CN110225649B

CN110225649B - Novel electromagnetic band gap structure for suppressing synchronous switch noise

Info

Publication number: CN110225649B
Application number: CN201910414536.0A
Authority: CN
Inventors: 赵文生; 张园园; 王高峰
Original assignee: Hangzhou Dianzi University
Current assignee: Hefei Minglong Electronic Technology Co ltd
Priority date: 2019-05-17
Filing date: 2019-05-17
Publication date: 2020-12-15
Anticipated expiration: 2039-05-17
Also published as: CN110225649A

Abstract

The invention discloses a novel electromagnetic band gap structure for inhibiting synchronous switching noise. The invention is etched on a power plane, each unit structure is connected through an S-shaped microstrip line, and an L-shaped microstrip line is arranged in each unit structure. The S-shaped bridge structure increases the inductance of the bridge structure of the electromagnetic band gap structure, so that the lower cut-off frequency of noise suppression is reduced, SSN noise is suppressed in a stop band range by the S-shaped bridge structure and cannot be transmitted outwards, the bandwidth range of noise suppression is effectively enlarged, and ultra-wideband suppression of synchronous switching noise between a power plane and a ground plane is realized. When the suppression depth is-40 dB, the suppression bandwidth range is 0.26GHz-25 GHz.

Description

Novel electromagnetic band gap structure for suppressing synchronous switch noise

Technical Field

The invention relates to a power distribution network with miniaturized electromagnetic band gap structure units, in particular to a novel electromagnetic band gap structure for suppressing synchronous switching noise.

Background

With the rapid development of microelectronic technology, modern electronic systems have increasingly high requirements for high performance, miniaturization, high integration and versatility. However, asynchronous switching of high speed digital circuits can cause Synchronous Switching Noise (SSN), especially when the edge rate is uniform, the operating frequency is high, and the supply voltage is low, the SSN between the supply and ground can cause serious signal and supply integrity problems. Therefore, in mixed signal systems, it is essential to suppress the propagation of SSNs within the wide stop band associated with good signals. In recent years, many researchers have attempted various methods to deal with the SSN problem. Such as increasing decoupling capacitance, selecting the number and location of vias, and using differential interconnects, these methods can effectively suppress the propagation of SSN. However, these methods have some disadvantages, either high frequency noise cannot be effectively suppressed or they are too costly to be effectively implemented.

An electromagnetic band-gap structure (EBG) is a periodic structure that originates from a photonic band gap structure and is the earliest used periodic structure in the antenna field. In recent years, due to the high impedance characteristic of the structure, electromagnetic waves cannot be transmitted in certain frequency bands, and particularly the EBG structure has great advantages in SSN suppression, so that the EBG structure has wide application prospects in mixed signal systems. The existing common plane type EBG structure is to use a band gap structure etched on a power plane to suppress synchronous switching noise, but the existing electromagnetic band gap structure cannot reduce the low cut-off frequency or realize ultra-wideband suppression while achieving the desired suppression depth for noise. The electromagnetic band gap structure provided by the invention can inhibit the depth to-40 dB, and meanwhile, the range of the inhibition bandwidth is 0.26GHz-25GHz, so that the lower cut-off frequency can be effectively reduced, and the ultra-wideband inhibition of the synchronous switching noise between the power plane and the ground plane is realized.

Disclosure of Invention

The invention aims to provide a novel electromagnetic band gap structure aiming at the defects of the prior art, which can effectively reduce the lower cut-off frequency and improve the stop band bandwidth while achieving the required suppression effect on the synchronous switching noise.

In order to achieve the purpose, the invention is realized according to the following technical scheme:

the invention provides a novel electromagnetic band gap structure which is a periodic structure and is loaded on the upper surface of an insulating medium layer, and the lower surface of the insulating medium layer is provided with a ground plane;

each structural unit is of a square structure and etched on a power supply plane; each side of the power plane is etched with a rectangular notch, the height of the left side wall of the rectangular notch is less than that of the right side wall, and a microstrip line is led out from the midpoint of the bottom of the notch; the microstrip line surrounds the power plane to the tail end of the next edge along the anticlockwise direction, and the part of the microstrip line positioned on the next edge enables the microstrip line led out from the rectangular gap on the edge to be positioned on the edge and is surrounded; meanwhile, the microstrip line is connected with the microstrip line of the adjacent structural unit to form an S-shaped microstrip line; the microstrip lines led out from the four rectangular gaps are arranged in a central symmetry manner;

the central area of the power plane is hollow, a small square plane plate is embedded in the power plane, four corners of the power plane are connected with the power plane through four L-shaped microstrip lines respectively, and the four L-shaped microstrip lines are clockwise surrounded and are symmetrical about the center.

More preferably, the structural units of the electromagnetic band gap structure have a size of 30mm × 30mm, and the units are connected with each other through S-shaped microstrip lines to form a3 × 3 periodic structure. 3 ports are embedded in the electromagnetic band gap structure, wherein one port serves as an input port, and the other 2 ports serve as output ports.

Further preferably, the height a1 of the left side wall of the rectangular notch is 4mm, the height a2 of the right side wall is 4.4mm, the distance from the S-shaped microstrip line in the rectangular notch to the inner wall S is 0.2mm, the closest distance d3 of the left side wall to the side perpendicular to the side where the rectangular notch is located on the power plane is 14.4mm, and the closest distance d2 of the right side wall to the side perpendicular to the side where the rectangular notch is located on the power plane is 14 mm.

The line width w1 of the S-shaped microstrip line in the rectangular gap and the part enclosed by the adjacent S-shaped microstrip lines is 0.2mm, and the line width g1 of the rest part is 0.1 mm.

The closest distance c of the rectangular notches on the two opposite sides of the structural unit is 20.6 mm.

The length d1 of the S-shaped microstrip line used for enclosing the adjacent S-shaped microstrip line part is 29.4 mm.

The central hollow area of the power plane is a square with a side length of a3, and a3 is 14.4 mm.

The square plane board is a square with a side length of a4, and a4 is 12.8 mm.

The line width w2 of the L-shaped microstrip line for connecting the square plane board part is 0.2 mm.

The L-shaped microstrip line is used for connecting the power plane part, and the line width w3 is 0.2 mm.

The width g2 of the gap between the L-shaped microstrip line and the square planar plate for connecting the power plane part and the square planar plate is 0.2 mm.

The electromagnetic band gap structure is etched on a power plane, and the ground is a complete plane, so that synchronous switching noise between the power plane and a ground plane is suppressed. The insulating medium layer is made of FR-4 material and is made of lossy medium material, the relative dielectric constant of the insulating medium layer is 4.4, the medium thickness is 0.4mm, and the loss tangent value is 0.02. The ground plane is a complete plane, and signal integrity is not affected.

Compared with the prior art, the invention has the following prominent substantive characteristics:

the adjacent structural units of the electromagnetic band gap structure are connected with each other to form an S-shaped bridge structure, so that the inductance of the bridge structure of the electromagnetic band gap structure is increased, the lower cut-off frequency of noise suppression is reduced, SSN noise is suppressed by the S-shaped bridge structure within the stop band range and cannot be transmitted outwards, the bandwidth range of the noise suppression is effectively enlarged, and ultra-wideband suppression of synchronous switching noise between a power plane and a ground plane is realized. When the suppression depth is-40 dB, the suppression bandwidth range is 0.26GHz-25 GHz.

Drawings

FIG. 1 is a schematic top-to-bottom view of the inventive structure;

FIG. 2 is a schematic diagram of the structural elements of the present invention;

FIG. 3 is a schematic view of a large flat panel of the structural base unit of the present invention;

FIG. 4 is a parameter labeling diagram of the basic unit of the structure of the present invention: (a) an external parameter label graph and (b) an internal parameter label graph;

FIG. 5 is a plan view of an electromagnetic bandgap structure of the present invention;

FIG. 6 is a graph of noise suppression transmission coefficients for each port of the present invention;

fig. 7 is a graph comparing the noise suppression performance of the inventive structure with other typical electromagnetic bandgap structures.

Detailed Description

The present invention will be described in further detail below with reference to specific embodiments thereof.

Fig. 1 is a schematic structural diagram of the present invention, which includes a power plane 1, an insulating medium layer 2, and a complete ground plane 3 from a top layer to a bottom layer, wherein the novel electromagnetic bandgap structure is etched on the power plane.

Fig. 2 is a schematic diagram of a basic unit of the structure of the present invention, wherein the basic unit structure is that a vertical line groove is etched on each side of a power plane shown in fig. 3, and a microstrip line is led out from the midpoint of the bottom of the groove, and the microstrip line surrounds the power plane to the end of the next side along the counterclockwise direction; the central area of the power plane is a hollow area, a small square plane plate is embedded in the hollow area, four sides of the hollow area are connected with the power plane through four L-shaped microstrip lines respectively, and the four L-shaped microstrip lines surround the power plane clockwise and are symmetrical about the center.

Fig. 4(a) and fig. 4(b) are labeled diagrams of external and internal parameters, respectively, d1 represents the size of the basic unit structure of the electromagnetic bandgap, where a1 and a2 represent the lengths of the shorter and longer sides of the groove on the large planar board, respectively, w1 represents the width of the groove-led microstrip line, s represents the width of the groove on both sides of the microstrip line, d2 and d3 represent the lengths of the shorter and longer sides of the groove on the large planar board, c represents the distance between the two grooves on the same horizontal line, a4 represents the size of the square planar board, w3 represents the width of the L-shaped microstrip line, and g2 represents the width of the groove on both sides of the L-shaped microstrip line, and the values of the parameters are obtained by optimization, as shown in table 1.

TABLE 1 values of the parameters

Parameter(s)	d₁	d2	d3	c	a1
						Numerical value (mm)	29.4	14	14.4	20.6	4
Parameter(s)	a2	a3	a4	s	w1
						Numerical value (mm)	4.4	14.4	12.8	0.2	0.2
Parameter(s)	w2	w3	g1	g2
						Numerical value (mm)	0.2	0.2	0.1	0.2

Fig. 5 is a schematic diagram showing the electromagnetic bandgap structure of the present invention, wherein the overall size is 90mm long × 90mm wide, and the 9 structural units are distributed in 3 rows × 3 columns. 3 ports as shown in FIG. 5 are embedded in the electromagnetic bandgap structure, wherein port 1(-30mm ) is used as an input port, and port 2(30mm ) and port 3(30mm, 0mm) are used as output ports.

As shown in fig. 6, which is a graph of noise suppression transmission coefficients of each port of the present invention, when port 1 is used as a noise input port, the S-parameter graph between the remaining 2 port positions and port 1 can see the noise suppression effect of the electromagnetic bandgap structure.

FIG. 7 is a graph comparing the structure of the present invention with a conventional L-bridge electromagnetic bandgap structure and a conventional S-bridge electromagnetic bandgap structure with respect to S21 parameters. When the suppression depth of the noise is-40 dB, the electromagnetic band gap structure can suppress the synchronous switching noise within the frequency range of 0.26GHz-25GHz, and the lower cut-off frequency of the electromagnetic band gap structure is obviously lower, and the noise suppression bandwidth range of the electromagnetic band gap structure is larger than the bandwidth ranges of the traditional L-bridge electromagnetic band gap structure and the traditional S-bridge electromagnetic band gap structure.

The invention has been described above with reference to the accompanying drawings, it is obvious that the invention is not limited to the specific implementation in the above-described manner, and it is within the scope of the invention to apply the inventive concept and solution to other applications without substantial modification, or with substantial modification.

Claims

1. An electromagnetic band gap structure for suppressing synchronous switching noise is a periodic structure and is composed of a plurality of structural units; the load is on the upper layer of the insulating medium layer, and the lower layer of the insulating medium layer is provided with a ground plane; the power supply is characterized in that each structural unit is of a square structure and etched on a power supply plane; each side of the power plane is etched with a rectangular notch, the height of the left side wall of the rectangular notch is less than that of the right side wall, and a microstrip line is led out from the midpoint of the bottom of the notch; the microstrip line surrounds the power plane to the tail end of the next edge along the anticlockwise direction, and the part of the microstrip line positioned on the next edge enables the microstrip line led out from the rectangular gap on the edge to be positioned on the edge and is surrounded; meanwhile, the microstrip line is connected with the microstrip line of the adjacent structural unit to form an S-shaped microstrip line;

the central area of the power plane is hollow, a square plane plate is embedded in the power plane, four corners of the power plane are respectively connected with the power plane through four L-shaped microstrip lines, and the four L-shaped microstrip lines surround clockwise and are symmetrical about the center;

the structural unit size of the electromagnetic band gap structure is

The units are connected with each other through an S-shaped microstrip line to form a structure 3

The periodic structure of (a);

3 ports are embedded in the electromagnetic band gap structure, wherein one port serves as an input port, and the other 2 ports serve as output ports;

the height a1 of the left side wall of the rectangular notch is 4mm, the height a2 of the right side wall is 4.4mm, the distance from the S-shaped microstrip line in the rectangular notch to the inner wall S is 0.2mm, the closest distance d3 from the left side wall to the side, perpendicular to the side where the rectangular notch is located, of the power plane is 14.4mm, and the closest distance d2 from the right side wall to the side, perpendicular to the side where the rectangular notch is located, of the power plane is 14 mm;

the line width w1 of the S-shaped microstrip line in the rectangular gap and the part enclosed by the adjacent S-shaped microstrip lines is 0.2mm, and the line width g1 of the rest part is 0.1 mm;

the nearest distance c of the rectangular gaps on the two opposite sides of the structural unit is 20.6 mm;

the length d1 of the S-shaped microstrip line used for enclosing the adjacent S-shaped microstrip line part is 29.4 mm;

the central blank area of the power plane is a square with the side length a3 of 14.4 mm;

the square plane board is a square with the side length a4 of 12.8 mm;

the L-shaped microstrip line is used for connecting the square plane board, and the line width w2 of the square plane board is 0.2 mm;

the L-shaped microstrip line is used for connecting the power plane part, and the line width w3 is 0.2 mm;

the L-shaped microstrip line is used for connecting the gap width g2 between the power supply plane part and the square plane plate to be 0.2 mm;

the insulating medium layer is made of FR-4 material and is made of lossy medium material, the relative dielectric constant of the insulating medium layer is 4.4, the medium thickness is 0.4mm, and the loss tangent value is 0.02;

the electromagnetic band gap structure is etched on a power plane, and the ground is a complete plane, so that synchronous switching noise between the power plane and a ground plane is suppressed.