CN115250570A - Electromagnetic band gap unit and printed circuit board - Google Patents
Electromagnetic band gap unit and printed circuit board Download PDFInfo
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- CN115250570A CN115250570A CN202210862926.6A CN202210862926A CN115250570A CN 115250570 A CN115250570 A CN 115250570A CN 202210862926 A CN202210862926 A CN 202210862926A CN 115250570 A CN115250570 A CN 115250570A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
- H05K1/0236—Electromagnetic band-gap structures
Abstract
The invention relates to an electromagnetic band gap unit and a printed circuit board, and belongs to the technical field of digital electronic circuits. An electromagnetic bandgap cell is a square coplanar metal pattern having a side length of a predetermined length, the pattern comprising: a square frame having a first preset width; two diagonal lines with a second preset width; two perpendicular lines having a third preset 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 so as to pass through the center of the pattern, and two perpendicular lines perpendicular to the frame can extend to the edges of the electromagnetic bandgap unit. By adopting the printed circuit board with the power supply layer formed by the electromagnetic band gap units, the signal integrity is better, the noise bandwidth suppression and cut-off depth index are also well improved, and the design mode of the power supply layer is more flexible.
Description
Technical Field
The invention relates to the technical field of digital electronic circuits, in particular to an electromagnetic band gap unit and a printed circuit board.
Background
In high frequency digital circuits, signals are subject to interference from many factors during transmission, thereby affecting signal integrity. The signal transmission method is characterized in that the signal is interfered in the process of being transmitted from a transmitting end to a receiving end, and a distorted signal is received at the receiving end. Interference factors may include signal-to-timing problems, signal ringing, signal reflections, near-end and far-end crosstalk, switching noise, ground bounce and power bounce, attenuation, capacitive loading, electromagnetic radiation, battery interference, and the like, with noise interference being particularly acute. Reducing noise is the best way to maintain signal integrity.
In the process of developing a current electronic product to a high speed, a small volume and a low voltage, under the condition that the operation speed of a server chip for providing operation for a terminal is faster and faster, the influence of GBN (Ground Bounce Noise) on a system is more and more significant, and therefore, it becomes more and more important to suppress the GBN effect. A common method is to form a parallel plate waveguide with a Power Plane (Power Plane) and a complete Ground Plane (Ground Plane) using an Electromagnetic Band Gap (EBG) cell structure at the Power Plane of a printed circuit board. The electromagnetic band gap unit structure of the power plane is equal to a series LC parallel high-order band elimination filter, so that the effect of suppressing the grounding bounce noise is achieved.
The electromagnetic band gap unit structure is developed from a High Impedance Surface (HIS), and the HIS structure can effectively block Surface current and attenuate electromagnetic waves so that the electromagnetic waves are difficult to propagate. Initially, the HIS structure was mostly applied to antenna design. After study and popularization, HIS has wide application range. As shown in fig. 1, the original HIS structure is composed of a metal plate (Patch) connected to a ground plane through a Via (Via), and dielectric material filled between the metal plate and the ground plane to form a HIS unit structure. Fig. 2 shows an equivalent circuit model of the HIS structure shown in fig. 1, in which a capacitor C is connected in parallel with an inductor L, wherein the capacitor is equivalent between two metal sheets, and the metal sheets, the via post and the ground layer are equivalent to the inductor. As shown in the following formula:
when the equivalent circuit generates resonance, the equivalent circuit is equivalent to a high-resistance transmission path, so that the signal in the frequency band is difficult to propagate, and the resonance frequency as the center frequency of the cut-off frequency band is as follows:
the HIS structure is applied to the PCB, and the effect of noise suppression can also be achieved. The linear channel electromagnetic bandgap unit structure (as shown in fig. 3, and the equivalent circuit thereof is as shown in fig. 4) which is only cut on the power layer in a regular shape has a certain noise suppression effect. The design of the linear electromagnetic bandgap cell structure pursues the reduction of the bandwidth for suppressing noise and the manufacturing cost. The design consideration focuses on the following four aspects: the method comprises the following steps of (1) suppressing noise bandwidth, (2) center frequency, (3) cut-off depth and (4) signal integrity. The existing electromagnetic band gap unit structure has great improvement on noise suppression width, center frequency and cut-off depth; however, signal integrity is affected by the basic cell gap, which is increased and causes imperfections in the power plane due to the gap with the channel center body. Therefore, a new electromagnetic bandgap cell structure is needed, which is important to improve signal integrity without excessively sacrificing other indexes.
Disclosure of Invention
In order to improve the signal integrity design problem of the electromagnetic bandgap unit structure, embodiments of the present invention provide an electromagnetic bandgap unit and a printed circuit board, which improve the signal integrity on the basis of ensuring the suppression noise bandwidth, the center frequency, and the cut-off depth index of the electromagnetic bandgap.
In order to solve one or more of the above technical problems, the technical solution adopted by the present invention is as follows:
in a first aspect, an electromagnetic bandgap cell is provided, where the electromagnetic bandgap cell is a square coplanar metal pattern with a preset side length, and the pattern includes:
a square frame with a first preset width;
two diagonal lines having a second preset width;
two perpendicular lines which have a third preset width, pass through the center of the pattern and are perpendicular to the frame;
a gap with a fourth preset width is arranged in the middle of each side of the frame; and the fourth preset width is larger than the third preset width, so that the two vertical lines extend to the edge of the electromagnetic bandgap unit.
Further, the pattern is a rotationally symmetric pattern having a rotation angle of 90 degrees.
Furthermore, the electromagnetic band gap units are periodically arranged on the first surface of the dielectric layer of the printed circuit board to form a power supply layer of the printed circuit board;
wherein, printed circuit board includes at least: the power supply layer, the dielectric layer and the grounding layer;
the dielectric layer also includes a second surface opposite the first surface, the second surface being adjacent to the ground layer.
Further, the electromagnetic bandgap cell is used to suppress a noise signal transmitted from the power supply layer to the ground layer.
In a second aspect, an electromagnetic bandgap printed circuit board is provided, which is characterized by at least comprising: the power supply layer, the dielectric layer and the grounding layer;
the dielectric layer includes: a first surface adjacent to the power plane, and a second surface opposite to the first surface, wherein the second surface is adjacent to the ground plane;
the power supply layer is formed by periodically arranging a plurality of electromagnetic bandgap units as described in the first aspect.
Further, the power layer is a metal layer with the thickness of the power layer.
Further, laterally adjacent electromagnetic bandgap cells have a first spacing;
longitudinally adjacent electromagnetic bandgap cells have a second spacing;
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 further comprises a metal connection pattern;
the width of the metal connecting pattern is a third preset width;
the thickness of the metal connecting pattern is the thickness of the power supply layer;
the metal connecting pattern is used for connecting the centers of the passing patterns of the adjacent electromagnetic band gap units and is perpendicular to the frame, so that the adjacent electromagnetic band gap units are electrically connected.
Further, the dielectric layer has a dielectric layer thickness;
the dielectric layer is made of FR4, and the relative dielectric constant is 4.2-4.7.
Further, the ground layer is a complete metal plane with a ground layer thickness.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
1. by adopting the printed circuit board with the power supply layer composed of the electromagnetic band gap units disclosed by the embodiment of the invention, the signal integrity is better;
2. compared with the traditional electromagnetic band gap unit with a linear channel, the electromagnetic band gap unit disclosed by the embodiment of the invention has the advantages that the indexes of noise bandwidth suppression and cut-off depth are also well improved;
3. the power layer is flexibly arranged, and the additional power layer added on the printed circuit board can be avoided by reasonably cutting the power layer channel, so that the cost is saved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic diagram of a square metal sheet HIS structure;
FIG. 2 is a schematic diagram of an equivalent circuit of a square metal sheet HIS structure;
FIG. 3 is a schematic diagram of a linear channel electromagnetic bandgap cell structure;
FIG. 4 is an equivalent circuit schematic diagram of a linear channel electromagnetic bandgap cell;
FIG. 5 is a top view of an electromagnetic bandgap cell provided by an embodiment of the present invention;
FIG. 6 is a top view of an electromagnetic bandgap cell having preferred dimensions provided by an embodiment of the present invention;
FIG. 7 is a schematic diagram of a power plane of a printed circuit board composed of electromagnetic bandgap units arranged periodically according to an embodiment of the present invention;
FIG. 8 is a top view of a 3 × 3 arrangement of electromagnetic bandgap cells provided by an embodiment of the present invention;
FIG. 9 is a schematic diagram of an electromagnetic bandgap printed circuit board provided by an embodiment of the present invention;
FIG. 10 is a signal eye diagram of a transmission line passing through a printed circuit board with an electromagnetic bandgap cell structure provided by an embodiment of the present invention as a power plane cell;
FIG. 11 is a signal eye diagram of a transmission line passing through a printed circuit board with a straight electromagnetic bandgap cell structure as a power plane cell;
fig. 12 is a graph comparing the S21 parameters using two types of electromagnetic bandgap cells.
Detailed Description
To make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of examples of the present invention, and not all examples. 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.
Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. Also, the use of the terms "a," "an," or "the" and similar referents do not denote a limitation of quantity, but rather denote the presence of at least one. The reference numerals in the drawings in the specification merely indicate the distinction between the respective functional components or modules, and do not indicate the logical relationship between the components or modules. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used only to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed 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 given to constituent parts having substantially the same or similar structures and functions, and repeated description thereof will be omitted.
In order to improve the signal integrity design problem of the electromagnetic band gap unit structure, the embodiment of the invention discloses an electromagnetic band gap unit and a printed circuit board, which improve the signal integrity on the basis of ensuring the indexes of the electromagnetic band gap such as the suppression noise bandwidth, the center frequency and the cut-off depth.
In one embodiment, as shown in fig. 5, an electromagnetic bandgap cell 4 is a square coplanar metal pattern having a side length of a predetermined length a, the pattern comprising:
a square frame 41 having a first preset width a;
two diagonal lines 42 having a second preset width b;
two perpendicular lines 43 having a third preset width c, passing through the center of the pattern, and perpendicular to the frame;
a gap with a fourth preset width d is arranged 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 two perpendicular lines 43 extend to the edge of the electromagnetic bandgap unit 4.
Preferably, the preset side length a is set to be 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 fig. 6.
The pattern is a rotationally symmetric pattern having a rotation angle of 90 degrees.
The electromagnetic bandgap cells 4 are arranged periodically on the first surface 21 of the dielectric layer 2 of the printed circuit board, and constitute the power supply layer 1 of the printed circuit board, as shown in fig. 7.
Wherein, printed circuit board includes at least: power plane 1, dielectric layer 2, ground plane 3.
The dielectric layer 2 further comprises a second surface 22 opposite the first surface 21, the second surface 22 being adjacent to the ground layer 3.
The electromagnetic bandgap cell 4 serves to suppress a noise signal transmitted from the power supply layer to the ground layer.
In one embodiment, a power layer of a printed circuit board composed of 9 electromagnetic bandgap units arranged in a 3 × 3 manner is taken as an example, and fig. 8 shows a top view of the arrangement manner.
In another embodiment, as shown in fig. 9, an electromagnetic bandgap printed circuit board 5 includes at least: power plane 1, dielectric layer 2, ground plane 3.
The dielectric layer 2 includes: a first surface 21 adjacent to the power plane 1, and a second surface 22 opposite to the first surface 21, wherein the second surface 22 is adjacent to the ground plane 3;
the power layer 1 is formed by periodically arranging a plurality of electromagnetic bandgap units 4.
The power layer 1 is a metal layer having a power layer thickness, which is determined according to a thickness designed for the printed circuit board.
As shown in FIG. 8, laterally adjacent electromagnetic bandgap cells 4 have a first spacing L a ；
Longitudinally adjacent electromagnetic bandgap cells 4 have a second spacing L b ；
First interval L a The second interval L b The plane size of the power supply layer is adjustable.
First interval L a According to the length P of the long side of the power layer 1 A And (6) determining. So that the length P of the long side of the power layer 1 A At most M complete electromagnetic bandgap cells 4 can be accommodated, M being a natural number, and being obtained by the following formula:
second interval L b According to the length P of the wide side of the power layer 1 B And (6) determining. So that the length P of the wide side of the power layer 1 B At most N complete electromagnetic bandgap cells 4 can be accommodated, N being a natural number, and being obtained by the following formula:
the electromagnetic bandgap printed circuit board further comprises a metal connection pattern;
the width of the metal connecting pattern is a third preset width c;
the thickness of the metal connecting pattern is the thickness of the power supply layer;
the metal connecting pattern is used for connecting the centers of the passing patterns of the adjacent electromagnetic band gap units and is perpendicular to the frame, so that the adjacent electromagnetic band gap units are electrically connected.
As shown in fig. 9, the connected electromagnetic bandgap cells 4 are electrically connected by metal connection patterns 6, wherein the first metal connection patterns 61 have a length of a first interval L a The length of the second metal connection pattern 62 is the second interval L b . The connected electromagnetic bandgap cells 4 may be made equipotential by the metal connection pattern 6. The connection can be made by connecting all the electromagnetic bandgap cells 4 of the power layer 1 in sequence, and in this connection, the potential of the power layer 1 is a power voltage; alternatively, a part of the electromagnetic bandgap cells 4 in the power layer 1 may be electrically connected, and another part of the electromagnetic bandgap cells 4 in the power layer 1 may be electrically connected, but there is no electrical connection between the two parts. One part of the connected electromagnetic bandgap cells 4 is equipotential with one power supply, and similarly, the other part of the connected electromagnetic bandgap cells 4 is equipotential with the other power supply. The power planes connected in this manner can provide two or more power supply voltages through one power plane. The flexibility of the arrangement of the power supply layer is improved, and the effect of avoiding the addition of an additional power supply layer on the printed circuit board is achieved by reasonably cutting the channel of the power supply layerAnd the cost is saved.
The dielectric layer 2 has a dielectric layer thickness determined according to a designed thickness of the printed circuit board.
The dielectric layer is made of FR4, and the relative dielectric constant of the dielectric layer is between 4.2 and 4.7.
The ground layer 3 is a complete metal plane with a ground layer thickness determined according to the designed thickness of the printed circuit board.
In order to verify the improvement of the electromagnetic band gap unit structure disclosed by the embodiment of the invention on the signal integrity, a transmission line comprises 9 electromagnetic band gap units disclosed by the embodiment of the invention, and a 3 multiplied by 3 arrangement power supply layer 1, L is adopted a ＝5mm，L b A signal integrity simulation experiment was performed on a printed circuit board of =5mm to obtain an eye diagram as shown in fig. 10. Meanwhile, the transmission lines pass through the power supply layer and are arranged in the same way, the unit size is the same, the printed circuit board of the linear electromagnetic band gap unit power supply layer is adopted, a signal integrity simulation experiment is carried out, and an eye diagram shown in fig. 11 is obtained. The comparison simulation results show that the transmission line comprises 9 electromagnetic band gap units disclosed by the embodiment of the invention through the power supply layer, and the 'eyes' in the eye pattern of the printed circuit board arranged by 3 multiplied by 3 are larger than those of the printed circuit board adopting the linear electromagnetic band gap unit structure shown in fig. 11. Embodied as its "eye width" and "eye height" are significantly larger. This shows that the signal integrity is greatly improved by adopting the electromagnetic bandgap unit structure disclosed by the embodiment of the invention.
Further comparison of the noise suppression width and the cut-off depth of the printed circuit boards using the two structures is shown in fig. 12. The electromagnetic band gap unit disclosed by the embodiment of the invention is adopted as the printed circuit board of the power supply layer, the noise suppression frequency is about extended from 1GHz to 10GHz, and the bandwidth is about 9GHz; the cut-off depth is raised to about-90 dB, with a large magnitude improvement.
All the above-mentioned optional technical solutions can be combined arbitrarily to form the optional embodiments of the present invention, and are not described herein again.
Example one
One embodiment of the present invention is specifically described below in conjunction with fig. 5-7. As shown in fig. 5, an electromagnetic bandgap cell 4 is a square coplanar metal pattern having a side length of a predetermined length a, the pattern comprising:
a square frame 41 having a first preset width a;
two diagonal lines 42 having a second preset width b;
two perpendicular 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 perpendicular lines 43 perpendicular to the frame extend to the edge of the electromagnetic bandgap unit 4.
In one embodiment of this embodiment, 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 fig. 6.
The pattern is a rotationally symmetric pattern having a rotation angle of 90 degrees.
The electromagnetic bandgap cells 4 are arranged periodically on the first surface 21 of the dielectric layer 2 of the printed circuit board, and constitute the power supply layer 1 of the printed circuit board, as shown in fig. 7.
Wherein, printed circuit board includes at least: power plane 1, dielectric layer 2, ground plane 3.
The dielectric layer 2 further comprises a second surface 22 opposite the first surface 21, the second surface 22 being adjacent to the ground layer 3.
The electromagnetic bandgap cell 4 serves to suppress a noise signal transmitted from the power supply layer to the ground layer.
Fig. 8 shows a power layer 1 composed of 9 electromagnetic bandgap cells arranged in a 3 × 3 arrangement.
Laterally adjacent electromagnetic bandgap cells 4 have a first spacing L a =5mm, the longitudinally adjacent electromagnetic bandgap cells 4 having a second spacing L b ＝5mm。
Example two
An electromagnetic bandgap printed circuit board is described below in conjunction with fig. 9.
An electromagnetic bandgap printed circuit board 5 comprising at least: power plane 1, dielectric layer 2, ground plane 3.
The dielectric layer 2 includes: a first surface 21 adjacent to the power plane 1, and a second surface 22 opposite to the first surface 21, wherein the second surface 22 is adjacent to the ground plane 3;
the power layer 1 is formed by periodically arranging a plurality of electromagnetic band gap units 4.
The power layer 1 is a metal layer having a power layer thickness determined according to a thickness designed for the printed circuit board.
Fig. 8 shows a power supply layer 1 composed of 9 electromagnetic bandgap cells arranged in a 3 × 3 arrangement.
Laterally adjacent electromagnetic bandgap cells 4 have a first spacing L a =5mm, the longitudinally adjacent electromagnetic bandgap cells 4 having a second spacing L b ＝5mm。
The electromagnetic bandgap printed circuit board further comprises a metal connection pattern;
the width of the metal connecting pattern is a third preset width c;
the thickness of the metal connecting pattern is the thickness of the power supply layer;
the metal connecting pattern is used for connecting the centers of the passing patterns of the adjacent electromagnetic band gap units and is perpendicular to the frame, so that the adjacent electromagnetic band gap units are electrically connected.
As shown in fig. 9, the respective connected electromagnetic bandgap cells 4 are connected by a metal connection pattern 6, wherein the length of the first metal connection pattern 61 is the first interval L a The length of the second metal connection pattern 62 is the second interval L b . The connected electromagnetic bandgap cells 4 may be made equipotential by the metal connection pattern 6. The connection may be made by connecting all the electromagnetic bandgap cells 4 of the power supply layer 1 in sequence, in which case the potential of the power supply layer 1 is a power supply voltage.
In another embodiment of this embodiment, a part of the electromagnetic bandgap cells 4 in the power layer 1 are electrically connected, and another part of the electromagnetic bandgap cells 4 in the power layer 1 are electrically connected, but there is no electrical connection between the two parts. A part of connected electromagnetic band gap units 4 are equipotential with a power supply; similarly, the other part of the connected electromagnetic bandgap units 4 is equipotential to another power supply. The power planes connected in this manner can supply two or more power supply voltages through one power plane. Through reasonable cutting power layer passageway, improve the flexibility that the power layer was arranged, reach the effect of avoiding printed circuit board to increase extra power layer, practice thrift the cost.
The dielectric layer 2 has a dielectric layer thickness determined according to a thickness designed for the printed circuit board.
The dielectric layer is made of FR4, and the relative dielectric constant of the dielectric layer is between 4.2 and 4.7.
The ground layer 3 is a complete metal plane with a ground layer thickness determined according to the designed thickness of the printed circuit board.
In order to verify the improvement of the signal integrity of the electromagnetic bandgap structure printed circuit board disclosed in the second embodiment, a signal integrity simulation experiment is performed on the transmission line through the electromagnetic bandgap structure printed circuit board disclosed in the second embodiment, so as to obtain an eye diagram shown in fig. 10. Meanwhile, the transmission lines pass through the power supply layer and are arranged in the same way, the unit size is the same, the printed circuit board of the power supply layer with the linear type electromagnetic band gap unit structure shown in fig. 3 is adopted, a signal integrity simulation experiment is carried out, and an eye pattern shown in fig. 11 is obtained. The comparison simulation results show that the transmission line comprises 9 electromagnetic band gap units through the power supply layer, and adopts a printed circuit board with 3 multiplied by 3 arranged power supply layers, wherein L a ＝5mm，L b =5mm, the "eye" in the eye pattern is larger than that of the printed circuit board using the linear electromagnetic bandgap cell structure shown in fig. 11. Embodied as its "eye width" and "eye height" are significantly larger. This shows that the signal integrity is greatly improved by adopting the electromagnetic bandgap unit structure disclosed by the embodiment of the invention.
Further comparison of the noise suppression width and the cut-off depth of the printed circuit boards using the two structures is shown in fig. 12. The electromagnetic band gap unit disclosed by the embodiment of the invention is adopted as the printed circuit board of the power supply layer, the noise suppression frequency is extended from 1GHz to 10GHz approximately, and the bandwidth is about 9GHz; the cut-off depth is raised to about-90 dB, with a large magnitude improvement.
By adopting the printed circuit board with the power supply layer composed of the electromagnetic band gap units disclosed by the embodiment of the invention, the signal integrity is better; compared with the traditional electromagnetic band gap unit with a linear channel, the electromagnetic band gap unit disclosed by the embodiment of the invention has the advantages that the indexes of noise bandwidth suppression and cut-off depth are also well improved; the power layer is flexibly arranged, and the additional power layer added on the printed circuit board can be avoided by reasonably cutting the power layer channel, so that the cost is saved.
In particular, according to embodiments of the application, the processes described above with reference to the flow diagrams may be implemented as computer software programs. For example, embodiments of the present application include a computer program product comprising a computer program loaded on a computer readable medium, the computer program comprising program code for performing the method illustrated in the flow chart. In such an embodiment, the computer program may be downloaded and installed from a network via the communication means, or installed from the memory, or installed from the ROM. The computer program, when executed by an external processor, performs the above-described functions defined in the methods of embodiments of the present application.
It should be noted that the computer readable medium of the embodiments of the present application may be a computer readable signal medium or a computer readable storage medium or any combination of the two. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples of the computer readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In embodiments of the application, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In embodiments of the present application, however, a computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated data signal may take many forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may also be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to: electrical wires, optical cables, RF (Radio Frequency), etc., or any suitable combination of the foregoing.
The computer readable medium may be embodied in the server; or may exist separately and not be assembled into the server. The computer readable medium carries one or more programs which, when executed by the server, cause the server to: when the peripheral mode of the terminal is detected to be not activated, acquiring a frame rate of an application on the terminal; when the frame rate meets the screen-off condition, judging whether a user is acquiring screen information of the terminal; and controlling the screen to enter an immediate dimming mode in response to the judgment result that the user does not acquire the screen information of the terminal.
Computer program code for carrying out operations for embodiments of the present application may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. 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 the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, the system or system embodiments, which are substantially similar to the method embodiments, are described in a relatively simple manner, and reference may be made to some descriptions of the method embodiments for relevant points. The above-described system and system embodiments are only illustrative, wherein the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement without inventive effort.
The technical solutions provided by the present application are introduced in detail above, and specific examples are applied in the present application to explain the principles and embodiments of the present application, and the descriptions of the above examples are only used to help understanding the method and the core ideas of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, the specific embodiments and the application range may be changed. In view of the above, the description should not be taken as limiting the application.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.
Claims (10)
1. An electromagnetic bandgap cell, wherein the cell is a square coplanar metal pattern having a side length of a predetermined length, the pattern comprising:
a square frame having a first preset width;
two diagonal lines having a second preset width;
two perpendicular lines having a third preset width, passing through the center of the pattern, and perpendicular to the frame;
a gap with a fourth preset width is arranged in the middle of each side of the frame; the fourth preset width is greater than the third preset width, so that the two perpendicular lines extend to the edge of the electromagnetic bandgap unit.
2. An electromagnetic bandgap cell according to claim 1, wherein the pattern is a rotationally symmetric pattern with an angle of rotation of 90 degrees.
3. The electromagnetic bandgap cell according to claim 1 or 2, wherein the electromagnetic bandgap cell is arranged periodically on a first surface of a dielectric layer of a printed circuit board, and constitutes a power supply layer of the printed circuit board;
wherein the printed circuit board includes at least: the power supply layer, the dielectric layer and the grounding layer;
the dielectric layer also includes a second surface opposite the first surface, the second surface being adjacent to the ground layer.
4. An electromagnetic bandgap cell as claimed in claim 3, wherein the electromagnetic bandgap cell is configured to suppress noise signals transmitted from the power layer to the ground layer.
5. An electromagnetic bandgap printed circuit board, characterized in that the printed circuit board comprises at least: a power layer, a dielectric layer and a ground layer;
the dielectric layer includes: a first surface adjacent to the power plane, and a second surface opposite the first surface, wherein the second surface is adjacent to the ground plane;
the power layer is formed by periodically arranging a plurality of the electromagnetic bandgap units as claimed in any one of claims 1 to 4.
6. The electromagnetic bandgap printed circuit board of claim 5, wherein the power layer is a metal layer having a power layer thickness.
7. An electromagnetic bandgap printed circuit board according to claim 5 or 6, wherein laterally adjacent electromagnetic bandgap cells have a first spacing;
longitudinally adjacent electromagnetic bandgap cells have a second spacing;
the first interval and the second interval are adjustable according to the plane size of the power supply layer.
8. The electromagnetic bandgap printed circuit board according to claim 7, further comprising a metal connection pattern;
the width of the metal connecting pattern is a third preset width;
the thickness of the metal connecting pattern is the thickness of the power supply layer;
the metal connecting pattern is used for connecting the centers of the passing patterns of the adjacent electromagnetic band gap units and is perpendicular to the frame, so that the adjacent electromagnetic band gap units are electrically connected.
9. An electromagnetic bandgap printed circuit board according to claim 5, wherein the dielectric layer has a dielectric layer thickness;
the dielectric layer is made of FR4, and the relative dielectric constant is 4.2-4.7.
10. An electromagnetic bandgap printed circuit board according to claim 5, wherein the ground plane is a full metal plane having a ground layer thickness.
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| CN202210862926.6A CN115250570B (en) | 2022-07-20 | 2022-07-20 | Electromagnetic band gap unit and printed circuit board |
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| CN115250570B (en) | 2024-02-02 |
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