CN116232387A

CN116232387A - Method and device for obtaining impedance

Info

Publication number: CN116232387A
Application number: CN202310122365.0A
Authority: CN
Inventors: 刘诗雨
Original assignee: Shenzhen Goodix Technology Co Ltd
Current assignee: Shenzhen Goodix Technology Co Ltd
Priority date: 2023-02-01
Filing date: 2023-02-01
Publication date: 2023-06-06

Abstract

The application provides a method and a device for acquiring impedance, which can effectively acquire the impedance of an antenna and an impedance matching circuit thereof. The method is applied to an antenna and an impedance matching circuit thereof, wherein the impedance matching circuit is connected between the antenna and a Near Field Communication (NFC) chip, the NFC chip comprises a transmitting circuit and a receiving circuit, and the method comprises the following steps: acquiring NFC data output by the NFC chip, wherein the NFC data comprises average power supply current TXI data of a power supply source of the NFC data output by the transmitting circuit and/or field signal strength indication FSSI data output by the receiving circuit; and determining the impedance of the antenna and the impedance matching circuit according to the NFC data.

Description

Method and device for obtaining impedance

Technical Field

Embodiments of the present application relate to the field of NFC, and more particularly, to a method and apparatus for obtaining impedance.

Background

A near field communication (Near Field Communication, NFC) chip receives and transmits wireless signals through an antenna. An impedance matching circuit is arranged between the NFC chip and the antenna and used for carrying out impedance matching on the antenna so as to ensure the receiving and transmitting performance of the antenna. In general, the impedance matching circuit needs to be tuned based on the impedance of the antenna and its impedance matching circuit. Therefore, how to effectively detect the impedance of the antenna and its impedance matching circuit becomes a problem to be solved.

Disclosure of Invention

The embodiment of the application provides a method and a device for acquiring impedance, which can effectively acquire the impedance of an antenna and an impedance matching circuit thereof.

In a first aspect, a method for obtaining impedance is provided, the method being applied to an antenna and an impedance matching circuit thereof, the impedance matching circuit being connected between the antenna and a near field communication NFC chip, the NFC chip including a transmitting circuit and a receiving circuit, the method comprising: acquiring NFC data output by the NFC chip, wherein the NFC data comprises average power supply current TXI data of a power supply source of the NFC data output by the transmitting circuit and/or FSSI data output by the receiving circuit; and determining the impedance of the antenna and the impedance matching circuit according to the NFC data.

In one implementation, the first port of the transmitting circuit is connected to a first end of a first device in the impedance matching circuit, the first port of the receiving circuit is connected to a second end of the first device via a peripheral circuit, the second port of the transmitting circuit is connected to a first end of a second device in the impedance matching circuit, the second port of the receiving circuit is connected to a second end of the second device via a peripheral circuit, and a matching sub-circuit formed by a portion of the impedance matching circuit other than the first device and the second device is connected to the second end of the first device and the second end of the second device.

In one implementation, at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to a first end of a first device of the impedance matching circuits, the first port of the receiving circuit is connected to a second end of the first device via a peripheral circuit, the second port of the receiving circuit is disconnected, and a matching sub-circuit formed by a portion of the impedance matching circuits other than the first device is connected to the second end of the first device.

In one implementation, the NFC data includes the TXI data and the FSSI data, and determining the impedance of the antenna and the impedance matching circuit according to the NFC data includes: determining a current value of the average supply current from the TXI data; determining an effective value of a voltage on an equivalent impedance formed by the matching sub-circuit and the antenna according to the FSSI data; and determining the real part and the imaginary part of the impedance according to the current value of the average power supply current and the effective value of the voltage on the equivalent impedance.

In one implementation, the determining the real part and the imaginary part of the impedance according to the current value of the average supply current and the effective value of the voltage across the equivalent impedance includes:

Determining the real part of the impedance according to the current value of the average supply current and the following formula:

the method comprises the steps of,

determining the imaginary parts of the impedance of the antenna and the impedance matching circuit according to the current value of the average supply current, the effective value of the voltage on the equivalent impedance and the following formula:

wherein VDD is the voltage of the power supply of the transmitting circuit, I _avg1 And I _avg2 Respectively, the internal resistance of the transmitting circuit is R _S1 And R is _S2 The current value of the average supply current, V _rx1 And V _rx2 Respectively, the internal resistance of the transmitting circuit is R _S1 And R is _S2 An effective value of the voltage across the equivalent impedance;

when the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device, respectively, V _S Is the effective value of the fundamental component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R _L +jX _L A series impedance for the first device and the second device;

when at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device, V _S R is the effective value of the fundamental component of the voltage of the at least one port to ground when the impedance matching circuit is not connected _L +jX _L Is the impedance of the first device.

In one implementation, the receiving circuit has a function of detecting phase information, the NFC data includes the FSSI data, and determining the impedance of the antenna and the impedance matching circuit according to the NFC data includes: determining an effective value of a voltage on an equivalent impedance formed by the matching sub-circuit and the antenna according to the FSSI data, and determining a phase difference between a phase value of the voltage on the equivalent impedance and a preset phase value; and determining the real part and the imaginary part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance and the phase difference.

In one implementation, when the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first terminal of the first device and the first terminal of the second device, respectively, the predetermined phase value is a phase value of a voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected; when at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device, the predetermined phase value is a phase value of a voltage of the at least one port to ground when the impedance matching circuit is not connected.

In one implementation, the determining the real part and the imaginary part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage across the equivalent impedance and the phase difference includes:

determining the real part of the impedance of the antenna and the impedance matching circuit from the effective value of the voltage across the equivalent impedance, the phase difference and the following equation:

the method comprises the steps of,

determining the imaginary parts of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance, the phase difference and the following formula:

wherein V is _rx R is the effective value of the voltage on the equivalent impedance _S For the internal resistance of the transmitting circuit,

is the phase difference;

In one implementation, the method further comprises: when the transmitting circuit sequentially outputs signals with a plurality of frequencies in a specific frequency range, respectively acquiring a plurality of impedances of the impedance matching circuit under the plurality of frequencies; and determining an impedance curve for representing the impedance of the antenna and the impedance matching circuit along with the frequency according to the correspondence relation between the plurality of impedances and the plurality of frequencies.

In one implementation, the method further comprises: and debugging the impedance matching circuit according to the impedance curve.

In one implementation, the impedance matching circuit includes a plurality of devices, and the types of the plurality of devices include at least one of inductance, resistance, and capacitance, where the first device is one of the plurality of devices or a combination of at least two of the plurality of devices connected in series or in parallel, and the second device is one of the plurality of devices or a combination of at least two of the plurality of devices connected in series or in parallel.

In a second aspect, there is provided an apparatus for obtaining impedance, the apparatus being applied to an antenna and an impedance matching circuit thereof, the impedance matching circuit being connected between the antenna and a near field communication NFC chip, the NFC chip including a transmitting circuit and a receiving circuit, the apparatus comprising: the information acquisition module is used for acquiring NFC data output by the NFC chip, wherein the NFC data comprises average power supply current TXI data of a power supply source of the NFC data output by the transmitting circuit and/or FSSI data output by the receiving circuit; and an information processing module for determining the impedance of the antenna and the impedance matching circuit according to the NFC data.

In one implementation, the information processing module is specifically configured to: determining a current value of the average supply current from the TXI data; determining an effective value of a voltage on an equivalent impedance formed by the matching sub-circuit and the antenna according to the FSSI data; and determining the real part and the imaginary part of the impedance of the antenna and the impedance matching circuit according to the current value of the average supply current and the effective value of the voltage on the equivalent impedance.

In one implementation, the information processing module is specifically configured to: determining the real part of the impedance of the antenna and the impedance matching circuit according to the current value of the average supply current and the following formula:

The method comprises the steps of,

when the first port of the transmitting circuit and the second port of the transmitting circuit are respectively connectedWhen connected to the first end of the first device and the first end of the second device, V _S Is the effective value of the fundamental component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R _L +jX _L A series impedance for the first device and the second device;

In one implementation manner, the receiving circuit has a function of detecting phase information, and the information processing module is specifically configured to: determining an effective value of a voltage on an equivalent impedance formed by the matching sub-circuit and the antenna according to the FSSI data, and determining a phase difference between a phase value of the voltage on the equivalent impedance and a preset phase value; and determining the real part and the imaginary part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance and the phase difference.

In one implementation, the information processing module is specifically configured to: determining the real part of the impedance of the antenna and the impedance matching circuit from the effective value of the voltage across the equivalent impedance, the phase difference and the following equation:

the method comprises the steps of,

is the phase difference;

In one implementation, the information processing module is further configured to: when the transmitting circuit sequentially outputs signals with a plurality of frequencies in a specific frequency range, respectively acquiring a plurality of impedances of the impedance matching circuit under the plurality of frequencies; and determining an impedance curve for representing the impedance of the antenna and the impedance matching circuit along with the frequency according to the correspondence relation between the plurality of impedances and the plurality of frequencies.

In one implementation, the impedance profile is used to debug the impedance matching circuit.

In a third aspect, there is provided an apparatus for obtaining an impedance, the apparatus comprising a processor and a memory for storing instructions, the processor for reading the instructions and performing the method of obtaining an impedance according to the first aspect or any of the possible implementations of the first aspect.

In a fourth aspect, there is provided an electronic device comprising: an NFC chip; an impedance matching network disposed between the NFC chip and the antenna; and means according to the second aspect or any possible implementation of the second aspect or means according to the third aspect or any possible implementation of the third aspect for obtaining the impedance of the antenna and the impedance matching network.

According to the method and the device, the NFC data are obtained from the NFC chip, the average power supply current TXI data of the power supply source of the NFC data are output by the transmitting circuit in the NFC chip, and/or the FSSI data are output by the receiving circuit in the NFC chip, so that the impedance of the NFC antenna and the impedance matching circuit of the NFC antenna is calculated according to the NFC data, and then the impedance curve of the impedance changing along with the frequency can be obtained. Therefore, when the impedance curve is required to be acquired to debug the impedance matching circuit based on the impedance curve, the equipment is not required to be disassembled and the flying leads are not required to be introduced, the problem that the matching performance is reduced due to impedance deviation caused by the flying leads is avoided, and the debugging efficiency and accuracy are effectively improved.

Drawings

Fig. 1 is a schematic flow chart of a method of acquiring impedance according to an embodiment of the present application.

Fig. 2 is a schematic diagram of an architecture of one possible impedance matching circuit according to an embodiment of the present application.

Fig. 3 is a schematic diagram of another possible architecture of an impedance matching circuit according to an embodiment of the present application.

Fig. 4 is a schematic diagram of an architecture of another possible impedance matching circuit according to an embodiment of the present application.

Fig. 5 is one possible implementation of the architecture of the impedance matching circuit shown in fig. 2.

Fig. 6 is one possible implementation of the architecture of the impedance matching circuit shown in fig. 3.

Fig. 7 is one possible implementation of the architecture of the impedance matching circuit shown in fig. 4.

Fig. 8 is an equivalent circuit diagram based on fig. 2 to 7.

Fig. 9 is a schematic diagram of the real part of the impedance of the antenna and its impedance matching circuit as a function of frequency.

Fig. 10 is a schematic diagram of the impedance imaginary part of the antenna and its impedance matching circuit as a function of frequency.

Fig. 11 is a schematic diagram of a Smith chart of the impedance of an antenna and its impedance matching circuit.

Fig. 12 is a schematic block diagram of an apparatus for acquiring impedance according to an embodiment of the present application.

Detailed Description

The technical solutions in the present application will be described below with reference to the accompanying drawings.

An impedance matching circuit is arranged between the NFC chip and the antenna and used for carrying out impedance matching on the antenna so as to ensure the receiving and transmitting performance of the antenna. The debugging of the impedance matching network is required to be performed in a complete machine environment, and because the impedance matching network is arranged on a main board of the terminal equipment, the complete machine of the terminal equipment and the main board thereof are generally required to be disassembled, flying leads are led out from ports of the impedance matching network and connected to a network analyzer and the like to measure the impedance of the antenna and the impedance matching network thereof so as to determine whether the antenna meets the matching requirement, if the matching degree does not meet the requirement, the process needs to be repeated for a plurality of times, is time-consuming and labor-consuming, and is easy to damage the main board. Meanwhile, the flying leads also introduce certain deviation, so that the debugging result has deviation, and the impedance matching performance is reduced.

Therefore, the present application aims to provide a method for obtaining the impedance of an antenna and an impedance matching network thereof, which solves the problem that the impedance of the antenna and the impedance matching network thereof cannot be detected efficiently and accurately. The NFC data is obtained from the NFC chip, the NFC data comprises average power supply current TXI data of a power supply source of the NFC chip, which are output by a transmitting circuit in the NFC chip, and/or FSSI data which are output by a receiving circuit, so that the impedance of the NFC antenna and the impedance matching circuit of the NFC antenna is calculated according to the NFC data. When the impedance curve is required to be acquired to debug the impedance matching circuit based on the impedance curve, the equipment is not required to be disassembled for many times and the flying leads are introduced, so that the problem of reduced matching performance caused by impedance deviation caused by the flying leads is avoided, and the debugging efficiency and accuracy are effectively improved.

In addition, in the mass production process, impedance deviation caused by the consistency problem of the antenna and the peripheral matching device is usually determined by measuring the power consumption of a transmitting circuit of the NFC chip or the matched frequency deviation, which is not intuitive. By adopting the method, the impedance deviation caused by the consistency problem of the antenna and the peripheral matching device can be accurately determined during mass production test.

Fig. 1 shows a schematic flow chart of a method of obtaining impedance according to an embodiment of the present application. As shown in fig. 1, the method 100 for obtaining impedance is applied to an antenna 400 and an impedance matching circuit 200 thereof, wherein the impedance matching circuit 200 is connected between the antenna 400 and an NFC chip 300, and the NFC chip 300 includes a Transmit (TX) circuit 310 and a Receive (RX) circuit 320. As shown in fig. 1, method 100 includes some or all of the following steps.

In step 110, NFC data output by the NFC chip 300 is acquired.

The NFC data includes average supply current TXI data of its supply source output by the transmitting circuit 310 and/or field signal strength indication (Field Signal Strength Indication, FSSI) data output by the receiving circuit 320.

In step 120, the impedance of the antenna 400 and its impedance matching circuit 200 is determined from the NFC data.

It will be appreciated that the NFC data is, for example, data in the form of binary information units 0 or 1, which includes data (denoted as TXI data) output by the transmitting circuit 310 for representing the average supply current of its power supply, and/or FSSI data output by the receiving circuit 320. The TXI data and FSSI data are, for example, data processed by analog-to-digital conversion circuits (Analog to Digital Converter, ADCs) output from the transmitting circuit 310 and output from the receiving circuit 320, respectively.

In this embodiment of the present application, the NFC data including the TXI data output by the transmitting circuit 310 and/or the FSSI data output by the receiving circuit 320 in the NFC chip 300 are obtained from the NFC chip 300, so that the impedance of the antenna 400 and the impedance matching circuit 200 thereof is calculated according to the NFC data, and an impedance curve of the impedance varying with the frequency can be obtained. Therefore, when the impedance curve is required to be acquired to debug the impedance matching circuit 200 based on the impedance curve, the equipment is not required to be disassembled for many times and the flying leads are introduced, so that the problem of reduced matching performance caused by impedance deviation caused by the flying leads is avoided, and the debugging efficiency and accuracy are effectively improved. And, the impedance deviation caused by the consistency problem of the peripheral matching device and the antenna 400 can be more accurately determined based on the impedance curve in the mass production test.

It will be appreciated that in step 120, the impedance obtained from the NFC data is the total impedance of the antenna 400 and the impedance matching circuit 200. Hereinafter, the impedance of the antenna 400 and the impedance matching circuit 200 refer to the total impedance of both.

The impedance matching circuit 200 is connected between the NFC chip 300 and the antenna 400, a port of the transmitting circuit 310 in the NFC chip 300 is connected to one end of a specific device in the impedance matching circuit 200, a port of the receiving circuit 320 in the NFC chip 300 is connected to the other end of the specific device through its peripheral circuit, other parts of the impedance matching circuit 200 than the specific device form a matching sub-circuit 220, and the matching sub-circuit 220 is connected to the other end of the specific device.

Wherein the TXI data may be used to determine a current value I of an average supply current of a power supply of the transmit circuit 310 _avg I.e. I _avg =f (TXI data), f representing the current value I for converting the TXI data into an average supply current for the transmit circuit 310 _avg Or a functional relationship.

The FSSI data may be used to determine the effective value of the voltage across the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400, e.g., the effective value of the fundamental component of the voltage, i.e., V _rx =g (FSSI data), g represents an operational relationship, or functional relationship, for converting FSSI data into an effective value of a voltage across the equivalent impedance.

If the receiving circuit 320 has a function of detecting phase information, the FSSI data can also be used to determine a phase difference between a phase value of a voltage on the equivalent impedance and a predetermined phase value, the predetermined phase value being a phase value of a voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected, or a phase value of a voltage of the first port TXP or the second port TXN to ground when the impedance matching circuit 200 is not connected, that is

(FSSI data), ->

An operational relationship, or functional relationship, for converting FSSI data into the phase difference is shown.

For example, the receiving circuit 320 includes an IQ demodulation module having a function of demodulating phase information from FSSI data according to

(FSSI data), phase information of the voltage across the equivalent impedance can be obtained.

The impedance matching circuit 200 includes a plurality of devices of a type including at least one of inductance, resistance, and capacitance. As an example, fig. 2-4 are schematic diagrams of several possible architectures of impedance matching circuit 200 provided in embodiments of the present application. Wherein fig. 2 is a differential matching architecture, fig. 3 is a balun-equipped architecture with a single-ended antenna, and fig. 4 is a balun-free architecture with a single-ended antenna.

As shown in fig. 2 and 3, the first port TXP of the transmitting circuit 310 is connected to a first end (left end in the drawing) of the first device 211 in the impedance matching circuit 200, the first port RXP of the receiving circuit 320 is connected to a second end (right end in the drawing) of the first device 211 via the peripheral circuit 321, the second port TXN of the transmitting circuit 310 is connected to a first end (left end in the drawing) of the second device 212 in the impedance matching circuit 200, the second port RXN of the receiving circuit 320 is connected to a second end (right end in the drawing) of the second device 212 via the peripheral circuit 322, the portions of the impedance matching circuit 200 other than the first device 211 and the second device 212 form a matching sub-circuit 220, and the matching sub-circuit 220 is connected to the second end of the first device 211 and the second end of the second device 212.

As shown in fig. 4, at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to a first end (left end in the drawing) of the first device 211 in the impedance matching circuit 200, the first port RXP of the receiving circuit 320 is connected to a second end (right end in the drawing) of the first device 211 via the peripheral circuit 321, the second port RXN of the receiving circuit 320 is disconnected, a matching sub-circuit 220 is formed in a portion of the impedance matching circuit 200 other than the first device 211, and the matching sub-circuit 220 is connected to the second end of the first device 211.

It should be appreciated that, by way of example, the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 shown in fig. 4 are both connected to a first end of the first device 211, and in other implementations, only the first port TXP may be connected to a first end of the first device 211 or only the second port TXN may be connected to a first end of the first device 211.

Wherein the first device 211 is one of a plurality of devices in the impedance matching circuit 200 or a combination of at least two of the plurality of devices in series or parallel. The second device 212 is one of the plurality of devices or a combination of at least two of the plurality of devices in series or parallel.

The first device 211 may be any one of an inductance, a resistance, and a capacitance or any combination of several series or parallel connections, and the second device 212 may be any one of an inductance, a resistance, and a capacitance or any combination of several series or parallel connections.

As a possible implementation manner of fig. 2, as shown in fig. 5, the impedance matching circuit 200 is a differential matching architecture, and the impedance matching circuit 200 includes an inductor L0, a capacitor C1, a capacitor C2, and a resistor R _q And devices, wherein the number of each device is 2 and symmetrically distributed. The inductor L0 and the capacitor C0 can realize a filtering function, the capacitor C1 and the capacitor C2 are used for impedance matching, and the resistor R _q The Q value of the antenna can be reduced. Wherein the first device 211 and the second device 212 are the inductor L0, the residual capacitor C0, the capacitor C1, the capacitor C2 and the resistor R _q The devices form a matching sub-circuit 220. The equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 is denoted as Z _E . Resistor R connected with first port RXP _A And capacitor C _A A peripheral circuit 321 forming a receiving circuit 320, a resistor R connected to the second port RXN _B And capacitor C _B Peripheral circuitry 322 of the receive circuitry 320 is formed.

As a possible implementation manner of fig. 3, as shown in fig. 6, the impedance matching circuit 200 is a balun structure, and the impedance matching circuit 200 includes an inductor L0, a capacitor C1, a capacitor C2, and a resistor R _q And balun and the like, wherein the number of the inductance L0 and the capacitance C0 is 2 and symmetrically distributed. The inductor L0 and the capacitor C0 can realize a filtering function, the capacitor C1 and the capacitor C2 are used for impedance matching, and the resistor R _q The Q value of the antenna can be reduced. Wherein the first device 211 and the second device 212 are the inductor L0, the residual capacitor C0, the capacitor C1, the capacitor C2 and the resistor R _q The devices form a matching sub-circuit 220. The equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 is denoted as Z _E . Resistor R connected with first port RXP _A And capacitor C _A Peripheral circuit 321 forming receiving circuit 320 and connected to second port RXNResistor R _B And capacitor C _B Peripheral circuitry 322 of the receive circuitry 320 is formed.

As a possible implementation manner of fig. 4, as shown in fig. 7, the impedance matching circuit 200 is a balun-free architecture, and the impedance matching circuit 200 includes an inductor L0, a capacitor C1, a capacitor C2, and a resistor R _q And the like. The inductor L0 and the capacitor C0 can realize a filtering function, the capacitor C1 and the capacitor C2 are used for impedance matching, and the resistor R _q The Q value of the antenna can be reduced. The first device 211 is an inductor L0, and the rest of the capacitors C0, C1, C2 and R _q The devices form a matching sub-circuit 220. Fig. 7 illustrates an example in which the first port TXP and the second port TXN are both connected to the inductor L0, and in practical applications, only one of the ports TXP and TXN may be connected to the inductor L0. The equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 is denoted as Z _E . Resistor R connected with first port RXP _A And capacitor C _A The peripheral circuit 321 forming the receiving circuit 320, the second port RXN is disconnected. Fig. 7 is only an example, but it is also possible to connect a resistor R between the second port RXN and the inductance L0 _B And capacitor C _B The peripheral circuit 322 is formed and the first port RXP is turned off.

It will be appreciated that the circuit structures in the block diagrams shown in fig. 2 to 4 may have other forms than those shown in fig. 5 to 7, and the method described in the embodiments of the present application can be applied to obtain the impedance of the antenna 400 and the impedance matching circuit 200 thereof, as long as the topology of the circuit can satisfy the connection relationship shown in fig. 2 to 4.

From the above-described fig. 2 to 7, the equivalent circuit diagram shown in fig. 8 can be obtained. As shown in fig. 8, V _S For an effective value of a voltage between the first port TXP and the second port TXN at a specific frequency point when the NFC chip 300 is not connected to the impedance matching circuit 200, for example, an effective value of a fundamental component of the voltage, refer to the architecture shown in fig. 2 and 3; alternatively V _S For an effective value of a voltage between at least one of the first port TXP and the second port TXN and ground at a specific frequency point when the NFC chip 300 is not connected to the impedance matching circuit 200, for example, an effective value of a fundamental component of the voltage, refer to the shelf shown in fig. 4 Constructing a structure. R is R _S Is the internal resistance of the transmit circuit 310, is typically adjustable. R is R _L +jX _L For the series impedance of the first device 211 and the impedance of the second device 212, refer to the architecture shown in fig. 2 and 3; alternatively, R _L +jX _L For the impedance of the first device 211, reference is made to the architecture shown in fig. 4. The impedance matching circuit includes a matching sub-circuit 220 formed by the remainder of the impedance matching circuit excluding the first device 211 and the second device 212, and the impedance of the equivalent circuit formed by the matching sub-circuit 220 and the antenna 400 is denoted as Z _E 。Z _E The voltages on the circuit are the voltages between the node A1 and the node A2 in fig. 8, the node A1 and the node A2 are the connection point between the matching sub-circuit 220 and the first device 211 and the connection point between the matching sub-circuit 220 and the second device 212, respectively, referring to the architecture shown in fig. 2 and 3; alternatively, node A1 and node A2 are the connection point between the matching subcircuit 220 and the first device 211 and ground, respectively, with reference to the architecture shown in fig. 4. The real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 are denoted as R and X, respectively. V for different matching architectures _S 、R _S 、R _L +jX _L 、Z _E May be different.

For non-sinusoidal periodically oscillating voltage signals, such as square wave signals, etc., fundamental and harmonic waves are typically included, wherein the sinusoidal component equal to the oscillation period is referred to as the fundamental component, and the amplitude value divided by 2 is the effective value of the fundamental component.

Hereinafter, based on the equivalent circuit diagram shown in fig. 8, how to calculate the impedance of the antenna 400 and the impedance matching circuit 200 thereof from the NFC data reported by the NFC chip 300 will be described in detail.

The transmitting circuit 310 of the NFC chip 300 includes a power supply for supplying power to the first port TXP and the second port TXN, the voltage of the power supply is denoted as VDD, and the average current value I of the power supply current is _avg The TXI data reported by the NFC chip 300 can be obtained through conversion, namely I _avg =f (TXI data). When the circuit implementation of the transmitting circuit 310 inside the NFC chip 300 is different, the TXI data and the current value I _avg The scaling relation f between them may be different.

The receiving circuit 320 mayDetecting the voltage across the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400, i.e. the voltage between node A1 and node A2 shown in FIGS. 2-4 and 8, the effective value V of the voltage _rx The FSSI data reported by the NFC chip 300 may be converted to V _rx =g (FSSI data). When the implementation manners of the circuit and the peripheral circuit of the receiving circuit 320 inside the NFC chip 300 are different, the FSSI data and the effective value V of the voltage on the equivalent impedance _rx The scaling relationship g between them may be different.

If the receiving circuit 320 further has a function of detecting phase information, for example, the receiving circuit 320 having an IQ demodulation module, the phase of the voltage signal between the node A1 and the node A2 may be obtained by conversion according to FSSI data reported by the NFC chip 300, compared with the phase difference between predetermined phase values

I.e. < ->

(FSSI data). When the circuit implementation of the receiving circuit 320 and its peripheral circuits are different, FSSI data and the phase difference +.>

The scaling relationship h between them may be different.

Wherein the predetermined phase value is a phase value of a voltage between the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected when the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 are connected to the first terminal of the first device 211 and the first terminal of the second device 212, respectively, as shown in fig. 2 and 3; when at least one of the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 is connected to the first end of the first device 211, the predetermined phase value is a phase value of a voltage of the at least one port to ground when the impedance matching circuit 200 is not connected, such as shown in fig. 4.

The present application provides two ways for calculating the impedance of the antenna 400 and its impedance matching circuit 200, each of which is described in detail below.

Mode 1

The impedance calculation method of embodiment 1 can be applied to a case where the receiving circuit 320 does not have a function of detecting phase information.

In one implementation, the NFC data reported by NFC chip 300 may include TXI data and FSSI data. At this time, in step 120, the impedance of the antenna 400 and the impedance matching circuit 200 thereof is determined based on the NFC data, including: determining the current value of the average supply current, i.e. I, from the TXI data _avg =f (TXI data); determining from the FSSI data an effective value V of the voltage across the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 _rx I.e. V _rx =g (FSSI data); current value I according to average supply current _avg And the effective value V of the voltage across the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 _rx The real part R and the imaginary part X of the impedance of the antenna 400 and its impedance matching circuit 200 are determined.

For example, the current value I can be based on the average supply current _avg And the following formulas (1) to (3), the real part R of the impedance of the antenna 400 and its impedance matching circuit 200 is determined:

also for example, the current value I can be based on the average supply current _avg Effective value V of voltage across equivalent impedance formed by matching sub-circuit 220 and antenna 400 _rx And the following equations (4) to (7), the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined:

X＝m ₁ ·(R _s1 +R)+n ₁ (4)，

alternatively, the current value I is based on the average supply current _avg Effective value V of voltage across equivalent impedance formed by matching sub-circuit 220 and antenna 400 _rx And the following equations (8) to (11), the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined:

X＝m ₂ ·(R _s2 +R)+n ₂ (8)，

in equations (1) to (11), VDD is the voltage of the power supply of the transmitting circuit 310, I _avg1 And I _avg2 Respectively, the internal resistance of the transmitting circuit 310 is R _S1 And R is _S2 The current value of the average supply current, V _rx1 And V _rx2 Respectively, the internal resistance of the transmitting circuit 310 is R _S1 And R is _S2 On the equivalent impedance formed by the time matching sub-circuit 220 and the antenna 400Is a valid value of the voltage of (a).

When the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 are coupled to a first end of the first device 211 and a first end of the second device 212, respectively, such as shown in fig. 2 and 3, V _S Is the effective value of the fundamental component of the voltage between the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 when the impedance matching circuit 200 is not connected, R _L +jX _L R is the series impedance of the first device 211 and the second device 212 _L And X _L The real and imaginary parts of the series impedance, respectively.

When both the first port TXP of the transmit circuitry 310 and the second port TXN of the transmit circuitry 310 are connected to the first end of the first device 211, such as shown in FIG. 4, V _S Is the effective value of the fundamental component of the voltage of the first port TXP of the transmitting circuit 310 to the ground or the effective value of the fundamental component of the voltage of the second port TXN of the transmitting circuit 310 to the ground when the impedance matching circuit 200 is not connected, R _L +jX _L R is the impedance of the first device 211 _L And X _L The real and imaginary parts of the impedance of the first device 211, respectively.

Hereinafter, how to obtain the above-described formulas (1) to (3) will be described.

Referring to fig. 8, for any pair of TXI data and FSSI data, one can obtain:

P＝VDD·I _avg ＝I ² ·(R _s +R) (12)，

V _s ² ＝I ² ·[(R _s +R) ² +X ² ] (13)，

dividing equation (12) by equation (13) yields:

the internal resistances of the transmitting circuits 310 are adjusted to be R respectively _S1 And R is _S2 Two pairs of TXI data and FSSI data are obtained, wherein the TXI data and the FSSI data are respectively:

assume that:

then, according to equation (14) and equation (16), we get:

further, the conversion of formula (17) yields:

R _e1 (R _s1 +R)＝(R _s1 +R) ² +X ² (18)，

R _e2 (R _s2 +R)＝(R _s2 +R) ² +X ² (19)，

subtracting equation (18) from equation (19) yields:

R _e2 (R _s2 +R)-R _e1 (R _s1 +R)＝(R _s2 +R) ² -(R _s1 +R) ² (20)，

the above equation (1) can be obtained by converting equation (20). According to the equations (1) to (3) and the TXI data reported by the NFC chip 300, the real part R of the impedance of the antenna 400 and the impedance matching circuit 200 thereof can be calculated.

Hereinafter, how to obtain the above-described formulas (4) to (7), and formulas (8) to (11) will be described.

Also, referring to fig. 8, equation (12) and equation (13) described above can be obtained for any pair of TXI data and FSSI data, and equation (14) described above can be obtained by dividing equation (12) by equation (13). Let R _S +r=t, then according to equation (14), we can get:

t ² +X ² ＝t·R _e (21)，

referring to fig. 8, it is possible to obtain:

Converting the formula (22) to obtain:

let R _S +r=t, then according to equation (23), we get:

combining equation (21) and equation (24) yields:

converting the formula (25) to obtain:

order the

The above-described formula (4) and formula (8) can be obtained by combining the formula (26) and the formula (27). According to the TXI data and FSSI data reported from the NFC chip 300, the imaginary part X of the impedance of the antenna 400 and the impedance matching circuit 200 thereof can be calculated according to the formulas (4) to (7) or the formulas (8) to (11).

Mode 2

The impedance calculation method of embodiment 2 can be applied to a case where the receiving circuit 320 has a function of detecting phase information. Of course, in the case where the receiving circuit 320 has a function of detecting phase information, the impedance of the antenna 400 and the impedance matching circuit 200 thereof can be calculated in the same manner as in the case of mode 1.

In one implementation, the NFC data reported by NFC chip 300 may include FSSI data. At this time, in step 120, the impedance of the antenna 400 and the impedance matching circuit 200 thereof is determined according to the NFC data, including: determining from the FSSI data an effective value V of the voltage across the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 _rx I.e. V _rx =g (FSSI data), and determining a phase difference between a phase value of the voltage across the equivalent impedance and a predetermined phase value

I.e. < ->

(FSSI data); according to the effective value V of the voltage of the matching sub-circuit 220 _rx And phase difference->

The real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 are determined.

As shown in fig. 2 and 3, the predetermined phase value is the phase value of the voltage between the first port TXP and the second port TXN of the transmitting circuit 310 when the impedance matching circuit 200 is not connected; alternatively, as shown in fig. 4, the predetermined phase value is a phase value of a voltage of at least one of the first port TXP and the second port TXN of the transmitting circuit 310 to ground.

For example, the effective value V of the voltage across the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 may be based on _rx The phase difference

And the following equations (26) to (29), the real part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined:

also for example, the effective value V of the voltage across the equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 may be based on _rx Phase difference

And the following equation (32), determining the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200:

wherein in the formulas (28) to (32), V _rx R is the effective value of the voltage on the equivalent impedance _S For the internal resistance of the transmitting circuit 310,

is the phase difference.

V when the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, respectively _S Is the effective value of the fundamental component of the voltage between the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 when the impedance matching circuit 200 is not connected, R _L +jX _L R is the series impedance of the first device 211 and the second device 212 _L And X _L The real and imaginary parts of the series impedance, respectively.

V when both the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 are connected to the first end of the first device 211 _S Is unconnected toAn effective value of a fundamental component of a voltage of the first port TXP of the transmitting circuit 310 to ground or an effective value of a fundamental component of a voltage of the second port TXN of the transmitting circuit 310 to ground when the impedance matching circuit 200 is connected, R _L +jX _L R is the impedance of the first device 211 _L And X _L The real and imaginary parts of the impedance of the first device 211, respectively.

Hereinafter, how to obtain the above-described formulas (28) to (32) is described.

Referring to fig. 8, it is known that:

assume that:

converting the formula (34) to obtain:

R-R _L +j(X-X _L )＝(R _s +R)m-Xn+j[Xm+(R _s +R)n](35)，

according to formula (35), we get:

from equation (36), equations (28) and (32) above can be derived. According to the formulas (28) to (32) and the FSSI data reported by the NFC chip 300, the real part R and the imaginary part X of the impedance of the antenna 400 and the impedance matching circuit 200 thereof can be calculated.

When the receiving circuit 320 of the NFC chip 300 cannot detect V _rx The TXI data and FSSI data of the transmitting circuit 310 at two different internal resistances need to be acquired simultaneously to estimate the real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200. When the receiving circuit 320 of the NFC chip 300 can detect V at the same time _rx When the voltage and phase information of (a) is obtained, FSSI data can be obtained only, and thenThe real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 are estimated.

If the frequency of the transmitting circuit 310 is adjustable, that is, the transmitting circuit 310 is capable of outputting a signal of any frequency within a certain frequency range, in one implementation, the method 100 further includes: when the transmitting circuit 310 sequentially outputs signals of a plurality of frequencies in the frequency range, a plurality of impedances of the impedance matching circuit 200 at the plurality of frequencies are respectively acquired; an impedance curve representing the impedance of the antenna 400 and its impedance matching circuit 200 as a function of frequency is determined from the correspondence between the plurality of impedances and the plurality of frequencies.

When the transmitting circuit 310 sequentially outputs signals of a plurality of frequencies, the impedance of the antenna 400 and the impedance matching circuit 200 thereof are calculated, and according to the obtained correspondence between the plurality of impedances and the plurality of frequencies, an impedance curve in which the impedance varies with the frequency can be plotted, for example, a curve in which the real part of the impedance of the antenna 400 and the impedance matching circuit 200 thereof varies with the frequency and a curve in which the imaginary part of the impedance varies with the frequency as shown in fig. 9 and 10, respectively. At this time, at a frequency of 13.56MHz, the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is 0, which corresponds to a pure resistance.

Fig. 11 shows a Smith chart of the impedance of the antenna 400 and its impedance matching circuit 200. The curve inside the circle in fig. 11 is the impedance curve of the antenna 400 and its impedance matching circuit 200, and the location identified by the triangle is the location of the impedance corresponding to 13.5MHz in the Smith chart. At this time, the position of the impedance corresponding to 13.56MHz is located on the real axis, that is, on the horizontal axis with the ordinate of 0 in fig. 11, and represents that the impedance of the antenna 400 and the impedance matching circuit 200 thereof has only the real part and the imaginary part of 0, which corresponds to the pure resistance.

Based on the method 100, the impedance curve of which the impedance changes along with the frequency can be efficiently and accurately obtained, when the impedance curve is required to be obtained to debug the impedance matching circuit 200 based on the impedance curve, the equipment is not required to be disassembled for many times and flying leads are introduced, the problem of reduced matching performance caused by impedance deviation caused by the flying leads is avoided, and the debugging efficiency and accuracy are effectively improved. And, the impedance deviation caused by the consistency problem of the peripheral matching device and the antenna 400 can be more accurately determined based on the impedance curve in the mass production test.

The present application further provides an apparatus 500 for obtaining impedance, as shown in fig. 12, the apparatus 500 is applied to an antenna 400 and an impedance matching circuit 200 thereof, the impedance matching circuit 200 is connected between the antenna 400 and a near field communication NFC chip 300, the NFC chip 300 includes a transmitting circuit 310 and a receiving circuit 320, and the apparatus 500 includes an information collecting module 510 and an information processing module 520.

The information acquisition module 510 is configured to acquire NFC data output by the NFC chip 300, where the NFC data includes average power supply current TXI data of a power supply thereof output by the transmitting circuit 310, and/or FSSI data output by the receiving circuit 320.

The information processing module 520 is configured to determine the impedance of the antenna 400 and the impedance matching circuit 200 thereof according to the NFC data acquired by the information acquiring module 510.

In one implementation, the first port TXP of the transmit circuit 310 is connected to a first terminal of a first device 211 in the impedance matching circuit 200, the first port RXP of the receive circuit 320 is connected to a second terminal of the first device 211 via a peripheral circuit, the second port TXN of the transmit circuit 310 is connected to a first terminal of a second device 212 in the impedance matching circuit 200, the second port RXN of the receive circuit 320 is connected to a second terminal of the second device 212 via a peripheral circuit, and the matching sub-circuit 220 formed by the antenna 400 and the portions of the impedance matching circuit 200 other than the first device 211 and the second device 212 are connected to the second terminal of the first device 211 and the second terminal of the second device 212.

In one implementation, at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to a first terminal of the first device 211 in the impedance matching circuit 200, the first port RXP of the receiving circuit 320 is connected to a second terminal of the first device 211 via a peripheral circuit, the second port RXN of the receiving circuit 320 is disconnected, and a matching sub-circuit 220 formed of the antenna 400 and a portion of the impedance matching circuit 200 other than the first device 211 is connected to the second terminal of the first device 211.

In one implementation, the NFC data includes TXI data and FSSI data, and determining the impedance of the antenna 400 and its impedance matching circuit 200 from the NFC data includes: determining a current value of the average supply current from the TXI data; determining an effective value of a voltage across an equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 from the FSSI data; the real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 are determined from the current value of the average supply current and the effective value of the voltage across the equivalent impedance.

In one implementation, the information processing module 520 is specifically configured to: the real part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined according to the current value of the average supply current and the following equation:

the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined from the current value of the average supply current, the effective value of the voltage across the equivalent impedance, and the following equation:

/>

or alternatively, the process may be performed,

wherein VDD is the voltage of the power supply of the transmitting circuit 310, I _avg1 And I _avg2 Respectively, the internal resistance of the transmitting circuit 310 is R _S1 And R is _S2 Current value of time average supply current, V _rx1 And V _rx2 Respectively, the internal resistance of the transmitting circuit 310 is R _S1 And R is _S2 The effective value of the voltage across the equivalent impedance;

When the first port TX of the transmitting circuit 310P and the second port TXN of transmit circuit 310 are connected to the first end of first device 211 and the first end of second device 212, respectively, V _S Is the effective value of the fundamental component of the voltage between the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 when the impedance matching circuit 200 is not connected, R _L +jX _L For the series impedance of the first device 211 and the second device 212,

v when at least one of the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 is connected to the first end of the first device 211 _S Is the effective value of the fundamental component of the voltage of the at least one port to ground when the impedance matching circuit 200 is not connected, R _L +jX _L Is the impedance of the first device 211.

In one implementation, the receiving circuit 320 has a function of detecting phase information, and the information processing module 520 is specifically configured to: determining an effective value of a voltage on an equivalent impedance formed by the matching sub-circuit 220 and the antenna 400 according to the FSSI data, and determining a phase difference between a phase value of the voltage of the matching sub-circuit 220 and a predetermined phase value; the real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 are determined based on the effective value and the phase difference of the voltages across the equivalent impedances.

In one implementation, the predetermined phase value is a phase value of a voltage between the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 when the impedance matching circuit 200 is not connected when the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, respectively; when at least one of the first port TXP of the transmitting circuit 310 and the second port TXN of the transmitting circuit 310 is connected to the first end of the first device 211, the predetermined phase value is a phase value of a voltage of the at least one port to ground when the impedance matching circuit 200 is not connected.

In one implementation, determining real and imaginary parts of the impedance of the antenna 400 and its impedance matching circuit 200 from the effective value of the voltage across the equivalent impedance and the phase difference includes:

the real part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined from the effective value of the voltage across the equivalent impedance, the phase difference and the following equation:

the method comprises the steps of,

the imaginary part of the impedance of the antenna 400 and its impedance matching circuit 200 is determined from the effective value of the voltage across the equivalent impedance, the phase difference and the following equation:

Wherein V is _rx R is the effective value of the voltage on the equivalent impedance _S For the internal resistance of the transmitting circuit 310,

is the phase difference;

v when the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 are connected to the first end of the first device 211 and the first end of the second device 212, respectively _S Is the effective value of the fundamental component of the voltage between the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 when the impedance matching circuit 200 is not connected, R _L +jX _L A series impedance of the first device 211 and the second device 212;

v when the first port TXP of the transmit circuit 310 and the second port TXN of the transmit circuit 310 are connected to the first end of the first device 211 _S Is the effective value of the fundamental component of the voltage of the first port TXP of the transmitting circuit 310 to the ground or the effective value of the fundamental component of the voltage of the second port TXN of the transmitting circuit 310 to the ground when the impedance matching circuit 200 is not connected, R _L +jX _L Is the impedance of the first device 211.

In one implementation, the information processing module 520 is further configured to: when the transmitting circuit 310 sequentially outputs signals of a plurality of frequencies in a specific frequency range, a plurality of impedances of the impedance matching circuit 200 at the plurality of frequencies are respectively acquired; an impedance curve representing the impedance of the antenna 400 and its impedance matching circuit 200 as a function of frequency is determined from the correspondence between the plurality of impedances and the plurality of frequencies. The impedance profile may be used, for example, to debug the impedance matching circuit 200.

In one implementation, the impedance matching circuit 200 includes a plurality of devices, where the plurality of devices includes at least one of an inductance, a resistance, and a capacitance, and the first device 211 is one of the plurality of devices or a combination of at least two of the plurality of devices in series or parallel, and the second device 212 is one of the plurality of devices or a combination of at least two of the plurality of devices in series or parallel.

The present application also provides an apparatus for obtaining an impedance, the apparatus comprising a processor and a memory, the memory for storing instructions, the processor for reading the instructions and performing the method for obtaining an impedance in any of the possible implementations described above.

The application also provides an electronic device, the electronic device comprising: NFC chip 300; an impedance matching circuit 200 disposed between the NFC chip 300 and the antenna 400; and means for obtaining the impedance of the antenna 400 and its impedance matching circuit 200 according to any of the possible implementations described above.

By way of example, and not limitation, the electronic device in the embodiments of the present application may be a portable or mobile computing device such as a terminal device, a mobile phone, a tablet computer, a notebook computer, a desktop computer, a game device, an in-vehicle electronic device, or a wearable smart device, and other electronic devices such as an electronic database, an automobile, and a bank automated teller machine (Automated Teller Machine, ATM). The wearable intelligent device comprises devices which are full in function, large in size and capable of achieving complete or partial functions independently of a smart phone, such as a smart watch or smart glasses, and devices which are only focused on certain application functions and are required to be matched with other devices such as the smart phone, such as various types of smart bracelets, smart jewelry and the like for physical sign monitoring.

It should be noted that, on the premise of no conflict, the embodiments described in the present application and/or the technical features in the embodiments may be arbitrarily combined with each other, and the technical solutions obtained after the combination should also fall into the protection scope of the present application.

The system, apparatus and method disclosed in the embodiments of the present application may be implemented in other manners. For example, some features of the method embodiments described above may be omitted or not performed. The above-described apparatus embodiments are merely illustrative, and the division of units is merely one logical function division, and there may be another division manner in actual implementation, and a plurality of units or components may be combined or may be integrated into another system. In addition, the coupling between the elements or the coupling between the elements may be direct or indirect, including electrical, mechanical, or other forms of connection.

It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working processes and technical effects of the apparatus and device described above may refer to corresponding processes and technical effects in the foregoing method embodiments, which are not described in detail herein.

It should be understood that the specific examples in the embodiments of the present application are only for helping those skilled in the art to better understand the embodiments of the present application, and not limit the scope of the embodiments of the present application, and those skilled in the art may make various improvements and modifications based on the above embodiments, and these improvements or modifications fall within the protection scope of the present application.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of obtaining impedance, the method being applied to an antenna and its impedance matching circuit, the impedance matching circuit being connected between the antenna and a near field communication NFC chip, the NFC chip comprising a transmitting circuit and a receiving circuit, the method comprising:

acquiring NFC data output by the NFC chip, wherein the NFC data comprises average power supply current TXI data of a power supply source of the NFC data output by the transmitting circuit and/or field signal strength indication FSSI data output by the receiving circuit;

And determining the impedance of the antenna and the impedance matching circuit according to the NFC data.

2. The method of claim 1, wherein a first port of the transmit circuit is connected to a first end of a first device in the impedance matching circuit, a first port of the receive circuit is connected to a second end of the first device via a peripheral circuit, a second port of the transmit circuit is connected to a first end of a second device in the impedance matching circuit, a second port of the receive circuit is connected to a second end of the second device via a peripheral circuit, and a matching sub-circuit formed in a portion of the impedance matching circuit other than the first device and the second device is connected to the second end of the first device and the second end of the second device.

3. The method of claim 1, wherein at least one of the first port of the transmit circuit and the second port of the transmit circuit is connected to a first end of a first device of the impedance matching circuits, the first port of the receive circuit is connected to a second end of the first device via a peripheral circuit, the second port of the receive circuit is disconnected, and a matching sub-circuit formed in a portion of the impedance matching circuits other than the first device is connected to the second end of the first device.

4. A method according to claim 2 or 3, wherein the NFC data comprises the TXI data and the FSSI data, and wherein determining the impedance of the antenna and the impedance matching circuit from the NFC data comprises:

determining a current value of the average supply current from the TXI data;

determining an effective value of a voltage on an equivalent impedance formed by the matching sub-circuit and the antenna according to the FSSI data;

and determining the real part and the imaginary part of the impedance of the antenna and the impedance matching circuit according to the current value of the average supply current and the effective value of the voltage on the equivalent impedance.

5. The method of claim 4, wherein said determining real and imaginary parts of the impedance of the antenna and the impedance matching circuit from the current value of the average supply current and the effective value of the voltage across the equivalent impedance comprises:

determining the real part of the impedance of the antenna and the impedance matching circuit according to the current value of the average supply current and the following formula:

X＝m ₁ ·(R _s1 +R)+n ₁ ，

Or (F)>

X＝m ₂ ·(R _s2 +R)+n ₂ ，

Wherein VDD is the voltage of the power supply of the transmitting circuit, I _avg1 And I _avg2 Respectively, the internal resistance of the transmitting circuit is R _S1 And R is _S2 The current value of the average supply current, V _rx1 And V _rx2 Respectively, the internal resistance of the transmitting circuit is R _S1 And R is _S2 The effective value of the voltage across the equivalent impedance,

when the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first end of the first device and the first end of the second device, respectively, V _S Is the effective value of the fundamental component of the voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected, R _L +jX _L For the series impedance of the first device and the second device,

6. A method according to claim 2 or 3, wherein the receiving circuit has a function of detecting phase information, the NFC data includes the FSSI data, and determining the impedance of the antenna and the impedance matching circuit from the NFC data includes:

Determining an effective value of a voltage on an equivalent impedance formed by the matching sub-circuit and the antenna according to the FSSI data, and determining a phase difference between a phase value of the voltage on the equivalent impedance and a preset phase value;

and determining the real part and the imaginary part of the impedance of the antenna and the impedance matching circuit according to the effective value of the voltage on the equivalent impedance and the phase difference.

7. The method of claim 6, wherein the step of providing the first layer comprises,

when the first port of the transmitting circuit and the second port of the transmitting circuit are connected to the first terminal of the first device and the first terminal of the second device, respectively, the predetermined phase value is a phase value of a voltage between the first port of the transmitting circuit and the second port of the transmitting circuit when the impedance matching circuit is not connected,

when at least one of the first port of the transmitting circuit and the second port of the transmitting circuit is connected to the first end of the first device, the predetermined phase value is a phase value of a voltage of the at least one port to ground when the impedance matching circuit is not connected.

8. The method according to claim 6 or 7, wherein said determining real and imaginary parts of the impedance of the antenna and the impedance matching circuit from the effective value of the voltage across the equivalent impedance and the phase difference comprises:

the method comprises the steps of,

for the purpose of the phase difference,

9. The method according to any one of claims 1 to 8, further comprising:

when the transmitting circuit sequentially outputs signals with a plurality of frequencies in a specific frequency range, respectively acquiring a plurality of impedances of the antenna and the impedance matching circuit under the plurality of frequencies;

and determining an impedance curve for representing the impedance of the antenna and the impedance matching circuit along with the frequency according to the correspondence relation between the plurality of impedances and the plurality of frequencies.

10. The method according to claim 9, wherein the method further comprises:

and debugging the impedance matching circuit according to the impedance curve.

11. The method of any one of claims 1 to 10, wherein the impedance matching circuit comprises a plurality of devices, the plurality of devices being of a type comprising at least one of inductance, resistance, and capacitance, wherein the first device is one of the plurality of devices or a combination of at least two of the plurality of devices in series or parallel, and the second device is one of the plurality of devices or a combination of at least two of the plurality of devices in series or parallel.

12. An apparatus for obtaining impedance, the apparatus being applied to an antenna and an impedance matching circuit thereof, the impedance matching circuit being connected between the antenna and a near field communication NFC chip, the NFC chip comprising a transmitting circuit and a receiving circuit, the apparatus comprising:

the information acquisition module is used for acquiring NFC data output by the NFC chip, wherein the NFC data comprises average power supply current TXI data of a power supply source of the NFC data output by the transmitting circuit and/or field signal strength indication FSSI data output by the receiving circuit; the method comprises the steps of,

and the information processing module is used for determining the impedance of the antenna and the impedance matching circuit according to the NFC data.

13. The apparatus of claim 12, wherein a first port of the transmit circuit is connected to a first end of a first device in the impedance matching circuit, a first port of the receive circuit is connected to a second end of the first device via a peripheral circuit, a second port of the transmit circuit is connected to a first end of a second device in the impedance matching circuit, a second port of the receive circuit is connected to a second end of the second device via a peripheral circuit, and a matching sub-circuit formed in a portion of the impedance matching circuit other than the first device and the second device is connected to the second end of the first device and the second end of the second device.

14. The apparatus of claim 12, wherein at least one of a first port of the transmit circuit and a second port of the transmit circuit is connected to a first end of a first device of the impedance matching circuits, a first port of the receive circuit is connected to a second end of the first device via a peripheral circuit, the second port of the receive circuit is disconnected, and a matching sub-circuit formed in a portion of the impedance matching circuits other than the first device is connected to the second end of the first device.

15. The apparatus according to claim 13 or 14, wherein the information processing module is specifically configured to:

determining a current value of the average supply current from the TXI data;

16. The apparatus of claim 15, wherein the information processing module is specifically configured to:

the method comprises the steps of,

X＝m ₁ ·(R _s1 +R)+n ₁ ，

or alternatively, the process may be performed,

X＝m ₂ ·(R _s2 +R)+n ₂ ，

17. The apparatus according to claim 13 or 14, wherein the receiving circuit has a function of detecting phase information, and the information processing module is specifically configured to:

18. The apparatus of claim 17, wherein the device comprises a plurality of sensors,

19. The apparatus of claim 18, wherein the information processing module is specifically configured to:

the method comprises the steps of,

wherein V is _rx Is effective for the voltage on the equivalent impedanceValue of R _S For the internal resistance of the transmitting circuit,

for the purpose of the phase difference,

20. The apparatus of any one of claims 12 to 19, wherein the information processing module is further configured to:

21. The apparatus of claim 20, wherein the impedance profile is used to debug the impedance matching circuit.

22. The apparatus of any one of claims 12 to 21, wherein the impedance matching circuit comprises a plurality of devices, the plurality of devices being of a type comprising at least one of inductance, resistance, and capacitance, wherein the first device is one of the plurality of devices or a combination of at least two of the plurality of devices in series or parallel, and the second device is one of the plurality of devices or a combination of at least two of the plurality of devices in series or parallel.

23. An apparatus for obtaining an impedance, the apparatus comprising a processor and a memory, the memory for storing instructions, the processor for reading the instructions and performing the method of obtaining an impedance according to any one of claims 1 to 11.

24. An electronic device, comprising:

a near field communication NFC chip;

an impedance matching network disposed between the NFC chip and the antenna; the method comprises the steps of,

the apparatus of any of claims 12 to 22, or the apparatus of claim 23, for obtaining the impedance of the antenna and the impedance matching network.