal of the antenna ANT is at a low level.

For example, the radio frequency signal RF is output at a level equal to or lower than the ground voltage GND, less than or equal to the threshold voltage (absolute value of Vt) of the NMOS transistor N3.

6 is another embodiment of the modulator 110 of FIG. 4.

The modulator 110_2 includes an NMOS transistor N5 that operates as a driver and an NMOS transistor N4 that is a switching element.

Here, the NMOS transistor N5 and the NMOS transistor N4 are connected in series between a power supply voltage terminal and a ground voltage terminal.

The NMOS transistor N5 is connected between the power supply voltage terminal of the antenna ANT and the NMOS transistor N4 so that the gate terminal is connected to the power supply voltage terminal.

In addition, the NMOS transistor N4 is connected between the NMOS transistor N5 and the ground voltage terminal, and the response signal TX is applied through the gate terminal.

In the modulation unit 110_2 having this configuration, the NMOS transistor N5 has + Vt (threshold voltage).

That is, when the response signal TX is applied at a high level and the NMOS transistor N4 is turned on, the ground voltage GND is applied to the NMOS transistor N5.

At this time, since the NMOS transistor N5 has a + Vt (threshold voltage), the signal is emitted through the antenna ANT only when the radio frequency signal RF output to the power voltage terminal of the antenna ANT is at a high level.

For example, the radio frequency signal RF is output at a level equal to or greater than the ground voltage GND by greater than or equal to the threshold voltage (absolute value of Vt) of the NMOS transistor N5.

FIG. 7 is another embodiment of the modulator 110 of FIG. 4.

The modulator 110_3 includes NMOS transistors N6 and N7 that operate as a driver, and an NMOS transistor N8 that is a switching element.

Here, the NMOS transistors N6 and N7 are connected in parallel to the power supply voltage terminal.

The NMOS transistor N6 is connected between the power supply voltage terminal of the antenna ANT and the NMOS transistor N8 so that the gate terminal and the source terminal are commonly connected. The NMOS transistor N6 serves as a diode.

The NMOS transistor N7 is connected between the power supply voltage terminal and the NMOS transistor N8 so that the gate terminal is connected to the power supply voltage terminal.

In addition, the NMOS transistor N8 is connected between the NMOS transistors N6 and N7 and the ground voltage terminal, and a response signal TX is applied through the gate terminal.

In the modulator 110_3 having this configuration, the NMOS transistor N6 serving as a diode has a -Vt (threshold voltage).

That is, when the response signal TX is applied at a high level and the NMOS transistor N8 is turned on, the ground voltage GND is applied to the gate terminal of the NMOS transistor N6 so that the NMOS transistor N6 is always turned off.

At this time, since the NMOS transistor N6 has a -Vt (threshold voltage), the signal is emitted through the antenna ANT only when the radio frequency signal RF output to the power voltage terminal of the antenna ANT is at a low level.

For example, the radio frequency signal RF is output at a level equal to or lower than the ground voltage GND to be equal to or less than a value obtained by subtracting the threshold voltage (absolute value of Vt) of the NMOS transistor N6.

In the modulator 110_3, the NMOS transistor N7 has + Vt (threshold voltage).

That is, when the response signal TX is applied at a high level and the NMOS transistor N8 is turned on, the ground voltage GND is applied to the NMOS transistor N7.

At this time, since the NMOS transistor N7 has a + Vt (threshold voltage), the signal is emitted through the antenna ANT only when the radio frequency signal RF output to the power voltage terminal of the antenna ANT is at a high level.

For example, the radio frequency signal RF is output at a level equal to or greater than the ground voltage GND by more than or equal to the threshold voltage (absolute value of Vt) of the NMOS transistor N7.

Accordingly, the embodiment of FIG. 7 outputs a radio frequency signal only in a section below the threshold voltage of the NMOS transistor N6 and above the threshold voltage of the NMOS transistor N7.

8 is another embodiment of the modulator 110 of FIG. 4.

Modulator 110_4 includes ferroelectric capacitor FC1, NMOS transistors N9 and N10 that operate as a driver, and NMOS transistor N11 serving as a switching element. In the embodiment of the present invention has been described as an example that the capacitor is composed of a ferroelectric, the embodiment of the present invention is not limited to this, but the capacitor may be made of a common dielectric.

Here, the ferroelectric capacitor FC1 is connected between the power supply voltage terminal of the antenna ANT and the NMOS transistors N9 and N10.

NMOS transistors N9 and N10 are connected in parallel to the ferroelectric capacitor FC1.

The NMOS transistor N9 is connected between one end of the ferroelectric capacitor FC1 and the NMOS transistor N11 so that the gate terminal and the source terminal are commonly connected. The NMOS transistor N9 serves as a diode.

The NMOS transistor N10 is connected between one end of the ferroelectric capacitor FC1 and the NMOS transistor N11 so that the gate terminal is commonly connected to the drain terminal.

In addition, the NMOS transistor N11 is connected between the NMOS transistors N9 and N10 and the ground voltage terminal, and a response signal TX is applied through the gate terminal.

In the modulator 110_4 having this configuration, the NMOS transistor N9 serving as a diode has a -Vt (threshold voltage).

That is, when the response signal TX is applied at a high level and the NMOS transistor N11 is turned on, the ground voltage GND is applied to the gate terminal of the NMOS transistor N9 so that the NMOS transistor N9 is always turned off.

At this time, since the NMOS transistor N9 has a -Vt (threshold voltage), the signal is emitted through the antenna ANT only when the radio frequency signal RF output to the power voltage terminal of the antenna ANT is at a low level.

For example, the radio frequency signal RF is output at a level equal to or less than the ground voltage GND, which is equal to or less than a value obtained by subtracting the threshold voltage (absolute value of Vt) of the NMOS transistor N9.

In the modulator 110_4, the NMOS transistor N10 has + Vt (threshold voltage).

That is, when the response signal TX is applied at a high level and the NMOS transistor N11 is turned on, the ground voltage GND is applied to the NMOS transistor N10.

At this time, since the NMOS transistor N10 has a + Vt (threshold voltage), the signal is emitted through the antenna ANT only when the radio frequency signal RF output to the power voltage terminal of the antenna ANT is at a high level.

For example, the radio frequency signal RF is output at a level equal to or greater than the ground voltage GND by more than the sum of the threshold voltage (absolute value of Vt) of the NMOS transistor N10.

In the embodiment of FIG. 8, the phase difference of the radio frequency signal RF is generated by the ferroelectric capacitor FC1. In other words, by delaying the radio frequency signal RF by the ferroelectric capacitor FC1 to have a phase difference, it is possible to distinguish signals by using a difference in response speed.

9 is another embodiment of the modulator 110 of FIG. 4.

The modulator 110_5 includes a diode D1 acting as a driver and an NMOS transistor N12 serving as a switching element.

Here, the diode D1 and the NMOS transistor N12 are connected in series between the power supply voltage terminal and the ground voltage terminal of the antenna ANT.

Diode D1 may be made of a PN diode. In the embodiment of the present invention has been described as an example that the diode is composed of a PN diode, the embodiment of the present invention is not limited to this, the diode may be made of Schottky diode.

Diode D1 is connected in the reverse direction between the supply voltage terminal of antenna ANT and NMOS transistor N12.

That is, the P-type node of the diode D1 is connected to the NMOS transistor N12, and the N-type node is connected to the power supply voltage terminal of the antenna ANT.

In addition, the NMOS transistor N12 is connected between the diode D1 and the ground voltage terminal, and the response signal TX is applied through the gate terminal.

FIG. 10 is another embodiment of the modulator 110 of FIG. 4.

The modulator 110_6 includes a diode D2 that operates as a driver and an NMOS transistor N13 that is a switching element.

Here, the diode D2 and the NMOS transistor N13 are connected in series between the power supply voltage terminal and the ground voltage terminal of the antenna ANT.

Diode D2 may be made of a PN diode. Diode D2 is forward connected between the power supply voltage terminal of antenna ANT and NMOS transistor N13.

That is, the P-type node of the diode D2 is connected to the power supply voltage terminal of the antenna ANT, and the N-type node is connected to the NMOS transistor N13.

In addition, the NMOS transistor N13 is connected between the diode D2 and the ground voltage terminal, and the response signal TX is applied through the gate terminal.

FIG. 11 illustrates another embodiment of the modulator 110 of FIG. 4.

The modulator 110_7 includes diodes D3 and D4 that operate as drivers and an NMOS transistor N14 that is a switching element.

Here, the diodes D3 and D4 are connected in parallel with the power supply voltage terminal of the antenna ANT. The diodes D3 and D4 may be formed of PN diodes.

Diode D3 is connected in the reverse direction between the supply voltage terminal of antenna ANT and NMOS transistor N14. That is, the P-type node of the diode D3 is connected to the NMOS transistor N14, and the N-type node is connected to the power supply voltage terminal of the antenna ANT.

The diode D4 is forwardly connected between the power supply voltage terminal of the antenna ANT and the NMOS transistor N14. That is, the P-type node of the diode D4 is connected to the power supply voltage terminal of the antenna ANT, and the N-type node is connected to the NMOS transistor N14.

In addition, the NMOS transistor N14 is connected between the diodes D3 and D4 and the ground voltage terminal, and the response signal TX is applied through the gate terminal.

12 is another embodiment of the modulator 110 of FIG. 4.

The modulator 110_8 includes a ferroelectric capacitor FC2, diodes D5 and D6 serving as driving units, and an NMOS transistor N15 serving as a switching element. In the embodiment of the present invention has been described as an example that the capacitor is composed of a ferroelectric, the embodiment of the present invention is not limited to this, but the capacitor may be made of a common dielectric.

Here, the ferroelectric capacitor FC2 is connected between the power supply voltage terminal of the antenna ANT and the diodes D5 and D6.

Diodes D5 and D6 are connected in parallel to the ferroelectric capacitor FC2.

Diode D5 is connected in the reverse direction between one end of ferroelectric capacitor FC2 and the NMOS transistor N15. That is, the P-type node of the diode D5 is connected to the NMOS transistor N15, and the N-type node is connected to the ferroelectric capacitor FC2.

The diode D6 is forward connected between one end of the ferroelectric capacitor FC2 and the NMOS transistor N15. That is, the P-type node of the diode D6 is connected to the ferroelectric capacitor FC2, and the N-type node is connected to the NMOS transistor N15.

In addition, the NMOS transistor N15 is connected between the diodes D5 and D6 and the ground voltage terminal, and the response signal TX is applied through the gate terminal.

13 is a view for explaining an operation area of the modulator 110 according to an exemplary embodiment of the present invention.

Modulator 110 according to an embodiment of the present invention does not emit an output to the antenna ANT in proportion to the input voltage region of the antenna ANT, as in the prior art, when the input level of the antenna ANT is above a certain threshold voltage (Vt) The output is emitted to the antenna ANT.

In addition, it can be seen that the output level of the antenna ANT rapidly increases in a region where the input voltage of the antenna ANT becomes equal to or greater than a specific threshold voltage Vt.

Here, the threshold voltage Vt means the threshold voltages of the transistors and diodes described in the embodiments of the modulator 110 described above.

That is, the embodiment of the present invention controls the output of the antenna ANT when the radio frequency signal RF becomes a specific input condition in order to control the output of the antenna ANT.

Accordingly, the embodiment of the present invention generates a stable power source so that the antenna ANT output control operation is performed to stably control the remote operation characteristics.

Claims (19)

In the RFID device for transmitting and receiving a radio frequency signal includes a modulator for modulating the internal response signal to output to the antenna,
The modulator
A switching element controlled according to the response signal; And
And a driving unit connected to a power supply voltage terminal of the antenna and outputting the radio frequency signal as a signal below a specific level when the switching element is turned on. Claim 2 has been abandoned due to the setting registration fee. The method of claim 1, wherein the driving unit
And a diode-type NMOS transistor connected between the power supply voltage terminal and the switching element so that a gate terminal and a source terminal are commonly connected. Claim 3 was abandoned when the setup registration fee was paid. The method of claim 1, wherein the driving unit
And a diode connected in a reverse direction between the power supply voltage terminal and the switching element. Claim 4 was abandoned when the registration fee was paid. The RFID device according to claim 1, wherein the radio frequency signal is output at a level below ground voltage. Claim 5 was abandoned upon payment of a set-up fee. The RFID device according to claim 1, wherein the radio frequency signal is output at a level equal to or lower than a ground voltage and less than a value obtained by subtracting the threshold voltage of the driving unit. In the RFID device for transmitting and receiving a radio frequency signal includes a modulator for modulating the internal response signal to output to the antenna,
The modulator
A switching element controlled according to the response signal; And
And a driving unit connected to a power supply voltage terminal of the antenna and outputting the radio frequency signal as a signal of a predetermined level or higher when the switching element is turned on. Claim 7 was abandoned upon payment of a set-up fee. The method of claim 6, wherein the driving unit
And an NMOS transistor connected between the power supply voltage terminal and the switching element, wherein a gate terminal and a drain terminal are commonly connected. Claim 8 was abandoned when the registration fee was paid. The method of claim 6, wherein the driving unit
And a diode connected in a forward direction between the power supply voltage terminal and the switching element. Claim 9 was abandoned upon payment of a set-up fee. The RFID device of claim 6, wherein the radio frequency signal is output at a level equal to or greater than a ground voltage. Claim 10 has been abandoned due to the setting registration fee. 7. The RFID device according to claim 6, wherein the radio frequency signal is output at a level equal to or greater than a ground voltage minus a threshold voltage of the driving unit. In the RFID device for transmitting and receiving a radio frequency signal includes a modulator for modulating the internal response signal to output to the antenna,
The modulator
A switching element controlled according to the response signal; And
And a driving unit connected to a power supply voltage terminal of the antenna and outputting a radio frequency signal only in a section above and below a specific level when the switching element is turned on. Claim 12 is abandoned in setting registration fee. The method of claim 11, wherein the driving unit
A first NMOS transistor of a diode type connected between the power supply voltage terminal and the switching element so that a gate terminal and a source terminal are commonly connected; And
And a second NMOS transistor connected between the power supply voltage terminal and the switching element to which a gate terminal and a drain terminal are commonly connected. Claim 13 was abandoned upon payment of a registration fee. The method of claim 11, wherein the driving unit
A first capacitor connected to the power supply voltage terminal;
A third NMOS transistor of a diode type connected between the first capacitor and the switching element so that a gate terminal and a source terminal are commonly connected; And
And a fourth NMOS transistor connected between the first capacitor and the switching element and having a gate terminal and a drain terminal connected to each other. Claim 14 has been abandoned due to the setting registration fee. The RFID device of claim 13, wherein the first capacitor comprises a ferroelectric capacitor. Claim 15 was abandoned upon payment of a registration fee. The RFID device according to claim 13, wherein the radio frequency signal is outputted with a phase shifted by the first capacitor. Claim 16 has been abandoned due to the setting registration fee. The method of claim 11, wherein the driving unit
A first diode connected in a reverse direction between the power supply voltage terminal and the switching element; And
And a second diode connected in a forward direction between the power supply voltage terminal and the switching element. Claim 17 has been abandoned due to the setting registration fee. The method of claim 11, wherein the driving unit
A second capacitor connected to the power supply voltage terminal;
A first diode connected in a reverse direction between the second capacitor and the switching element; And
And a second diode connected in a forward direction between the second capacitor and the switching element. Claim 18 was abandoned upon payment of a set-up fee. 18. The RFID device of claim 17, wherein the second capacitor comprises a ferroelectric capacitor. Claim 19 was abandoned upon payment of a registration fee. 18. The RFID device of claim 17, wherein the radio frequency signal is outputted with a phase shifted by the second capacitor.

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