CN110225649B - A Novel Electromagnetic Bandgap Structure for Suppressing Synchronous Switching Noise - Google Patents

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

A Novel Electromagnetic Bandgap Structure for Suppressing Synchronous Switching Noise

technical field

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

Background technique

With the rapid development of microelectronics technology, modern electronic systems have higher and higher 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 power supply and ground can cause severe signaling and power integrity issues. Therefore, in mixed-signal systems, it is very necessary to suppress SSN propagation in the wide stopband associated with good signals. In recent years, many researchers have tried various methods to deal with the SSN problem. For example, increasing decoupling capacitance, selecting the number and position of vias, and adopting differential interconnection, etc., these methods can effectively suppress the propagation of SSN. However, these methods suffer from some inadequacies, either they cannot suppress high-frequency noise effectively, or they are too expensive to implement effectively.

Electromagnetic band-gap structure (EBG) is a periodic structure, which originated from the photonic band-gap structure, and is the earliest periodic structure used in the field of antennas. In recent years, due to the high impedance characteristics of the structure, electromagnetic waves cannot propagate in certain frequency bands, especially in suppressing SSN, which has great advantages, so the EBG structure has a wide range of application prospects in mixed-signal systems. At present, the commonly used planar EBG structure adopts the bandgap structure etched on the power plane to suppress the synchronous switching noise. Lower cutoff frequency, or UWB rejection cannot be achieved. The electromagnetic bandgap structure proposed by the invention can suppress the depth of -40dB while the suppression bandwidth range is 0.26GHz-25GHz, which can effectively reduce the lower cut-off frequency and realize the ultra-wideband for synchronous switching noise between the power plane and the ground plane. inhibition.

SUMMARY OF THE INVENTION

The purpose of the present invention is mainly to address the deficiencies of the prior art, and propose a novel electromagnetic bandgap structure, which can effectively reduce the lower cutoff frequency and increase the stopband bandwidth while achieving the required suppression effect on synchronous switching noise.

To achieve the above object, the present invention is realized according to the following technical solutions:

The invention provides a novel electromagnetic bandgap structure, which is a periodic structure, loaded on the upper surface of an insulating medium layer, and a ground plane is set on the lower surface of the insulating medium layer;

Each structural unit is a square structure and is etched on the power 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 the height of the right side wall, and a microstrip line is drawn from the midpoint of the bottom of the notch ; The microstrip line surrounds the power plane in the counterclockwise direction to the end of its next side, and the microstrip line is located in the "next side" part and is surrounded by the microstrip line drawn from the rectangular gap on this side; At the same time, the microstrip line is connected with the adjacent structural unit microstrip line to form an S-type microstrip line; the center of the microstrip line drawn from the above-mentioned four rectangular gaps is symmetrically arranged;

The central area of the power plane is hollowed out, and a small square plane board is embedded, and the four corners are respectively connected to the power plane through four L-shaped microstrip lines, and the four L-shaped microstrip lines are surrounded in a clockwise direction. and symmetrical about the center.

Further preferably, the size of the structural units of the electromagnetic bandgap structure is 30mm×30mm, and the units are connected to each other by S-type microstrip lines, forming a 3×3 periodic structure. Three ports are embedded in the electromagnetic bandgap structure, one of which is used as an input port, and the other two ports are used 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 between the S-shaped microstrip line in the rectangular notch and the inner wall s is 0.2mm, and the distance between the left side wall and the rectangular notch on the power plane is 0.2mm. The shortest distance d3 of the vertical side is 14.4mm, and the shortest distance d2 of the right side wall from the side vertical to the side of the rectangular notch on the power plane is 14mm.

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

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

The length d1 of the S-shaped microstrip line used to enclose adjacent S-shaped microstrip lines is 29.4 mm.

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

The square plane plate is a square with side length a4, a4=12.8mm.

The L-shaped microstrip line is used to connect the part of the square flat plate with a line width w2 of 0.2mm.

The L-shaped microstrip line is used to connect the power plane and the line width w3 is 0.2mm.

The L-shaped microstrip line is used to connect the power plane part and the gap width g2 between the square plane plate is 0.2mm.

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

Compared with the prior art, the present invention has the following outstanding substantive features:

The adjacent structural unit microstrip lines of the electromagnetic bandgap structure are connected to each other, thereby forming an S-shaped bridge structure, which increases the inductance of the bridge structure of the electromagnetic bandgap structure, thereby reducing the lower cut-off frequency of noise suppression, The S-shaped bridge structure suppresses the SSN noise in the stopband range and cannot propagate outward, thereby effectively increasing the bandwidth range of noise suppression and realizing ultra-wideband suppression of synchronous switching noise between the power plane and the ground plane. When the suppression depth of the present invention is -40dB, the suppression bandwidth range is 0.26GHz-25GHz.

Description of drawings

1 is a schematic diagram of the structure of the present invention from top to bottom;

Fig. 2 is the schematic diagram of the structural basic unit of the present invention;

Figure 3 is a schematic diagram of a large flat plate of the structural basic unit of the present invention;

Fig. 4 is the parameter labeling drawing of the structural basic unit of the present invention: (a) external parameter labeling drawing, (b) internal parameter labeling drawing;

Fig. 5 is the electromagnetic bandgap structure plan view of the present invention;

Fig. 6 is the noise suppression transmission coefficient diagram of each port of the present invention;

FIG. 7 is a comparison diagram of the noise suppression performance of the structure of the present invention and other typical electromagnetic bandgap structures.

Detailed ways

The present invention will be further described in detail below with reference to the specific embodiments of the accompanying drawings.

Figure 1 is a schematic diagram of the structure of the present invention. The top to bottom structures are power plane 1, insulating medium layer 2, and complete ground plane 3, wherein the novel electromagnetic bandgap structure is etched on the power plane.

Figure 2 is a schematic diagram of the basic unit of the structure of the present invention. The basic unit structure is that a vertical line groove is etched on each side of a power plane as shown in Figure 3, and a micro-groove is drawn from the midpoint of the bottom of the groove. Strip line, the microstrip line surrounds the power plane in the counterclockwise direction to the end of its next side; the central area of the power plane is a hollow area, and a small square plane board is embedded, and the four sides pass through four The L-shaped microstrip lines are connected to the power plane, and the four L-shaped microstrip lines surround clockwise and are symmetrical about the center.

Figures 4(a) and 4(b) are the external and internal parameter annotation diagrams, respectively, d1 represents the size of the basic unit structure of the electromagnetic bandgap, and a1 and a2 represent the shorter and shorter grooves on the large flat plate, respectively. The length of the long side, w1 represents the width of the microstrip line leading out of the groove, s represents the width of the groove on both sides of the microstrip line, d2, d3 represent the lengths of the shorter and longer sides of the groove on the large flat plate, c Represents the distance between two grooves on the same horizontal line, a4 represents the size of the small square flat plate, w3 represents the width of the L-shaped microstrip line, g2 represents the width of the grooves on both sides of the L-shaped microstrip line, and each parameter is obtained through optimization. values, as shown in Table 1.

Table 1 Values of each parameter

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

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

Figure 6 shows the noise suppression transmission coefficient diagram of each port of the present invention. When port 1 is used as the noise input port, the S-parameter diagram between the other two port positions and port 1 shows the electromagnetic bandgap structure. Noise suppression.

As shown in FIG. 7 , the structure of the present invention is compared with the traditional L-bridge electromagnetic bandgap structure and the traditional S-bridge electromagnetic bandgap structure with respect to the S21 parameter. When the noise suppression depth is -40dB, the electromagnetic bandgap structure of the present invention can suppress the synchronous switching noise in the frequency range of 0.26GHz-25GHz. It can be seen that the lower cutoff frequency of the electromagnetic bandgap structure of the present invention is obviously lower, And its noise suppression bandwidth is larger than that of the traditional L-bridge electromagnetic bandgap structure and the traditional S-bridge electromagnetic bandgap structure.

The present invention has been exemplarily described above in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods, as long as various insubstantial improvements made by the method concept and technical solutions of the present invention are adopted, or no improvement is made. It is within the protection scope of the present invention to directly apply the concepts and technical solutions of the present invention to other occasions.

Claims (1)

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.

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