CN212725599U

CN212725599U - Single-ended NFC antenna matching circuit

Info

Publication number: CN212725599U
Application number: CN202022024389.7U
Authority: CN
Inventors: 沈勇坚; 胡永刚
Original assignee: Dynamicode Co Ltd
Current assignee: Dynamicode Co Ltd
Priority date: 2020-09-15
Filing date: 2020-09-15
Publication date: 2021-03-16
Anticipated expiration: 2030-09-15

Abstract

The utility model discloses a single-ended NFC antenna matching circuit, which comprises a PCB board, a chip and an NFC antenna, wherein the chip and the NFC antenna are arranged on the PCB board; a receiving circuit connected to the chip; the low-pass filter circuit and the matching circuit are connected with the chip; two ends of the matching circuit are respectively connected with the low-pass filter circuit and the NFC antenna; the circuit consists of a first capacitor, a second capacitor and a resistor; the first capacitor and the resistor are connected in series in the circuit, and the second capacitor is connected in parallel in the circuit; the first capacitor, the second capacitor and the resistor are matched and connected with each other to form a single-end matching circuit. When the matching value is debugged, only 2 capacitance values and resistance values are needed to be debugged, so that the circuit and parts in the circuit are simplified, the cost and debugging difficulty are reduced, and the debugging rate is greatly improved.

Description

Single-ended NFC antenna matching circuit

Technical Field

The utility model relates to an electronic information technical field, concretely relates to single-ended NFC antenna matching circuit.

Background

With the development of NFC technology, various products with NFC function are coming out endlessly. However, in the products with related NFC functions in the current market, the circuits of the internal antennas all adopt a dual-end matching method. The circuit is complex, the debugging time is long, the number of components is large, and the production cost is high. In addition, due to the precision of multiple components, it is difficult to ensure circuit matching consistency, which results in some products with abnormal NFC functionality in mass production.

Therefore, how to simplify the circuit and improve the debugging rate is a problem to be solved in the field.

SUMMERY OF THE UTILITY MODEL

There is the technical problem that the circuit is complicated to current inside antenna circuit of NFC, the utility model aims to provide a single-ended NFC antenna matching circuit, its fine solution foretell problem.

In order to achieve the above object, the present invention provides a single-ended NFC antenna matching circuit, which includes a PCB, a chip mounted on the PCB, and an NFC antenna; the matching circuit is connected with the NFC antenna, and the receiving circuit is connected with the chip; the low-pass filter circuit is respectively connected with the chip and the matching circuit; the matching circuit consists of a first capacitor, a second capacitor and a resistor; the first capacitor and the resistor are connected in series in the circuit; the second capacitor is connected in parallel in the circuit; the first capacitor, the second capacitor and the resistor are mutually matched and connected to form a single-ended matching circuit.

Furthermore, the chip is provided with a first transmitting end, a second transmitting end and a receiving end; the low-pass filter is connected with any one of the first transmitting end and the second transmitting end; the receiving end is connected with the receiving circuit.

The utility model provides a pair of single-ended NFC antenna matching circuit, for prior art, its compatible bi-polar matching circuit, at the matching in-process, can directly debug capacitance value and resistance value on the matching circuit, until transferring to matching value and quality factor and all satisfy the demands, simplified the circuit, improved debugging efficiency.

Drawings

The invention is further described with reference to the following drawings and detailed description.

Fig. 1 is a schematic structural diagram of a single-ended NFC antenna matching circuit in this scheme.

Detailed Description

In order to make the technical means, creation features, achievement purposes and functions of the present invention easy to understand and understand, the present invention is further explained by combining with the specific drawings.

The present disclosure provides a single-ended NFC antenna matching circuit, which mainly includes a PCB (not shown), a chip 100, a low-pass filter 200, a receiving circuit 300, a matching circuit 400, and an NFC antenna 500.

The radio wave transmitted by the transmitting end of the chip 100 of the initiating device sequentially passes through the low-pass filter circuit 200, and the matching circuit 400 is then wirelessly connected with the read device through the NFC antenna 500 to exchange data at a certain speed; meanwhile, the initiating device receives and reads the data of the device under test through the receiving circuit 300 of the chip at the same speed.

The chip 100 is a radio frequency card reading chip, and is used for transmitting data and reading data. The radio frequency card reading chip 100 is mounted on a PCB board.

Further, the radio frequency card reading chip 100 has two transmitting terminals, namely a first transmitting terminal 110 and a second transmitting terminal 120. The first transmitting terminal 110 and the second transmitting terminal 120 are independently arranged, and any section of the first transmitting terminal and the second transmitting terminal can be connected with the low-pass filter circuit 200. The radio frequency card reading chip 100 converts data in the device into electromagnetic waves and transmits the electromagnetic waves to the low-pass filter circuit 200 for corresponding processing of the electromagnetic waves.

The rf card reading chip 100 further has a receiving end 130, the receiving end 130 is connected to a receiving circuit 300, and the receiving circuit 300 is used for receiving the electromagnetic wave transmitted by the read device.

The low-pass filter circuit 200 and the receiving circuit 300 are well known to those skilled in the art, and the configuration thereof will not be described herein.

Further, one end of the matching circuit 400 is connected to the low-pass filter circuit 200, and the other end is connected to the NFC antenna 500; it is composed of a first capacitor 410, a second capacitor 420 and a resistor 430. The capacitance value of the first capacitor 410 and the capacitance value of the second capacitor 420 can be adjusted to achieve a required matching value; the quality factor value is satisfied by tuning the resistor 430.

Wherein the first capacitor 410 is connected in series with the resistor 430, and the second capacitor 420 is connected in parallel with the ground 600. The first capacitor 410, the second capacitor 420 and the resistor 430 are connected with each other to form a single-ended matching circuit, which simplifies the circuit structure compared with the existing double-ended circuit.

The NFC antenna 500 is used to transmit signals to a device under test, is mounted on a PCB board, and has one end connected to the matching circuit 400 and the other end connected to the ground 600.

NFC antenna 500 is well known to those skilled in the art and will not be described in detail herein.

The working process of the scheme in application is illustrated below.

When the scheme is applied specifically, the low-pass filter circuit 200 is arbitrarily connected to one of the radiation ends of the radio frequency card reading chip 100, and the radiation end at the other end of the radio frequency card reading chip 100 is suspended.

The radio frequency card reading chip 100 in the initiating device converts data into electromagnetic waves, transmits the electromagnetic waves to the low-pass filter circuit 200 through a radiation end at a certain speed for processing, and finally transmits signals to the tested device through the NFC antenna 500 after passing through the matching circuit 400; when the initiating device transmits a signal to the device to be tested at a certain speed, the initiating device receives and reads the electromagnetic wave of the device to be tested through the receiving circuit 300 at the same speed, so that the data between the two devices can be exchanged quickly.

For example, when the matching consistency is difficult to ensure due to the deviation of precision generated by the internal components during production, thereby causing the abnormality of the NFC function, the matching value in the NFC antenna matching circuit can be debugged by the vector network analyzer.

In the scheme, when the vector network analyzer is used for debugging impedance matching, one end of a debugging test point is the front end of the low-pass filter circuit 200, and the other end of the debugging test point is grounded.

The low pass filter circuit 200 is generally a fixed module, and the vector network analyzer only needs to debug the first capacitance 410, the second capacitance 420 and the resistance 430.

When the matching value in the circuit is debugged, the resistance value is defaulted to 0 ohm, and at the moment, only the first capacitance value 410 and the second capacitance value 420 need to be debugged until the matching value meets the requirement; after the matching value is reached, if the quality factor value in the circuit is too large, the resistance 430 may be increased, and then the first capacitance 410 and the second capacitance 420 may be trimmed until both the matching value and the quality factor value meet the requirements.

When the single-ended NFC antenna matching circuit formed by the scheme is specifically applied, the single-ended NFC antenna matching circuit has the following advantages:

(1) compatible bi-polar matching circuit can directly adjust on bi-polar matching circuit's basis, need not to change the PCB board, to the PCB of volume production, after the matching value of calling out the antenna change BOM can, reduce manpower and time.

(2) The circuit matching is simple, and the debugging efficiency of research personnel can be improved.

(3) And fewer components are used, the variable limited by the precision of the components is reduced, and the matching consistency is further ensured.

(4) Compared with a double-end matching circuit, the cost is reduced by half.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above embodiments, and that the foregoing embodiments and descriptions are provided only to illustrate the principles of the present invention without departing from the spirit and scope of the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. A single-ended NFC antenna matching circuit comprises a PCB, a chip and an NFC antenna, wherein the chip and the NFC antenna are mounted on the PCB; the matching circuit is connected with the NFC antenna, and the receiving circuit is connected with the chip; the circuit is characterized by also comprising a low-pass filter circuit which is respectively connected with the chip and the matching circuit; the matching circuit consists of a first capacitor, a second capacitor and a resistor; the first capacitor and the resistor are connected in series in the circuit; the second capacitor is connected in parallel in the circuit; the first capacitor, the second capacitor and the resistor are mutually matched and connected to form a single-ended matching circuit.

2. The single-ended NFC antenna matching circuit according to claim 1, wherein said chip has a first transmitting end, a second transmitting end and a receiving end; the low-pass filter is connected with any one of the first transmitting end and the second transmitting end; the receiving end is connected with the receiving circuit.