CN211352595U - Radio frequency printed circuit board, radio frequency device and terminal equipment - Google Patents
Radio frequency printed circuit board, radio frequency device and terminal equipment Download PDFInfo
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- CN211352595U CN211352595U CN201922326239.9U CN201922326239U CN211352595U CN 211352595 U CN211352595 U CN 211352595U CN 201922326239 U CN201922326239 U CN 201922326239U CN 211352595 U CN211352595 U CN 211352595U
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Abstract
The application provides a radio frequency printed circuit board, a radio frequency device and a terminal device. The radio frequency printed circuit board comprises a circuit layer and insulating layers, wherein the circuit layer and the insulating layers are alternately arranged; the circuit layer comprises a first circuit layer positioned on the surface of the radio frequency printed circuit board and a plurality of circuit layers positioned below the first circuit layer, wherein the plurality of circuit layers comprise a second circuit layer which is closest to the first circuit layer; the first circuit layer comprises a microstrip line and a pad arranged on the first circuit layer, and the pad is connected with the microstrip line; the area that corresponds the pad on the second circuit layer is the fretwork part or the multilayer circuit layer includes the second circuit layer and with the second circuit layer corresponds on the circuit layer of a plurality of layers adjacent in proper order the area of pad is the fretwork part, makes the impedance of pad with the impedance of microstrip line equals.
Description
Technical Field
The embodiment of the application relates to the field of radio frequency, in particular to a radio frequency printed circuit board, a radio frequency device and terminal equipment.
Background
In the transmission process of radio frequency signals, in order to reduce the loss of the radio frequency signals, a pi-type circuit structure and a T-type circuit structure are often used as matching networks on a circuit board, so that the impedance of a radio frequency chip and an antenna are matched. The pi-type circuit structure and the T-type circuit structure comprise some electronic components such as resistors, capacitors, inductors and the like. Due to the limitation of the specification of the components, the pads corresponding to the electronic components such as the resistor, the capacitor, the inductor and the like are generally wider and thicker than the microstrip line. On the same circuit board, factors influencing the impedance of the surface microstrip line include the width of the microstrip line, the thickness of the microstrip line and the height from the microstrip line to the reference plane. The wider the microstrip line, the smaller the corresponding impedance; the thicker the thickness of the microstrip line is, the smaller the corresponding impedance is; the longer the height of the microstrip line to the reference plane, the greater the corresponding impedance. The same applies to the impedance of the pads connected to the microstrip line. Because the height from the microstrip line and the pad arranged on the same surface of the radio frequency printed circuit board to the reference plane is equal, and the thickness and the width of the pad are both larger than the width and the thickness of the microstrip line, on the same circuit board, the impedance of the pad is smaller than the impedance of the microstrip line, which affects the consistency of transmission line impedance, and leads to the phenomena of signal ringing, reflection and the like when radio frequency signals pass through places with discontinuous impedance, such as the junction of the pad and the microstrip line, so that the problems of small power of transmitted signals and low receiving sensitivity are caused.
In some prior arts, the width of the microstrip line is selected to be made to be consistent with that of the pad, but the method cannot meet the condition that the thickness of the microstrip line is equal to that of the pad, and the impedances of the pad and the microstrip line are still slightly different, so that when a radio frequency signal passes through a place with discontinuous impedance, the phenomena of signal reflection and the like still exist; and this scheme needs more space resources, in some high-density super small space's product application, for example bracelet watch class product, does not have enough space resources can satisfy such wide line of walking. Therefore, especially under the condition of small space resources, how to solve the problem of impedance consistency of transmission lines on the radio frequency circuit board is a problem to be solved urgently.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application provides a radio frequency circuit board, a radio frequency device and terminal equipment. The radio frequency circuit board, the radio frequency device and the terminal equipment can solve the problem of inconsistent impedance of transmission lines on the radio frequency circuit board.
In one aspect, an embodiment of the present application provides a radio frequency printed circuit board, including circuit layers and insulating layers, where the circuit layers and the insulating layers are alternately arranged; the circuit layer comprises a first circuit layer positioned on the surface of the radio frequency printed circuit board and a plurality of circuit layers positioned below the first circuit layer, wherein the plurality of circuit layers comprise a second circuit layer which is closest to the first circuit layer; the first circuit layer comprises a microstrip line and a pad arranged on the first circuit layer, and the pad is connected with the microstrip line; the area that corresponds the pad on the second circuit layer is the fretwork part or the multilayer circuit layer includes the second circuit layer and with the second circuit layer corresponds on the circuit layer of a plurality of layers adjacent in proper order the area of pad is the fretwork part, makes the impedance of pad with the impedance of microstrip line equals.
The area corresponding to the bonding pad is hollowed on one layer which is located below the bonding pad and takes the second circuit layer as the starting point and comprises the second circuit layer or a plurality of layers of circuit layers which are adjacent in sequence until the impedance of the bonding pad is equal to that of the microstrip line. The application can ensure that the impedance of the transmission line keeps consistent even if a fine microstrip line is used under the condition of less space resources, thereby not occupying more space resources and obtaining stronger transmitting power.
Optionally, the hollow part is located right below the corresponding pad.
Optionally, the shape of the cross section of the hollow part is the same as the shape of the corresponding pad.
Optionally, the cross-sectional area of the hollowed-out portion is greater than or equal to the area of the corresponding pad.
Optionally, the impedance of the pad and the microstrip line is equal to the matching impedance of the radio frequency network in which the pad and the microstrip line are located.
The embodiment of the application also provides a radio frequency device which comprises the radio frequency printed circuit board.
The embodiment of the application also provides terminal equipment, and the terminal equipment comprises the radio frequency printed circuit board.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
FIG. 1 is a top view of an embodiment according to the present application;
FIG. 2 is a front view according to an embodiment of the present application.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Some concepts in the present application are explained and illustrated first. The radio frequency printed circuit board comprises a circuit layer and an insulating layer, wherein the circuit layer is used for distributing wires or electronic components and the like to form a working circuit, and the insulating layer is used for separating the circuit layers on different layers. In practice, the rf pcb is embodied as a structure in which circuit layers and insulating layers alternately appear, and the number of layers of the rf pcb is defined by the number of layers of the circuit layers, for example, a four-layer rf pcb including four circuit layers may be embodied as circuit layers-insulating layers-circuit layers. The electronic components are distributed on the surface of the radio frequency printed circuit board and connected to the radio frequency high-speed wires through the bonding pads, and the radio frequency high-speed wires distributed on the surface of the radio frequency printed circuit board are called microstrip lines. In the present application, the pad refers specifically to a pad connected to a microstrip line, and the trace refers specifically to a line for transmitting a radio frequency signal, and the pad and the trace that do not form a radio frequency operating circuit are not within the range referred to in the present application.
The pad and the microstrip line have corresponding reference planes, and the reference plane refers to a return path of a radio frequency transmission line signal. Due to the special structure of the radio frequency printed circuit board: the routing is on the surface layer, and the return path is on the lower layer, so the return path of the radio frequency transmission line signal generally appears in a planar form, referred to as a reference plane for short. The reference plane generally includes a ground plane, a power plane, and the like. In general, in design, the area of the circuit layer below the pad and the microstrip line corresponding to the pad and the microstrip line will avoid the trace and the via hole, so the reference plane of the pad or the microstrip line is generally the adjacent circuit layer below the layer where the pad or the microstrip line is located.
In practical applications, once the rf chip and the antenna have been determined, the corresponding impedance matching network may be determined accordingly. In actual board manufacturing, since the specifications of microstrip lines designed by different users may be different, the widths and thicknesses of microstrip lines with the same impedance designed by different users may be different, and likewise, the thickness of a pad connected to the microstrip line will also change along with the change of the thickness of the microstrip line, so that the impedance of the pad will change. In order to ensure that the impedance matching network does not change after being determined, the impedance of the microstrip line and the impedance of the pad can be matched with the impedance of the pad during design, so that the impedance matching network, the microstrip line and the pad can be designed independently, and the design workload is greatly reduced. The transmission line comprises the microstrip line and the bonding pad connected to the microstrip line, and how to keep the impedance of the transmission line consistent has important significance.
The application provides a radio frequency printed circuit board, which comprises a circuit layer and an insulating layer, wherein the circuit layer and the insulating layer are alternately arranged; the circuit layer comprises a first circuit layer positioned on the surface of the radio frequency printed circuit board and a plurality of circuit layers positioned below the first circuit layer, wherein the plurality of circuit layers comprise a second circuit layer which is closest to the first circuit layer; the first circuit layer comprises a microstrip line and a pad arranged on the first circuit layer, and the pad is connected with the microstrip line; the area that corresponds the pad on the second circuit layer is the fretwork part or the multilayer circuit layer includes the second circuit layer and with the second circuit layer corresponds on the circuit layer of a plurality of layers adjacent in proper order the area of pad is the fretwork part, makes the impedance of pad with the impedance of microstrip line equals.
Referring to fig. 1 and 2, fig. 1 is a top view and fig. 2 is a front view of an embodiment of the present application. The embodiment is a four-layer printed circuit board, which comprises a first circuit layer to a fourth circuit layer from top to bottom in sequence. The first circuit layer includes a first pad 11, a second pad 12, and a microstrip line 13. The four printed circuit layers further include a hollow portion 41, that is, a circuit layer under the first pad 11 corresponds to a hollowed-out region of the first pad 11, a hollow portion 32, that is, a circuit layer under the second pad 12 corresponds to a hollowed-out region of the second pad 12, and further include the insulating layer 20, the circuit layer 30, a reference plane 40 of the second pad 12 (that is, an upper surface of the third circuit layer), and a reference plane 50 of the first pad 11 (that is, an upper surface of the fourth circuit layer). Due to the limitation of the component specification, the first pad 11 and the second pad 12 are wider and thicker than the microstrip line 13, and in this specific embodiment, the first pad 11 is wider and thicker than the second pad 12. According to an impedance calculation formula Z of the microstrip line and the pad, wherein the impedance calculation formula Z is 87/SQRT (r +1.41) x ln [ (5.98h)/(0.8w + t) ], wherein r is a dielectric constant of a material of the radio frequency printed circuit board, h is a height from the microstrip line or the pad to a corresponding reference plane, w is a width of the microstrip line or the pad, and t is a thickness of the microstrip line or the pad. Generally, the heights of the first pad 11, the second pad 12 and the microstrip line 13 in the same circuit layer from the reference plane are all equal, and the heights of the first pad 11, the second pad 12 and the microstrip line 13 from the reference plane are all distances from the lower surface of the first pad to the upper surface of the second circuit layer. As can be seen from the above formula, the impedance of the first pad 11 is smaller than the impedance of the second pad 12, and the impedance of the second pad 12 is smaller than the impedance of the microstrip line 13. To keep the impedance of the transmission line uniform, the impedance of the first pad 11 and the second pad 12 can be increased by increasing the height h of the first pad 11 and the second pad 12 to their reference planes. In the embodiment of the present application, the areas of the second circuit layer and the third circuit layer corresponding to the first pads 11 are hollowed, so the reference plane of the first pads 11 is the fourth circuit layer, the height from the first pads 11 to the reference plane is the distance from the lower surface of the first pads 11 to the upper surface 50 of the fourth circuit layer, and similarly, the height from the second pads 12 to the reference plane is the distance from the lower surface of the second pads 12 to the upper surface 40 of the third circuit layer, so that the impedances of the first pads 11, the second pads 12 and the microstrip lines 13 are equal.
The impedance of the pad is increased by increasing the height h from the pad to the reference plane in the embodiment of the application, so that the impedance of the pad is consistent with that of the microstrip line, and the height h meets the classical formula of a surface layer impedance microstrip line: and Z is 87/SQRT (r +1.41) x ln [ (5.98h)/(0.8w + t) ], wherein w is the width of the microstrip line or the bonding pad, and t is the thickness of the microstrip line or the bonding pad. The application can realize that the impedance of the transmission line is consistent by using the fine microstrip line under the limited space resource, thereby not occupying more space resources.
Optionally, the hollow part is located right below the corresponding pad.
Optionally, the shape of the cross section of the hollow part is the same as the shape of the corresponding pad.
Optionally, the cross-sectional area of the hollowed-out portion is greater than or equal to the area of the corresponding pad.
Optionally, the impedance of the pad and the microstrip line is equal to the matching impedance of the radio frequency network in which the pad and the microstrip line are located. When the impedances of the bonding pad and the microstrip line are equal to the matching impedance of the radio frequency network where the bonding pad and the microstrip line are located, the bonding pad, the microstrip line and the impedance matching network can be designed separately, the workload of design is reduced, signal reflection caused by inconsistent impedance can be avoided in the process of transmission of radio frequency signals, effective transmission of the radio frequency signals is guaranteed, and loss attenuation of the radio frequency signals is avoided.
The embodiment of the application also provides a radio frequency device which comprises the radio frequency printed circuit board.
The embodiment of the application also provides terminal equipment, and the terminal equipment comprises the radio frequency printed circuit board. Such as a smart watch, smart bracelet, active pen. The terminal devices are small in size and small in space resource, so that wide and thick microstrip lines cannot be supported, the technical scheme of the application can meet the requirement that the transmission line has consistent impedance and supports fine microstrip lines, and the problem of small space resource can be solved.
It should be noted that, without conflict, the embodiments and/or technical features in the embodiments described in the present application may be arbitrarily combined with each other, and the technical solutions obtained after the combination also fall within the protection scope of the present application.
It should be understood that the specific examples in the embodiments of the present application are for the purpose of promoting a better understanding of the embodiments of the present application, and are not intended to limit the scope of the embodiments of the present application, and that various modifications and variations can be made by those skilled in the art based on the above embodiments and fall within the scope of the present application.
The above description is only for the 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 conceive of the changes or substitutions within the technical scope of the present application, and shall 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 (8)
1. A radio frequency printed circuit board is characterized by comprising circuit layers and insulating layers, wherein the circuit layers and the insulating layers are alternately arranged;
the circuit layer comprises a first circuit layer positioned on the surface of the radio frequency printed circuit board and a plurality of circuit layers positioned below the first circuit layer, wherein the plurality of circuit layers comprise a second circuit layer which is closest to the first circuit layer;
the first circuit layer comprises a microstrip line and a pad arranged on the first circuit layer, and the pad is connected with the microstrip line;
the area that corresponds the pad on the second circuit layer is the fretwork part or the multilayer circuit layer includes the second circuit layer and with the second circuit layer corresponds on the circuit layer of a plurality of layers adjacent in proper order the area of pad is the fretwork part, makes the impedance of pad with the impedance of microstrip line equals.
2. The radio frequency printed circuit board according to claim 1, wherein the impedances of the pad and the microstrip line satisfy a relationship: and Z is 87/SQRT (r +1.41) x ln [ (5.98h)/(0.8w + t) ], wherein h is the height of the pad or the microstrip line to a reference plane thereof, w is the width of the pad or the microstrip line, and t is the thickness of the pad or the microstrip line.
3. The radio frequency printed circuit board of claim 2, wherein the hollowed-out portion is located directly below the corresponding pad.
4. The radio frequency printed circuit board according to claim 3, wherein the cross section of the hollowed-out portion has the same shape as the corresponding pad.
5. The RF printed circuit board of claim 4, wherein the cross-sectional area of the hollowed-out portion is greater than or equal to the area of the corresponding pad.
6. The RF printed circuit board of claim 5, wherein the pad and the microstrip have an impedance equal to a matching impedance of the RF network.
7. A radio frequency device, characterized in that it comprises a radio frequency printed circuit board according to any one of claims 1 to 6.
8. A terminal device, characterized in that it comprises a radio frequency printed circuit board according to any one of claims 1 to 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922326239.9U CN211352595U (en) | 2019-12-19 | 2019-12-19 | Radio frequency printed circuit board, radio frequency device and terminal equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922326239.9U CN211352595U (en) | 2019-12-19 | 2019-12-19 | Radio frequency printed circuit board, radio frequency device and terminal equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211352595U true CN211352595U (en) | 2020-08-25 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201922326239.9U Active CN211352595U (en) | 2019-12-19 | 2019-12-19 | Radio frequency printed circuit board, radio frequency device and terminal equipment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN211352595U (en) |
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2019
- 2019-12-19 CN CN201922326239.9U patent/CN211352595U/en active Active
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