CN115250570A - Electromagnetic band gap unit and printed circuit board - Google Patents

Abstract

The invention relates to an electromagnetic band gap unit and a printed circuit board, belonging to the technical field of digital electronic circuits. An electromagnetic bandgap unit is a square coplanar metal pattern with a side length of a preset side length, the pattern comprising: a square frame with a first preset width; two diagonal lines with a second preset width; having a third preset width, passing through the center of the pattern, and two vertical lines perpendicular to the frame; a gap of a fourth preset width is provided in the middle of each side of the frame so as to pass the pattern and the two vertical lines perpendicular to the frame can extend to the edge of the electromagnetic bandgap unit. By using the printed circuit board with the power supply layer composed of the above electromagnetic bandgap units, the integrity of the passing signal has better quality, the noise suppression bandwidth and cut-off depth indicators are also well improved, and the design method of the power supply layer is more flexible.

Description

A kind of electromagnetic bandgap unit and printed circuit board

technical field

The invention relates to the technical field of digital electronic circuits, in particular to an electromagnetic bandgap unit and a printed circuit board.

Background technique

In high-frequency digital circuits, the signal will be interfered by many factors during the transmission process, thus affecting the signal integrity. The performance is that the signal is interfered during transmission from the sending end to the receiving end, and a distorted signal is received at the receiving end. Interference factors may include signal-to-timing problems, signal ringing, signal reflection, near-end and long-range crosstalk, switching noise, ground bounce and power bounce, attenuation, capacitive load, electromagnetic radiation, battery interference, etc., especially noise interference serious. Therefore reducing noise is the best way to maintain signal integrity.

In the current process of electronic products developing towards high speed, small size, and low voltage, and the computing speed of server chips that provide computing for terminals is getting faster and faster, the impact of GBN (Ground Bounce Noise) on the system is increasing. Significantly, therefore, suppression of GBN effects becomes increasingly important. A common method is to use an Electromagnetic Band Gap (EBG) unit structure on the power plane of the printed circuit board to make the power plane (Power Plane) and the complete ground plane (Ground Plane) form a parallel plate waveguide. The electromagnetic bandgap unit structure of the power plane is equivalent to a series LC parallel high-order band-stop filter, so as to achieve the effect of suppressing ground bounce noise.

The electromagnetic bandgap unit structure is developed from HIS (High Impedance Surface, high impedance surface). The HIS structure can effectively block the surface current, making it attenuated and difficult to propagate electromagnetic waves. Initially, the HIS structure was mostly used in antenna design. After being discussed and promoted by scholars, the application range of HIS is quite extensive. The initial HIS structure is shown in Figure 1. The square metal sheet (Patch) is connected to the ground plane through the connecting column (Via). The dielectric material is filled between the metal sheet and the ground plane to form the HIS unit structure. The HIS unit is periodic Arranged in a positive manner to form a HIS, preventing electromagnetic waves of a specific frequency band from propagating in all directions. Figure 2 shows the equivalent circuit model of the HIS structure shown in Figure 1, where a capacitor C and an inductor L are connected in parallel, where the two metal sheets are equivalent to a capacitor, and the metal sheet, connecting column and ground layer are equivalent to an inductance. As shown in the following formula:

When this equivalent circuit resonates, it is equivalent to a high-impedance transmission path, making it difficult for signals in this frequency band to propagate. The resonance frequency as the center frequency of the cut-off frequency band is:

Applying the HIS structure to PCB can also suppress noise. For the linear channel electromagnetic bandgap unit structure (as shown in Fig. 3 and its equivalent circuit shown in Fig. 4) which is only cut in a regular shape on the power layer, it already has a certain noise suppression effect. The design of the linear electromagnetic bandgap unit structure pursues the bandwidth of suppressing noise and the reduction of manufacturing cost. Its design considerations focus on the following four aspects: (1) noise suppression bandwidth, (2) center frequency, (3) cutoff depth, and (4) signal integrity. The existing electromagnetic bandgap unit structure has greatly improved the noise suppression width, center frequency, and cut-off depth; but for signal integrity, the gap between the basic unit is enlarged, and the gap between the central body of the channel causes power The effect of planar incompleteness. Therefore, there is an urgent need for a new electromagnetic bandgap unit structure that focuses on improving signal integrity without excessively sacrificing other indicators.

SUMMARY OF THE INVENTION

In order to focus on improving the signal integrity design of the electromagnetic bandgap unit structure, an embodiment of the present invention provides an electromagnetic bandgap unit and a printed circuit board, on the basis of ensuring the electromagnetic bandgap noise suppression bandwidth, center frequency, and cut-off depth indicators , focusing on improving signal integrity.

In order to solve above-mentioned one or more technical problems, the technical scheme that the present invention adopts is as follows:

In the first aspect, an electromagnetic bandgap unit is provided. The electromagnetic bandgap unit is a square coplanar metal pattern with a side length equal to a preset side length. The above-mentioned pattern includes:

a square border with a first preset width;

two diagonal lines with a second preset width;

two vertical lines with a third preset width, passing through the center of the pattern, and perpendicular to the border;

A gap of a fourth preset width is provided in the middle of each side of the frame; wherein, the fourth preset width is greater than the third preset width, so that the above two perpendicular lines extend to the edge of the electromagnetic bandgap unit.

Further, the above pattern is a rotationally symmetrical pattern with a rotation angle of 90 degrees.

Further, the electromagnetic bandgap unit is arranged periodically on the first surface of the dielectric layer of the printed circuit board to form the power layer of the printed circuit board;

Wherein, the printed circuit board at least includes: a power layer, a dielectric layer, and a ground layer;

The dielectric layer also includes a second surface opposite to the first surface, and the second surface is adjacent to the ground layer.

Further, the electromagnetic bandgap unit is used to suppress noise signals transmitted from the power supply layer to the ground layer.

In a second aspect, an electromagnetic bandgap printed circuit board is provided, wherein the printed circuit board at least includes: a power supply layer, a dielectric layer, and a ground layer;

The dielectric layer includes: a first surface adjacent to the power layer, and a second surface opposite to the first surface, wherein the second surface is adjacent to the ground layer;

The power supply layer is formed by periodic arrangement of several electromagnetic bandgap units as described in the first aspect above.

Further, the power layer is a metal layer with a thickness of the power layer.

Further, laterally adjacent electromagnetic bandgap units have a first interval;

longitudinally adjacent electromagnetic bandgap units have a second interval;

The first interval and the second interval are adjustable according to the plane size of the power supply layer.

Further, the electromagnetic bandgap printed circuit board also includes metal connection patterns;

The width of the metal connection pattern is a third preset width;

The thickness of the metal connection pattern is the thickness of the power layer;

The metal connection pattern is used to connect adjacent electromagnetic bandgap units through the center of the pattern, and a vertical line perpendicular to the frame makes the adjacent electromagnetic bandgap units form an electrical connection.

Further, the dielectric layer has a dielectric layer thickness;

The material of the dielectric layer is FR4, and the relative permittivity is between 4.2-4.7.

Further, the ground layer is a complete metal plane with a thickness of the ground layer.

The beneficial effects brought by the technical solution provided by the embodiments of the present invention are:

1. By using a printed circuit board comprising an electromagnetic bandgap unit disclosed in the embodiment of the present invention to form a power layer, the signal integrity has better quality;

2. Compared with the electromagnetic bandgap unit of the traditional linear channel, the electromagnetic bandgap unit disclosed in the embodiment of the present invention also has a good improvement on the noise suppression bandwidth and the cut-off depth index;

3. For the flexible layout of the power layer, by cutting the power layer channel reasonably, it can avoid adding an additional power layer to the printed circuit board and save costs.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative effort.

Fig. 1 is a schematic diagram of the structure of a square metal sheet HIS;

Fig. 2 is a schematic diagram of an equivalent circuit of a square metal sheet HIS structure;

Fig. 3 is a schematic structural diagram of a linear channel electromagnetic bandgap unit;

Fig. 4 is a schematic diagram of an equivalent circuit of a linear channel electromagnetic bandgap unit;

Fig. 5 is a top view of an electromagnetic bandgap unit provided by an embodiment of the present invention;

Fig. 6 is a top view of an electromagnetic bandgap unit with preferred dimensions provided by an embodiment of the present invention;

7 is a schematic diagram of a power layer of a printed circuit board composed of periodically arranged electromagnetic bandgap units provided by an embodiment of the present invention;

Fig. 8 is a top view of electromagnetic bandgap units arranged in a 3×3 arrangement according to an embodiment of the present invention;

9 is a schematic diagram of an electromagnetic bandgap printed circuit board provided by an embodiment of the present invention;

10 is a signal eye diagram of a transmission line passing through a printed circuit board with an electromagnetic bandgap unit structure provided by an embodiment of the present invention as a power layer unit;

11 is a signal eye diagram of a transmission line passing through a printed circuit board with a linear electromagnetic bandgap unit structure as a power layer unit;

Fig. 12 is a comparison diagram of S21 parameters using two kinds of electromagnetic bandgap units.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only Some, but not all, embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the usual meanings understood by those skilled in the art to which the present disclosure belongs. "First", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Likewise, words like "a", "an" or "the" do not denote a limitation of quantity, but mean that there is at least one. The numbers in the drawings of the specification only indicate the distinction of each functional component or module, and do not indicate the logical relationship between the components or modules. "Comprising" or "comprising" and similar words mean that the elements or items appearing before the word include the elements or items listed after the word and their equivalents, without excluding other elements or items. Words such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "Down", "Left", "Right" and so on are only used to indicate the relative positional relationship. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

Hereinafter, various embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. It is to be noted that, in the drawings, the same reference numerals are assigned to components having substantially the same or similar structures and functions, and repeated descriptions about them will be omitted.

In order to focus on improving the signal integrity design of the electromagnetic bandgap unit structure, the embodiment of the present invention discloses an electromagnetic bandgap unit and a printed circuit board, on the basis of ensuring the electromagnetic bandgap's noise suppression bandwidth, center frequency, and cut-off depth indicators , focusing on improving signal integrity.

In one embodiment, as shown in FIG. 5 , an electromagnetic bandgap unit 4 is a square coplanar metal pattern whose side length is a preset side length A, and the above-mentioned pattern includes:

a square border 41 with a first preset width a;

two diagonal lines 42 with a second preset width b;

Two vertical lines 43 having a third preset width c, passing through the center of the pattern, and perpendicular to the frame;

A gap of a fourth preset width d is provided in the middle of each side of the frame 41, wherein the fourth preset width d is greater than the third preset width c, so that the above-mentioned two vertical lines 43 extend to the electromagnetic bandgap unit 4 edges.

Preferably, the preset side length A is set to 30mm, the first preset width a is 5mm, the second preset width b is 3mm, the third preset width c is 2mm, and the fourth preset width d is 6mm, as shown in Figure 6 shown.

The above pattern is a rotationally symmetrical pattern with a rotation angle of 90 degrees.

The electromagnetic bandgap units 4 are arranged periodically on the first surface 21 of the dielectric layer 2 of the printed circuit board to form the power layer 1 of the printed circuit board, as shown in FIG. 7 .

Wherein, the printed circuit board at least includes: a power supply layer 1 , a dielectric layer 2 , and a ground layer 3 .

The dielectric layer 2 further includes a second surface 22 opposite to the first surface 21 , and the second surface 22 is adjacent to the ground layer 3 .

The electromagnetic bandgap unit 4 is used to suppress the noise signal transmitted from the power layer to the ground layer.

In one embodiment, taking a power layer of a printed circuit board composed of 9 electromagnetic bandgap units arranged in 3×3 as an example, FIG. 8 shows a top view of its arrangement.

In another embodiment, as shown in FIG. 9 , an electromagnetic bandgap printed circuit board 5 at least includes: a power layer 1 , a dielectric layer 2 , and a ground layer 3 .

The dielectric layer 2 includes: a first surface 21 adjacent to the power layer 1, and a second surface 22 opposite to the first surface 21, wherein the second surface 22 is adjacent to the ground layer 3;

The power supply layer 1 is formed by periodically arranging several electromagnetic bandgap units 4 as mentioned above.

The power layer 1 is a metal layer having a thickness of the power layer, and the thickness of the power layer is determined according to the designed thickness of the printed circuit board.

As shown in FIG. 8 , the laterally adjacent electromagnetic bandgap units 4 have a first interval L _a ;

longitudinally adjacent electromagnetic bandgap units 4 have a second interval L _b ;

The first interval L _a and the second interval L _b are adjustable according to the plane size of the power supply layer.

The specific value of the first interval _{L a} is determined according to the length PA of the long side of the power layer 1 . The length PA of the long side of the power supply layer ₁ can accommodate M complete electromagnetic bandgap units 4 at most, and M is a natural number, obtained by the following formula:

The specific value of the second interval L _b is determined according to the length P _B of the wide side of the power layer 1 . The length P _B of the wide side of the power supply layer 1 can accommodate at most N complete electromagnetic bandgap units 4, N is a natural number, obtained by the following formula:

The electromagnetic bandgap printed circuit board also includes metal connection patterns;

The width of the metal connection pattern is a third preset width c;

The thickness of the metal connection pattern is the thickness of the power layer;

The metal connection pattern is used to connect adjacent electromagnetic bandgap units through the center of the pattern, and a vertical line perpendicular to the frame makes the adjacent electromagnetic bandgap units form an electrical connection.

As shown in FIG. 9, each connected electromagnetic bandgap unit 4 is electrically connected through the metal connection pattern 6, wherein the length of the first metal connection pattern 61 is the first interval L _a , and the length of the second metal connection pattern 62 is is the second interval L _b . The connected electromagnetic bandgap unit 4 can be equipotentialized by the metal connection pattern 6 . This connection can be to connect all the electromagnetic bandgap units 4 of the power layer 1 in sequence. In this connection mode, the potential of the power layer 1 is a power supply voltage; The unit 4 is electrically connected to another part of the electromagnetic bandgap unit 4 in the power layer 1 , but there is no electrical connection between the two parts. Then a part of the connected electromagnetic bandgap units 4 is at the same potential as one power supply, and similarly, another part of the connected electromagnetic bandgap units 4 is at the same potential as another power supply. The power planes connected in this way can provide two or more power supply voltages through one power plane. Improve the flexibility of the layout of the power layer. By cutting the power layer channel reasonably, the effect of avoiding the addition of an additional power layer on the printed circuit board is achieved, and the cost is saved.

The dielectric layer 2 has a dielectric layer thickness, which is determined according to the designed thickness of the printed circuit board.

The material of the dielectric layer is FR4, and its relative permittivity is between 4.2-4.7.

The ground layer 3 is a complete metal plane with a thickness of the ground layer, and the thickness of the ground layer is determined according to the designed thickness of the printed circuit board.

In order to verify the improvement of signal integrity by the electromagnetic bandgap unit structure disclosed in the embodiment of the present invention, the transmission line passes through and includes 9 electromagnetic bandgap units disclosed in the embodiment of the present invention, and the power supply layer 1 is arranged in 3×3, L _a =5 mm, L _b =5 mm printed circuit board to conduct signal integrity simulation experiments, and obtain the eye diagram shown in FIG. 10 . At the same time, use the same layout and the same unit size for the transmission line passing through the power layer, and use the printed circuit board of the linear electromagnetic bandgap unit power layer to conduct signal integrity simulation experiments, and obtain the eye diagram shown in Figure 11. Comparing the simulation results, it is found that the transmission line contains nine electromagnetic bandgap units disclosed in the embodiment of the present invention through the power supply layer, and the printed circuit boards arranged in 3×3 are used. Compared with the "eye" in the eye diagram shown in Fig. 11 The "eye" in the eye diagram of a printed circuit board with a linear electromagnetic bandgap cell structure is larger. The specific performance is that its "eye width" and "eye height" are significantly larger. This shows that the use of the electromagnetic bandgap unit structure disclosed in the embodiment of the present invention can greatly improve the signal integrity.

A further comparison of the suppressed noise width and cut-off depth of printed circuit boards with two structures is shown in Figure 12. Using the electromagnetic bandgap unit disclosed in the embodiment of the present invention as the printed circuit board of the power layer, the suppressed noise frequency extends from about 1GHz to 10GHz, and the bandwidth is about 9GHz; the cut-off depth is increased to about -90dB, which is greatly improved.

All the above optional technical solutions can be combined in any way to form an optional embodiment of the present invention, which will not be repeated here.

Example 1

An embodiment of the present invention will be described in detail below with reference to FIGS. 5-7 . As shown in Figure 5, an electromagnetic bandgap unit 4 is a square coplanar metal pattern whose side length is a preset side length A, and the above-mentioned pattern includes:

a square border 41 with a first preset width a;

two diagonal lines 42 with a second predetermined width b;

Two vertical lines 43 having a third preset width c, passing through the center of the pattern, and perpendicular to the frame;

A gap of a fourth preset width d is provided in the middle of each side of the frame 41, wherein the fourth preset width d is greater than the third preset width c, so as to pass through the center of the pattern, and two vertical lines perpendicular to the frame 43 extends to the edge of the electromagnetic bandgap unit 4 .

In one implementation of this embodiment, the preset side length A is set to 30 mm, the first preset width a is 5 mm, the second preset width b is 3 mm, the third preset width c is 2 mm, and the fourth preset width Let the width d be 6mm, as shown in Figure 6.

The above pattern is a rotationally symmetrical pattern with a rotation angle of 90 degrees.

The electromagnetic bandgap units 4 are arranged periodically on the first surface 21 of the dielectric layer 2 of the printed circuit board to form the power layer 1 of the printed circuit board, as shown in FIG. 7 .

Wherein, the printed circuit board at least includes: a power supply layer 1 , a dielectric layer 2 , and a ground layer 3 .

The dielectric layer 2 further includes a second surface 22 opposite to the first surface 21 , and the second surface 22 is adjacent to the ground layer 3 .

The electromagnetic bandgap unit 4 is used to suppress the noise signal transmitted from the power layer to the ground layer.

FIG. 8 shows a power supply layer 1 composed of nine electromagnetic bandgap units arranged in a 3×3 manner.

The transversely adjacent electromagnetic bandgap units 4 have a first interval L _a =5 mm, and the longitudinally adjacent electromagnetic bandgap units 4 have a second interval L _b =5 mm.

Embodiment 2

An electromagnetic bandgap printed circuit board is described below with reference to FIG. 9 .

An electromagnetic bandgap printed circuit board 5 at least includes: a power layer 1 , a dielectric layer 2 , and a ground layer 3 .

The dielectric layer 2 includes: a first surface 21 adjacent to the power layer 1, and a second surface 22 opposite to the first surface 21, wherein the second surface 22 is adjacent to the ground layer 3;

The power supply layer 1 is formed by periodically arranging several electromagnetic bandgap units 4 as mentioned above.

The power layer 1 is a metal layer having a thickness of the power layer, and the thickness of the power layer is determined according to the designed thickness of the printed circuit board.

FIG. 8 shows a power supply layer 1 composed of nine electromagnetic bandgap units arranged in a 3×3 manner.

The transversely adjacent electromagnetic bandgap units 4 have a first interval L _a =5 mm, and the longitudinally adjacent electromagnetic bandgap units 4 have a second interval L _b =5 mm.

The electromagnetic bandgap printed circuit board also includes metal connection patterns;

The width of the metal connection pattern is a third preset width c;

The thickness of the metal connection pattern is the thickness of the power layer;

The metal connection pattern is used to connect adjacent electromagnetic bandgap units through the center of the pattern, and a vertical line perpendicular to the frame makes the adjacent electromagnetic bandgap units form an electrical connection.

As shown in FIG. 9, each connected electromagnetic bandgap unit 4 is connected through the metal connection pattern 6, wherein the length of the first metal connection pattern 61 is the first interval L _a , and the length of the second metal connection pattern 62 is the first interval. Two intervals L _b . The connected electromagnetic bandgap unit 4 can be equipotentialized by the metal connection pattern 6 . This connection may be to connect all the electromagnetic bandgap units 4 of the power supply layer 1 sequentially. In this connection mode, the potential of the power supply layer 1 is a power supply voltage.

In another implementation of this embodiment, some of the electromagnetic bandgap units 4 in the power layer 1 form an electrical connection, and another part of the electromagnetic bandgap units 4 in the power layer 1 forms an electrical connection, but there is no connection between the two parts. electrical connection. A part of the connected electromagnetic bandgap units 4 is at the same potential as one power supply; similarly, another part of the connected electromagnetic bandgap units 4 is at the same potential as another power supply. The power planes connected in this way can provide two or more power supply voltages through one power plane. By cutting the power layer channels reasonably, the flexibility of the power layer layout is improved, and the effect of avoiding the addition of an additional power layer on the printed circuit board is achieved, which saves costs.

The dielectric layer 2 has a dielectric layer thickness, which is determined according to the designed thickness of the printed circuit board.

The material of the dielectric layer is FR4, and its relative permittivity is between 4.2-4.7.

The ground layer 3 is a complete metal plane with a thickness of the ground layer, and the thickness of the ground layer is determined according to the designed thickness of the printed circuit board.

In order to verify the improvement of signal integrity by the electromagnetic bandgap junction printed circuit board structure disclosed in Embodiment 2, a signal integrity simulation experiment was carried out on the transmission line passing through the electromagnetic bandgap junction printed circuit board disclosed in the embodiment, and the obtained results are as shown in the figure The eye diagram shown in 10. At the same time, adopt the same layout and the same unit size for the transmission line passing through the power layer, and use the printed circuit board of the power layer with the linear electromagnetic bandgap unit structure as shown in Figure 3 to conduct signal integrity simulation experiments, and obtain the signal integrity as shown in Figure 11 Eye. Comparing the simulation results, it is found that the transmission line passes through the power layer and contains 9 electromagnetic bandgap units disclosed in the embodiment of the present invention, using a printed circuit board with a 3×3 arrangement of the power layer, where L _a = 5mm, L _b = 5mm, and its eye diagram The "eye" of is larger than the "eye" in the eye diagram of the printed circuit board using the linear electromagnetic bandgap unit structure shown in FIG. 11 . The specific performance is that its "eye width" and "eye height" are significantly larger. This shows that the use of the electromagnetic bandgap unit structure disclosed in the embodiment of the present invention can greatly improve the signal integrity.

A further comparison of the suppressed noise width and cut-off depth of printed circuit boards with two structures is shown in Figure 12. Using the electromagnetic bandgap unit disclosed in the embodiment of the present invention as the printed circuit board of the power layer, the suppressed noise frequency extends from about 1GHz to 10GHz, and the bandwidth is about 9GHz; the cut-off depth is increased to about -90dB, which is greatly improved.

By using a printed circuit board comprising an electromagnetic bandgap unit disclosed in Embodiment 1 of the present invention to form a power layer, the signal integrity has better quality; compared with the electromagnetic bandgap unit of the traditional linear channel, the present invention The electromagnetic bandgap unit disclosed in Embodiment 1 also has a good improvement on the noise suppression bandwidth and the cut-off depth index; the layout of the power layer is flexible, and by cutting the power layer channel reasonably, it is possible to avoid adding an additional power layer to the printed circuit board and save costs .

In particular, according to the embodiments of the present application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, the embodiments of the present application include a computer program product, which includes a computer program loaded on a computer-readable medium, where the computer program includes program codes for executing the methods shown in the flowcharts. In such an embodiment, the computer program may be downloaded and installed from a network through the communication means, or installed from a memory, or installed from a ROM. When the computer program is executed by the external processor, the above-mentioned functions defined in the methods of the embodiments of the present application are executed.

It should be noted that the computer-readable medium in the embodiments of the present application may be a computer-readable signal medium or a computer-readable storage medium, or any combination of the above two. A computer readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to, electrical connections with one or more wires, portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable Programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination of the above. In the embodiments of the present application, a computer-readable storage medium may be any tangible medium containing or storing a program, and the program may be used by or in combination with an instruction execution system, apparatus, or device. However, in the embodiments of the present application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, in which computer-readable program codes are carried. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the foregoing. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium, which can transmit, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device . The program code contained on the computer readable medium can be transmitted by any appropriate medium, including but not limited to: electric wire, optical cable, RF (Radio Frequency, radio frequency), etc., or any suitable combination of the above.

The above-mentioned computer-readable medium may be included in the above-mentioned server; or it may exist independently without being incorporated into the server. The above-mentioned computer-readable medium carries one or more programs, and when the above-mentioned one or more programs are executed by the server, the server: in response to detecting that the peripheral mode of the terminal is not activated, obtains the frame rate of the application on the terminal ; When the frame rate meets the off-screen condition, determine whether the user is obtaining the screen information of the terminal; in response to the determination result that the user has not obtained the screen information of the terminal, control the screen to enter the immediate dimming mode.

Computer program codes for performing the operations of the embodiments of the present application may be written in one or more programming languages or combinations thereof, including object-oriented programming languages—such as Java, Smalltalk, C++, including A conventional procedural programming language - such as the "C" language or a similar programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In cases involving a remote computer, the remote computer can be connected to the user computer through any kind of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (such as through an Internet service provider). Internet connection).

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and for related parts, please refer to the part of the description of the method embodiment. The systems and system embodiments described above are only illustrative, and the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is It can be located in one place, or it can be distributed to multiple network elements. Part or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. It can be understood and implemented by those skilled in the art without creative effort.

The technical solution provided by this application has been introduced in detail above, and specific examples have been used in this paper to illustrate the principle and implementation of this application. The description of the above embodiments is only used to help understand the method and core idea of this application; At the same time, for those skilled in the art, there will be changes in specific implementation methods and application scopes based on the idea of the present application. To sum up, the contents of this specification should not be understood as limiting the application.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. An electromagnetic bandgap unit, characterized in that, the unit is a square coplanar metal pattern whose side length is a preset side length, and the pattern includes: a square border with a first preset width; two diagonal lines with a second preset width; two vertical lines having a third predetermined width, passing through the center of the pattern, and perpendicular to the frame; A gap of a fourth preset width is provided in the middle of each side of the frame; wherein, the fourth preset width is greater than the third preset width, so that the two perpendicular lines extend to the electromagnetic strip edge of the gap unit. 2 . The electromagnetic bandgap unit according to claim 1 , wherein the pattern is a rotationally symmetric pattern with a rotation angle of 90 degrees. 3 . 3. A kind of electromagnetic bandgap unit according to claim 1 or 2, is characterized in that, described electromagnetic bandgap unit is used for being periodically arranged on the first surface of the medium layer of printed circuit board, forms described printed circuit The power layer of the board; Wherein, the printed circuit board at least includes: a power layer, a dielectric layer, and a ground layer; The dielectric layer also includes a second surface opposite to the first surface, and the second surface is adjacent to the ground layer. 4 . The electromagnetic bandgap unit according to claim 3 , wherein the electromagnetic bandgap unit is used to suppress noise signals transmitted from the power supply layer to the ground layer. 5. An electromagnetic bandgap printed circuit board, characterized in that the printed circuit board at least comprises: a power layer, a dielectric layer, and a ground layer; The dielectric layer includes: a first surface adjacent to the power supply layer, and a second surface opposite to the first surface, wherein the second surface is adjacent to the ground layer; The power supply layer is formed by periodically arranging several electromagnetic bandgap units according to any one of claims 1-4. 6 . The electromagnetic bandgap printed circuit board according to claim 5 , wherein the power supply layer is a metal layer having a thickness of the power supply layer. 7. A kind of electromagnetic bandgap printed circuit board according to claim 5 or 6, is characterized in that, described electromagnetic bandgap unit laterally adjacent has a first interval; The longitudinally adjacent electromagnetic bandgap units have a second interval; The first interval and the second interval are adjustable according to the plane size of the power supply layer. 8. A kind of electromagnetic bandgap printed circuit board according to claim 7, is characterized in that, described electromagnetic bandgap printed circuit board also comprises metal connection pattern; The width of the metal connection pattern is a third preset width; The thickness of the metal connection pattern is the thickness of the power layer; The metal connection pattern is used to connect the adjacent electromagnetic bandgap units through the center of the pattern, and a vertical line perpendicular to the frame, so that the adjacent electromagnetic bandgap units form an electrical connection. 9. A kind of electromagnetic bandgap printed circuit board according to any one of claim 5, characterized in that, the dielectric layer has a dielectric layer thickness; The material of the dielectric layer is FR4, and the relative permittivity is between 4.2-4.7. 10 . The electromagnetic bandgap printed circuit board according to claim 5 , wherein the ground layer is a complete metal plane with a thickness of the ground layer. 11 .

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