Quadrangular meander-shaped broadband electromagnetic bandgap structure

Abstract

The application discloses a four-corner serpentine bridge broadband electromagnetic bandgap structure, which belongs to the field of circuit microwave technology. The structure is etched in the shape of a complementary open resonant ring in the center, and the inductance between the electromagnetic bandgap units is increased by a serpentine bridge structure between adjacent units, thereby effectively suppressing SSN in a low frequency band, having a relatively wide bandwidth, and being capable of effectively suppressing SSN in a stopband. The four edges of the EBG structure are etched into a rectangle, and adjacent elements are connected to form a bridge. Compared with a conventional L bridge structure, the surface current path can be increased by designing the serpentine structure, so as to increase the equivalent inductance and the equivalent capacitance. The gap between the resonant rings will generate a gap current and a resonant circuit, which can effectively reduce the lower cutoff frequency and improve the width of the stopband. With the standard of a suppression depth of 30 dB, the ultra-wide stopband of 23.8 GHz can be achieved, which is obviously superior to a conventional electromagnetic bandgap structure and can better suppress synchronous switching noise.

Description

TECHNICAL FIELD

[0001] The present application relates to a four-cornered serpentine bridge wideband electromagnetic bandgap structure, which belongs to the field of circuit microwave technology. BACKGROUND

[0002] In recent years, high impedance surfaces constructed by EBG structures have become a new method to suppress high frequency SSN (Simultaneous Switch Noise). EBG structures were first introduced by Yablonovitch and Jonh. Experts proposed mushroom-type EBG structures and coplanar EBG structures to suppress the propagation of power supply noise in high-density integrated system package circuits. Several common coplanar EBG structures include: uniplanar-compact EBG (UC-EBG) structure, L-bridge EBG structure, and alternating impedance EBG (AI-EBG) structure. Coplanar EBG structures have evolved into microstrip-interconnected EBG structures, zigzag coplanar EBG structures, etc. Coplanar EBG structures have the advantage of being manufactured using standard PCB technology, without the need for special design of vias and use of multiple metal layers, breaking through the design bottleneck of mushroom-type EBG structures that require punching and use of multiple metal layers.

[0003] With the continuous improvement of the function and component integration of integrated circuit (IC) system-in-package (SIP), electromagnetic coupling and parasitic phenomena in the interconnection network also grow rapidly, which accordingly exacerbates the noise problem in the power distribution network and signal path. Among them, with the rapid rise of signal along the rise rate, clock frequency and signal transmission rate, the synchronous switching noise in the power network is becoming more and more significant, which threatens the power supply quality and signal quality, and becomes the main problem faced by the design of SIP power integrity and signal integrity. SUMMARY

[0004] In order to solve the problems existing in the prior art, the present application provides a four-cornered serpentine bridge wideband electromagnetic bandgap structure, which aims to design a small-sized wideband electromagnetic bandgap structure to solve the power integrity problem caused by synchronous switching noise in system-in-package.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a four-corner serpentine bridge broadband electromagnetic bandgap structure, characterized in that: a complementary open resonant ring is set at the center of the device body, and four sets of serpentine bridge structures are set clockwise at the four corners of the device body. The serpentine bridge structure adopts a straight edge and a serpentine edge. The two ends of the straight edge of the serpentine bridge are a straight edge connection end and a straight edge extension end. The serpentine edge of the serpentine bridge adopts a concave-convex zigzag structure, and the two ends are a serpentine edge connection end and a serpentine edge free end.

[0006] The straight edge of the serpentine bridge is connected to the device body, and a gap between the straight edge of the serpentine bridge and the device body is provided; the straight edge protruding end is connected to the serpentine edge connecting end of the serpentine bridge; the serpentine bridge is located on the outside of the straight edge of the serpentine bridge in the next clockwise group of serpentine bridge structures.

[0007] Furthermore, the side length of the structure is L1=30 mm, the line width of the serpentine side of the serpentine bridge is L2=0.2 mm, the width of the concave-convex groove of the serpentine side of the serpentine bridge is L3=0.8 mm, the depth of the concave-convex groove of the serpentine side of the serpentine bridge is L4=1.425 mm, the distance from the concave edge of the groove to the straight edge of the serpentine bridge is L5=0.85 mm, the line width of the straight edge of the serpentine bridge is L6=0.525 mm, and the width of the gap between the straight edge body is L7=0.3 mm, L8=3.45 mm, and L9=0.3 mm.

[0008] The quadrangular serpentine bridge broadband electromagnetic bandgap structure array is constructed using the aforementioned quadrangular serpentine bridge broadband electromagnetic bandgap structure. The number of arrays in the length direction is at least 2, and the number of arrays in the width direction is at least 2.

[0009] Furthermore, the array employs a serpentine bridge between adjacent electromagnetic bandgap structures, where the serpentine edges of the serpentine sides are self-connected.

[0010] Furthermore, the array is interconnected by serpentine bridges with zigzag grooves and convex edges between adjacent electromagnetic bandgap structures.

[0011] The key point of the structure is that the L-bridge type snake bridge structure is etched at the four corners of the square patch, and the complementary split-ring resonator (CSRR) shape etching is performed at the center, the inductance between the electromagnetic bandgap units is increased by the snake bridge structure between the adjacent units, the SSN in the low frequency band is effectively suppressed, the bandwidth is relatively wide, and the SSN in the stop band can be effectively suppressed. On the basis of the L bridge structure, the snake structure is increased. The corresponding sizes are l1=30mm, l2=0.2mm, l3=0.8mm, l4=1.425mm, l5=0.85mm, l6=0.525mm, l7=0.3mm, l8=3.45mm, l9=0.3mm. The four sides of the EBG structure are etched into a rectangle, and the adjacent elements are connected to form a bridge.

[0012] The beneficial effects of the application are: compared with the conventional coplanar structure and the EBG structure proposed in other documents, the application performs complementary split-ring resonator (CSRR) shape etching at the center, increases the inductance between the electromagnetic bandgap units by the snake bridge structure between the adjacent units, effectively suppresses the SSN in the low frequency band, has a relatively wide bandwidth, and can effectively suppress the SSN in the stop band. The four sides of the EBG structure are etched into a rectangle, and the adjacent elements are connected to form a bridge. Compared with the traditional L bridge structure, the surface current path can be increased by designing such a snake structure, thereby increasing the equivalent inductance and equivalent capacitance. At the same time, CSRR is etched in the inner center of the unit structure. The gap between the resonant rings will generate a gap current and a resonant circuit, which can effectively reduce the lower cutoff frequency and improve the width of the stop band.

[0013] The electromagnetic suppression frequency range of the novel EBG structure of the application is greatly expanded, and when the suppression depth is-30dB, 2.7GHz-26.5GHz can be effectively covered, and the effective suppression of SSN in the high-density integrated system packaging circuit is realized. Compared with the reference board, when the suppression depth is-30dB, the stop band range of the traditional L bridge EBG structure is 0.38GHz to 7.5GHz in the 0-10GHz band. The stop band range of the EBG structure in the application is 2.7GHz to 26.5GHz, which is much larger than the traditional structure. Signal integrity is mainly measured by eye diagram, and the quality of eye diagram is measured by maximum eye height (MEO) and maximum eye width (MEW). Generally speaking, the larger the MEO and MEW, the better the eye diagram quality, and the better the time domain transmission characteristics of the signal line. In order to improve the quality of the received signal, a differential line pair is used to transmit the signal. The differential pair can reduce the coupling of the transmission line. Compared with the single-ended line, the MEO of the differential line output mode increases by 30.8%, and the MEW is almost unchanged, and the signal integrity problem is significantly improved.

[0014] A novel EBG structure is designed to solve the power integrity problem caused by simultaneous switching noise in high-density system-in-package. The structure is formed by a complementary split-ring resonator unit structure and a snake-shaped inter-unit bridge structure. Rectangular etching is used to reduce the effective capacitance of the patch, and the length-width ratio of the bridge is increased to increase the effective inductance of the patch. The proposed structure is modeled and simulated using electromagnetic full-wave simulation software HFSS. The simulation results show that, with a suppression depth of -30 dB as the standard, an ultra-wide bandgap of 23.8 GHz can be achieved, which is significantly better than the conventional EBG structure and can better suppress simultaneous switching noise. BRIEF DESCRIPTION OF DRAWINGS

[0015] The application will be further described below with reference to the drawings and examples.

[0016] Figure 1 is a novel EBG structure of the application.

[0017] Figure 2 is the insertion loss diagram of the novel EBG simulation, measurement and reference board.

[0018] Figure 3 is the simulation eye diagram of the reference board using single-ended signals.

[0019] Figure 4 is the simulation eye diagram of the EBG board using single-ended signals.

[0020] Figure 5 is the simulation eye diagram of the EBG board using differential signals.

[0021] Figure 6 is a novel 2*2 array EBG and simulation port schematic diagram.

[0022] Figure 7 is the EBG structure and measurement device.

[0023] Figure 8 is a single-ended and differential transmission line structure: the left side of the figure is a single-ended transmission line structure, and the right side is a differential transmission line structure.

[0024] In the figure: 1, device body, 2, complementary split-ring resonator, 3, snake-shaped bridge straight edge, 4, snake-shaped bridge serpentine edge, 4a, concave-convex zigzag groove, 4b, zigzag groove convex edge, 4c, zigzag groove concave edge, 5, straight edge connection end, 6, straight edge extension end, 7, straight edge body gap, 8, snake-shaped edge connection end, 9, snake-shaped edge free end. DETAILED DESCRIPTION

[0025] The key point of the new EBG structure is to etch the L-bridge-like snake bridge structure at the four corners of the square patch, and to etch the complementary split-ring resonator (CSRR) shape at the center. The inductance between the electromagnetic bandgap units is increased by the snake bridge structure between adjacent units, effectively suppressing the SSN in the low frequency band, having a relatively wide bandwidth, and effectively suppressing the SSN in the stop band. Figure 1 A new EBG structure is shown. The four-corner snake bridge wide-band electromagnetic bandgap structure is provided with a complementary split-ring resonator 2 at the center of the device body 1, and four groups of snake bridge structures are arranged in the clockwise direction on the four corners of the device body 1. The snake bridge structure adopts a snake bridge straight edge 3 and a snake bridge curved edge 4. The two ends of the snake bridge straight edge 3 are straight edge connection ends 5 and straight edge extension ends 6. The snake bridge curved edge 4 adopts a concave-convex polyline structure, and the two ends are curved edge connection ends 8 and curved edge free ends 9.

[0026] The straight edge connection end 5 of the snake bridge straight edge 3 is connected to the device body 1, and a straight edge body gap 7 is provided between the snake bridge straight edge 3 and the device body 1. The straight edge extension end 6 is connected to the curved edge connection end 8 of the snake bridge curved edge 4. The snake bridge curved edge 4 is arranged outside the snake bridge straight edge 3 in the next group of snake bridge structures in the clockwise direction.

[0027] In some embodiments, the four-corner snake bridge wide-band electromagnetic bandgap structure array is composed of the above-mentioned four-corner snake bridge wide-band electromagnetic bandgap structure. The number of arrays in the length direction of the array is at least 2, and the number of arrays in the width direction of the array is at least 2.

[0028] In some embodiments, the arrays are connected to each other by the curved edge connection ends 8 of the snake bridge curved edges 4 between adjacent electromagnetic bandgap structures.

[0029] In some embodiments, the arrays are connected to each other by the polyline groove convex edges 4b of the snake bridge curved edges 4 between adjacent electromagnetic bandgap structures.

[0030] On the basis of the L-bridge structure, a serpentine structure is added. The side length L1 of the structure is 30 mm, the line width L2 of the serpentine bridge is 0.2 mm, the width L3 of the concave-convex fold line groove of the serpentine bridge is 0.8 mm, the depth L4 of the concave-convex fold line groove of the serpentine bridge is 1.425 mm, the distance L5 from the concave edge of the fold line groove to the straight edge of the serpentine bridge is 0.85 mm, the line width L6 of the straight edge of the serpentine bridge is 0.525 mm, the width L7 of the gap between the straight edges is 0.3 mm, the diameter L8 of the internal complementary resonant ring is 3.45 mm, and the ring width L9 is 0.3 mm. The four sides of the EBG structure are etched into a rectangle, and adjacent elements are connected to form a bridge. Compared with the traditional L-bridge structure, the surface current path can be increased by designing such a serpentine structure, thereby increasing the equivalent inductance and equivalent capacitance. At the same time, a CSRR is etched in the center of the unit structure. The gap between the resonant rings will generate a gap current and produce a resonant circuit, which can also reduce the lower cutoff frequency and improve the width of the stopband.

[0031] Compared with the conventional coplanar structure and the EBG structure proposed in other documents, the electromagnetic suppression frequency band range of the novel EBG structure in the application is greatly expanded, and when the suppression depth is-30 dB, 2.7 GHz-26.5 GHz can be effectively covered, and the effective suppression of SSN in the high-density integrated system packaging circuit is realized. The application can effectively suppress the SSN in the high-density integrated system packaging circuit by Figure 7 The S21 is measured by a vector network analyzer (Agilent N5252APNA-X), and the results are shown in Figure 2 . Figure 2 The insertion loss of the novel EBG simulation, measurement and reference board is shown. Compared with the reference board, when the suppression depth is-30 dB, the stopband range of the traditional L-bridge EBG structure is 0.38 GHz to 7.5 GHz in the 0-10 GHz band. The stopband range of the novel EBG structure is 2.7 GHz to 26.5 GHz, which is much larger than that of the traditional structure. As shown in Figure 2 , the measurement results are basically consistent with the simulation results. Due to the experimental conditions cannot completely restore the simulation conditions, the small error between the simulation results and the measurement results is acceptable. The signal integrity is mainly measured by the eye diagram, and the quality of the eye diagram is measured by the maximum eye height (MEO) and the maximum eye width (MEW). Generally speaking, the larger the MEO and MEW, the better the eye diagram quality, and the better the time domain transmission characteristics of the signal line. The eye diagram simulation results of the complete power plane with a single-ended transmission signal and the power ground plane etched with the EBG structure are as follows: Figure 3 The MEO of the complete power plane with a single-ended transmission signal is 794 mV, and the MEW value is 285.3 ps. Figure 4The eye diagram of signal integrity in the new EBG power plane using single-ended line to transmit signal is shown, the MEO value is 652 mV, and the MEW value is 280 ps. In order to improve the quality of the received signal, the signal is transmitted using a differential line pair. The differential pair can reduce the coupling of the transmission line. Figure 5 The eye diagram of signal integrity in the new EBG power plane using a differential line pair is shown, the MEO value is 853 mV, and the MEW value is 279.4 ps. Compared with single-ended line, the MEO of differential line output mode increases by 30.8%, the MEW is almost unchanged, and the signal integrity problem is significantly improved.

[0032] Figure 6 The schematic diagram of the new 2*2 array EBG and the simulation port, that is, the transmission coefficient S21 between port 1 and port 2. The transmission coefficient S21 between port 1 and port 2 is shown in the following figure. Figure 5 The upper left corner of the board structure is taken as the coordinate origin, two lumped ports are set, port 1 (15 mm, 15 mm) is set as the input port, and port 2 (45 mm, 45 mm) is set as the output port. The insertion loss, that is, the transmission coefficient S21 between port 1 and port 2, is obtained by simulation. Figure 8 The single-ended and differential transmission line structures are used, and four-layer PCB (signal layer, power layer, ground layer, signal layer) is used to study the signal integrity performance. The view of the four-layer board is shown in the following figure. Figure 8 The 1 mm thick FR4 dielectric layer material is used between the boards, and the characteristic impedance of the signal transmission line is 50 Ω. The signal line passes through the via hole from the top layer to the bottom layer, and returns to the top layer through the signal trace of the bottom layer and the second via hole, so as to experiment the signal integrity of the new EBG structure.

Claims

1. A quadrangular meandered bridge broad band electromagnetic bandgap structure, characterized in that: Complementary open resonant ring (2) is arranged at the center of device body (1), four groups of serpentine bridge structures are arranged clockwise on the four corners of device body (1), the serpentine bridge structure adopts serpentine bridge straight edge (3) and serpentine bridge serpentine edge (4), the two ends of serpentine bridge straight edge (3) are straight edge connecting end (5) and straight edge extending end (6), serpentine bridge serpentine edge (4) adopts concave-convex polyline structure, and the two ends are serpentine edge connecting end (8) and serpentine edge free end (9); The straight edge connecting end (5) of the serpentine bridge straight edge (3) is connected with the device body (1), and the straight edge body gap (7) is arranged between the serpentine bridge straight edge (3) and the device body (1); the straight edge extending end (6) is connected with the serpentine edge connecting end (8) of the serpentine bridge serpentine edge (4); the serpentine bridge serpentine edge (4) is arranged outside the serpentine bridge straight edge (3) in the next group of serpentine bridge structures clockwise.

2. The quad-angelform meanderline EBG structure of claim 1, wherein: The length L1 of the structure is 30mm, the line width L2 of the serpentine bridge serpentine edge is 0.2mm, the width L3 of the serpentine bridge serpentine edge concave-convex polyline groove is 0.8mm, the depth L4 of the serpentine bridge serpentine edge concave-convex polyline groove is 1.425mm, the distance L5 from the concave edge of the serpentine bridge serpentine edge polyline groove to the serpentine bridge straight edge is 0.85mm, the line width L6 of the serpentine bridge straight edge is 0.525mm, the width L7 of the straight edge body gap is 0.3mm, the diameter L8 of the internal complementary resonant ring is 3.45mm, and the ring width L9 is 0.3mm.

3. An array of quad- serpentine bridge wide band electromagnetic bandgap structures, characterized by: The four-corner serpentine bridge wide-band electromagnetic bandgap structure of claim 1 or 2 is used to form an array, and the number of arrays in the length direction of the array is at least 2, and the number of arrays in the width direction of the array is at least 2.

4. The array of quad-angelform meanderline EBG structures of claim 3, wherein: The polyline groove convex edges (4b) of the serpentine bridge serpentine edges (4) between adjacent electromagnetic bandgap structures are connected to each other.

5. The array of quad-angelform meanderline EBG structures of claim 4, wherein: The polyline groove convex edges (4b) of the serpentine bridge serpentine edges (4) between adjacent electromagnetic bandgap structures are connected to each other.

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