Power supply noise suppression structure based on electromagnetic band gap structure and filtering method thereof

Abstract

The invention discloses a power supply noise suppression structure based on an electromagnetic band gap structure and a filtering method thereof, the power supply noise suppression structure is formed by a plurality of electromagnetic band gap structure units through a preset periodic arrangement structure, and the plurality of electromagnetic band gap structure units comprise power lines, decoupling capacitors and through holes. The method comprises the steps of determining an upper limit cut-off frequency and a lower limit cut-off frequency of the power supply noise filter; determining structure parameters and device parameters of the power supply noise filter and the number of periodic units of the electromagnetic band gap structure; determining a periodic unit arrangement mode of the power supply noise filter by combining an actual application area; determining equivalent circuit parameters; and performing equivalent circuit simulation, determining parameters of a power supply noise filter according to a simulation result, and realizing power supply noise filtering of the target chip. According to the embodiment of the invention, the upper limit cut-off frequency and the lower limit cut-off frequency of the power supply noise stop band can be expanded, and a large-area circuit board does not need to be occupied. The method can be widely applied to the technical field of power distribution network design.

Description

Technical Field

[0001] The present application relates to the technical field of power distribution network design, and in particular to a power noise suppression structure based on an electromagnetic bandgap structure and a filtering method thereof. Background Art

[0002] The power distribution network is the largest interconnected network on the printed circuit board. Its function is to transmit a stable and clean power supply voltage to the integrated circuit power pads on the circuit board. The noise on the power distribution network may come from the coupling noise of the digital signal lines before and after the voltage regulation module, the resonator formed by the power ground plane pair, or other electromagnetic interference sources. These power supply noises are distributed in the frequency range of 10 MHz to 10 GHz, which may affect all integrated circuits on the same power rail, especially reducing the performance of noise-sensitive circuits such as low-noise amplifiers, phase-locked loop circuits, and precision voltage reference sources. Modern wired communications are developing towards high speed, high integration, and low power consumption, and therefore have more serious power supply noise problems. The design of the power distribution network of the circuit system needs to pay more attention to the problem of power supply noise suppression. The power supply noise suppression solution needs to cover a wider frequency band, while having lower cost and smaller size.

[0003] A related method is to place decoupling capacitors near the power pins of the integrated circuit to bypass the power noise to the ground plane. This power noise suppression scheme has a limited effective decoupling frequency range and cannot suppress high-frequency power noise above hundreds of megahertz. In order to further reduce the equivalent series inductance and improve the suppression effect of high-frequency power noise, some new capacitor structures have been proposed, such as length-width reversal capacitors and three-terminal capacitors. For example, the use of through-hole capacitors instead of two-terminal capacitors reduces the equivalent series inductance and equivalent series resistance, and realizes power noise filtering. However, its technology is not yet mature or costly, so it cannot be manufactured and used on a large scale. Therefore, a power noise filtering method based on decoupling capacitors needs to be designed to meet the power noise suppression needs of modern high-speed circuit systems.

[0004] In order to meet the demand for low power supply noise and the high-speed requirements of modern wired communications, other widely used power supply noise suppression solutions include adding etched grooves and electromagnetic bandgap structures on the power or ground planes. Among them, the electromagnetic bandgap structure shows a strong noise suppression effect and has an ultra-wide power supply noise stopband covering the gigahertz range. The limitations of these power supply noise suppression solutions are that they are all based on planar power supply noise suppression structures, which require a large area of ​​PCB board material and even require additional metal layers, resulting in higher costs and affecting the device layout and wiring on the PCB.

[0005] In summary, the technical problems existing in the relevant technologies need to be improved. Summary of the invention

[0006] The main purpose of the embodiments of the present application is to propose a power supply noise suppression structure based on an electromagnetic bandgap structure and a filtering method thereof, which can extend the upper cutoff frequency and the lower cutoff frequency of the power supply noise stopband and does not require occupying a large area of ​​the circuit board.

[0007] To achieve the above-mentioned purpose, an embodiment of the present application proposes a power supply noise suppression structure based on an electromagnetic bandgap structure, wherein the power supply noise suppression structure is composed of a plurality of electromagnetic bandgap structures through a preset periodic arrangement structure, wherein the plurality of electromagnetic bandgap structures include a power line, a decoupling capacitor and a through hole, wherein a first end of the decoupling capacitor is connected to the power line, and a second end of the decoupling capacitor and one end of the through hole are grounded, wherein: The other end of the power line is connected to the power modulation module and the power supply integrated circuit pin pad, and the power line is used to adjust the bandwidth upper limit cutoff frequency of the power supply noise stop band; The decoupling capacitor is used to adjust the lower cutoff frequency of the power supply noise stopband; The other end of the through hole is grounded.

[0008] In some embodiments, the preset periodic arrangement structure includes a straight line structure and a folded structure, wherein the straight line structure represents that the two ends of the power lines in several of the electromagnetic band gap structures are cascaded in sequence, and the folded structure represents that the power lines in several of the electromagnetic band gap structures are folded into a serpentine shape and then cascaded in sequence, and the decoupling capacitors are welded on the same side of the power lines.

[0009] In some embodiments, for the straight line structure, the equivalent circuit of the electromagnetic bandgap structure includes a first inductor, a second inductor, a first equivalent capacitor, a second equivalent capacitor, a third inductor and a fourth inductor, wherein the power line is represented by the first inductor, the second inductor and the first equivalent capacitor, the decoupling capacitor is represented by the second equivalent capacitor and the third inductor, and the through hole is represented by the fourth inductor.

[0010] In some embodiments, the second end of the first inductor, the first end of the second inductor, the first end of the first equivalent capacitor and the first end of the second equivalent capacitor are connected, the second end of the second equivalent capacitor is connected to the first end of the third inductor, the second end of the third inductor is connected to the first end of the fourth inductor, and the second end of the first equivalent capacitor is connected to the second end of the fourth inductor and grounded.

[0011] In some embodiments, for the folded structure, the equivalent circuit of the electromagnetic bandgap structure includes a fifth inductor, a sixth inductor, a first capacitor, a second capacitor, a third capacitor, a first mutual capacitance, a second mutual capacitance, a first equivalent inductor, a second equivalent inductor and a third equivalent capacitance, wherein the fifth inductor and the sixth inductor are introduced by the distributed inductance of the power line, the first capacitance and the second capacitance are introduced by the distributed capacitance of the power line, the third capacitance is introduced by the decoupling capacitor, the first mutual capacitance and the second mutual capacitance are introduced by the coupling capacitance of the adjacent power line, the first equivalent inductor is introduced by the equivalent series inductance of the decoupling capacitor, the pad, and the wiring layout at the connection between the capacitor and the pad, the second equivalent inductor is introduced by the through hole, and the third equivalent capacitance is introduced by the coupling capacitance between the pad and the adjacent power line.

[0012] In some embodiments, the first end of the fifth inductor and the first end of the first capacitor are connected to the first end of the first mutual capacitor, the second end of the fifth inductor and the first end of the sixth inductor are connected to the first end of the third capacitor, the second end of the sixth inductor and the first end of the second mutual capacitor are connected to the first end of the second capacitor, the second end of the first mutual capacitor and the second end of the second mutual capacitor are connected to the second end of the third equivalent capacitor, the second end of the third capacitor is connected to the second end of the first equivalent inductor, the second end of the first equivalent inductor and the first end of the second equivalent inductor are connected to the first end of the third equivalent capacitor, and the second end of the first capacitor, the second end of the second capacitor, and the second end of the second equivalent inductor are all grounded.

[0013] To achieve the above object, another aspect of the embodiment of the present application provides a filtering method of a power supply noise suppression structure based on an electromagnetic bandgap structure, the method comprising the following steps: The resonant frequency of the power supply noise filter is set according to actual application requirements, and the upper cutoff frequency and the lower cutoff frequency of the power supply noise filter are determined according to the resonant frequency; Determining structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter according to the upper cut-off frequency and the lower cut-off frequency; Determine the arrangement of the periodic units of the power supply noise filter according to the structural parameters, the device parameters and the number of periodic units of the electromagnetic bandgap structure, combined with the area of ​​actual application; Determine equivalent circuit parameters according to the periodic unit arrangement of the power supply noise filter and in combination with the structural parameters of the power supply noise filter; Equivalent circuit simulation is performed on the equivalent circuit parameters, and power supply noise filter parameters are determined according to the simulation results to achieve power supply noise filtering for the target chip.

[0014] In some embodiments, determining the structural parameters, device parameters, and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter according to the upper cut-off frequency and the lower cut-off frequency includes: Determine the capacitance of the decoupling capacitor and the capacitance of the equivalent capacitor between the power line and the ground layer according to the upper cut-off frequency and the lower cut-off frequency; Determine the width and period length of the power line according to the capacitance of the equivalent capacitance between the power line and the ground layer, and obtain the structural parameters and device parameters of the power noise filter in combination with the capacitance of the decoupling capacitor; The number of periodic units of the electromagnetic bandgap structure is determined in combination with actual application requirements.

[0015] In some embodiments, the calculation expressions of the structural parameters and device parameters of the power supply noise filter are: ; ; ; In the above formula, represents the upper cutoff frequency, represents the lower cutoff frequency, represents the equivalent inductance of the via, Indicates the capacitance of the decoupling capacitor. represents the equivalent capacitance between the power line and the ground layer in one period unit, Indicates the width of the power line, represents the cycle length of the power line, represents the relative dielectric constant of the dielectric layer, Indicates the height of the power line, Indicates the height of the dielectric layer.

[0016] In some embodiments, performing equivalent circuit simulation on the equivalent circuit parameters, determining power supply noise filter parameters according to the simulation results, and implementing power supply noise filtering on the target chip includes: Drawing the power line on a metal layer required by the circuit board; Arranging the decoupling capacitors on the top or bottom metal layer of the circuit board according to the periodic unit arrangement of the power noise filter; A through hole is provided, and an electrical connection between the ground terminal of the decoupling capacitor and the ground layer is established through the through hole. In combination with the equivalent circuit parameters, a power signal is applied to the power noise filter to achieve power noise filtering of the target chip.

[0017] The embodiments of the present application include at least the following beneficial effects: The present application provides a power supply noise suppression structure based on an electromagnetic bandgap structure and a filtering method thereof. The scheme adopts a periodic repetitive structure similar to the electromagnetic bandgap structure to extend the upper cutoff frequency of the power supply noise stopband. By combining a decoupling capacitor, the power supply noise filtering structure extends the lower cutoff frequency of the power supply noise stopband when the frequency is low. The geometric flexibility of the electromagnetic bandgap structure is improved by presetting a periodic arrangement structure, and it can be applied to a variety of high-density circuit board occasions with restricted layouts. The manufacturing cost can be further saved through the power line, and a large area of ​​the circuit board is not required. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A three-dimensional schematic diagram of a typical mushroom-shaped electromagnetic bandgap structure periodic unit; Figure 2 It is an equivalent circuit diagram of a typical mushroom-shaped electromagnetic bandgap structure periodic unit; Figure 3 It is a three-dimensional schematic diagram of a periodic unit of a broadband power supply noise filtering structure based on an electromagnetic bandgap structure provided in an embodiment of the present application; Figure 4 It is a side view schematic diagram of a periodic unit of a broadband power supply noise filtering structure based on an electromagnetic bandgap structure provided in an embodiment of the present application; Figure 5 is an equivalent circuit diagram of a periodic unit of a broadband power supply noise filtering structure based on an electromagnetic bandgap structure provided in an embodiment of the present application; Figure 6 It is a top view of a linear broadband power supply noise filtering structure based on an electromagnetic bandgap structure and including 6 periodic units provided in an embodiment of the present application; Figure 7 It is a schematic diagram comparing insertion losses of a power line embedded with a single decoupling capacitor and a power line embedded with a linear broadband power noise filter structure based on an electromagnetic bandgap structure (6 period units) provided in an embodiment of the present application; Figure 8 It is a schematic diagram comparing insertion losses of a power line embedded with a single decoupling capacitor and a power line embedded with a linear broadband power noise filter structure based on an electromagnetic bandgap structure (12 period units) provided in an embodiment of the present application; Fig. 9 It is an equivalent circuit diagram of a folded broadband power supply noise filtering structure based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.10 It is a top view of a folded broadband power supply noise filtering structure based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.11This is a schematic diagram of insertion loss of a folded broadband power supply noise filter structure based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.12 It is a top view of a folded structure of a first arrangement mode of a broadband power supply noise filter structure design based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.13 It is a top view of a folded structure of a second arrangement mode of a broadband power supply noise filter structure design based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.14 It is a top view of a folded structure of a third arrangement mode of a broadband power supply noise filter structure design based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.15 It is a top view of a folded structure of a fourth arrangement mode of a broadband power supply noise filter structure design based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.16 It is a top view of a folded structure of a fifth arrangement mode of a broadband power supply noise filter structure design based on an electromagnetic bandgap structure provided in an embodiment of the present application; Fig.17 It is a schematic flow chart of the steps of a filtering method of a power supply noise suppression structure based on an electromagnetic bandgap structure provided in an embodiment of the present application.

[0019] Description of the drawings: 11, power layer; 12, electromagnetic bandgap structure layer; 13, ground layer; 14, via; 21, horizontal equivalent inductance; 22, equivalent capacitance; 23, vertical equivalent inductance; 31, power line within a period unit; 32, decoupling capacitor; 33, pad; 34, through hole; 35, ground layer; 51, first inductance; 52, second inductance; 53, first equivalent capacitance; 54, second equivalent capacitance; 55, third inductance; 56, fourth inductance inductance; 91. a power line of a periodic unit and its adjacent periodic unit; 92. an equivalent circuit of a power line of a periodic unit and its adjacent periodic unit; 93. a first inductance combination; 94. a first capacitance combination; 95. a third capacitance; 96. a first mutual capacitance combination; 97. a first equivalent inductance; 98. a second equivalent inductance; 99. a third equivalent capacitance; 910. a first mutual inductance; 911. a second mutual inductance; 912. a third mutual inductance; 913. a fourth mutual inductance. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of systems and methods consistent with some aspects of the embodiments of the present application as detailed in the attached claims.

[0021] It is understood that the terms "first", "second", etc. used in this application can be used to describe various concepts in this article, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another concept. For example, without departing from the scope of the embodiment of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein can be interpreted as "at the time of" or "when" or "in response to determination".

[0022] The terms "at least one", "multiple", "each", "any", etc. used in this application, at least one includes one, two or more, multiple includes two or more, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0024] First of all, it should be noted that a typical mushroom-shaped electromagnetic bandgap structure periodic unit is Figure 1 As shown. In practical applications, this periodic unit is periodically embedded between the power layer 11 and the ground layer 13, and an additional electromagnetic bandgap structure layer 12 is required in the middle. In each periodic unit, the electromagnetic bandgap structure layer 12 and the ground layer 13 are connected through a via 14. The equivalent circuit composed of this mushroom-shaped electromagnetic bandgap structure periodic unit is shown in Figure 2As shown. Among them, the horizontal equivalent inductance 21 is introduced by the planar inductance of the square piece in the power layer, the equivalent capacitance 22 is introduced by the substrate between the power layer and the electromagnetic bandgap structure layer, and the vertical equivalent inductance 23 is mainly introduced by the via connecting the electromagnetic bandgap structure layer and the ground layer. The structure behaves as a band-stop filter, and its resonant frequency is determined by the equivalent capacitance 22 and the vertical equivalent inductance 23. When the distance between the power layer and the electromagnetic bandgap structure layer decreases, the equivalent capacitance 22 increases, and the lower limit cutoff frequency of the power supply noise stopband expands to the low frequency range; when the period of the electromagnetic bandgap structure decreases, the first inductance 51 and the second inductance 52 decrease, and the upper limit cutoff frequency of the power supply noise stopband expands to the high frequency range. Through these two design methods, the stopband width of the power supply noise can be expanded, but it needs to occupy a large area of ​​the circuit board material, and even requires an additional metal layer, resulting in higher costs and affecting the device layout and wiring on the circuit board.

[0025] Based on this, the embodiment of the present invention uses a decoupling capacitor with a large capacitance value to replace the equivalent capacitor 22 in the equivalent circuit to form a new power line filter structure based on an electromagnetic bandgap structure, in which a three-dimensional schematic diagram of a periodic unit is shown as follows: Figure 3 As shown, its side view is as Figure 4 As shown, it specifically includes a power line 31, a decoupling capacitor 32, a pad 33, a through hole 34, and a ground layer 35 in a periodic unit. The periodic unit is composed of a decoupling capacitor, a section of a power line and a corresponding ground plane. One end of the decoupling capacitor is welded to the power line and the other end is welded to the pad. The pad is connected to the ground plane through a through hole, which realizes a -30dB power supply noise stopband spanning nearly 5 orders of magnitude in the frequency domain, realizes power supply noise suppression from about 20 kHz to nearly 10 GHz, and realizes geometric flexibility of the structure through folding of the linear structure.

[0026] Reference Figure 3 and Figure 4 , Figure 3 A schematic diagram of a power supply noise suppression structure based on an electromagnetic bandgap structure provided by an embodiment of the present invention, referring to Figure 3 The power supply noise suppression structure is composed of a plurality of electromagnetic bandgap structures through a preset periodic arrangement structure, wherein the plurality of electromagnetic bandgap structures include a power line, a decoupling capacitor and a through hole, wherein a first end of the decoupling capacitor is connected to the power line, and a second end of the decoupling capacitor and one end of the through hole are grounded, wherein: The other end of the power line is connected to the power modulation module and the power supply integrated circuit pin pad, and the power line is used to adjust the bandwidth upper limit cutoff frequency of the power supply noise stop band; Decoupling capacitors are used to adjust the lower cutoff frequency of the power supply noise stopband; The other end of the via is connected to ground.

[0027] In summary, the power noise suppression structure of the embodiment of the present invention is composed of a one-dimensional arrangement of several identical electromagnetic bandgap structure periodic units, and each periodic unit is composed of a power line, a decoupling capacitor and a through hole. Among them, the power line is connected to the power modulation module and the integrated circuit pin pad powered by it; one end of the decoupling capacitor is connected to the power line, and the other end is connected to the through hole, and the through hole connects the capacitor to the ground plane. The arrangement of the periodic unit can be a straight line, or it can be folded into a serpentine structure. By adjusting the width of the power line and the length of the unit period, the bandwidth upper limit cutoff frequency of the power noise stopband can be adjusted; by adjusting the capacitance of the decoupling capacitor, the lower limit cutoff frequency of the power noise stopband can be adjusted; by adjusting the arrangement of the periodic structure, the geometric flexibility of the structure can be achieved. The structure can be embedded in the power routing of the circuit board and can be designed on a two-layer circuit board or a multi-layer circuit board.

[0028] It should be noted that the preset periodic arrangement structure includes a straight line structure and a folded structure, wherein the straight line structure means that the two ends of the power lines in several electromagnetic band gap structures are cascaded in sequence, and the folded structure means that the power lines in several electromagnetic band gap structures are folded into a serpentine shape and then cascaded in sequence, and the decoupling capacitors are welded on the same side of the power lines.

[0029] Further, for the straight line structure, the equivalent circuit of the electromagnetic bandgap structure includes a first inductor 51, a second inductor 52, a first equivalent capacitor 53, a second equivalent capacitor 54, a third inductor 55 and a fourth inductor 56, wherein the power line is represented by the first inductor, the second inductor and the first equivalent capacitor, the decoupling capacitor is represented by the second equivalent capacitor and the third inductor, and the through hole is represented by the fourth inductor.

[0030] Among them, the second end of the first inductor, the first end of the second inductor, the first end of the first equivalent capacitor and the first end of the second equivalent capacitor are connected, the second end of the second equivalent capacitor is connected to the first end of the third inductor, the second end of the third inductor is connected to the first end of the fourth inductor, and the second end of the first equivalent capacitor is connected to the second end of the fourth inductor and grounded.

[0031] In summary, the equivalent circuit of the new electromagnetic bandgap structure periodic unit composed of a decoupling capacitor and a power line is as follows: Figure 5As shown. The power line is equivalent to the T model, as shown in the figure by the first inductor 51, the second inductor 52 and the first equivalent capacitor 53. The values ​​of the first inductor 51 and the second inductor 52 are determined by the product of the distributed inductance of the power line and the half period length, and the value of the first equivalent capacitor 53 is determined by the product of the distributed capacitance of the power line and the period length; the second equivalent capacitor 54 is introduced by the chip decoupling capacitor, and the capacitance is generally greater than 1uF; the third inductor 55 is mainly introduced by the equivalent series inductance of the chip decoupling capacitor, the pad, the connection between the capacitor and the pad, and the wiring layout, and the inductance is about 0.7nH; the fourth inductor 56 is introduced by the via, and the inductance is about 0.3nH. Among them, the value of the second equivalent capacitor 54 is much larger than the value of the first equivalent capacitor 53, so that the equivalent circuit of the period unit can be considered as a band-stop filter whose resonant frequency is jointly determined by the second equivalent capacitor 54, the third inductor 55 and the fourth inductor 56, thereby producing a power supply noise filtering effect in the frequency range near the resonant frequency.

[0032] Multiple equivalent circuits are cascaded to form a periodic structure, thereby achieving a wider range of power supply noise filtering effects. The lower limit cutoff frequency of the periodic structure is dominated by the decoupling capacitor capacitance. The larger the capacitance value, the lower the lower limit cutoff frequency; the upper limit cutoff frequency of the periodic structure is dominated by the first equivalent capacitor 53 of the power line. The smaller the capacitance value, the higher the upper limit cutoff frequency.

[0033] By cascading the proposed periodic unit structure through the two ends of the power line, the one-dimensional expansion of the structure in space can be achieved, and a power supply noise suppression structure can be obtained. The top view of the structure containing 6 periodic units is shown in the figure. Figure 6 As shown. In one embodiment, the structure is applied to a double-layer circuit board, the top and bottom metal thicknesses are both 0.035mm, the intermediate dielectric material is FR4 material with a dielectric constant of 4.4 and a thickness of 0.8mm, all through-hole diameters are 0.3mm, and the via-in-disk, resin plugging and electroplating capping processes are used. The periodic structure unit length is 1.4mm, the chip decoupling capacitor value is 1uF, the package size is 0201; the power line width is 20mil.

[0034] In order to test the power supply noise suppression effect of the present invention, two ports are selected at both ends of the present structure, and the insertion loss is used as an indicator of the power supply noise suppression effect. The insertion loss of a typical power line embedded with a single chip decoupling capacitor (the capacitance and package of the decoupling capacitor are consistent with those selected in the present structure) and the structure proposed by the present invention (including 6 units) are compared in the frequency domain, as shown in the figure. Figure 7 As shown; and the insertion loss of the structure proposed by the present invention (including 12 units) in the frequency domain is compared, as shown Figure 8As shown. The results show that the insertion loss of the present invention presents a double V-shape in the frequency domain, and the resonant frequency is about 5.03MHz. Below 3MHz, the present invention exhibits a lumped characteristic, which is equivalent to multiple ideal decoupling capacitors in parallel, which is equivalent to a 6 or 12-fold increase in parallel capacitance, and the noise suppression level is enhanced, resulting in the first V-shape; above 5MHz, it exhibits the characteristics of the electromagnetic bandgap structure, so the stopband in the high-frequency range extends to the high frequency, forming a second larger and deeper V-shape. Taking the -30dB level as the bandwidth evaluation index for power supply noise suppression, Figure 6 It is shown that the power line embedded with a single chip decoupling capacitor achieves a power noise stopband of 0.26 MHz to 270 MHz; the present invention including 6 units achieves a power noise stopband of 45.2 kHz to 6.38 GHz; Figure 7 It shows that the present invention including 12 units realizes a power supply noise stopband of -30dB level from 22.2 kHz to 8.15 GHz. The present invention extends the upper cutoff frequency of the power supply noise suppression bandwidth by about two orders of magnitude; the lower cutoff frequency is extended by one order of magnitude. This shows that the present invention breaks the limitation of the decoupling capacitor equivalent series inductance on the effective decoupling frequency band and realizes an ultra-wide power supply noise suppression stopband.

[0035] Furthermore, for the folded structure, the equivalent circuit of the electromagnetic bandgap structure includes a fifth inductor, a sixth inductor, a first capacitor, a second capacitor, a third capacitor 95, a first mutual capacitance, a second mutual capacitance, a first equivalent inductor 97, a second equivalent inductor 98 and a third equivalent capacitor 99, wherein the fifth inductor and the sixth inductor are introduced by the distributed inductance of the power line, the first capacitor and the second capacitor are introduced by the distributed capacitance of the power line, the third capacitor is introduced by the decoupling capacitor, the first mutual capacitance and the second mutual capacitance are introduced by the coupling capacitance of adjacent power lines, the first equivalent inductor is introduced by the equivalent series inductance of the decoupling capacitor, the pad, and the wiring layout at the connection between the capacitor and the pad, the second equivalent inductor is introduced by the through hole, and the third equivalent capacitance is introduced by the coupling capacitance between the pad and the adjacent power line.

[0036] Among them, the first end of the fifth inductor and the first end of the first capacitor are connected to the first end of the first mutual capacitor, the second end of the fifth inductor and the first end of the sixth inductor are connected to the first end of the third capacitor, the second end of the sixth inductor and the first end of the second mutual capacitor are connected to the first end of the second capacitor, the second end of the first mutual capacitor and the second end of the second mutual capacitor are connected to the second end of the third equivalent capacitor, the second end of the third capacitor is connected to the second end of the first equivalent inductor, the second end of the first equivalent inductor and the first end of the second equivalent inductor are connected to the first end of the third equivalent capacitor, and the second end of the first capacitor, the second end of the second capacitor, and the second end of the second equivalent inductor are all grounded.

[0037] It should be noted that since the above-mentioned structure is a linear structure formed by a one-dimensional expansion of the periodic unit, it may not be satisfactory for some circuit board design occasions where the area or layout is strictly limited. Therefore, in order to achieve geometric flexibility in the design, the present invention proposes a method for serpentine-bending the linear structure while still maintaining a good power supply noise suppression effect. In these folding structures, the power line is folded into a serpentine shape, the arrangement of the periodic unit is changed, and all the decoupling capacitors are welded on the same side of the power line. As a result, the geometric shape of the broadband power line decoupling structure based on the electromagnetic bandgap structure can be changed from a narrow and long straight line to a flexible rectangle.

[0038] In summary, the foldable structure can be analyzed and designed through equivalent circuits, such as Fig. 9 As shown. Among them, 91 represents the power line of a periodic unit and its adjacent periodic unit; 92 represents the equivalent circuit of the power line of a periodic unit and its adjacent periodic unit. In part 92, the first inductance combination 93 is introduced by the distributed inductance of the power line, and the first inductance combination 93 includes the fifth inductance and the sixth inductance; the first capacitance combination 94 is introduced by the distributed capacitance of the power line, and the first capacitance combination 94 includes the first capacitance and the second capacitance; the third capacitance 95 is introduced by the patch decoupling capacitance; the first mutual capacitance combination 96 is introduced by the coupling capacitance of the adjacent power line, and the first mutual capacitance combination 96 includes the first mutual capacitance and the second mutual capacitance; the first equivalent inductance 97 is introduced by the equivalent series inductance of the patch decoupling capacitance, the pad, the connection between the capacitor and the pad, and the wiring layout; the equivalent inductance 98 is introduced by the via; the third equivalent capacitance 99 is introduced by the coupling capacitance between the pad and the adjacent power line. The periodic units can be cascaded to achieve periodic expansion of the structure in space. The equivalent circuit takes into account the coupling effect between the vias in adjacent periodic units. Fig. 9 In the figure, the first mutual inductance 910 and the second mutual inductance 911 both represent the mutual inductance between vias, where the mutual inductance represented by 910 is for two vias separated by a power line; the mutual inductance represented by 911 is for vias of two periodic units directly cascaded. The third mutual inductance 912 is introduced by the coupling between the first equivalent inductances 97 of adjacent periodic units. The fourth mutual inductance 913 is introduced by the coupled inductance of adjacent power lines. In actual design, the values ​​of the above parameters can be extracted through electromagnetic simulation software.

[0039] According to the analysis of the equivalent circuit, a folding structure can be designed, and its top view is as follows: Fig.10As shown. The folded structure contains 12 periodic units, which are arranged in groups of 2 × 6 columns. This structure is still used in double-layer circuit boards, and the circuit board manufacturing process is the same as above. The length of the periodic structure unit is 1mm, the decoupling capacitor value is 1uF, and the package size is 0201; the power line width is 20mil, and the spacing between adjacent power lines of the serpentine fold is 1mm. The insertion loss of this structure is shown in Fig.11 As shown, the results show that the folded structure has a double V-shaped insertion loss characteristic similar to the straight-line structure in the frequency domain, forming a power supply noise stopband from 21.3 kHz to 9.22 GHz.

[0040] In addition to the above-mentioned methods, the folding method of the present invention can also be transformed as follows: for a structure containing 6 periodic units, there are 3 units in a group × 2 columns, such as Fig.12 As shown; 2 as a group × 3 columns arrangement, such as Fig.13 As shown; for a structure containing 12 periodic units, there are 6 groups × 2 columns, such as Fig.14 As shown; 4 in a group × 3 columns, such as Fig.15 As shown; 3 in a group × 4 columns, such as Fig.16 The arrangement shown. The number of periodic units included in the present invention is not limited to 6 or 12, but the number of periodic units can be appropriately selected. The more periodic units there are, the better the power supply noise suppression effect will be, but correspondingly, the cost will increase and the occupied area will also be larger.

[0041] See also Fig.17 The embodiment of the present application also provides a filtering method of a power supply noise suppression structure based on an electromagnetic bandgap structure, which can realize the above-mentioned power supply noise suppression structure based on an electromagnetic bandgap structure, and the method includes the following steps: S100, setting the resonant frequency of the power supply noise filter according to actual application requirements, and determining the upper limit cutoff frequency and the lower limit cutoff frequency of the power supply noise filter according to the resonant frequency; S200, determining structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter according to the upper cut-off frequency and the lower cut-off frequency; It should be noted that, in some embodiments, step S200 may include: S210, determining the capacitance of the decoupling capacitor and the capacitance of the equivalent capacitance between the power line and the ground layer according to the upper cut-off frequency and the lower cut-off frequency; S220, determining the width and period length of the power line according to the capacitance of the equivalent capacitance between the power line and the ground layer, and obtaining the structural parameters and device parameters of the power supply noise filter in combination with the capacitance of the decoupling capacitor; S230, determining the number of periodic units of the electromagnetic bandgap structure in combination with actual application requirements.

[0042] In some specific embodiments, the step of determining the structural parameters, device parameters and number of periodic units of the electromagnetic bandgap structure of the power supply noise filter includes: based on the given upper and lower cut-off frequencies, estimating according to the following expression: and The value of is expressed as: ; ; In the above formula, and Represent the upper and lower cut-off frequencies respectively; Represents the equivalent inductance of the via (in H), that is Figure 5 The fourth inductor 56; Indicates the capacitance of the decoupling capacitor (in F), that is Figure 5 A second equivalent capacitor 54; It represents the equivalent capacitance between the power line and the ground layer in one period unit (in F), that is, Figure 5 The first equivalent capacitor 53 in.

[0043] in, The steps to determine the inductance are as follows: According to the PCB process, determine the height of the dielectric layer, the appropriate via hole diameter and the pad size, and extract the equivalent inductance of the via through electromagnetic simulation software, which is Based on the determined The value of the power line can be determined according to the following formula to determine the appropriate power line width (in mm) and cycle length (unit: m), its expression is: ; In the above formula, The unit is pF, is the relative dielectric constant of the dielectric layer, is the height of the power cord (in mm), is the height of the dielectric layer (in mm). The number of periodic units of the electromagnetic bandgap structure used in the power supply noise filter is generally not less than 6. The more periodic units there are, the better the noise suppression effect.

[0044] S300, determining the arrangement of the periodic units of the power supply noise filter according to the structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure, combined with the area of ​​actual application; In some specific embodiments, a suitable arrangement of periodic units is determined according to the determined structural parameters, the number of periodic units and the area of ​​actual application. A linear type or a serpentine folding structure with different arrangements can be used.

[0045] S400, determining equivalent circuit parameters according to the periodic unit arrangement of the power supply noise filter and the structural parameters of the power supply noise filter; In some specific embodiments, the equivalent inductance of the power line within a half cycle is ,Right now Fig. 9 The first inductor combination 93 in the decoupling capacitor, the pad, the connection between the capacitor and the pad, and the parasitic inductance introduced by the wiring layout ,Right now Fig. 9 The first equivalent inductance 97 in the adjacent power line coupling capacitance ,Right now Fig. 9 The first mutual capacitance combination 96 in the pad and the coupling capacitance between the adjacent power lines ,Right now Fig. 9 The third equivalent capacitance 99 in the adjacent power lines; the mutual inductance ,Right now Fig. 9 The fourth mutual inductance 913 in the adjacent periodic units; the mutual inductance between the parasitic inductances ,Right now Fig. 9 The third mutual inductance 912 in the via mutual inductance ,Right now Fig. 9 The first mutual inductance 910 in the via mutual inductance ,Right now Fig. 9 The second mutual inductance 911 in.

[0046] Among them, based on the determined equivalent circuit parameters, the equivalent circuit simulation is performed, the steps are: based on the above determined , and the number of periodic units and the arrangement of periodic units are determined according to Fig. 9 , build an equivalent circuit and perform simulation.

[0047] S500, performing equivalent circuit simulation on equivalent circuit parameters, determining power supply noise filter parameters according to the simulation results, and implementing power supply noise filtering for the target chip; It should be noted that, in some embodiments, step S500 may include: S510, drawing a power line on the metal layer required by the circuit board; S520, arranging decoupling capacitors on the top or bottom metal layer of the circuit board according to the periodic unit arrangement of the power noise filter; S530, setting a through hole, establishing an electrical connection between the ground terminal of the decoupling capacitor and the ground layer through the through hole, and applying a power signal to the power noise filter in combination with the equivalent circuit parameters to achieve power noise filtering of the target chip.

[0048] In some specific embodiments, a power line is drawn on the metal layer required by the circuit board; decoupling capacitors are periodically arranged on the top or bottom metal layer in a determined arrangement; vias are provided to establish an electrical connection between the ground terminal of the decoupling capacitor and the ground layer through the vias; and a power signal is applied to the filter to achieve a broadband noise suppression effect.

[0049] In summary, the embodiment of the present invention first designs the resonant frequency, upper and lower cut-off frequencies of the power supply noise filter according to actual application requirements; determines the structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter; determines the arrangement of the periodic units of the power supply noise filter; based on the determined structural parameters, uses simulation software to extract equivalent circuit parameters; based on the determined equivalent circuit parameters, performs equivalent circuit simulation to verify that the filtering characteristics meet the application requirements; when the power supply noise filter parameter configuration is completed, uses the filter to perform power supply noise filtering on the target chip.

[0050] Therefore, the advantages of the embodiments of the present invention are: 1) A periodic repetitive structure similar to the electromagnetic bandgap structure is adopted, which greatly expands the upper cutoff frequency of the -30dB power supply noise stopband, breaking through the frequency range limitation of the power supply noise suppression solution based on traditional decoupling capacitors.

[0051] 2) Multiple decoupling capacitors are connected in parallel. The power supply noise filtering structure exhibits the characteristics of a lumped capacitor at low frequencies, extending the lower cutoff frequency of the -30dB power supply noise stopband.

[0052] 3) A large decoupling capacitor value and a small period unit length are used to make the period unit have a compact arrangement, which has the advantage of small size compared with other power supply noise filtering structures.

[0053] 4) The foldable periodic unit arrangement makes it have high geometric flexibility and is suitable for a variety of high-density circuit board occasions with restricted layout.

[0054] 5) The power line structure is adopted, which saves manufacturing costs compared with other plane-based power noise suppression solutions, and does not require a large area of ​​​​the circuit board, and the scope of application is expanded.

[0055] It can be understood that the contents of the above method embodiments are all applicable to the present system embodiments, the functions specifically implemented by the present system embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0056] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the rights of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present invention should be within the scope of the rights of the present invention.

Claims

1. A power supply noise suppression structure based on an electromagnetic bandgap structure, characterized in that: The power supply noise suppression structure is composed of a plurality of electromagnetic bandgap structures through a preset periodic arrangement structure, wherein the plurality of electromagnetic bandgap structures include a power line, a decoupling capacitor and a through hole, wherein a first end of the decoupling capacitor is connected to the power line, and a second end of the decoupling capacitor and one end of the through hole are grounded, wherein: One end of the power line is connected to the power modulation module, and the other end is connected to the power supply integrated circuit pin pad, and the power line is used to adjust the bandwidth upper limit cutoff frequency of the power supply noise stop band; The decoupling capacitor is used to adjust the lower cutoff frequency of the power supply noise stopband; The other end of the through hole is grounded.

2. The power supply noise suppression structure according to claim 1, characterized in that: The preset periodic arrangement structure includes a straight line structure and a folded structure, wherein the straight line structure represents that the two ends of the power lines in the electromagnetic band gap structures are cascaded in sequence, and the folded structure represents that the power lines in the electromagnetic band gap structures are folded into a serpentine shape and then cascaded in sequence, and the decoupling capacitors are welded on the same side of the power lines.

3. The power supply noise suppression structure according to claim 2, characterized in that: For the straight line structure, the equivalent circuit of the electromagnetic bandgap structure includes a first inductor, a second inductor, a first equivalent capacitor, a second equivalent capacitor, a third inductor and a fourth inductor, wherein the power line is represented by the first inductor, the second inductor and the first equivalent capacitor, the decoupling capacitor is represented by the second equivalent capacitor and the third inductor, and the through hole is represented by the fourth inductor.

4. The power supply noise suppression structure according to claim 3, characterized in that: The second end of the first inductor, the first end of the second inductor, the first end of the first equivalent capacitor and the first end of the second equivalent capacitor are connected, the second end of the second equivalent capacitor is connected to the first end of the third inductor, the second end of the third inductor is connected to the first end of the fourth inductor, and the second end of the first equivalent capacitor is connected to the second end of the fourth inductor and is grounded.

5. The power supply noise suppression structure according to claim 2, characterized in that: For the folded structure, the equivalent circuit of the electromagnetic bandgap structure includes a fifth inductor, a sixth inductor, a first capacitor, a second capacitor, a third capacitor, a first mutual capacitance, a second mutual capacitance, a first equivalent inductor, a second equivalent inductor and a third equivalent capacitance, wherein the fifth inductor and the sixth inductor are introduced by the distributed inductance of the power line, the first capacitance and the second capacitance are introduced by the distributed capacitance of the power line, the third capacitance is introduced by the decoupling capacitor, the first mutual capacitance and the second mutual capacitance are introduced by the coupling capacitance of the adjacent power line, the first equivalent inductor is introduced by the equivalent series inductance of the decoupling capacitor, the pad, and the wiring layout at the connection between the capacitor and the pad, the second equivalent inductor is introduced by the through hole, and the third equivalent capacitance is introduced by the coupling capacitance between the pad and the adjacent power line.

6. The power supply noise suppression structure according to claim 5, characterized in that: The first end of the fifth inductor and the first end of the first capacitor are connected to the first end of the first mutual capacitor, the second end of the fifth inductor and the first end of the sixth inductor are connected to the first end of the third capacitor, the second end of the sixth inductor and the first end of the second mutual capacitor are connected to the first end of the second capacitor, the second end of the first mutual capacitor and the second end of the second mutual capacitor are connected to the second end of the third equivalent capacitor, the second end of the third capacitor is connected to the second end of the first equivalent inductor, the second end of the first equivalent inductor and the first end of the second equivalent inductor are connected to the first end of the third equivalent capacitor, and the second end of the first capacitor, the second end of the second capacitor, and the second end of the second equivalent inductor are all grounded.

7. A filtering method for a power supply noise suppression structure based on an electromagnetic bandgap structure, characterized in that: The method comprises the following steps: The resonant frequency of the power supply noise filter is set according to actual application requirements, and the upper cutoff frequency and the lower cutoff frequency of the power supply noise filter are determined according to the resonant frequency; Determining structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter according to the upper cut-off frequency and the lower cut-off frequency; Determine the arrangement of the periodic units of the power supply noise filter according to the structural parameters, the device parameters and the number of periodic units of the electromagnetic bandgap structure, combined with the area of ​​actual application; Determine equivalent circuit parameters according to the periodic unit arrangement of the power supply noise filter and in combination with the structural parameters of the power supply noise filter; Equivalent circuit simulation is performed on the equivalent circuit parameters, and power supply noise filter parameters are determined according to the simulation results to achieve power supply noise filtering for the target chip.

8. The method according to claim 7, characterized in that According to the upper cut-off frequency and the lower cut-off frequency, determining the structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter includes: Determine the capacitance of the decoupling capacitor and the capacitance of the equivalent capacitor between the power line and the ground layer according to the upper cut-off frequency and the lower cut-off frequency; Determine the width and period length of the power line according to the capacitance of the equivalent capacitance between the power line and the ground layer, and obtain the structural parameters and device parameters of the power noise filter in combination with the capacitance of the decoupling capacitor; The number of periodic units of the electromagnetic bandgap structure is determined in combination with actual application requirements.

9. The method according to claim 8, characterized in that The calculation expressions of the structural parameters and device parameters of the power supply noise filter are as follows: ； ； ； In the above formula, represents the upper cutoff frequency, represents the lower cutoff frequency, represents the equivalent inductance of the via, Indicates the capacitance of the decoupling capacitor. represents the equivalent capacitance between the power line and the ground layer in one period unit, Indicates the width of the power line, represents the cycle length of the power line, represents the relative dielectric constant of the dielectric layer, Indicates the height of the power line, Indicates the height of the dielectric layer.

10. The method according to claim 7, characterized in that The equivalent circuit parameters are subjected to equivalent circuit simulation, and power supply noise filter parameters are determined according to the simulation results to implement power supply noise filtering for the target chip, including: Drawing the power line on a metal layer required by the circuit board; Arranging the decoupling capacitors on the top or bottom metal layer of the circuit board according to the periodic unit arrangement of the power noise filter; A through hole is provided, and an electrical connection between the ground terminal of the decoupling capacitor and the ground layer is established through the through hole. In combination with the equivalent circuit parameters, a power signal is applied to the power noise filter to achieve power noise filtering of the target chip.

Images