WO2009127157A1

WO2009127157A1 - Sim card chip with radio frequency recognition function

Info

Publication number: WO2009127157A1
Application number: PCT/CN2009/071325
Authority: WO
Inventors: 金可威
Original assignee: 上海坤锐电子科技有限公司
Priority date: 2008-04-18
Filing date: 2009-04-17
Publication date: 2009-10-22
Also published as: CN101561889B; CN101561889A; CN101276429A

Abstract

A SIM card chip with the radio frequency recognition function at least includes a RF interface unit, the RF interface unit at least includes a receiving amplification circuit, a demodulation circuit, a modulation circuit and a sending power amplification circuit. Wherein, the receiving amplification circuit is used for amplifying the communication signal obtained by a mobile telephone and transmitting the signal to the demodulation circuit, the demodulation circuit is used for demodulating the communication signal amplified by the receiving amplification circuit, the modulation circuit is used for modulating the communication signal to be sent of the mobile telephone, the sending power amplification circuit is used for amplifying the communication signal modulated by the modulation circuit. The SIM card chip with the radio frequency recognition function can improve the thing affecting the communication effect between the mobile telephone and the reader due to the shield of the mobile telephone battery and the circuit board.

Description

OP090180

One one

SIM card chip with radio frequency identification

The present application claims priority to Chinese Patent Application No. 200810036253.9, entitled "SIM Card Chip with Radio Frequency Identification Function", filed on April 18, 2008, the entire contents of which is incorporated herein by reference. in.

Technical field

The present invention relates to the field of mobile communications, and in particular to a SIM card chip with radio frequency identification function.

Background technique

After more than ten years of development, Radio Frequency Identification (RFID) technology, including non-contact integrated circuit cards (IC cards), has penetrated into every corner of modern life and is widely used. Public transportation, access control, small electronic payment and other fields. Radio frequency identification technology is a kind of automatic identification technology. The composition of the radio frequency identification system generally includes at least two parts: (1) electronic label, the English name is Tag; (2) reader, the English name is Reader, and the electronic label is generally saved. Electronic data with an agreed format. In practical applications, an electronic tag is attached to the surface of the object to be identified. The reader, also known as a reading device, can read and recognize the electronic data stored in the electronic tag without contact, thereby achieving the purpose of automatically recognizing the object. Further, through the computer and the computer network, management functions such as collection, processing, and remote transmission of object identification information can be realized. For most RFID systems, a fixed frequency will be used and a standard protocol will be used to match it.

Digital modulation techniques such as ASK, FSK and PSK modulation are widely used in the RFID field. Amplitude Shift Keying (ASK) takes different values according to the amplitude of the carrier, for example, corresponding to binary 0, the carrier amplitude is 0; corresponding to binary 1, the carrier amplitude is 1. The amplitude modulation technique is simple to implement, but is susceptible to gain variations. Frequency Shift Keying (FSK) modulates the frequency of a carrier by the value of digital data (such as 0 or 1). For example, the carrier frequency corresponding to binary 0 is F1, and the carrier frequency corresponding to binary 1 is F2. The technology has good anti-interference performance, but it occupies a large bandwidth. Phase Shift Keying (FSK) modulates the carrier phase by the value of the digital data. For example, a phase shift of 180 is used to indicate 1 and a phase shift of 0 is used to represent 0. This modulation technique has the best anti-interference performance, and the phase change can also be used as timing information to synchronize the clocks of the transmitter and receiver, and double the transmission rate. These kinds of modulation methods are all existing OP090180

The mature modulation technology of -2- is widely used in various communication systems.

In recent years, driven by the demand for rail transit, logistics management, anti-counterfeiting, and identification, RFID technology continues to advance and applications are becoming more and more popular. The market urgently needs all kinds of RFID electronic tags and identification devices. There is usually an electronic wallet inside the electronic tag. The cardholder deposits a certain amount in the electronic tag in advance, and deducts the transaction amount directly from the stored value account during the transaction. However, single-function electronic tags also have some disadvantages, such as: electronic tag recharge must go to a special recharge center, relatively large transactions, no way to set a password, and can not combine RFID payment and mobile payment.

At the same time, mobile communication terminals have experienced rapid development for more than 20 years, and have almost become a necessary portable device for consumers. The penetration rate is very high, and there is a tendency to integrate more functions on mobile terminals. It is a mature technology to use the mobile communication network of the mobile phone itself, such as GSM, CDMA, etc., but the effective combination of the mobile phone and the electronic tag, so that the mobile phone is conveniently used like a bus card is the development direction of the current radio frequency identification, and is also provided by the device. Business and mobile operators are currently aggressively exploring the market.

Affected by mobile payments in Japan and South Korea, micropayments are an area that operators have always expected to enter. With a very good solution for real-time payment and on-site payment, contactless proximity RFID has a very broad application prospect and will bring unprecedented opportunities to the slow-moving mobile payment industry. The combination of mobile terminals and RFID technology can be a new development direction in the next decade. Especially in the 3G era, ubiquitous RFID readers with wireless connectivity and RFID for contactless applications will be the top priority. At present, there are two main solutions based on contactless technology in the industry: Combi SIM card solution and Near Field Communication (NFC) solution.

The Combi SIM card solution, also known as the dual interface SIM card solution, refers to replacing the internal SIM card of the mobile phone with a Combi SIM card, and adding a non-contact IC card application interface based on the function of the SIM card retaining the original contact interface. There are two typical methods: 1. The non-contact antenna of the non-contact IC card is printed on the plastic film and attached to the surface of the SIM card. 2. The non-contact antenna of the non-contact IC card is attached to the mobile phone as a separate component. , the antenna is led to the front or back of the mobile phone, and the antenna is connected to the C4 and C8 interfaces that are not used by the SIM card. However, the disadvantages of these two schemes are: The antenna is attached to the surface of the SIM card or led to the front or back of the mobile phone. During the installation process, the antenna is easily broken and damaged, and the user is inconvenient to use, and at the same time, due to the battery of the mobile phone and the circuit board. The shielding function, the signal of the reader received by the dual interface SIM card and the signal reflected to the reader are very weak. Therefore, dual interface SIM OP090180

-3 - The quality of the communication between the card and the reader is very poor, and the reader can hardly receive the response from the dual interface SIM card.

The NFC solution is a new solution for RFID recognition by companies such as Nokia and Philips in recent years. The basic approach is to add RFID modules for payment to newly designed mobile phones. Special communication between RFID modules and mobile phones is used. The protocols communicate with each other. This method can better solve the problem of using the mobile phone for RFID, but the disadvantage is that the user has to modify the existing mobile phone, or even buy a brand new mobile phone, which is not a method acceptable to all users at this stage, and It is also a great waste of resources for the whole society.

Please refer to FIG. 1 for the internal structure of a typical dual interface IC card in the prior art and FIG. 2 is a schematic diagram of an RF interface circuit of a typical dual interface IC card. The typical dual-interface IC card chip structure diagram introduced by Gemplus is shown in Figure 1. The contact part communication standard conforms to the ISO/IEC7816 standard, and the non-contact part communication standard conforms to the ISO/IEC 14443 TYPEA/TYPEB standard. The typical dual-interface IC card chip is mainly composed of a radio frequency (RF) interface and a central processing unit.

(Central Processing Unit, hereinafter referred to as CPU), interrupt handler, random number generator, read only memory (ROM), EEPROM (programmable electrical erase read only memory), external RAM

(ie random access memory), cyclic redundancy check (CRC) module, clock module, ISO/IEC7816 and other modules. The RF interface is a communication interface between the dual interface IC card and the 13.56 MHz reader; the CPU is a central processing unit of the dual interface IC card, and is mainly used for the communication of the mobile phone and the completion of the 13.56 MHz reader transaction together with the internal software; The interrupt processor is mainly used to process interrupts of various peripherals; the ROM is used to store internal firmware programs; the EEPROM and external RAM are used to store data and intermediate variables of the dual interface IC card; and the CRC module is used to generate cyclic redundancy. The verification code ensures the integrity of the data during communication; the clock module is used for internal clock processing; the ISO/IEC7816 module is the communication interface between the mobile phone and the dual interface IC card, and is the channel through which the mobile phone provides power to the IC card.

As shown in Fig. 2, the RF interface is mainly composed of a 13.56 MHz non-contact antenna, a demodulation circuit, a digital quantization circuit, and a modulation circuit.

The signal sent by the reader to the dual interface IC card is received through the 13.56 MHz antenna. Since the signal sent from the reader to the dual interface IC card is a 100% ASK modulated signal, the demodulation circuit in the dual interface IC card uses the diode peak package. Demodulation is performed by means of network detection. After the detection output, the signal will be quantized by the quantization circuit to become the baseband signal required by the logic circuit, and then sent to the CPU for processing. OP090180

One 4 one

When the dual interface IC card responds to the reader, it is coded by the CPU and sent to the modulation circuit for modulation. The response reflection of the signal is completed by changing the load resistance in the modulation circuit of the RF interface.

Due to the shielding effect of the mobile phone battery and the circuit board, if the dual interface IC card replaces the existing ordinary SIM card application into the mobile phone environment, the dual interface IC card will not be able to reliably receive the command signal sent by the reader, and the dual interface IC card is issued. The signal will be greatly attenuated after passing through the mobile phone environment, and such a small response signal cannot be received and distinguished by the reader.

Summary of the invention

The invention solves the problem of poor communication quality between the dual interface SIM card and the reader when the prior art dual interface SIM card is applied to the mobile phone environment.

In order to solve the above problems, the present invention provides a SIM card chip having a radio frequency identification function, comprising at least a radio frequency interface unit, where the radio frequency interface unit includes at least a receiving and amplifying circuit, a demodulating circuit, a modulating circuit, and a transmitting power amplifying circuit, where

a receiving amplification circuit for amplifying and transmitting the communication signal obtained by the mobile phone to the demodulation circuit; a demodulation circuit for demodulating the communication signal amplified by the receiving amplification circuit; and a modulation circuit for transmitting the mobile phone The communication signal is modulated;

And a transmit power amplifying circuit for amplifying the communication signal modulated by the modulation circuit.

Compared with the prior art, the above-mentioned SIM card chip with radio frequency identification has the following advantages: the communication signal obtained by the mobile phone is amplified by the receiving amplifying circuit to improve the attenuation of the received communication signal due to the shielding of the mobile phone battery and the circuit board. Happening. Correspondingly, the modulated mobile phone to be transmitted signal is amplified by the transmission power amplifying circuit to improve the attenuation of the transmitted communication signal due to the shielding of the mobile phone battery and the circuit board.

In addition, the SIM card manufactured by the above SIM card chip can be used as an ordinary single-interface contact SIM card, or can be used as a dual-interface SIM card and a mobile communication device in the RFID field to realize radio frequency identification such as mobile payment and access control. application.

DRAWINGS

In the drawings of the specification:

1 is a schematic diagram showing the internal structure of a typical dual interface IC card of the prior art;

2 is a schematic diagram of an RF interface circuit of a typical dual interface IC card of the prior art;

Figure 3a is a junction of a dual interface SIM card including a SIM card chip having radio frequency identification function of the present invention OP090180 structure diagram;

Figure 3b is a cross-sectional view of Figure 3a in the A-A direction;

4 is a schematic diagram of an embodiment of a radio interface unit and a non-contact antenna in a SIM card chip with radio frequency identification function according to the present invention;

5a is a schematic diagram of an example of a receiving and amplifying circuit in the radio frequency interface unit shown in FIG. 4; FIG. 5b is a schematic diagram of an example of a receiving and amplifying circuit in the radio frequency interface unit shown in FIG. 4; FIG. 6b is a schematic diagram of another example of a demodulation circuit in the radio frequency interface unit shown in FIG. 4. FIG. 7 is a transmission power amplification in the radio frequency interface unit shown in FIG. An example of a circuit. detailed description

In order to explain the technical contents, structural features, objects and effects of the present invention in detail, the embodiments will be described in detail below with reference to the drawings. The SIM chip with radio frequency identification function comprises a radio frequency interface unit, a CPU, an interrupt processor, a random number generator, a ROM, an EEPROM, an external RAM, a cyclic redundancy check module, a clock module, an ISO/IEC7816 module, and a power pin. , reset pin, clock pin, first antenna pin, second antenna pin, 10 pin, spare pin, ground pin.

When the dual interface SIM card including the SIM chip with radio frequency identification function of the present invention is used in the RFID field, the non-contact part communication conforms to the ISO/IEC 14443 standard, the ISO/IEC 15693 standard or the IS011784/IS011785 standard.

As shown in FIG. 3a and FIG. 3b, the non-contact antenna 11 of the dual-interface SIM card is directly embedded in the SIM card base 13, and the SIM card chip 12 and the non-contact antenna 11 are in the same plane. Both ends of the antenna 11 are respectively connected to the two contact first antenna pins and the second antenna pins of the SIM card chip 12.

The SIM card chip 12 further includes a plurality of gold wires, and the respective pins of the SIM card chip 12 are connected by respective portions of the gold wire and the contact card metal contacts 14. The power supply of the dual interface SIM card is provided by a mobile communication device (such as a mobile phone), that is, the power supply of the SIM card chip 12 is provided by the mobile communication device, and the power supply and the ground wire pass through the contact card metal contacts 14 and the gold wire 151 respectively. , 152 is connected to the power supply pin and ground pin. OP090180

One 6-

The interface between the SIM card and the mobile communication device includes a reset pin, a clock pin and a 10-pin in the SIM card chip 12. The communication protocol follows the ISO/IEC 7816 standard. The mobile communication device provides a reset signal to the dual interface SIM card through the reset pin; the clock for the dual interface SIM card is provided by the mobile communication device through the clock pin; the serial communication data between the dual interface SIM card and the mobile communication device passes 10 The pin is made. Alternate pins are generally not used during normal operation.

As shown in FIG. 4, the radio frequency interface unit in the SIM card chip having the radio frequency identification function includes: a receiving and amplifying circuit 20, a demodulating circuit 21, a digital quantizing circuit 22, a modulating circuit 25, and a transmitting power amplifying circuit 26, wherein

The receiving and amplifying circuit 20 is configured to amplify and transmit the communication signal obtained by the mobile phone to the demodulation circuit 21; the demodulation circuit 21 is configured to demodulate the communication signal amplified by the receiving and amplifying circuit 20; and the digital quantization circuit 22 The communication signal demodulated by the demodulation circuit 21 is converted into a digital signal; the receiving digital circuit interface 23 is configured to decode the digital signal output by the digital quantization circuit 22 according to the used protocol, and send it to the SIM card chip. CPU;

The transmitting digital circuit interface 24 is configured to receive the digital signal sent by the CPU in the SIM card chip, and digitally encode the digital signal according to the protocol used, and send the encoded signal to the modulation circuit 25;

a modulating circuit 25, configured to modulate the encoded mobile phone to be transmitted by the transmitting digital circuit interface 24;

A transmission power amplifying circuit 26 for amplifying the communication signal modulated by the modulation circuit 25.

The receiving amplifier circuit 20 obtains a signal via the non-contact antenna 27, and the transmission power amplifying circuit 26 amplifies the modulated signal and transmits it via the non-contact antenna 27.

The above description of the radio frequency interface unit is further illustrated by some examples.

Due to the difference in the installation position, installation method and surrounding mechanical metal environment of the SIM card in different mobile phones, the signals transmitted by the reader to the dual interface SIM card through the mobile phone battery, circuit board, etc. have different attenuation, so the signal is transmitted via the SIM card. The input of the contactless antenna 27 to the receiving amplifying circuit 20 is quite different. On the other hand, the output terminal of the receiving amplifying circuit 20, that is, the input terminal of the demodulating circuit 21, is expected to have a stable signal to be demodulated for different mobile phone environments. Therefore, after the receiving and amplifying circuit 20 obtains the input signal via the non-contact antenna 27, in addition to being able to achieve amplification of the input signal, the input signal should be able to be processed so that even if the input signal varies greatly, Output The amplitude of the amplified signal of the OP090180 is also small. Thereby, the demodulation circuit 21 is provided as a stable signal to be demodulated.

Based on this, the receiving amplifying circuit 20 can be an automatic gain control circuit. Referring to FIG. 5a, an embodiment of the automatic gain control circuit may include: a controllable gain amplifier 201, a control signal generating circuit 202, a comparator 203, and a level detecting circuit 204.

The controllable gain amplifier 201 is configured to determine a corresponding gain according to the gain control signal sent by the control signal generating circuit 202, and amplify the received AC input signal with the gain and output the signal to the demodulation circuit;

The level detecting circuit 204 is configured to convert the AC output signal outputted by the controllable gain amplifier 201 into a DC signal, and send it to the comparator 203;

The comparator 203 is configured to compare the DC signal sent by the level detecting circuit 204 with the reference signal, and send the corresponding comparison result to the control signal generating circuit 202;

The control signal generating circuit 202 is configured to generate and send a corresponding gain control signal to the controllable gain amplifier 201 according to the comparison result sent by the comparator 203.

The DC signal and the reference signal are DC voltages. The gain control signal can be a control voltage.

The following describes the working process of the above automatic gain control circuit as follows:

The controllable gain amplifier 201 initially has a preset gain that amplifies the AC input signal with the preset gain after the AC input signal transmitted by the non-contact antenna 27 is obtained.

The level detecting circuit 204 converts the amplified AC signal outputted by the controllable amplifier 201 into a DC signal. The conversion of the AC signal to a DC signal is here to facilitate comparison of the comparator 203. That is, after the level detecting circuit 204 transmits the converted DC signal to the comparator 203, the comparator 203 can conveniently compare the obtained DC signal with the reference signal.

For the comparator 203, for example, when the DC signal and the reference signal are both DC voltages, the comparator 203 can perform voltage comparison. Specifically, when the voltage corresponding to the DC signal is greater than the voltage corresponding to the reference signal, the output DC signal is greater than the comparison result of the reference signal; when the voltage corresponding to the DC signal is less than the voltage corresponding to the reference signal, the output DC signal is smaller than the reference signal. Result: when the voltage corresponding to the DC signal is equal to the voltage corresponding to the reference signal, the output DC signal is equal to the reference signal OP090180

One 8—

The comparison result of the number.

The control signal generating circuit 202, after obtaining the comparison result sent by the comparator 203, can generate and transmit a corresponding gain control signal to the controllable gain amplifier 201. Specifically, when the comparison result of the DC signal is smaller than the reference signal, a control signal with an increased gain is generated; when the comparison result of the DC signal is greater than the reference signal, a control signal with a reduced gain is generated; and the DC signal is equal to the reference signal. When the comparison result is obtained, a control signal that maintains the gain constant is generated. The gain control signal can be sent to the controllable gain amplifier 201 in a controlled voltage manner, and after the controllable gain amplifier 201 obtains the control voltage, the gain can be increased, the gain can be reduced, or the gain can be maintained unchanged. The amplification of the AC input signal produces a corresponding change.

According to the above description of the automatic gain control circuit, it can be changed according to the size of the received AC input signal, and when the AC input signal is large, the amplification of the AC input signal can be reduced by reducing the gain. Coefficient; When the AC input signal is small, the amplification factor for the AC input signal is increased by increasing the gain. Therefore, in a case where the variation amplitude of the AC input signal is large, the controllable gain amplifier 201 can still output an AC output signal having a relatively stable amplitude change, so that the demodulation circuit 21 located at the output end of the reception amplification circuit 20 can Get a stable signal input.

Referring to FIG. 5b, another embodiment of the automatic gain control circuit may include a controllable gain amplifier 201, a control signal generating circuit 202, a comparator 203, a level detecting circuit 204, and a low pass filter 205. The low-pass filter 205 is configured to filter the interference signal in the DC signal converted by the level detecting circuit 204, thereby providing the comparator 203 a more accurate DC signal to be compared, so that the corresponding gain control is performed. More precise. Other descriptions of the gain amplifier 201, the control signal generating circuit 202, the comparator 203, and the level detecting circuit 204 can be referred to the above example, and will not be described again.

After the receiving amplifier circuit 20 amplifies the AC input signal received by the non-contact antenna 27, the demodulation circuit 20 demodulates the amplified signal. The demodulation circuit 20 can be applied to, but not limited to, a demodulation circuit that implements a coherent demodulation method or a non-coherent demodulation method. For example, for the non-coherent demodulation method, a non-coherent demodulation method such as diode peak envelope demodulation, average envelope demodulation, or the like can be used. Corresponding circuits in the prior art that can implement coherent or non-coherent demodulation methods can be used as the demodulation circuit 20 herein. OP090180

-9- Figure 6a shows a simplified diagram of a circuit that implements a coherent demodulation method. The demodulation circuit includes a multiplier 210, a low-pass filter 211, and an input signal Vi amplified by the receiving and amplifying circuit 20, and the local carrier signal is processed by the multiplier 210, and then filtered by the low-pass filter 211 to generate The output signal Vo is demodulated.

Figure 6b shows a simplified diagram of a circuit for implementing a non-coherent demodulation method for diode peak envelope demodulation. The demodulation circuit includes a detector diode 212, a capacitor C connected at one end to the cathode of the detector diode 212, and a resistor R connected at one end to the cathode of the detector diode 212, and the capacitor C and the resistor R are connected in parallel. After receiving the input signal Vi, the demodulation circuit performs non-coherent demodulation of the diode peak envelope demodulation and outputs a demodulated output signal Vo.

The signal demodulated by the demodulation circuit 20 is converted into a digital signal via the digital quantization circuit 22. The digital quantization circuit 22 can convert an analog signal output from the demodulation circuit 20 into a digital signal using an analog-to-digital converter (ADC) or a comparator (i.e., Comparator) circuit.

After the analog-to-digital conversion, the receiving digital circuit interface 23 decodes the digital signal according to the protocol used and sends it to the CPU in the SIM card chip.

The transmitting digital circuit interface 24, after obtaining the digital signal from the CPU in the SIM card chip, digitally encodes it according to the protocol used, and sends the encoded signal to the modulation circuit 25.

After the modulation circuit 25 obtains the corresponding signal via the transmitting digital circuit interface 24, modulation is performed to obtain a modulated signal that meets the communication requirements. The modulation circuit 25 can be used without limitation to existing modulation circuits that implement ASK or FSK or PSK. Further, since the modulation circuit 25 uses digital modulation techniques such as ASK or PSK or FSK, it can directly receive the digital signal transmitted from the transmission digital circuit interface 24 when it is modulated.

The transmission power amplifying circuit 26 is for amplifying the communication signal modulated by the modulation circuit 25. The transmit power amplifying circuit 26 can be implemented using a class C or class D power amplifier, or other corresponding custom circuits can be used.

Fig. 7 is a schematic diagram showing a transmission power amplifying circuit. The amplification circuit shown is a high efficiency resonant power amplifier circuit comprising: first to fourth inverters 261 to 264, a first PNP transistor Q3, a second PNP transistor Q5, a first NPN transistor Q4, and a second NPN transistor. Q6, first to third capacitors C3 to C5, a first resistor R11, a second resistor R12, a first antenna load terminal ANT1, and a second antenna load terminal ANT2. OP090180

- 10- wherein the input of the first inverter 261 receives the first modulated control signal RFTXD1 and the output is coupled to the base of the second NPN transistor Q6. The input of the second inverter 262 receives the second modulated control signal RFTXD2, and the output is coupled to the base of the second PNP transistor Q5. The input of the third inverter 263 receives the third modulated control signal RFTXD3, and the output terminal is connected to the base of the first PNP transistor Q3. The input of the fourth inverter 264 receives the fourth modulated control signal RFTXD4, and the output is coupled to the base of the first NPN transistor Q4.

The collector of the second PNP transistor Q5 is grounded, and the emitter is connected to the emitter of the second NPN transistor Q6. The collector of the second NPN transistor Q6 is connected to VCC via a first resistor R11. The collector of the first PNP tube Q3 is grounded, and the emitter is connected to the emitter of the first NPN tube Q4. The collector of the first NPN transistor Q4 is connected to VCC via a second resistor R12.

The first end of the first capacitor C3 is connected to the emitter of the second PNP tube Q5 and the emitter of the second NPN tube Q6. The first end of the second capacitor C4 is connected to the emitter of the first PNP tube Q3 and the emitter of the first NPN tube Q4. Both ends of the third capacitor C5 are respectively connected to the second ends of the first capacitor C3 and the second capacitor C4. Both ends of the third capacitor C5 are respectively connected to the first antenna load terminal ANT1 and the second antenna load terminal ANT2.

The above amplifying circuit is controlled by the switching of four modulated control signals of RFTXD1, RFTXD2, RFTXD3, and RFTXD4, so that the NPN tubes Q5, Q6, and the PNP tubes Q3, Q4 are alternately turned on/off, thereby simultaneously amplifying the modulated signal. The antenna load end emits a radio frequency signal that meets the frequency requirement. The four modulated control signals RFTXD1, RFTXD2, RFTXD3, and RFTXD4 are generated by the modulation circuit 25. RFTXD1/RFTXD2 and RFTXD3/RFTXD4 are the opposite phase pairs. The phase between RFTXD1 and RFTXD2 is basically the same, between RFTXD3 and RFTXD4. The phases are basically the same.

Through the above description of the radio frequency interface unit, it can be seen that, for example, when the mobile phone communicates with the reader, when the reader sends a command signal to the mobile phone, the radio frequency interface unit in the SIM card chip is obtained via the non-contact antenna 27. The command signal is amplified by the receiving and amplifying circuit 20, sent to the demodulating circuit 21 for demodulation, and after demodulating and obtaining the demodulated signal, the digital demodulating signal is converted into a digital signal by the digital quantizing circuit 22, and is received via the receiving digital circuit. The interface 23 transmits the digital signal to the inside of the SIM card chip. Since the receiving amplifying circuit 20 amplifies the received command signal, the attenuation of the command signal by the shielding of the mobile phone battery and the circuit board is compensated, so that the mobile phone can correctly obtain the command letter sent by the reader. OP090180

- number 11.

When the mobile phone responds to the signal by the reader, the response signal is encoded by the CPU in the SIM card chip, modulated by the modulation circuit 25, and sent to the transmission power amplifying circuit 26 for power amplification, and then passed through the The non-contact antenna 27 is described as being transmitted. Since the transmission power amplifying circuit 26 performs power amplification on the response signal, the power attenuation of the shielding signal to the response signal of the mobile phone battery and the circuit board is compensated, and the attenuation effect of the shielding on the response signal is improved.

A person skilled in the art will recognize that various modifications and changes can be made thereto without departing from the spirit and scope of the invention. Accordingly, it is intended that the present invention cover the modifications and the modifications

Claims

OP090180 - 12- Claims

A SIM card chip having a radio frequency identification function, comprising at least a radio frequency interface unit, wherein the radio frequency interface unit comprises at least a receiving and amplifying circuit, a demodulating circuit, a modulating circuit, and a transmitting power amplifying circuit.

2. The SIM card chip with radio frequency identification function according to claim 1, wherein the receiving amplifying circuit is an automatic gain control circuit.

3. The SIM card chip with radio frequency identification function according to claim 1, wherein the automatic gain control circuit comprises: a controllable gain amplifier, a control signal generating circuit, a comparator, and a level detecting circuit.

The controllable gain amplifier is configured to determine a corresponding gain according to a gain control signal sent by the control signal generating circuit, and amplify the received AC input signal with the gain and output the signal to the demodulation circuit;

The level detecting circuit is configured to convert an AC output signal output by the controllable gain amplifier into a DC signal, and send the signal to a comparator;

The comparator is configured to compare the DC signal sent by the level detecting circuit with the reference signal, and send the corresponding comparison result to the control signal generating circuit;

The control signal generating circuit is configured to generate and send a corresponding gain control signal to the controllable gain amplifier according to a comparison result sent by the comparator.

4. The SIM card chip with radio frequency identification function according to claim 3, wherein the automatic gain control circuit further comprises a low pass filter for filtering out interference signals in the DC signal converted by the level detecting circuit. And sent to the comparator.

5. The SIM card chip with radio frequency identification function according to claim 3, wherein the DC signal and the reference signal are DC voltages.

6. The SIM card chip with radio frequency identification function according to claim 3, wherein the gain control signal is a control voltage. OP090180

- 13 -

7. The SIM card chip with radio frequency identification function according to claim 1, wherein the transmission power amplifying circuit is a class C or class D power amplifier.

The SIM card chip with radio frequency identification function according to claim 1, wherein the transmission power amplifying circuit comprises: first to fourth inverters, a first PNP tube, a second PNP tube, and a first NPN a second NPN tube, first to third capacitors, a first resistor, a second resistor, a first antenna load end, and a second antenna load end,

The input end of the first inverter receives the first modulated control signal, the output end is connected to the base of the second NPN tube, the input end of the second inverter receives the second modulated control signal, and the output end is connected to the second PNP The base of the tube is connected, the input end of the third inverter receives the third modulated control signal, the output end is connected to the base of the first PNP tube, and the input end of the fourth inverter receives the fourth modulated control signal, The output end is connected to the base of the first NPN tube;

The collector of the second PNP tube is grounded, the emitter is connected to the emitter of the second NPN tube, the collector of the second NPN tube is connected to VCC via the first resistor, the collector of the first PNP tube is grounded, the emitter is first The emitter of the NPN tube is connected, and the collector of the first NPN tube is connected to VCC via a second resistor; the first end of the first capacitor is connected to the emitter of the second PNP tube and the emitter of the second NPN tube, and the second capacitor The first end is connected to the emitter of the first PNP tube and the emitter of the first NPN tube, and the two ends of the third capacitor are respectively connected to the first capacitor and the second end of the second capacitor, and the two ends of the third capacitor are respectively Connected to the first antenna load end and the second antenna load end.

9. The SIM card chip with radio frequency identification function according to claim 1, wherein the demodulation method of the demodulation circuit is coherent demodulation or non-coherent demodulation.

10. The SIM card chip with radio frequency identification function according to claim 1, wherein the non-coherent demodulation is diode peak envelope demodulation or average envelope demodulation.

11. The SIM card chip with radio frequency identification function according to claim 1, wherein the modulation method of the modulation circuit is ASK or FSK or PSK modulation.