Method and device for adjusting modulation index of NFC (Near Field Communication) equipment and NFC equipment

Abstract

The invention discloses a modulation index adjusting method and device of NFC (Near Field Communication) equipment and the NFC equipment, which are used for improving the adjustment efficiency of a modulation index and enabling the modulation index to be within a protocol requirement range. The method comprises the following steps: acquiring an electrical parameter reflecting the load effect of the NFC chip; according to the electrical parameter, calculating an equivalent conduction resistance value which needs to be configured for the power amplifier; and configuring the equivalent conduction resistance value of the power amplifier according to the equivalent conduction resistance value needing to be configured, so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after configuration is within a protocol requirement range.

Description

Technical Field

[0001] The present invention relates to the field of near field communication technology, and in particular to a NFC Modulation index adjustment method and device for equipment NFC equipment. Background Art

[0002] Near Field Communication When the chip works in the card reader mode and sends commands to the outside, it needs to meet the modulation index (modulation index) specified in the protocol. ), the modulation index It means that the high and low levels of the carrier envelope sent out must meet a certain ratio. NFC When the chip is used, the load effect will cause the modulation index Changes may occur, or even exceed the protocol requirements. Therefore, the modulation index needs to be dynamically adjusted according to the size of the load effect. The size of the modulation index can always be within the scope of the agreement.

[0003] Current dynamic regulation modulation index The method is generally based on The emission current of the transmitting circuit in the chip is achieved by adjusting the on-resistance of the power amplifier by looking up the table. The emission current refers to NFC The power supply of the chip provides the average current of the power amplifier of the transmitting circuit. This method requires the establishment of a lookup table for different antennas and impedance matching circuits. When the transmitting current deviation is large, the adjustment efficiency is low, which will also cause the modulation index to There is an urgent need for a new dynamic modulation index way. Summary of the Invention

[0004] The embodiment of the present invention provides a modulation index adjustment method, device and NFC devices to address low regulation efficiency and modulation index There are issues that go beyond the scope of the agreement.

[0005] A modulation index adjustment method for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFC The chip includes a signal transmission circuit, the signal transmission circuit includes a power amplifier, and the method includes: Get reflects the NFC Electrical parameters of the chip's load effect; Calculating an equivalent on-resistance value required for the power amplifier based on the electrical parameters; According to the equivalent on-resistance value to be configured, the equivalent on-resistance value of the power amplifier is configured so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after configuration is within the range required by the protocol.

[0006] In one implementation, the equivalent on-resistance value to be configured includes the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage, or the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope non-modulation stage; Configuring the equivalent on-resistance value of the power amplifier according to the required equivalent on-resistance value so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after the configuration is within the range required by the protocol includes: The equivalent on-resistance value of the power amplifier in the carrier envelope modulation stage is configured according to the equivalent on-resistance value that needs to be configured for the power amplifier in the carrier envelope modulation stage, while the equivalent on-resistance value of the power amplifier in the carrier envelope non-modulation stage remains unchanged, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after adjustment is within the range required by the protocol; or; According to the equivalent on-resistance value that needs to be configured for the power amplifier during the carrier envelope non-modulation stage, the equivalent on-resistance value of the power amplifier during the carrier envelope non-modulation stage is configured, while the equivalent on-resistance value of the power amplifier remains unchanged during the carrier envelope modulation stage, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after adjustment is within the range required by the protocol.

[0007] In one implementation, the electrical parameter includes a power supply current supplied to the power amplifier by the power supply of the signal transmission circuit, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, The amplitude of the component of the voltage supplied by the power supply to the power amplifier corresponding to the carrier frequency, supplying a power supply current to the power amplifier through the power supply, The power supply supplies a DC voltage to the power amplifier.

[0008] In one implementation, The average current of the power supply current supplied by the power supply to the power amplifier.

[0009] In one implementation, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance.

[0010] In one implementation, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance.

[0011] In one implementation, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance.

[0012] In one implementation, the power amplifier may be configured in a differential matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit and a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit and a fourth switch unit; The first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; The second end of the first switch unit and the first end of the third switch unit are connected in common and connected to the first end of the impedance matching circuit; the second end of the second switch unit and the first end of the fourth switch unit are connected in common and connected to the second end of the impedance matching circuit; The second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, and the second end of the third resistor and the second end of the fourth resistor are both connected to the ground; If the power amplifier operates in differential matching mode, the sum of the resistance values of the first resistance unit and the fourth resistance unit, and the sum of the resistance values of the second resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

[0013] In one implementation, the power amplifier may be configured in a first single-ended matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit, and a third switch unit; A first end of the first resistor unit is connected to the power supply, a second end of the first resistor unit is connected to the first end of the first switch unit, a second end of the first switch unit and a first end of the third switch unit are commonly connected to the first end of the impedance matching circuit, a second end of the third switch unit is connected to the first end of the third resistor, and a second end of the third resistor and a second end of the impedance matching circuit are both connected to ground; If the power amplifier operates in the first single-ended matching mode, the resistance values of the first resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

[0014] In one implementation, the power amplifier may be configured in a second single-ended matching mode, the power amplifier including a first resistor unit, a third resistor unit, a first switch unit and a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit and a fourth switch unit; The first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; The second end of the first switch unit, the second end of the second switch unit, the first end of the third switch unit and the first end of the fourth switch unit are commonly connected to the first end of the impedance matching circuit; The second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, and the second end of the third resistor, the second end of the fourth resistor, and the second end of the impedance matching circuit are all connected to the ground; If the power amplifier operates in the second single-ended matching mode, the parallel resistance value of the first resistance unit and the second resistance unit, and the parallel resistance value of the third resistance unit and the fourth resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured in the carrier envelope modulation stage.

[0015] In one implementation, the first resistance unit and the first switch unit, the second resistance unit and the second switch unit, the third resistance unit and the third switch unit, and the fourth resistance unit and the fourth switch unit can be equivalently implemented by one or more transistors in a chip.

[0016] In one implementation, the modulation index is a center value of a range required by the protocol.

[0017] A near field communication NFC device for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFC The chip includes a signal transmitting circuit, the signal transmitting circuit includes a power amplifier, the NFC The device includes: Acquisition module, used to obtain the NFC Electrical parameters of the chip's load effect; A processing module is used to calculate the equivalent on-resistance value that needs to be configured for the power amplifier based on the electrical parameters; and configure the equivalent on-resistance value of the power amplifier according to the equivalent on-resistance value that needs to be configured, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after configuration is within the range required by the protocol.

[0018] A sort of NFC equipment, NFC The device includes a processor and a memory, wherein the memory is used to store instructions, and the processor is used to read the instructions and execute the modulation index adjustment method according to any one of the above items.

[0019] A sort of NFC Equipment, including: NFC chip; Set in the NFC Impedance matching circuit between chip and antenna; And a method for implementing the modulation index adjustment method as described in any one of the above NFC Controller.

[0020] In one of the solutions implemented in this application, the equivalent on-resistance of the power amplifier can be automatically calculated based on some electrical parameters that reflect the size of the load effect, so that the modulation index Always meet the range required by the protocol. In this way, there is no need to waste time and effort to build a lookup table for different antennas and impedance matching circuits, which improves the modulation index The regulation efficiency is good, and there is no situation where the modulation index range required by the protocol is exceeded. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 It is the non-modulation stage in the present invention NFC The high level of the carrier envelope transmitted by the chip through the signal transmission circuit ( V a ) and the low level of the carrier envelope during the modulation phase ( V b ) a schematic diagram; Figure 2 In one embodiment of the present invention NFC Schematic diagram of an equivalent relationship between a chip, an impedance matching circuit, and its antenna; Figure 3 This is a schematic diagram of a process for adjusting the modulation index in one embodiment of the present invention; Figure 4 In the differential matching mode of an embodiment of the present invention NFC A circuit diagram of the chip, matching impedance circuit, and antenna; Figure 5 In one embodiment of the present invention, the 2TX single-ended matching mode NFC A circuit diagram of the chip, matching impedance circuit, and antenna; Figure 6In one embodiment of the present invention, the 1TX single-ended mode NFC A circuit diagram of the chip, matching impedance circuit and antenna. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0024] NFC Equipment includes NFC Chip and antenna, NFC An impedance matching circuit is provided between the chip and the antenna to match the impedance of the antenna to ensure the antenna's transceiver performance. NFC The chip includes a signal transmitting circuit, which includes components such as a power amplifier. NFC The chip is used to transmit through the signal transmission circuit NFC Signals / data required for communication. NFC The chip generally includes card reader mode, point-to-point mode and card emulation mode; among them, in card reader mode, NFC The device uses a signal transmitting circuit to generate a radio frequency field that can be used to read or write external NFC Tags to read or write NFC Data in the tag‌ .

[0025] NFC When the device sends commands in reader mode, it must meet the modulation index specified in the protocol. ), the modulation index It means that the high and low levels of the carrier envelope sent out must meet a certain ratio. Figure 1 As shown, the non-modulation stage NFC The high level of the carrier envelope transmitted by the chip through the signal transmission circuit ( V a ) and the low level of the carrier envelope during the modulation phase ( V b ) must meet the requirements of the protocol. This relative ratio is the modulation index, that is: (1) It is understandable that the modulation index may vary depending on the protocol type or technology type. It can fluctuate within the range of 7.5% to 19%, with no specific limit.

[0026] Exemplarily, the protocol types include NFC forum, International Organization for Standardization / International Electrotechnical Commission (ISO / IEC), or EMV standards (Europay, MasterCard, and VisaCo, EMVCo); technology types include B Technology B Communication Mode) or F Technology F communication mode).

[0027] like Figure 2 As shown, you can NFC The chip's power supply, power amplifier and control clock module are equivalent to voltage sources , the internal resistance is ; The component amplitude corresponding to the carrier frequency (such as 13.56M) of the voltage source provided to the power amplifier by the power supply, is the equivalent on-resistance of the power amplifier; is the equivalent matching impedance formed by the impedance matching circuit and the antenna. For the first method, the equivalent on-resistance Keep the voltage source unchanged There are two transmitting voltages, high and low, which can be used to generate the high and low levels of the carrier envelope to adjust the modulation index. ; The second method, voltage source Remains unchanged, the equivalent on-resistance There are two configurations, small and large, which can be used to generate the high and low levels of the carrier envelope respectively. For the second method, when there is metal or a card close to NFC When the chip is connected, the load effect changes, which will cause the equivalent matching impedance changes, resulting in a modulation index changes, which in some extreme cases may result in a modulation index Therefore, it is necessary to automatically adjust the equivalent on-resistance of the power amplifier according to the size of the load effect. The scheme makes the modulation index Keep it within the range required by the protocol. It is worth noting that the equivalent on-resistance corresponding to the low level of the carrier envelope in the modulation stage can be adjusted , the equivalent on-resistance corresponding to the high level of the carrier envelope in the non-modulation stage Generally, it transmits with the minimum internal resistance to maintain the strongest outward carrier. Of course, the equivalent on-resistance corresponding to the high level of the carrier envelope in the non-modulation stage can also be adjusted. .

[0028] The current plan is based on NFC The power supply current of the chip (Also called transmit current) size lookup table to adjust the equivalent on-resistance corresponding to the low level of the carrier envelope in the modulation stage that needs to be configured Therefore, it is necessary to establish a lookup table for different antennas and matching impedance circuits. This process is time-consuming and labor-intensive. In addition, due to the limited range of the lookup table, the modulation index obtained by adjustment may still be incorrect under certain extreme conditions. For example, situations beyond the scope of the agreement, >=3700, =12 EUR, =10%, then >=6000, modulation index It is still possible to exceed the range.

[0029] To this end, this application aims to provide a modulation index adjustment method to solve the problem of traditional modulation index adjustment. It takes a lot of time and effort to build a table and the modulation index Technical issues beyond the scope of the agreement. NFC The electrical parameters of the chip's load effect; based on the electrical parameters, the equivalent on-resistance value that the power amplifier needs to be configured is calculated; then, according to the equivalent on-resistance value that needs to be configured, the equivalent on-resistance value of the power amplifier is configured so that the modulation index of the carrier envelope emitted by the signal transmission circuit after configuration is within the range required by the protocol. It can be seen that when the modulation index needs to be adjusted When the load effect is reflected, the equivalent on-resistance of the power amplifier to be configured can be automatically calculated based on some electrical parameters that reflect the size of the load effect, so that the modulation index after configuration is Always meet the range required by the protocol. In this way, there is no need to waste time and effort to build a lookup table for different antennas and impedance matching circuits, which improves the modulation index The regulation efficiency is guaranteed and there is no situation that exceeds the scope required by the agreement.

[0030] like Figure 3 The process shown in FIG. 1 is a flow chart showing that, in one embodiment, a modulation index adjustment method is provided. NFC Controller implementation for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFCThe chip includes a signal transmission circuit, which includes a power amplifier and includes the following steps: S10A, obtaining the information reflecting the NFC Electrical parameters of the chip's load effect; S20A, calculating an equivalent on-resistance value required for the power amplifier based on the electrical parameters; S30C: Configure the equivalent on-resistance value of the power amplifier according to the required equivalent on-resistance value, so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after configuration is within the range required by the protocol.

[0031] As an example, NFC The connection relationship and equivalent relationship between the chip, impedance matching circuit and antenna can be found in Figure 2 As shown, no repetition is given here.

[0032] In step S10A, when metal or card approaches NFC When the chip is used, the load effect will cause the modulation index If the modulation index changes, or even exceeds the requirements of the modulation index protocol, in this embodiment, the NFC The electrical parameters of the chip's load effect, for example, include the equivalent matching impedance formed by the impedance matching circuit and the antenna , or the power supply current supplied to the power amplifier by the power supply, specifically the average current of the power supply current Understandably, the NFC The chip is configured to support acquisition of the above electrical parameters.

[0033] In the steps S20A-S30A, the equivalent on-resistance value to be configured for the power amplifier is calculated based on the electrical parameters, and the equivalent on-resistance value of the power amplifier is configured according to the equivalent on-resistance value to be configured, so that the modulation index of the carrier signal transmitted by the signal transmitting circuit after adjustment is within the scope of the agreement.

[0034] It should be noted that in this embodiment, since the calculated equivalent on-resistance value required to adjust the modulation index is a theoretical value, it is necessary to consider the actual value. NFC The chip supports the configuration of internal resistance gear. For example, if the calculated equivalent on-resistance value to be configured is 2 ohms, the equivalent on-resistance value of the power amplifier can be configured according to 2 ohms or a resistance value close to it. Specifically, as an example, if NFC The chip supports configuring the equivalent on-resistance value of the power amplifier to the calculated equivalent on-resistance value to be configured, and then directly configure it according to the equivalent on-resistance value to be configured; ifNFC The chip does not support the equivalent on-resistance value of the power amplifier If the calculated equivalent on-resistance value is configured, the device that is close to the equivalent on-resistance value to be configured will be selected. NFC The equivalent on-resistance value supported by the chip is configured to ensure the modulation index after adjustment within the scope of the agreement.

[0035] It can be seen that in this embodiment, the equivalent on-resistance of the power amplifier can be automatically calculated and adjusted based on some electrical parameters that reflect the size of the load effect, so that the modulation index Always meet the range required by the protocol. In this way, there is no need to waste time and effort to build a lookup table for different antennas and impedance matching circuits, which improves the modulation index The regulation efficiency is good, and there is no situation where the modulation index range required by the protocol is exceeded.

[0036] As described above, the high level of the carrier envelope in the non-modulation stage ( ) and the low level of the carrier envelope during the modulation phase ( ) is the modulation index Therefore, the equivalent on-resistance of the power amplifier can be adjusted during the carrier envelope modulation phase, or the equivalent on-resistance of the power amplifier can be adjusted during the carrier envelope non-modulation phase. Below, these two methods are divided into two embodiments for complete description.

[0037] Method 1 In one embodiment, a modulation index adjustment method is provided. NFC Controller implementation for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFC The chip includes a signal transmission circuit, which includes a power amplifier and includes the following steps: S10B, obtain the information reflecting the NFC Electrical parameters of the chip's load effect; S20B. Calculating an equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage based on the electrical parameters; S30B. According to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, the equivalent on-resistance value of the power amplifier during the carrier envelope modulation stage is configured, while the equivalent on-resistance value of the power amplifier remains unchanged during the carrier envelope non-modulation stage, so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after adjustment is within the range required by the protocol.

[0038] The step S10B may refer to the aforementioned step S10A, and will not be described again here.

[0039] In steps S20B-S30B, an equivalent on-resistance value that needs to be configured for the power amplifier during the carrier-envelope modulation phase is calculated based on the electrical parameters. The equivalent on-resistance value of the power amplifier during the carrier-envelope modulation phase is configured according to the equivalent on-resistance value that needs to be configured for the power amplifier during the carrier-envelope modulation phase. The equivalent on-resistance value of the power amplifier during the carrier-envelope non-modulation phase remains unchanged, so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after adjustment is within the range required by the protocol.

[0040] Similarly, in this embodiment, the calculated equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage is a theoretical value, so it is necessary to look at the NFC The chip supports the configuration of internal resistance gears. For example, if the calculated equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage is 2 ohms, the equivalent on-resistance value of the power amplifier during the carrier envelope modulation stage is configured according to a resistance value of 2 ohms or thereabouts.

[0041] In this embodiment, it is possible to directly use some of the NFC The chip's load effect size electrical parameters automatically calculate the equivalent on-resistance value of the power amplifier during the carrier envelope modulation stage and configure it, while the equivalent on-resistance value of the power amplifier remains unchanged during the carrier envelope non-modulation stage, making the modulation index Always meet the range required by the protocol. In this way, there is no need to waste time and effort to build a lookup table for different antennas and impedance matching circuits, which improves the modulation index The regulation efficiency is high, and there is no situation where the modulation index range required by the protocol is exceeded; in addition, this embodiment can only adjust the low level of the carrier envelope in the modulation stage ( V b ) corresponds to the equivalent on-resistance during the non-regulation modulation stage, and the equivalent on-resistance during the non-regulation modulation stage remains unchanged. However, since the equivalent on-resistance during the non-regulation modulation stage is generally transmitted with the minimum equivalent on-resistance, the strongest outward carrier can be maintained.

[0042] It should be noted that the power amplifier includes multiple operating modes, including a single-ended matching mode and a differential matching mode, and the single-ended matching mode includes a first single-ended matching mode ( 1TX Single-ended matching mode) and the second single-ended matching mode ( 2TX Single-ended matching mode), TX Represents the transmitter. As an example, the relationship between the power amplifier, matching impedance circuit and antenna in differential matching mode is similar to that shown in Figure 4As shown, 1TX The relationship between the power amplifier, matching impedance circuit and antenna in single-ended matching mode can be shown as follows: Figure 5 As shown, 2TX The relationship between the power amplifier, matching impedance circuit and antenna in single-ended matching mode can be shown as follows: Figure 6 As shown, whether it is differential matching mode or single-ended matching mode, use a transmitter TX Two transmitters TX , which can be equivalent to the equivalent on-resistance is , the amplitude is voltage source.

[0043] From this, the active power injected into the antenna during the non-modulation phase can be obtained as: (2) (3) (4) Among them, in differential matching mode: n=2, m=1, single-ended matching mode has 2 transmitters ( 2TX ) when n=1, m=1, 1 transmitter ( 1TX ): n=1, m=2, that is, n is 2 in differential mode and 1 in single-ended mode, and m is 2TX When single-ended, it is 1. 1TX When single-ended, it is 2. and are the real and imaginary parts of the equivalent matching impedance of the impedance matching circuit measured or calculated, and ESR (Equivalent Series Resistance) represents the equivalent series resistance value of the inductor L0. represents the equivalent on-resistance value of the power amplifier in the non-modulation stage, The power supply supplies a DC voltage to the power amplifier.

[0044] From the above equations (2), (3) and (4), the antenna current in the non-modulation stage can be obtained as: (5) Similarly, the antenna current in the modulation stage can be obtained as: (6) The magnetic field emitted by the antenna is proportional to the current in the antenna, so the modulation index can be obtained : (7) According to the above derivation, the modulation index can be calculated according to the following formula : (8) According to the above formula (8), we can get , during the carrier envelope modulation stage, the equivalent on-resistance value that the power amplifier needs to be configured with is: (9) If Xt=0, then the above formula (9) can be simplified to: (10) It is worth noting that due to deviation and load effects, It is not necessarily 0, so according to formula (10) we can get Actual amount obtained There will be a certain deviation. The advantage of formula (10) is that it is easier to implement than formula (9) because there are no square and square root operations.

[0045] In addition to the above two methods to obtain In addition, equivalent matching impedance can also be used Modulus substitution Substituting into formula (10), we can get: (11) In addition, if the current It can be measured accurately and Substituting into formula (10), we get: (12) (13) Based on the above analysis and deduction, it can be concluded that in the embodiment of the present application, the power supply of the signal transmission circuit can be used to supply the power supply current of the power amplifier. Or the equivalent matching impedance formed by the impedance matching circuit and the antenna, to calculate the equivalent on-resistance value that the power amplifier needs to be configured with during the above-mentioned carrier envelope modulation stage. In the embodiment of the present application, at least four methods of calculating the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage based on electrical parameters are provided, which are described in detail below.

[0046] In one embodiment, the electrical parameter includes the power supply current supplied by the power supply of the signal transmitting circuit to the power amplifier. (Also called transmit current), calculate the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage according to the following formula: is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, where is the modulation index determined based on the range required by the protocol, The amplitude of the component of the voltage supplied by the power supply to the power amplifier at the carrier frequency (such as 13.56M), The power supply supplies the power amplifier with a power supply current. Can NFC The supply current provided to the power amplifier measured or calculated by the controller, The power supply supplies a DC voltage to the power amplifier.

[0047] It can be seen that in this embodiment, a method for calculating the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage is provided. If the power supply current supplied to the power amplifier by the power supply is Can be measured or calculated, then according to the above formula, according to the power supply current The size of the calculation needs to be configured to configure the equivalent on-resistance value corresponding to the low level of the carrier envelope in the modulation stage; solve the modulation index The modulation efficiency is low, and the modulation index after modulation is In compliance with the requirements of the agreement; moreover, due to the supply current It can be measured or calculated, which also facilitates dynamic modulation modulation index convenience.

[0048] As an example, the supply current Can be NFC The average current provided to the power amplifier by the power supply measured or calculated by the controller is used to increase the equivalent on-resistance value required to be configured by the power amplifier during the calculated carrier envelope modulation stage. accuracy.

[0049] As an example, the modulation index For example, if the protocol requires a range of 8-15%, the modulation index can be taken as the center value of the range to reduce the calculated error, thereby further ensuring that the equivalent on-resistance value required for the power amplifier during the calculated carrier envelope modulation stage is within the range. effectiveness.

[0050] It should be understood that the component amplitude according to The calculated value is an intermediate value; NFC The chip configuration mode (such as single-ended matching mode or differential matching mode) is related. Please refer to the formula derivation in the previous article for further details.

[0051] In one embodiment, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the measured or calculated equivalent matching impedance.

[0052] Similarly, as an example, the modulation index It can be the center value of the range required by the protocol. For example, if the protocol requires a range of 8-15%, the modulation index can be is the center value of the range to reduce the calculation error, thereby further improving the calculated first resistance value. effectiveness.

[0053] It can be seen that in this embodiment, a method for calculating the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage is provided. If the equivalent matching impedance at the carrier frequency (including the real part ) can be measured or calculated, then according to the above formula, the equivalent matching impedance real part Calculate the equivalent on-resistance value corresponding to the low level of the carrier envelope in the modulation stage that needs to be configured; solve the modulation index The modulation efficiency is low, and the modulation index after modulation is It complies with the modulation index range; moreover, since the equivalent matching impedance is a pure configuration after the change, the calculation method in this embodiment will be more accurate.

[0054] In one embodiment, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance.

[0055] Similarly, as an example, the modulation index It can be the center value of the range required by the protocol. For example, if the protocol requires a range of 8-15%, the modulation index can be is the center value of the range to reduce the calculation error, thereby further improving the calculated first resistance value. effectiveness.

[0056] It can be seen that in this embodiment, a method for calculating the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage is provided. If the equivalent matching impedance at the carrier frequency (including the real part and the imaginary part ) can be measured or calculated, then the equivalent on-resistance value corresponding to the low level of the carrier envelope in the modulation stage to be configured can be calculated according to the above formula based on the modulus of the equivalent matching impedance; solve the modulation index The modulation efficiency is low, and the modulation index after modulation is It complies with the modulation index range; and similarly, since the equivalent matching impedance is a pure configuration after the change, the calculation method in this embodiment will also be more accurate.

[0057] In one embodiment, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance.

[0058] Similarly, as an example, the modulation index It can be the center value of the range required by the protocol. For example, if the protocol requires a range of 8-15%, the modulation index can be is the center value of the range to reduce the calculation error, thereby further improving the calculated first resistance value. effectiveness.

[0059] It can be seen that in this embodiment, a method for calculating the first resistance value for adjusting the modulation index is provided. If the equivalent matching impedance at the carrier frequency is Z t (including the real part and the imaginary part ) can be measured or calculated, then according to the above formula, the real part of the equivalent matching impedance can be and the imaginary part Calculate the equivalent on-resistance value corresponding to the low level of the carrier envelope in the modulation stage that needs to be configured; solve the modulation index The modulation efficiency is low, and the modulation index after modulation is It complies with the modulation index range; and similarly, since the equivalent matching impedance is a pure configuration after the change, the calculation method in this embodiment will also be more accurate.

[0060] It should be noted that the above provides four methods for calculating the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage based on electrical parameters, which ensures the diversity and feasibility of the scheme. According to any of the above four methods, the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage is obtained. The equivalent on-resistance of the power amplifier that is closest to the equivalent on-resistance value to be configured or the same as the equivalent on-resistance value to be configured can be selected for configuration to achieve adjustment of the modulation index. purpose.

[0061] In one embodiment, as an example, Figure 4 As shown, the power amplifier can be configured as a differential matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit and a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit and a fourth switch unit; the first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; the second end of the first switch unit and the first end of the third switch unit are commonly connected and connected to the first end of the impedance matching circuit, the second end of the second switch unit and the first end of the fourth switch unit are commonly connected and connected to the second end of the impedance matching circuit; the second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, and the second end of the third resistor and the second end of the fourth resistor are both connected to the ground; wherein the first resistor unit and the second resistor unit are both R p0 , the third resistance unit and the fourth resistance unit are R n0; The impedance matching circuit is a differential matching architecture, as an example, Figure 4 As shown, the impedance matching circuit includes an inductor L 0. Capacitor C 0. Capacitor C 1. Capacitor C 2 and resistor R q The number of each device is 2 and they are symmetrically distributed. L 0 and capacitor C 0 can realize the filtering function, the capacitor C 1 and capacitor C 2 is used for impedance matching, resistance R q Can reduce the antenna Q value; the antenna can be equivalent to include capacitance C a 、 R a With inductance L a , the connection relationship is as follows Figure 4 shown.

[0062] It can be seen that if the power amplifier operates in differential matching mode, the sum of the resistance values of the first resistance unit and the fourth resistance unit, and the sum of the resistance values of the second resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

[0063] As an example, the first resistance unit and the first switch unit, the second resistance unit and the second switch unit, the third resistance unit and the third switch unit, and the fourth resistance unit and the fourth switch unit can be equivalently implemented by one or more transistors in a chip.

[0064] In one embodiment, as an example, Figure 6 As shown, the power amplifier can be configured in a first single-ended matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit, and a third switch unit; the first end of the first resistor unit is connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, the second end of the first switch unit and the first end of the third switch unit are commonly connected to the first end of the impedance matching circuit, the second end of the third switch unit is connected to the first end of the third resistor, and the second end of the third resistor and the second end of the impedance matching circuit are both connected to the ground; wherein, Figure 6 In the example, the first resistance unit can be represented by R p , the third resistance unit is expressed as R n .

[0065] It can be seen that if the power amplifier operates in the first single-ended matching mode, the resistance values of the first resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

[0066] In one embodiment, the power amplifier can be configured as a second single-ended matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit and a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit and a fourth switch unit; the first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; the second end of the first switch unit, the second end of the second switch unit, the first end of the third switch unit and the first end of the fourth switch unit are commonly connected and connected to the first end of the impedance matching circuit; the second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, the second end of the third resistor, the second end of the fourth resistor and the second end of the impedance matching circuit are all connected to the ground, wherein the first resistor unit and the second resistor unit are R p0 , the third resistance unit and the fourth resistance unit are R n0 .

[0067] As an example, Figure 5 As shown, the impedance matching circuit is a structure without balun. The impedance matching circuit includes an inductor. L 0. Capacitor C 0. Capacitor C 1. Capacitor C 2. Resistance R q Inductors L 0 and capacitor C 0 can realize the filtering function, the capacitor C 1 and capacitor C 2 is used for impedance matching, resistance R q Can reduce the antenna Q value. Figure 5 The first port TXP and the second port TXN Both connected to the inductor L 0 as an example, in actual application, you can also just TXP and TXN One of the inductors is connected to L 0.

[0068] It can be seen that if the power amplifier operates in the second single-ended matching mode, the parallel resistance value of the first resistance unit and the second resistance unit, and the parallel resistance value of the third resistance unit and the fourth resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured during the carrier envelope modulation stage.

[0069] Combine Figures 4 - 6 As can be seen from the example shown, the voltage source and The specific calculated values need to be adjusted according to the matching mode type, such as differential matching mode or single-ended matching mode. The above example clarifies the voltage source in different power amplifier operating modes. and The calculation difference of the single method broadens the different application scenarios and helps to improve the calculation accuracy.

[0070] Method 2 In one embodiment, a modulation index adjustment method is provided. NFC Controller implementation for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFC The chip includes a signal transmission circuit, which includes a power amplifier and includes the following steps: S10C, obtain the information reflecting the NFC Electrical parameters of the chip's load effect; S20C. Calculating an equivalent on-resistance value that needs to be configured for the power amplifier during a carrier-envelope non-modulation phase based on the electrical parameters; S30C. According to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope non-modulation stage, the equivalent on-resistance value of the power amplifier during the carrier envelope non-modulation stage is configured, while the equivalent on-resistance value of the power amplifier remains unchanged during the carrier envelope modulation stage, so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after adjustment is within the range required by the protocol.

[0071] The step S10C may refer to the aforementioned step S10A, and will not be described again here.

[0072] In steps S20C-S30C, the equivalent on-resistance value required for the power amplifier during the carrier-envelope non-modulation phase is calculated based on the electrical parameters. The equivalent on-resistance value of the power amplifier during the carrier-envelope non-modulation phase is then configured based on the equivalent on-resistance value required for the power amplifier during the carrier-envelope non-modulation phase. During the carrier-envelope modulation phase, the equivalent on-resistance value of the power amplifier remains unchanged, ensuring that the modulation index of the carrier-envelope transmitted by the signal transmission circuit after adjustment is within the protocol requirements. This embodiment differs from the aforementioned second approach in that the equivalent on-resistance value required for the power amplifier during the carrier-envelope non-modulation phase is calculated and adjusted.

[0073] Similarly, in this embodiment, since the calculated equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope non-modulation stage is a theoretical value, it is necessary to look at the NFC The chip supports the configured internal resistance unit. For example, if the calculated equivalent on-resistance value of the power amplifier in the carrier-envelope non-modulation stage is 9 ohms, the equivalent on-resistance value of the power amplifier in the carrier-envelope non-modulation stage is configured according to 9 ohms or a resistance value thereabouts.

[0074] It can be seen that in this embodiment, similarly, it is also possible to directly use some of the NFC The electrical parameters of the load effect of the device automatically calculate the equivalent on-resistance value of the power amplifier of the signal transmission circuit when the carrier envelope is not modulated, while the equivalent on-resistance value of the power amplifier remains unchanged during the carrier envelope modulation stage, so that the modulation index The range required by the protocol is always met. Therefore, there is no need to waste time and effort to build lookup tables for different antennas and impedance matching circuits, which improves the modulation index. The regulation efficiency is improved, and there is no situation where the modulation index range required by the protocol is exceeded; in addition, it is worth noting that this embodiment can only adjust the equivalent on-resistance corresponding to the high level of the carrier envelope in the non-modulation stage, while the corresponding equivalent on-resistance in the modulation stage remains unchanged. It is a variation of the first method, which ensures the diversity of the implementation of the solution and is more flexible.

[0075] It should be understood that in the second method, it is explained that the modulation index can also be adjusted in the non-modulation stage. Specifically, the method for calculating the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope non-modulation stage according to the electrical parameters can refer to the above four methods for calculating the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage. R S0 use R S1The mathematical relationship remains unchanged and will not be described in detail here. For other implementation details, such as the form of the matching impedance circuit, the working mode of the power amplifier, etc., please refer to the aforementioned embodiments and will not be described in detail here.

[0076] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0077] In one embodiment, there is provided a NFC device for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFC The chip includes a signal transmitting circuit, the signal transmitting circuit includes a power amplifier, the NFC The device includes: Acquisition module, used to obtain the NFC Electrical parameters of the chip's load effect; A processing module is used to calculate the equivalent on-resistance value that needs to be configured for the power amplifier based on the electrical parameters; and configure the equivalent on-resistance value of the power amplifier according to the equivalent on-resistance value that needs to be configured, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after configuration is within the range required by the protocol.

[0078] In one embodiment, the equivalent on-resistance value to be configured includes the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage, or the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope non-modulation stage; the processing module is specifically configured to: The equivalent on-resistance value of the power amplifier in the carrier envelope modulation stage is configured according to the equivalent on-resistance value that needs to be configured for the power amplifier in the carrier envelope modulation stage, while the equivalent on-resistance value of the power amplifier in the carrier envelope non-modulation stage remains unchanged, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after adjustment is within the range required by the protocol; or; According to the equivalent on-resistance value that needs to be configured for the power amplifier during the carrier envelope non-modulation stage, the equivalent on-resistance value of the power amplifier during the carrier envelope non-modulation stage is configured, while the equivalent on-resistance value of the power amplifier remains unchanged during the carrier envelope modulation stage, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after adjustment is within the range required by the protocol.

[0079] In one embodiment, the electrical parameter includes a power supply current supplied to the power amplifier by the power supply of the signal transmission circuit, and the processing module is configured to calculate an equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, The amplitude of the component of the voltage supplied by the power supply to the power amplifier corresponding to the carrier frequency, supplying a power supply current to the power amplifier through the power supply, The power supply supplies a DC voltage to the power amplifier.

[0080] In one embodiment, The average current of the power supply current supplied by the power supply to the power amplifier.

[0081] In one embodiment, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance.

[0082] In one embodiment, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance 。 In one embodiment, the electrical parameters include an equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance.

[0083] In one embodiment, the power amplifier may be configured in a differential matching mode, the power amplifier comprising a first resistor unit, a third resistor unit, a first switch unit, a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit, and a fourth switch unit; The first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; The second end of the first switch unit and the first end of the third switch unit are connected in common and connected to the first end of the impedance matching circuit; the second end of the second switch unit and the first end of the fourth switch unit are connected in common and connected to the second end of the impedance matching circuit; The second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, and the second end of the third resistor and the second end of the fourth resistor are both connected to the ground; If the power amplifier operates in differential matching mode, the sum of the resistance values of the first resistance unit and the fourth resistance unit, and the sum of the resistance values of the second resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

[0084] In one embodiment, the power amplifier may be configured in a first single-ended matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit, and a third switch unit; A first end of the first resistor unit is connected to the power supply, a second end of the first resistor unit is connected to the first end of the first switch unit, a second end of the first switch unit and a first end of the third switch unit are commonly connected to the first end of the impedance matching circuit, a second end of the third switch unit is connected to the first end of the third resistor, and a second end of the third resistor and a second end of the impedance matching circuit are both connected to ground; If the power amplifier operates in the first single-ended matching mode, the resistance values of the first resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

[0085] In one embodiment, the power amplifier may be configured in a second single-ended matching mode, the power amplifier comprising a first resistor unit, a third resistor unit, a first switch unit, a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit, and a fourth switch unit; The first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; The second end of the first switch unit, the second end of the second switch unit, the first end of the third switch unit and the first end of the fourth switch unit are commonly connected to the first end of the impedance matching circuit; The second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, and the second end of the third resistor, the second end of the fourth resistor, and the second end of the impedance matching circuit are all connected to the ground; If the power amplifier operates in the second single-ended matching mode, the parallel resistance value of the first resistance unit and the second resistance unit, and the parallel resistance value of the third resistance unit and the fourth resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured in the carrier envelope modulation stage.

[0086] In one embodiment, the first resistance unit and the first switch unit, the second resistance unit and the second switch unit, the third resistance unit and the third switch unit, and the fourth resistance unit and the fourth switch unit can be equivalently implemented by one or more transistors in a chip.

[0087] In one embodiment, the modulation index is a center value of the range required by the protocol.

[0088] about NFC The specific definition of the device can be found in the definition of the modulation index adjustment method above, which will not be repeated here.NFC Each module in the device may be implemented in whole or in part by software, hardware or a combination thereof.

[0089] In one embodiment, there is provided a NFC equipment, NFC The device includes a processor and a memory, the memory is used to store instructions, and the processor is used to read the instructions and execute the modulation index adjustment method described in any one of the above embodiments.

[0090] In one embodiment, there is provided a NFC equipment, NFC Equipment includes: NFC Chip; provided in the NFC An impedance matching circuit between the chip and the antenna; and a method for implementing the modulation index adjustment method as described in any of the above NFC Controller.

[0091] about NFC The specific definition of the device can be found in the definition of the modulation index adjustment method above, which will not be repeated here.

[0092] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0093] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A modulation index adjustment method, characterized in that: Used for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFC The chip includes a signal transmission circuit, the signal transmission circuit includes a power amplifier, and the method includes: Get the reflection NFC Electrical parameters of the chip's load effect; Calculating an equivalent on-resistance value required for the power amplifier based on the electrical parameters; According to the equivalent on-resistance value to be configured, the equivalent on-resistance value of the power amplifier is configured so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after configuration is within the range required by the protocol.

2. The modulation index adjustment method according to claim 1, characterized in that: The equivalent on-resistance value to be configured includes the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage; Configuring the equivalent on-resistance value of the power amplifier according to the required equivalent on-resistance value so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after the configuration is within the range required by the protocol includes: The equivalent on-resistance value of the power amplifier in the carrier envelope modulation stage is configured according to the equivalent on-resistance value that needs to be configured for the power amplifier in the carrier envelope modulation stage, while the equivalent on-resistance value of the power amplifier remains unchanged in the carrier envelope non-modulation stage, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after adjustment is within the range required by the protocol.

3. The modulation index adjustment method according to claim 1, characterized in that: The equivalent on-resistance value to be configured includes the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope non-modulation stage; Configuring the equivalent on-resistance value of the power amplifier according to the required equivalent on-resistance value so that the modulation index of the carrier envelope transmitted by the signal transmitting circuit after the configuration is within the range required by the protocol includes: According to the equivalent on-resistance value that needs to be configured for the power amplifier during the carrier envelope non-modulation stage, the equivalent on-resistance value of the power amplifier during the carrier envelope non-modulation stage is configured, while the equivalent on-resistance value of the power amplifier remains unchanged during the carrier envelope modulation stage, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after adjustment is within the range required by the protocol.

4. The modulation index adjustment method according to claim 2 or 3, characterized in that: The electrical parameters include the power supply current supplied to the power amplifier by the power supply of the signal transmission circuit, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, The amplitude of the component of the voltage supplied by the power supply to the power amplifier corresponding to the carrier frequency, supplying a power supply current to the power amplifier through the power supply, The power supply supplies a DC voltage to the power amplifier.

5. The modulation index adjustment method according to claim 4, characterized in that: The average current of the power supply current supplied by the power supply to the power amplifier.

6. The modulation index adjustment method according to claim 2 or 3, characterized in that: The electrical parameters include the equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance.

7. The modulation index adjustment method according to claim 2 or 3, characterized in that: The electrical parameters include the equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance.

8. The modulation index adjustment method according to claim 2 or 3, characterized in that: The electrical parameters include the equivalent matching impedance formed by the impedance matching circuit and the antenna, and the equivalent on-resistance value to be configured for the power amplifier during the carrier envelope modulation stage is calculated according to the following formula: in, is the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage, is the equivalent on-resistance of the power amplifier in the carrier envelope non-modulation stage, is the modulation index determined based on the range required by the protocol, is the real part of the equivalent matching impedance, is the imaginary part of the equivalent matching impedance.

9. The modulation index adjustment method according to claim 2 or 3, characterized in that: The power amplifier may be configured in a differential matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit, a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit, and a fourth switch unit; The first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; The second end of the first switch unit and the first end of the third switch unit are connected in common and connected to the first end of the impedance matching circuit; the second end of the second switch unit and the first end of the fourth switch unit are connected in common and connected to the second end of the impedance matching circuit; The second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, and the second end of the third resistor and the second end of the fourth resistor are both connected to the ground; If the power amplifier operates in differential matching mode, the sum of the resistance values of the first resistance unit and the fourth resistance unit, and the sum of the resistance values of the second resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

10. The modulation index adjustment method according to claim 2 or 3, characterized in that: The power amplifier can be configured in a first single-ended matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit, and a third switch unit; A first end of the first resistor unit is connected to the power supply, a second end of the first resistor unit is connected to the first end of the first switch unit, a second end of the first switch unit and a first end of the third switch unit are commonly connected to the first end of the impedance matching circuit, a second end of the third switch unit is connected to the first end of the third resistor, and a second end of the third resistor and a second end of the impedance matching circuit are both connected to ground; If the power amplifier operates in the first single-ended matching mode, the resistance values of the first resistance unit and the third resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured with during the carrier envelope modulation stage.

11. The modulation index adjustment method according to claim 2 or 3, characterized in that: The power amplifier may be configured in a second single-ended matching mode, and the power amplifier includes a first resistor unit, a third resistor unit, a first switch unit, a third switch unit, a second resistor unit, a fourth resistor unit, a second switch unit, and a fourth switch unit; The first end of the first resistor unit and the first end of the second resistor are respectively connected to the power supply, the second end of the first resistor unit is connected to the first end of the first switch unit, and the second end of the second resistor unit is connected to the first end of the second switch unit; The second end of the first switch unit, the second end of the second switch unit, the first end of the third switch unit and the first end of the fourth switch unit are commonly connected to the first end of the impedance matching circuit; The second end of the third switch unit is connected to the first end of the third resistor, the second end of the fourth switch unit is connected to the first end of the fourth resistor, and the second end of the third resistor, the second end of the fourth resistor, and the second end of the impedance matching circuit are all connected to the ground; If the power amplifier operates in the second single-ended matching mode, the parallel resistance value of the first resistance unit and the second resistance unit, and the parallel resistance value of the third resistance unit and the fourth resistance unit are equal to the equivalent on-resistance value that the power amplifier needs to be configured in the carrier envelope modulation stage.

12. The modulation index adjustment method according to claim 9, 10 or 11, characterized in that: The first resistance unit and the first switch unit, the second resistance unit and the second switch unit, the third resistance unit and the third switch unit, and the fourth resistance unit and the fourth switch unit are equivalently implemented by one or more transistors in the chip.

13. The modulation index adjustment method according to claim 4, characterized in that: The modulation index is the center value of the range required by the protocol.

14. A near-field communication NFC The device is characterized in that Used for NFC Chip, the NFC An impedance matching circuit is connected between the chip and the antenna. NFC The chip includes a signal transmitting circuit, the signal transmitting circuit includes a power amplifier, the NFC The device includes: Acquisition module, used to obtain the NFC Electrical parameters of the chip's load effect; A processing module is used to calculate the equivalent on-resistance value that needs to be configured for the power amplifier based on the electrical parameters; and configure the equivalent on-resistance value of the power amplifier according to the equivalent on-resistance value that needs to be configured, so that the modulation index of the carrier envelope transmitted by the signal transmission circuit after configuration is within the range required by the protocol.

15. A NFC The device is characterized in that described NFC The device includes a processor and a memory, wherein the memory is used to store instructions, and the processor is used to read the instructions and execute the modulation index adjustment method according to any one of claims 1 to 12.

16. A NFC The device is characterized in that include: NFC chip; Set in the NFC Impedance matching circuit between chip and antenna; And a method for implementing the modulation index adjustment method according to any one of claims 1 to 12 NFC Controller.

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