CN104348525B - Transmission device for near field communication device and near field communication device - Google Patents

Abstract

A transmission device for a near field communication device and a near field communication device. The transmission device includes: a matching circuit; a connection interface, having a first width, for connecting an operation circuit of the near field communication device; the first transmission line is electrically connected between an antenna of the near field communication device and the matching circuit; and a second transmission line electrically connected between the connection interface and the matching circuit, including a line width increasing section and a constant line width section, wherein the width of the second transmission line in the line width increasing section is increased from the first width to a second width, and the width of the second transmission line in the constant line width section substantially maintains the second width, and the second width is greater than the first width and is related to the first width. The invention can make the impedance between the transmission device and the antenna consistent, and reduce the noise between the transmission device and the operating circuit, thereby reducing the transmission loss of high-frequency signals and improving the transmission efficiency.

Description

Transmission device for near field communication device and near field communication device

technical field

The invention relates to a transmission device and a near-field communication device for a near-field communication device, in particular to a transmission device and a near-field communication device for a near-field communication device that can reduce transmission loss of high-frequency signals.

Background technique

Near Field Communication (Near Field Communication) technology is a short-range high-frequency wireless communication technology that allows electronic devices to conduct contactless short distances (within 20 cm (cm)) in the 13.56MHz frequency band. ) data transmission, and thus has been widely used in portable electronic devices to provide users with more convenient e-commerce services.

Generally speaking, a near-field communication device includes three parts: an operating circuit (such as a frequency modulation component, a filter component, a computing chip, a memory, etc.), a matching circuit, and an antenna. The matching circuit is connected, and the matching circuit is electrically connected to the antenna through another transmission line. The operation mode of the near field communication technology is a well-known technology in the field. It mainly processes the high-frequency signal induced by the antenna by the operating circuit or transmits the high-frequency signal through the antenna, and the matching circuit controls the high-frequency signal transmitted between the operating circuit and the antenna. The signal is matched to ensure the integrity of the signal. However, although NFC technology is used for short-distance wireless transmission, due to its low power, it is more likely to cause loss during high-frequency signal transmission, thus affecting the sensing distance and convenience of use. Therefore, how to effectively reduce the high-frequency signal transmission loss of the near field communication device has become one of the goals of the industry.

Therefore, it is necessary to provide a transmission device for a near field communication device and a near field communication device to solve the above problems.

Contents of the invention

Therefore, the main purpose of the present invention is to provide a transmission device and a near field communication device to reduce transmission loss of high frequency signals.

The invention discloses a transmission device for a near-field communication device. The transmission device includes: a matching circuit; a connection interface, which is used to connect an operating circuit of the near-field communication device and has a first width ; a first transmission line, the first transmission line is electrically connected between an antenna of the near field communication device and the matching circuit; and a second transmission line, the second transmission line is electrically connected between the connection interface and the matching circuit Between, including a line width increasing section and a line width section, the width of the second transmission line in the line width increasing section gradually increases from the first width to a second width, and the second transmission line in these The width of the line width segment substantially maintains the second width, which is greater than and relative to the first width.

The present invention also discloses a near-field communication device, which includes: an operating circuit; an antenna; and a transmission device, the transmission device is coupled between the operating circuit and the antenna, and is used for the operating circuit The output high-frequency signal is transmitted to the antenna, or the high-frequency signal induced by the antenna is transmitted to the operating circuit, and the transmission device includes: a matching circuit; a connection interface, which is used to connect the operating circuit, And has a first width; a first transmission line, the first transmission line is electrically connected between the antenna and the matching circuit; and a second transmission line, the second transmission line is electrically connected between the connection interface and the matching circuit Between, including a line width increasing section and a line width section, the width of the second transmission line in the line width increasing section gradually increases from the first width to a second width, and the second transmission line in these The width of the line width segment substantially maintains the second width, which is greater than and relative to the first width.

The present invention makes the impedance between the transmission device and the antenna consistent by properly designing the transmission line impedance, line width, etc., and reduces the noise between the transmission device and the operating circuit, thereby reducing the transmission loss of high-frequency signals to improve transmission efficiency.

Description of drawings

FIG. 1 is a schematic diagram of a near field communication device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a transmission line according to an embodiment of the present invention.

FIG. 3 is a schematic diagram of a metal wire according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a transmission line according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of a transmission device according to an embodiment of the present invention.

FIG. 6 is a schematic diagram of a transmission line according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of a transmission line according to an embodiment of the present invention.

FIG. 8A is an L-shaped high-pass matching circuit.

FIG. 8B is a π-shaped low-pass matching circuit.

FIG. 8C is a T-shaped low-pass matching circuit.

FIG. 8D is an L-shaped low-pass matching circuit.

Description of main component symbols:

detailed description

Please refer to FIG. 1 , which is a schematic diagram of a near field communication device 10 according to an embodiment of the present invention. The near field communication device 10 includes an operating circuit 100 , an antenna 102 and a transmission device 104 for short-distance high-frequency wireless communication. The operating circuit 100 can process the high-frequency signal induced by the antenna 102 or transmit the high-frequency signal through the antenna 102, and the transmission device 104 is interposed between the operating circuit 100 and the antenna 102 to transmit the high-frequency signal output by the operating circuit 100 transmit to the antenna 102 , or transmit the high-frequency signal induced by the antenna 102 to the operation circuit 100 . The transmission device 104 includes a matching circuit 106 , a connection interface 108 , a first transmission line 110 and a second transmission line 112 . The first transmission line 110 is electrically connected between the antenna 102 and the matching circuit 106, the second transmission line 112 is electrically connected between the connection interface 108 and the matching circuit 106, and the matching circuit 106 can connect the first transmission line 110 and the second transmission line The high frequency signal transmitted by 112 is matched or converted. In addition, the specification of the connection interface 108 corresponds to the specification of a signal terminal 118 on the operating circuit 100. For example, if the signal terminal 118 is a gold finger socket with three pins, then the connection interface 108 is a male gold socket that conforms to the gold finger socket. Finger joints. In this way, when the connection interface 108 is inserted or combined with the signal terminal 118 in other ways, the operation circuit 100 can exchange signals with the antenna 102 through the transmission device 104 to realize near field communication operation. In addition, the transmission device 104 can effectively reduce the high-frequency signal transmission loss between the operation circuit 100 and the antenna 102 through the first transmission line 110 and the second transmission line 112 to improve signal quality.

In detail, the impedance of the first transmission line 110 matches the impedance of the antenna 102 , preferably making the two impedances consistent. In this way, the impedance of the connecting surface between the first transmission line 110 and the antenna 102 is continuous in the working frequency domain, which can reduce the loss of the transmission signal. In addition, if the first transmission line 110 and the antenna 102 are made of microstrip lines or metal sheets with the same or similar thickness, the first transmission line 110 and the antenna 102 can have the same width, so that impedances are consistent and production complexity is reduced.

On the other hand, as shown in FIG. 1, according to the variation of the line width, the second transmission line 112 can be divided into a line width gradually increasing section 114 and a line width section 116, that is, the line width increasing section 114 of the second transmission line 112 The width is gradually increased from the first width W1 to the second width W2 , and the width of the equal line width section 116 is approximately maintained at the second width W2 . Wherein, the first width W1 is the width of the connection interface 108 , and the second width W2 is greater than the first width W1 and is related to the first width W1 . In other words, the second transmission line 112 is wider than the connection interface 108, thereby reducing impedance and noise, thereby improving signal quality. It should be noted that FIG. 1 is used to illustrate the concept of the present invention, and those skilled in the art should make appropriate changes according to different system requirements. For example, in FIG. 1, the first transmission line 110 and the second transmission line 112 are used to represent the connection relationship or line width variation among the antenna 102, the matching circuit 106 and the operation circuit 100. In fact, the first transmission line 110 and the second transmission line The transmission lines 112 may respectively be composed of a plurality of metal wires. For example, in one embodiment, the antenna 102 has two signal terminals, the first transmission line 110 includes two metal wires corresponding to the two signal terminals of the antenna 102, and the matching circuit 106 can convert the output signal of the operation circuit 100 to Antenna 102.

In addition, the number of metal lines included in the second transmission line 112 matches the design of the matching circuit 106 and the operation circuit 100. For example, in one embodiment, the second transmission line 112 may include three metal lines, and the line width of these three metal lines should be It is properly adjusted according to the width of the connection interface 108 . For example, please refer to FIG. 2 , which is a schematic diagram of a transmission line 20 according to an embodiment of the present invention. The transmission line 20 can realize the second transmission line 112 in FIG. 1 , which includes metal lines L1 , L2 , and L3 , and is divided into a section 202 with increasing line width and a section 204 with an equal line width. In this embodiment, a connection interface 200 includes pins P1 , P2 , and P3 corresponding to the specifications of relevant signal terminals (such as the signal terminal 118 of the operating circuit 100 ). The widths of the pins P1 , P2 , and P3 are all Wp, and adjacent pins are separated by a distance G1 , so that the total width of the connection interface 200 is the first width W1 . Wherein, the pins P1 and P3 are used to transmit differential output signals, and the pin P2 is used to provide grounding. Furthermore, as shown in FIG. 2 , the widths of the metal lines L1, L2, and L3 are gradually increased from Wp to W_L1, W_L2, and W_L3 in the line width increasing section 202, and the distance between adjacent metal lines is gradually increased from G1 to G2. , so that the width of the transmission line 20 is increased from W1 to W2; and in the equal line width section 204, the widths of the metal lines L1, L2, and L3 are maintained at W_L1, W_L2, and W_L3, and the distance between adjacent metal lines is maintained at G2, The width of the transmission line 20 remains W2. Among them, the ratio of the width W_L1, W_L2, W_L3 of the metal lines L1, L2, L3 to Wp, and the ratio of the distance G2 to the distance G1 are shown in Table 1 below:

(Table I)

Width and spacing of metal lines L1, L2, L3 Ratio of width to pitch compared to pins P1, P2, P3 W_L1 (3.4～4.0)×Wp W_L2 (3.5～4.5)×Wp W_L3 (3.4～4.0)×Wp G2 (1.2～1.5)×G1

In other words, the widths W_L1 and W_L3 are respectively 3.4 to 4 times the width Wp, the width W_L2 is 3.5 to 4.5 times the width Wp, and the gap G2 is 1.2 to 1.5 times the gap G1. Therefore, the second width W2 (substantially determined by the widths W_L1 , W_L2 , W_L3 and the distance G2 ) is greater than the first width W1 (substantially determined by the width Wp and the distance G1 ), and is relative to the first width W1 . In addition, it can be seen from the above that the metal line L2 used for grounding has a larger line width, which can stabilize the grounding system and effectively reduce noise. It should be noted that, in this embodiment, the first width W1 or the second width W2 also includes a gap GS with a fixed width on both sides, and the gap GS can be between 0.2 mm and 1 mm to protect the metal lines L1 and L3 , but in other embodiments, the gap GS can also be removed depending on system requirements, and is not limited thereto.

In FIG. 2 , the widths of the metal lines L1, L2, and L3 gradually increase to W_L1, W_L2, and W_L3 in the line width increasing section 202 in a smooth increasing (that is, linearly changing) manner. However, this is only an embodiment, and any The structure of gradually increasing width can be used for the line width increasing section 202 . For example, FIG. 3 is a schematic diagram of a metal line 30 according to an embodiment of the present invention. The width of the metal line 30 is increased from Wp to W_L1 in three stages, so the metal line 30 can replace the metal line L1 in FIG. ).

On the other hand, in FIG. 1 (or FIG. 2 ), the line width increasing section 114 (or 202 ) of the second transmission line 112 (or 20 ) gradually increases the line width in a left-right symmetrical manner, but it is not limited thereto. For example, FIG. 4 is a schematic diagram of a transmission line 40 according to an embodiment of the present invention. The transmission line 40 increases in width to the left in FIG. 4, which can also be used in the present invention.

In addition, in FIG. 1 , both the first transmission line 110 and the second transmission line 112 extend along a straight line, but it is not limited thereto. For example, FIG. 5 is a schematic diagram of a transmission device 50 according to an embodiment of the present invention. The structure of the transmission device 50 is the same as that of the transmission device 104 in FIG. 1 , so the same components are denoted by the same symbols. As shown in FIG. 5, a first transmission line 500 and a second transmission line 502 of the transmission device 50 both include bends, and the width of the second transmission line 502 increases gradually in the line width increasing section 504, while in the first line The width of the wide section 506 remains substantially the same, which also meets the requirements of the present invention. It should be noted that the connection between the equal line width segment 506 and the matching circuit 106 is matched or adapted to the structure of the matching circuit 106, causing the width of some metal lines to change, but the main line segment still maintains the equal line width, which still meets the requirements of this specification. scope of invention. Except that the shape can be appropriately changed, the material of the first transmission line 110 and the second transmission line 112 is not limited, for example, it can be a flexible transmission line, such as a flexible printed circuit board (Flexible Printed Circuit), a flexible flat cable ( Flexible FlatCable), etc., or hard transmission lines, such as FR4 (Flame Retardant4), high-frequency circuit boards, etc.

In addition, as mentioned above, the number of metal wires included in the second transmission line 112 (or 502 ) matches the design of the matching circuit 106 and the operation circuit 100 , and is not limited to a specific number. For example, please refer to FIG. 6 , which is a schematic diagram of a transmission line 60 according to an embodiment of the present invention. The transmission line 60 can implement the second transmission line 112 in FIG. 1 , which includes the metal lines aL1 - aL5 and is divided into a section 602 with increasing line width and a section 604 with an equal line width. In this embodiment, a connection interface 600 corresponds to the specifications of related signal terminals (such as the signal terminal 118 of the operation circuit 100 ), and includes pins aP1 - aP5 . The widths of the pins aP1 - aP5 are all aWp, and adjacent pins are separated by a distance aG1 , so that the total width of the connection interface 600 is the first width W1 . Among them, the pins aP1 and aP5 are used to receive differential input signals, the pins aP2 and aP4 are used to transmit differential output signals, and the pin aP3 is used to provide grounding. Furthermore, as shown in FIG. 6 , the width of the metal lines aL1-aL5 gradually increases from aWp to aW_L1-aW_L5, and the distance between adjacent metal lines gradually increases from aG1 to aG2, so that the transmission line 60 The width of the transmission line is increased from W1 to W2; and in the equal line width segment 604, the width of the metal lines aL1-aL5 is maintained at aW_L1-aW_L5, and the distance between adjacent metal lines is maintained at aG2, so the width of the transmission line 60 is maintained at W2 . Among them, the ratio of the widths aW_L1 to aW_L5 of the metal lines aL1 to aL5 to aWp, and the ratio of the distance aG2 to the distance aG1 are shown in Table 2 below:

(Table II)

Width and spacing of metal lines aL1~aL5 Compared with the ratio of the width and pitch of the pins aP1 to aP5 aW_L1 (2.5～3.0)×aWp aW_L2 (3.4～4.0)×aWp aW_L3 (3.5～4.5)×aWp aW_L4 (3.4～4.0)×aWp aW_L5 (2.5～3.0)×aWp aG2 (1.2～1.5)×aG1

In other words, the widths aW_L1 and aW_L5 are respectively 2.5 to 3.0 times the width aWp, the widths aW_L2 and aW_L4 are respectively 3.4 to 4.0 times the width aWp, the width aW_L3 is 3.5 to 4.5 times the width aWp, and the distance aG2 is 1.2 to 4.0 times the distance aG1. 1.5 times. Therefore, the second width W2 (generally determined by the widths aW_L1 - aW_L5 and the distance aG2 ) is larger than the first width W1 (generally determined by the width aWp and the distance aG1 ), and is related to the first width W1 . In addition, in this embodiment, the first width W1 or the second width W2 also includes a gap aGS with a fixed width on both sides, which can be adjusted appropriately depending on system requirements, and is not limited thereto.

Similarly, please refer to FIG. 7 , which is a schematic diagram of a transmission line 70 according to an embodiment of the present invention. The transmission line 70 can implement the second transmission line 112 in FIG. 1 , which includes metal lines bL1 - bL7 and is divided into a section 702 with increasing line width and a section 704 with an equal line width. In this embodiment, a connection interface 700 corresponds to the specifications of related signal terminals (such as the signal terminal 118 of the operation circuit 100 ), and includes pins bP1 - bP7 . The widths of the pins bP1 - bP7 are all bWp, and adjacent pins are separated by a distance bG1 , so that the total width of the connection interface 700 is the first width W1 . Among them, the pins bP1, bP2, bP6 and bP7 are used to receive differential input signals, the pins bP3 and bP5 are used to transmit differential output signals, and the pin bP4 is used to provide grounding. Furthermore, as shown in FIG. 6 , the width of the metal lines bL1-bL7 gradually increases from bWp to bW_L1-bW_L7, and the distance between adjacent metal lines gradually increases from bG1 to bG2, so that the transmission line 70 The width of the transmission line is increased from W1 to W2; and in the equal line width section 704, the width of the metal lines bL1~bL7 is maintained at bW_L1~bW_L7, and the distance between adjacent metal lines is maintained at bG2, so the width of the transmission line 70 is maintained at W2 . Among them, the ratio of the width bW_L1 to bW_L7 of the metal lines bL1 to bL7 to bWp, and the ratio of the spacing bG2 to the spacing bG1 are shown in Table 3 below:

(Table 3)

Width and spacing of metal lines bL1 to bL7 Compared to the ratio of the width and pitch of pins bP1 to bP7 bW_L1 (2.5～3.0)×bWp bW_L2 (2.5～3.0)×bWp bW_L3 (3.4～4.0)×bWp bW_L4 (3.5～4.5)×bWp bW_L5 (3.4～4.0)×bWp bW_L6 (2.5～3.0)×bWp bW_L7 (2.5～3.0)×bWp bG2 (1.2～1.5)×bG1

In other words, the widths bW_L1, bW_L2, bW_L6, bW_L7 are respectively 2.5 to 3.0 times the width bWp, the widths bW_L3, bW_L5 are respectively 3.4 to 4.0 times the width bWp, the width bW_L4 is 3.5 to 4.5 times the width bWp, and the pitch bG2 is the pitch 1.2 to 1.5 times that of bG1. Therefore, the second width W2 (determined by the widths bW_L1 ˜ bW_L7 and the distance bG2 ) is greater than the first width W1 (determined by the width bWp and the distance bG1 ), and is related to the first width W1 . In addition, in this embodiment, the first width W1 or the second width W2 further includes a gap bGS with a fixed width on both sides, which can be adjusted appropriately according to system requirements, and is not limited thereto.

Fig. 6 and Fig. 7 are the disposition mode of the transmission line under five and seven pins respectively, and it is the embodiment of the present invention, and the number of metal lines, the width change mode etc. are for the purpose of example, not limited to this, those in the art Ordinary technicians should be able to moderately adjust such as the number of metal lines included in the transmission line, the change mode or magnification of the width of the metal lines, etc. according to system requirements. In addition, in order to improve design efficiency, when determining the width or magnification of the metal line, it is better to first determine the ground line (such as the metal line L2 in Figure 2, the metal line aL3 in Figure 6, and the metal line bL4 in Figure 7), and then determine Differential output signal lines (such as metal lines L1 and L3 in Figure 2, metal lines aL2 and aL4 in Figure 6, and metal lines bL3 and bL5 in Figure 7); if there are differential input signal lines, then determine the differential input signal lines (as shown in 6 metal lines aL1 , aL5 , and metal lines bL1 , bL2 , bL6 , and bL7 in FIG. 7 ).

In addition, the matching circuit 106 is used for matching or converting the high-frequency signal, which is not limited to a specific form, and can be properly adjusted according to system requirements. For example, FIG. 8A shows an L-shaped high-pass matching circuit, and FIGS. 8B to 8D show π-shaped, T-shaped and L-shaped low-pass matching circuits respectively, all of which are applicable to the present invention.

In the known technology, since the transmission impedance of the near field communication device is discontinuous and the noise cannot be effectively reduced, it is easy to cause high frequency signal transmission loss. In contrast, the present invention makes the impedance between the transmission device and the antenna consistent by properly designing the transmission line impedance, line width, etc., and reduces the noise between the transmission device and the operating circuit, thereby reducing the transmission loss of high-frequency signals to improve transmission efficiency .

Claims (20)

1. A transmission device for a near field communication device, the transmission device comprising: a matching circuit; a connection interface, the connection interface is used to connect an operating circuit of the near field communication device, and has a first width; a first transmission line electrically connected between an antenna of the near field communication device and the matching circuit; and A second transmission line, the second transmission line is electrically connected between the connection interface and the matching circuit, including a line width increasing section and a line width section, the width of the second transmission line in the line width increasing section is determined by The first width gradually increases to a second width, and the width of the second transmission line in the line width segments maintains the second width, the second width is greater than the first width and is related to the first width; Wherein the connection interface includes a plurality of pins, the second transmission line includes a plurality of metal lines, and the plurality of metal lines correspond to the plurality of pins. 2. The transmission device as claimed in claim 1, wherein the impedance of the first transmission line matches the impedance of the antenna. 3 . The transmission device as claimed in claim 1 , wherein the width of the second transmission line increases gradually from the first width to the second width in a plurality of stages in the line width increasing section. 4 . 4. The transmission device as claimed in claim 1, wherein the width of the second transmission line in the line-width increasing section gradually increases from the first width to the second width in a linearly changing manner. 5. The transmission device as claimed in claim 1, wherein a width of each of the plurality of pins is equal to a third width. 6. The transmission device as claimed in claim 5, wherein after the sum of the widths of the plurality of metal lines in the line width increasing section gradually increases from the first width to the second width, the widths of the plurality of metal lines are equal to ratio of the third width. 7. The transmission device of claim 6, wherein the plurality of ratios are related to functions of the plurality of pins. 8. The transmission device as claimed in claim 1, wherein the first transmission line or the second transmission line comprises at least one bend. 9. The transmission device as claimed in claim 1, wherein the line width sections are electrically connected between the matching circuit and the line width increasing section, and include a width change at the connection with the matching circuit, so as to adapt to the matching circuit. 10. The transmission device as claimed in claim 1, wherein the matching circuit is selected from the group consisting of L-shape, π-shape and T-shape. 11. A near field communication device, the near field communication device comprising: - operating circuit; an antenna; and A transmission device, the transmission device is coupled between the operation circuit and the antenna, and is used to transmit the high-frequency signal output by the operation circuit to the antenna, or transmit the high-frequency signal induced by the antenna to the operation circuit , the transmission device includes: a matching circuit; a connection interface, the connection interface is used to connect the operating circuit, and has a first width; a first transmission line electrically connected between the antenna and the matching circuit; and A second transmission line, the second transmission line is electrically connected between the connection interface and the matching circuit, including a line width increasing section and a line width section, the width of the second transmission line in the line width increasing section is determined by The first width gradually increases to a second width, and the width of the second transmission line in the line width segments maintains the second width, the second width is greater than the first width and is related to the first width; Wherein the connection interface includes a plurality of pins, the second transmission line includes a plurality of metal lines, and the plurality of metal lines correspond to the plurality of pins. 12. The near field communication device as claimed in claim 11, wherein the impedance of the first transmission line matches the impedance of the antenna. 13 . The near field communication device as claimed in claim 11 , wherein the width of the second transmission line increases gradually from the first width to the second width in a plurality of stages in the line width increasing section. 14 . 14 . The near field communication device as claimed in claim 11 , wherein the width of the second transmission line increases from the first width to the second width in a linearly changing manner in the line width increasing section. 15. The near field communication device as claimed in claim 11, wherein a width of each of the plurality of pins is equal to a third width. 16. The near field communication device as claimed in claim 15, wherein after the sum of the widths of the plurality of metal lines in the line width increasing section gradually increases from the first width to the second width, the plurality of metal lines The width is proportional to the third width. 17. The near field communication device of claim 16, wherein the ratios are related to functions of the pins. 18. The near field communication device as claimed in claim 11, wherein the first transmission line or the second transmission line comprises at least one bend. 19. The near field communication device according to claim 11, wherein the equal line width sections are electrically connected between the matching circuit and the line width increasing section, and include a width change at the connection with the matching circuit, so as to adapted to the matching circuit. 20. The near field communication device as claimed in claim 11, wherein the matching circuit is selected from the group consisting of L-shape, π-shape and T-shape.