WO2022252403A1

WO2022252403A1 - Near field communication transmission circuit, related chip, and electronic device

Info

Publication number: WO2022252403A1
Application number: PCT/CN2021/113237
Authority: WO
Inventors: 袁广凯
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2021-05-31
Filing date: 2021-08-18
Publication date: 2022-12-08
Also published as: CN113037337A; CN113037337B

Abstract

The present application discloses a near field communication transmission circuit, a related chip, and an electronic device, comprising a waveform modulation unit and an output switch unit. The waveform modulation unit generates a first pulse width modulation signal according to the sine wave and the carrier wave, and generates a first square wave signal according to the sine wave. The output switch unit comprises a first switch and a second switch. The first switch is coupled to a first voltage and is configured to correspondingly output the first voltage on the basis of the control of the first pulse width modulation signal. The second switch is coupled to a second voltage and is configured to correspondingly output the second voltage on the basis of the control of the first square wave signal. In the first half cycle of the sine wave, the waveform modulation unit modulates the sine wave and the carrier wave to generate the first pulse width modulation signal, and the first square wave signal is maintained at a low potential. In the second half cycle of the sine wave, the first pulse width modulation signal is maintained at a low potential, and the first square wave signal is maintained at a high potential.

Description

Near field communication transmission circuit, related chip and electronic device

technical field

The present application relates to a near-field communication transmission circuit, in particular to a near-field communication transmission circuit using a sinusoidal pulse width modulation signal and a chip and an electronic device containing the near-field communication transmission circuit.

Background technique

Near field communication circuits in the prior art often use antenna circuits to send square wave signals for data transmission. However, the spectral characteristics of the square wave signal often lead to large third-order, fifth-order, and seventh-order low-order harmonic noise in the communication process. In order to prevent the low-order harmonic noise from affecting the quality of the near-field communication, low-pass filter is often used for filtering to remove the low-order harmonic noise, and an inductor is set in the low-pass filter to enhance the filtering effect. Due to the large volume and high cost of the inductor, the design of the near field communication circuit is relatively inflexible, and it is difficult to meet the needs of users.

Contents of the invention

One of the objectives of the present application is to disclose a near field communication transmission circuit, a related chip and an electronic device to solve the above problems.

An embodiment of the present application provides a near field communication transmission circuit. The near field communication transmission circuit includes a first output terminal, a waveform modulation unit and an output switch unit. The waveform modulation unit is used for receiving the sine wave and the carrier wave, generating a first pulse width modulation signal according to the sine wave and the carrier wave, and generating a first square wave signal according to the sine wave. The output switch unit includes a first switch and a second switch. The first switch has a first end, a second end and a control end, the first end of the first switch is coupled to a first voltage, the second end of the first switch is coupled to the first An output terminal and the control terminal of the first switch are used for receiving the first pulse width modulation signal. The second switch has a first end, a second end and a control end, the first end of the second switch is coupled to a second voltage, the second end of the second switch is coupled to the first An output end, and the control end of the second switch are used for receiving the first square wave signal. The frequency of the carrier wave is greater than the frequency of the sine wave, the first voltage is greater than the second voltage, and in the first half cycle of the sine wave, the first pulse width modulation signal is at the When the absolute value of the amplitude of the sine wave is greater than the absolute value of the amplitude of the carrier wave, it has a high potential, and when the absolute value of the amplitude of the sine wave is smaller than the absolute value of the amplitude of the carrier wave, it has a low potential, and at the first of the sine wave In a half cycle, the first square wave signal is kept at the low potential. During the second half cycle of the sine wave, the first PWM signal is kept at the low level, and the first square wave signal is kept at the high level.

Another embodiment of the present application provides a chip, including the near field communication transmitting circuit.

Another embodiment of the present application provides an electronic device, including the aforementioned chip and an antenna module. An antenna module is coupled to the first output end of the near field communication controller, and the antenna module includes an electromagnetic compatibility filter, a matching unit and an antenna. The electromagnetic compatibility filter is used for filtering the first output signal output by the first output terminal. The matching unit is used for providing an impedance matched with the first output signal to receive the filtered first output signal. The antenna is used for sending the first output signal received by the matching unit.

The near-field communication transmission circuit, related chips, and electronic devices provided by the embodiments of the present application can use the waveform modulation unit to modulate the sine wave to generate a pulse width modulation signal with a higher frequency, so that the low-order harmonics can be reduced Therefore, the quality of signal transmission is improved, and the setting of inductance can be reduced, so that the cost and area of the electronic device can be reduced.

Description of drawings

FIG. 1 is a schematic diagram of a near field communication transmission circuit according to an embodiment of the present application.

FIG. 2 is a timing diagram of signals in the NFC transmission circuit of FIG. 1 .

FIG. 3 is a schematic diagram of the relationship between the amplitude of the sine wave and the duty ratio of the first PWM signal.

FIG. 4 is a schematic diagram of a near field communication transmission circuit according to another embodiment.

FIG. 5 is a signal timing diagram of the NFC transmission circuit shown in FIG. 4 .

Detailed ways

The following disclosure provides various implementations or illustrations, which can be used to achieve different features of the disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. It will be appreciated that these descriptions are merely examples and are not intended to limit the disclosure. For example, in the description below, forming a first feature on or over a second feature may include some embodiments wherein the first and second features are in direct contact with each other; and may also include In some embodiments, additional elements are formed between the first and second features, such that the first and second features may not be in direct contact. In addition, this disclosure may reuse element symbols and/or labels in various embodiments. Such repetition is for the sake of brevity and clarity, and does not in itself represent a relationship between the different embodiments and/or configurations discussed.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the application are approximations, the relative numerical values set forth in the specific examples are reported here as precisely as possible. Any numerical value, however, inherently inherently contain standard deviations resulting from their individual testing methodology. As used herein, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range. Alternatively, the term "about" means that the actual value falls within an acceptable standard error of the mean, as considered by one of ordinary skill in the art to which this application pertains. It should be understood that, except for the experimental examples, or unless otherwise clearly stated, all ranges, quantities, numerical values and percentages used herein (for example, to describe the amount of material used, the length of time, temperature, operating conditions, ratios of quantities and others) similar) are modified by "about". Therefore, unless otherwise stated to the contrary, the numerical parameters disclosed in this specification and the appended patent claims are approximate values and may be changed as required. At least these numerical parameters should be understood as the value obtained by applying the normal rounding method to the indicated effective digits. Herein, numerical ranges are expressed as being from one endpoint to another endpoint or between two endpoints; unless otherwise stated, the numerical ranges stated herein are inclusive of the endpoints.

FIG. 1 is a schematic diagram of a near field communication transmission circuit 100 according to an embodiment of the present application. The near field communication transmission circuit 100 includes a first output terminal OUT1 , a waveform modulation unit 110 , an output switch unit 120 , a processor 130 , a sine wave generation unit 140 and a carrier generation unit 150 .

The sine wave generation unit 140 can generate the sine wave SSN, the carrier generation unit 150 can generate the carrier SCR, and the waveform modulation unit 110 can receive and generate the first pulse width modulation signal SPWM1 according to the sine wave SSN and the carrier SCR, and according to the sine wave SSN generates a first square wave signal SSQ1. In this embodiment, the waveform modulation unit 110 can generate the first square wave signal SSQ1 according to the voltage polarity of the sine wave SSN. In addition, due to the NFC (Near Field Communication, NFC) standard, the sine wave generating unit 140 can set the frequency of the sine wave SSN to 13.56 MHz, and the error range is within plus or minus 7 kHz. In this embodiment, the frequency of the carrier SCR can be greater than the frequency of the sine wave SSN, and the maximum amplitude of the carrier SCR can be greater than the maximum amplitude of the sine wave SSN, so the waveform modulation unit 110 can modulate the sine wave SSN according to the carrier SCR to generate the first pulse width modulation signal SPWM1. The generation methods of the first pulse width modulation signal SPWM1 and the first square wave signal SSQ1 will be described in detail in the following paragraphs.

The output switch unit 120 can generate a first output signal SO1 with strong driving capability according to the first pulse width modulation signal SPWM1 , and output the first output signal SO1 to the antenna module AM1 through the first output terminal OUT1 for external transmission. For example, the first output signal SO1 may have a larger current or voltage to enhance its driving capability, thus reducing excessive energy consumption during the output process.

FIG. 2 is a timing diagram of signals in the NFC transmission circuit 100 . In FIG. 2, the carrier SCR may be a sawtooth wave, but in other embodiments, the carrier SCR may also be a triangular wave.

In FIG. 2 , the waveform modulation unit 110 can modulate the sine wave SSN according to the carrier SCR in the first half period HP1 of the sine wave SSN to generate the first pulse width modulation signal SPWM1 . For example, in the first half cycle HP1 of the sine wave SSN, the waveform modulation unit 110 will make the first pulse width modulation signal SPWM1 have a high value when the absolute value of the amplitude of the sine wave SSN is greater than the absolute value of the amplitude of the carrier SCR. Potential VH, and when the absolute value of the amplitude of the sine wave SSN is smaller than the absolute value of the amplitude of the carrier wave, the first pulse width modulation signal SPWM1 has a low potential VL. In addition, in the first half period HP1 of the sine wave SSN, the waveform modulation unit 110 keeps the first square wave signal SSQ1 at the low potential VL.

In the embodiment of Fig. 2, the sine wave SSN will have a positive voltage during the first half cycle HP1 of the sine wave SSN. Furthermore, in the first half cycle HP1 of the sine wave SSN, the carrier SCR will also have a positive voltage. In this case, the waveform modulation unit 110 can compare the voltages of the sine wave SSN and the carrier SCR through a comparator to generate the first pulse width modulation signal SPWM1, so that the amplitude of the first pulse width modulation signal SPWM1 is absolutely absolute in the amplitude of the sine wave SSN. When the value is greater than the absolute value of the amplitude of the carrier SCR, it has a high potential VH, and when the absolute value of the amplitude of the sine wave SSN is smaller than the absolute value of the amplitude of the carrier SCR, it has a low potential VL. In this embodiment, since the waveform modulation unit 110 performs modulation in the first half period HP1 when the sine wave SSN and the carrier SCR are at positive voltages, the comparator can directly compare the sine wave SSN and the carrier SCR through two input terminals. voltage amplitude.

Next, in the second half period HP2 of the sine wave SSN, the sine wave SSN and the carrier SCR will have a negative voltage, at this time the waveform modulation unit 110 can keep the first pulse width modulation signal SPWM1 at a low potential VL, and make the The first square wave signal SSQ1 is kept at a high potential VH. For example, the waveform modulating unit 110 may further include a detection circuit and a switch circuit. When the detection circuit detects that the sine wave SSN is a positive voltage, it controls the switch circuit to output the first The pulse width modulation signal SPWM1, and when the sine wave SSN is detected as a negative voltage, the switch circuit is controlled to connect the port outputting the first pulse width modulation signal SPWM1 to a voltage source for providing a low potential VL, so that the second A pulse width modulation signal SPWM1 is kept at a low potential VL.

In FIG. 1 , the output switch unit 120 may include a first switch 122 and a second switch 124 . The first switch 122 has a first terminal, a second terminal and a control terminal, the first terminal of the first switch 122 can be coupled to the first voltage V1, the second terminal of the first switch 122 is coupled to the first output terminal OUT1, The control terminal of the first switch 122 can receive the first pulse width modulation signal SPWM1.

The second switch 124 can have a first terminal, a second terminal and a control terminal, the first terminal of the second switch 124 can be coupled to the second voltage V2, and the second terminal of the second switch 124 can be coupled to the first output terminal OUT1, and the control terminal of the second switch 124 can receive the first square wave signal SSQ1. In this embodiment, the first voltage V1 may be greater than the second voltage V2. For example, the first voltage V1 may be the operating voltage provided by the power circuit in the system, and the second voltage V2 may be the ground voltage.

In this case, in the first half period HP1 of the sine wave SSN, the output of the first square wave signal SSQ1 is a low potential VL, so that the second switch 124 is turned off, so when the first pulse width modulation signal SPWM1 is at a high When the potential is VH, the first switch 122 will be turned on, and the first output signal SO1 will have the first voltage V1 at this time. And when the first pulse width modulation signal SPWM1 is at the low potential VL, the first switch 122 will be turned off, and at this time the first output signal SO1 will be quickly consumed in the output process and pulled down to the ground voltage, so in In the first half period HP1 of the sine wave SSN, the waveform of the first output signal SO1 is very similar to that of the first PWM signal SPWM1 .

Then, when the first half period HP1 of the sine wave SSN ends and enters the second half period HP2, the first square wave signal SSQ1 jumps to a high potential VH, and in the second half period HP2, the first square wave signal SSQ1 will remain at a high potential VH, and the first pulse width modulation signal SPWM1 will remain at a low potential, at this time the first switch 122 will be turned off, the second switch 124 will be turned on, and the first output signal SO1 will remain at the Second voltage V2.

In this embodiment, the first switch 122 and the second switch 124 can be made of larger components, so the first switch 122 and the second switch 124 can withstand larger current and voltage. In this case, the output switch unit 120 can directly output the first voltage V1 provided by the power supply circuit as the first output signal SO1 according to the control of the first pulse width modulation signal SPWM1. Therefore, the first voltage V1 can be stably provided when the load draws current. In this way, the first output signal SO1 also has a stronger driving capability, thereby reducing the situation that the waveform of the first output signal SO1 is damaged when driving the antenna module AM1 . In contrast, since the first pulse width modulation signal SPWM1 only needs to be able to turn on or off the first switch 122, the driving capability required by the first pulse width modulation signal SPWM1 is relatively low, and the required The voltage may also be lower, that is, in some embodiments, the first voltage V1 may be greater than the high potential VH. In this case, the waveform modulation unit 110 can be manufactured with smaller components, and can more sensitively modulate the sine wave SSN and the carrier SCR to generate the first pulse width modulation signal SPWM1.

In addition, in this embodiment, the processor 130 can adjust the amplitude of the sine wave SSN according to the digital signal to be transmitted to adjust the duty cycle of the first pulse width modulation signal SPWM1 and the first output signal SO1 . Fig. 3 is a schematic diagram of the relationship between the amplitude of the sine wave SSN and the duty cycle of the first pulse width modulation signal SPWM1. In FIG. 3 , the amplitude of the sine wave SSN in the period T1 is greater than the amplitude of the sine wave SSN in the period T2 . In this case, the duty ratio of the first pulse width modulation signal SPWM1 in the period T1 is larger than the duty ratio of the first pulse width modulation signal SPWM1 in the period T2. In this embodiment, the duty ratio of the first pulse width modulation signal SPWM1 in the period T1 refers to the time length during which the first pulse width modulation signal SPWM1 is at the high potential VH in the period T1, which accounts for the entire time of the period T1 ratio of length.

Since the amplitude of the sinusoidal wave obtained by the first output signal SO1 after filtering is related to the duty cycle of the first output signal SO1, the receiving end of the near field communication can obtain the sinusoidal wave after filtering the received signal. The magnitude of the amplitude is used to judge the value represented by the signal. For example, when the duty cycle of the first output signal SO1 is greater than, for example but not limited to, greater than 60%, the amplitude of the sine wave obtained by the receiving end after filtering the first output signal SO1 will be greater than the first value, for example, at this time The receiving end can judge that the value of the first output signal SO1 is logic 1, and when the duty ratio of the first output signal SO1 is, for example but not limited to, less than 40%, the receiving end obtains the value after filtering the first output signal SO1 The amplitude of the sine wave is, for example, smaller than the second value. At this time, the receiving end can determine that the value of the first output signal SO1 is logic 0.

Since the waveform modulation unit 110 can modulate the sine wave SSN according to the carrier SCR to generate the first pulse width modulation signal SPWM1, therefore, in the first pulse width modulation signal SPWM1, except for signals with the same frequency as the sine wave SSN In addition, it also includes a high-frequency signal with the same frequency as the carrier SCR, so that the switching frequency of the output switching unit 120 is increased, thereby reducing the low-order harmonics generated during the transmission process. In this case, the filter circuit in the antenna module AM1 does not need to provide an inductor, but can perform filtering through a capacitor. In some embodiments, in order to effectively reduce the low-order harmonics generated during the transmission of the first pulse width modulation signal SPWM1 , the frequency of the carrier SCR can be set to 20 to 40 times the frequency of the sine wave SSN.

FIG. 4 is a schematic diagram of a near field communication transmission circuit 200 according to an embodiment of the present application. The near field communication transmission circuit 200 has a similar structure to the near field communication transmission circuit 100 and can operate according to a similar principle. However, in the near field communication transmission circuit 200, the waveform modulation unit 210 generates the first A pulse width modulation signal SPWM1, and generate the first square wave signal SSQ1 according to the sine wave SSN, and generate a second pulse width modulation signal SPWM2 according to the sine wave SSN and the carrier SCR, and generate a second square wave signal according to the sine wave SSN wave signal SSQ2, and the output switch unit 220 can also generate a second output signal SO2 according to the second pulse width modulation signal SPWM2 and the second square wave signal SSQ2. Correspondingly, the NFC transmission circuit 200 may further include a second output terminal OUT2, and may output the second output signal SO2 through the second output terminal OUT2.

In FIG. 4 , the output switch unit 220 may further include a third switch 226 and a fourth switch 228 . The third switch 226 has a first terminal, a second terminal and a control terminal, the first terminal of the third switch 226 can be coupled to the first voltage V1, and the second terminal of the third switch 226 can be coupled to the second output terminal OUT2 , and the control terminal of the third switch 226 can receive the second pulse width modulation signal SPWM2. The fourth switch 228 may have a first terminal, a second terminal and a control terminal, the first terminal of the fourth switch 228 may be coupled to the second voltage V2, and the second terminal of the fourth switch 228 may be coupled to the second output terminal. OUT2, and the control terminal of the fourth switch 228 can receive the second square wave signal SSQ2.

FIG. 5 is a signal timing diagram of the NFC transmission circuit 200 . In Fig. 5, in the first half period HP1 of the sine wave SSN, the potentials of the sine wave SSN and the carrier SCR are positive, and in the second half period HP2 of the sine wave SSN, the potentials of the sine wave SSN and the carrier SCR are burden.

In this embodiment, the waveform modulation unit 210 modulates the sine wave SSN according to the carrier SCR in the first half cycle HP1 of the sine wave SSN to generate the first pulse width modulation signal SPWM1, and makes the first square wave Signal SSQ1 is kept at low potential VL. In this way, in the first half period HP1 of the sine wave SSN, the first switch 122 in the output switch unit 220 will be turned on and off correspondingly according to the potential change of the first pulse width modulation signal SPWM1, so as to drive the The first output signal SO1 with stronger capability is output from the first output terminal OUT1.

Next, in the second half period HP2 of the sine wave SSN, the waveform modulation unit 210 will modulate the sine wave SSN according to the carrier SCR to generate the second pulse width modulation signal SPWM2, and keep the second square wave signal SSQ2 at Low potential VL. For example, in the second half period HP2 of the sine wave SSN, the waveform modulation unit 210 will make the second pulse width modulation signal SPWM2 have a high value when the absolute value of the amplitude of the sine wave SSN is greater than the absolute value of the amplitude of the carrier SCR. Potential VH, and when the absolute value of the amplitude of the sine wave SSN is smaller than the absolute value of the amplitude of the carrier SCR, the second pulse width modulation signal SPWM2 has a low potential VL. For example, the waveform modulation unit 210 can compare the amplitudes of the sine wave SSN and the carrier SCR through a comparator, and output the second pulse width modulation signal SPWM2 according to the comparison result. In addition, in some other embodiments, the comparator can also be matched with other components, and the negative voltage sine wave SSN and the carrier SCR are transformed into positive voltage by other components, and then the comparator is used to compare the amplitudes.

In this way, in the second half period HP2 of the sine wave SSN, the third switch 216 in the output switch unit 220 will be turned on and off correspondingly according to the potential change of the second pulse width modulation signal SPWM2, thereby turning the The second output signal SO2 with stronger driving capability is output from the second output terminal OUT2.

In addition, in the first half cycle HP1 of the sine wave SSN, the waveform modulation unit 210 will keep the second pulse width modulation signal SPWM2 at the low potential VL, and keep the second square wave signal SSQ2 at the high potential VH, therefore The second output signal SO2 will remain at the second voltage V2. In the second half cycle HP2 of the sine wave SSN, the first pulse width modulation signal SPWM1 will be kept at a low potential VL, and the first square wave signal SSQ1 will be kept at a high potential VH, so the first output signal SO1 will be kept at The second voltage V2.

That is to say, the NFC controller 200 can respectively generate the first output signal SO1 and the second output signal SO2 with pulse width modulation waveforms in the first half cycle HP1 and the second half cycle HP2 of the sine wave SSN, and pass The first output terminal OUT1 outputs the first output signal SO1 to the first terminal of the antenna module AM2, and outputs the second output signal SO2 to the second terminal of the antenna module AM2 through the second output terminal OUT2. In this case, if the signal voltage received by the antenna module AM2 is determined in a differential form, for example, the voltage of the signal received by the first terminal voltage of the antenna module AM2 minus the voltage of the second terminal is used to determine the signal voltage received by the antenna module AM2. The signal voltage received in the first half period HP1 of the sine wave SSN will have the opposite polarity to the signal voltage received by the antenna module AM2 in the second half period HP2 of the sine wave SSN, so it can be judged that The signal difference in a half cycle.

In the embodiment of FIG. 1 , the near field communication controller 100 modulates the sine wave SSN according to the carrier SCR in the first half period HP1 of the sine wave SSN to generate the first pulse width modulation signal SPWM1 and the first output signal SO1, however, in some other embodiments, the near field communication controller 100 can also modulate the sine wave SSN according to the carrier SCR in the second half period HP2 of the sine wave SSN to generate the second pulse width modulation signal SPWM2 and the second output signal SO2 without generating the first pulse width modulation signal SPWM1 and the first output signal SO1.

In FIG. 4 , the antenna module AM2 can be coupled to the first output terminal OUT1 and the second output terminal OUT2 of the NFC controller 200 . The antenna module AM2 may include an Electromagnetic Compatibility (EMC) filter EF, a matching unit MU and an antenna AT.

The electromagnetic compatibility filter EF can filter the first output signal SO1 and the second output signal SO2. In this embodiment, since the first output signal SO1 and the second output signal SO2 are generated by modulating the sine wave SSN according to the carrier SCR, the low-order harmonics generated during the transmission process are small, so that the electromagnetic compatibility filter EF There is no need to set an inductance, but a capacitor can be used to achieve the required filtering effect. For example, the EMC filter EF may include capacitors C1 and C2. The capacitor C1 has a first terminal and a second terminal, the first terminal of the capacitor C1 can be coupled to the first output terminal OUT1, and the second terminal of the capacitor C1 can be coupled to the second voltage V2. Similarly, the capacitor C2 has a first terminal and a second terminal, the first terminal of the capacitor C2 can be coupled to the second output terminal OUT2, and the second terminal of the capacitor C2 can be coupled to the second voltage V2.

The matching unit MU can provide an impedance matched with the first output signal SO1 and the second output signal SO2 to receive the filtered first output signal SO1 and the second output signal SO2 . In FIG. 4 , the matching unit MU may include capacitors C3 , C4 , C5 , and C6 . However, in some other embodiments, the matching unit MU may also be provided with other electronic components, such as but not limited to resistors, according to requirements. The antenna AT may, for example, include an inductor La, a capacitor Ca and a resistor Ra. The antenna AT can transmit the first output signal SO1 and the second output signal SO2 received by the matching unit MU to the outside.

In the embodiment of FIG. 1 , the near field communication transmission circuit 100 can be designed as a chip CP1 and can be arranged with the antenna module AM1 in an electronic device that requires near field communication. However, in the embodiment of FIG. 4, since the functions of the processor 130, the sinusoidal wave generation unit 140, and the carrier generation unit 150 in the near field communication transmission circuit 100 can be performed by corresponding circuits in the electronic device, the near field communication transmission The circuit 200 can omit the processor 130 , the sine wave generation unit 140 and the carrier generation unit 150 in the near field communication transmission circuit 100 , and can directly receive the sine wave SSN and the carrier SCR input from the outside.

In summary, the near-field communication transmission circuit, related chips and electronic devices provided by the embodiments of the present application can use the waveform modulation unit to modulate the sine wave to generate a pulse width modulation signal with a higher frequency, so it can The generation of low-order harmonics is reduced, thereby improving the quality of signal transmission, and the setting of inductance can be reduced, so that the cost and area of the electronic device can be reduced.

The foregoing description briefly sets forth features of certain embodiments of the present application, so that those skilled in the art to which the present application pertains can more fully understand the various aspects of the present disclosure. Those with ordinary knowledge in the technical field to which this application belongs should understand that they can easily use the disclosure as a basis to design or modify other processes and structures to achieve the same purpose and/or achieve the same advantages. Those with ordinary knowledge in the technical field of the present application should understand that these equivalent embodiments still belong to the spirit and scope of the present disclosure, and various changes, substitutions and changes can be made without departing from the spirit of the present disclosure. with range.

Claims

A near-field communication transmission circuit, characterized in that it comprises:

first output terminal;

a waveform modulation unit, configured to receive a sine wave and a carrier wave, generate a first pulse width modulation signal according to the sine wave and the carrier wave, and generate a first square wave signal according to the sine wave; and

Output switching unit, including:

The first switch has a first terminal, a second terminal and a control terminal, the first terminal of the first switch is coupled to a first voltage, and the second terminal of the first switch is coupled to the a first output terminal, and the control terminal of the first switch are used to receive the first pulse width modulation signal; and

The second switch has a first end, a second end and a control end, the first end of the second switch is coupled to a second voltage, the second end of the second switch is coupled to the a first output terminal, and the control terminal of the second switch are used to receive the first square wave signal;

in:

The frequency of the carrier wave is greater than the frequency of the sine wave;

the first voltage is greater than the second voltage;

In the first half cycle of the sine wave:

The first PWM signal has a high potential when the absolute value of the amplitude of the sine wave is greater than the absolute value of the amplitude of the carrier wave, and when the absolute value of the amplitude of the sine wave is smaller than the absolute value of the amplitude of the carrier wave has a low potential at the time; and

said first square wave signal is maintained at said low potential; and

In the second half cycle of the sine wave:

said first PWM signal is maintained at said low level; and

The first square wave signal is kept at the high potential.
The near field communication transmission circuit as claimed in claim 1, wherein the frequency of the sine wave is 13.56 MHz, and the error range is within plus or minus 7 kHz.
The near field communication transmission circuit according to claim 1 or 2, wherein the frequency of said carrier wave is 20 to 40 times the frequency of said sine wave.
The near field communication transmission circuit according to claim 1 or 2, wherein the carrier wave is a triangle wave or a sawtooth wave.
The near field communication transmitting circuit as claimed in claim 1, wherein:

In the first half period of the sine wave, the potentials of the sine wave and the carrier are positive, and in the second half period of the sine wave, the potentials of the sine wave and the carrier are positive. is negative; or

In the first half cycle of the sine wave, the potentials of the sine wave and the carrier are negative, and in the second half cycle of the sine wave, the potentials of the sine wave and the carrier are negative. is positive.
The near field communication transmission circuit according to claim 1, further comprising:

The second output terminal is used to output a second output signal;

in:

The waveform modulation unit is also used to generate a second pulse width modulation signal and a second square wave signal according to the sine wave and the carrier wave;

The output switch unit also includes:

The third switch has a first terminal, a second terminal and a control terminal, the first terminal of the third switch is coupled to the first voltage, and the second terminal of the third switch is coupled to The second output terminal and the control terminal of the third switch are used to receive the second pulse width modulation signal; and

The fourth switch has a first terminal, a second terminal and a control terminal, the first terminal of the fourth switch is coupled to the second voltage, and the second terminal of the fourth switch is coupled to The second output terminal and the control terminal of the fourth switch are used for receiving the second square wave signal.
The near field communication transmitting circuit as claimed in claim 6, wherein:

During said first half cycle of said sine wave, said sine wave has a positive potential and during said second half cycle of said sine wave, said sine wave has a negative potential;

In the second half cycle of the sine wave:

The second pulse width modulation signal has the high potential when the absolute value of the amplitude of the sine wave is greater than the absolute value of the amplitude of the carrier, and when the absolute value of the amplitude of the sine wave is smaller than the amplitude of the carrier has said low potential in absolute value; and

the second square wave signal is maintained at the low level; and

In the first half cycle of the sine wave:

said second PWM signal is maintained at said low level; and

The second square wave signal remains at the high potential.
The near field communication transmission circuit according to any one of claims 1, 2, 5 and 6, further comprising:

a sine wave generating unit for generating the sine wave; and

a carrier generating unit, configured to generate the carrier;

Wherein the maximum amplitude of the sine wave is smaller than the maximum amplitude of the carrier wave.
The near field communication transmitting circuit as claimed in claim 8, further comprising:

The processor is configured to adjust the amplitude of the sine wave according to the digital signal to be transmitted so as to adjust the duty ratio of the first pulse width modulation signal.
A chip, characterized in that it comprises:

The near field communication transmission circuit according to any one of claims 1 to 9.
An electronic device, characterized in that it comprises:

the chip of claim 10; and

An antenna module, coupled to the first output end of the near field communication controller, the antenna module includes:

an electromagnetic compatibility filter, configured to filter the first output signal output by the first output terminal;

a matching unit, configured to provide an impedance matched with the first output signal to receive the filtered first output signal; and

An antenna, configured to send the first output signal received by the matching unit.
The electronic device according to claim 11, wherein the electromagnetic compatibility filter comprises a capacitor having a first end and a second end, the first end of the capacitor is coupled to the first output end, and the The second end of the capacitor is coupled to the second voltage.