A power supply noise suppression structure based on electromagnetic bandgap structure and a filtering method thereof

Abstract

The application discloses a power supply noise suppression structure based on an electromagnetic bandgap structure and a filtering method thereof. The power supply noise suppression structure is composed of a plurality of electromagnetic bandgap structure units through a preset periodic arrangement structure. The plurality of electromagnetic bandgap structure units include a power supply line, a decoupling capacitor and a through hole. The method comprises the following steps: determining an upper limit cutoff frequency and a lower limit cutoff frequency of a power supply noise filter; determining structure parameters, device parameters and the number of electromagnetic bandgap structure periodic units of the power supply noise filter; determining a periodic unit arrangement mode of the power supply noise filter in combination with an actual application area; determining equivalent circuit parameters; performing equivalent circuit simulation; determining power supply noise filter parameters according to a simulation result; and realizing power supply noise filtering of a target chip. The embodiment of the application can expand the upper limit cutoff frequency and the lower limit cutoff frequency of a power supply noise stopband, and does not need to occupy a large-area circuit board. The application 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

[0002] The power distribution network is the largest interconnection network on a printed circuit board, and its function is to transmit stable and clean power supply voltage to the power supply pads of integrated circuits on the circuit board. The noise on the power distribution network can come from the coupling noise of the digital signal lines before and after the voltage regulation module, and can come from the resonator formed by the power ground plane or other electromagnetic interference sources. These power supply noises are distributed in the frequency range of 10 MHz to 10 GHz, which can 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 communication is developing towards high speed, high integration and low power consumption, and therefore has more serious power noise problems. The design of the power distribution network of the circuit system needs to pay more attention to the problem of power noise suppression, and the power noise suppression scheme needs to cover a wider frequency band, while having lower cost and smaller size.

[0003] A related method is to place a decoupling capacitor near the power pin of an 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 several hundred megahertz. Further, in order to reduce the equivalent series inductance and improve the suppression effect of high-frequency power noise, some new capacitor structures have been proposed, such as long-width-reversed capacitors and three-terminal capacitors. For example, a through-hole capacitor is used instead of a two-terminal capacitor to reduce the equivalent series inductance and equivalent series resistance, and to achieve power noise filtering. However, the technology is not yet mature or the cost is high, so it cannot be mass-produced and used. Therefore, the 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 needs of low power noise and the high speed needs of modern wired communication, other widely used power noise suppression schemes include adding etched slots on the power or ground plane and electromagnetic bandgap structures. Among them, the electromagnetic bandgap structure shows strong noise suppression effect and has an ultra-wide power noise stop band covering the gigahertz range. The limitation of these power noise suppression schemes is that they are all planar power noise suppression structures that need to occupy a large area of the circuit board material, and even require additional metal layers, resulting in high cost and affecting the device layout and wiring on the circuit board.

[0005] In summary, the technical problems in the related art need to be improved. SUMMARY

[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 and lower cutoff frequencies of the power supply noise stopband and does not require a large area of ​​the circuit board.

[0007] To achieve the above objectives, one aspect of an embodiment of the present application provides a power supply noise suppression structure based on an electromagnetic bandgap structure. The power supply noise suppression structure is composed of a plurality of electromagnetic bandgap structures arranged in a preset periodic structure. The plurality of electromagnetic bandgap structures include power lines, decoupling capacitors, and through-holes. 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:

[0008] 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;

[0009] The decoupling capacitor is used to adjust the lower cutoff frequency of the power supply noise stop band;

[0010] The other end of the through hole is grounded.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] In some embodiments, for the folded structure, an equivalent circuit of the EBG structure includes a fifth inductor, a sixth inductor, a first capacitor, a second capacitor, a third capacitor, a first mutual capacitor, a second mutual capacitor, a first equivalent inductor, a second equivalent inductor, and a third equivalent capacitor, wherein the fifth inductor and the sixth inductor are introduced by the distributed inductance of the power supply line, the first capacitor and the second capacitor are introduced by the distributed capacitance of the power supply line, the third capacitor is introduced by the decoupling capacitor, the first mutual capacitor and the second mutual capacitor are introduced by the coupling capacitance of adjacent power supply lines, the first equivalent inductor is introduced by the equivalent series inductance of the decoupling capacitor, the layout of the pad, the capacitor, and the pad connection, the second equivalent inductor is introduced by the via, and the third equivalent capacitor is introduced by the coupling capacitance between the pad and the adjacent power supply line.

[0015] In some embodiments, a first end of the fifth inductor, a first end of the first capacitor, and a first end of the first mutual capacitor are connected, a second end of the fifth inductor, a first end of the sixth inductor, and a first end of the third capacitor are connected, a second end of the sixth inductor, a first end of the second mutual capacitor, and a first end of the second capacitor are connected, a second end of the first mutual capacitor, a second end of the second mutual capacitor, and a second end of the third equivalent capacitor are connected, a second end of the third capacitor and a second end of the first equivalent inductor are connected, a second end of the first equivalent inductor, a first end of the second equivalent inductor, and a first end of the third equivalent capacitor are connected, a second end of the first capacitor, a second end of the second capacitor, and a second end of the second equivalent inductor are grounded.

[0016] To achieve the above object, another aspect of the embodiments of the present application proposes a filtering method of a power supply noise suppression structure based on an EBG structure, which comprises the following steps:

[0017] Setting a resonant frequency of the power supply noise filter according to actual application requirements, determining an upper limit cutoff frequency of the power supply noise filter and a lower limit cutoff frequency of the power supply noise filter according to the resonant frequency;

[0018] Determining a structure parameter, a device parameter, and a number of periodic units of an EBG structure of the power supply noise filter according to the upper limit cutoff frequency and the lower limit cutoff frequency;

[0019] Determining a periodic unit arrangement of the power supply noise filter according to the structure parameter, the device parameter, and the number of periodic units of the EBG structure, and combining the area of actual application;

[0020] Determining an equivalent circuit parameter according to the periodic unit arrangement of the power supply noise filter and the structure parameter of the power supply noise filter;

[0021] The equivalent circuit parameters are simulated by an equivalent circuit simulation, and parameters of a power supply noise filter are determined according to a simulation result, so as to realize power supply noise filtering of the target chip.

[0022] In some embodiments, according to the upper limit cutoff frequency and the lower limit cutoff frequency, a structure parameter, a device parameter and a number of periodic units of the electromagnetic bandgap structure of the power supply noise filter are determined, including:

[0023] According to the upper limit cutoff frequency and the lower limit cutoff frequency, a capacitance value of a decoupling capacitor and a capacitance value of an equivalent capacitor between the power supply line and the ground layer are determined.

[0024] According to the capacitance value of the equivalent capacitor between the power supply line and the ground layer, a width of the power supply line and a period length are determined, and in combination with the capacitance value of the decoupling capacitor, the structure parameter and the device parameter of the power supply noise filter are obtained.

[0025] The number of periodic units of the electromagnetic bandgap structure is determined in combination with actual application requirements.

[0026] In some embodiments, a calculation expression of the structure parameter and the device parameter of the power supply noise filter is:

[0027] ;

[0028] ;

[0029] ;

[0030] In the above formula, represents the upper limit cutoff frequency, represents the lower limit cutoff frequency, represents an equivalent inductance of a via, represents a capacitance value of a decoupling capacitor, represents an equivalent capacitor between a power supply line and a ground layer in a periodic unit, represents a width of the power supply line, represents a period length of the power supply line, represents a relative dielectric constant of a dielectric layer, represents a height of the power supply line, represents a height of the dielectric layer.

[0031] In some embodiments, the equivalent circuit simulation of the equivalent circuit parameters, the determination of the power supply noise filter parameters according to the simulation result, and the realization of the power supply noise filtering of the target chip include:

[0032] The power supply line is drawn on a metal layer required by a circuit board;

[0033] The decoupling capacitor is arranged on the top layer or bottom layer metal layer of the circuit board according to the periodic unit arrangement mode of the power supply noise filter;

[0034] The through hole is arranged, and the electrical connection between the ground end of the decoupling capacitor and the ground layer is established through the through hole. The power supply signal is applied to the power supply noise filter by combining the equivalent circuit parameters, and the power supply noise filtering of the target chip is realized.

[0035] The embodiment of the present application at least has the following beneficial effects: the present application provides a power supply noise suppression structure based on the electromagnetic bandgap structure and a filtering method thereof. The scheme adopts a periodic repeating structure similar to the electromagnetic bandgap structure, expands the upper limit cutoff frequency of the power supply noise stopband, and expands the lower limit cutoff frequency of the power supply noise stopband by combining the decoupling capacitor when the frequency is low. The geometric flexibility of the electromagnetic bandgap structure is improved by the preset periodic arrangement structure, which can be applied to various high-density circuit board occasions with layout restrictions. The manufacturing cost is further saved by the power supply line, and a large area of the circuit board does not need to be occupied. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 It is a three-dimensional schematic view of a typical mushroom-shaped electromagnetic bandgap structure periodic unit;

[0037] Figure 2 It is an equivalent circuit diagram of a typical mushroom-shaped electromagnetic bandgap structure periodic unit;

[0038] Figure 3 It is a three-dimensional schematic view of a periodic unit of a wideband power supply noise filtering structure based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0039] Figure 4 It is a side view schematic view of a periodic unit of a wideband power supply noise filtering structure based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0040] Figure 5 It is an equivalent circuit diagram of a periodic unit of a wideband power supply noise filtering structure based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0041] Figure 6 It is a top view of a wideband power supply noise filtering structure based on the electromagnetic bandgap structure containing 6 periodic units provided by the embodiment of the present application;

[0042] Figure 7 It is an insertion loss comparison schematic view of a power supply line embedded with a single decoupling capacitor and a power supply line embedded with a linear wideband power supply noise filtering structure based on the electromagnetic bandgap structure (6 periodic units) provided by the embodiment of the present application;

[0043] Figure 8 is an insertion loss comparison diagram of a power line embedded with a single decoupling capacitor and a power line (12 periodic units) embedded with a linear type broadband power noise filtering structure based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0044] Figure 9 is an equivalent circuit diagram of a folded type broadband power noise filtering structure based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0045] Figure 10 is a top view of a folded type broadband power noise filtering structure based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0046] Figure 11 is an insertion loss diagram of a folded type broadband power noise filtering structure based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0047] Figure 12 is a top view of a first arrangement mode folded type structure of a broadband power noise filtering structure design based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0048] Figure 13 is a top view of a second arrangement mode folded type structure of a broadband power noise filtering structure design based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0049] Figure 14 is a top view of a third arrangement mode folded type structure of a broadband power noise filtering structure design based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0050] Figure 15 is a top view of a fourth arrangement mode folded type structure of a broadband power noise filtering structure design based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0051] Figure 16 is a top view of a fifth arrangement mode folded type structure of a broadband power noise filtering structure design based on the electromagnetic bandgap structure provided by the embodiment of the present application;

[0052] Figure 17 is a step flow diagram of a filtering method of a power noise suppression structure based on the electromagnetic bandgap structure provided by the embodiment of the present application.

[0053] BRIEF DESCRIPTION OF DRAWINGS: 11, power layer; 12, electromagnetic band gap structure layer; 13, ground layer; 14, via; 21, horizontal equivalent inductance; 22, equivalent capacitance; 23, vertical equivalent inductance; 31, power line within one period unit; 32, decoupling capacitance; 33, pad; 34, via hole; 35, ground layer; 51, first inductance; 52, second inductance; 53, first equivalent capacitance; 54, second equivalent capacitance; 55, third inductance; 56, fourth inductance; 91, power line of one period unit and its adjacent period unit; 92, equivalent circuit of power line of one period unit and its adjacent period unit; 93, first inductance combination; 94, first capacitance combination; 95, third capacitance; 96, first mutual capacitance combination; 97, first equivalent inductance; 98, second equivalent inductance; 99, third equivalent capacitance; 910, first mutual inductance; 911, second mutual inductance; 912, third mutual inductance; 913, fourth mutual inductance. DETAILED DESCRIPTION

[0054] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application. When the following description refers to the accompanying drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with 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 appended claims.

[0055] It can be understood that the terms "first", "second" and the like as used herein can be used to describe various concepts, but unless specifically stated, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. For example, without departing from the scope of the embodiments of the present application, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information. Depending on the context, the word "if" as used herein can be interpreted as "when" or "upon" or "in response to determining".

[0056] The terms "at least one", "multiple", "each", "any" and the like used herein include one, two or more than two, multiple includes two or more than two, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0057] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.

[0058] First of all, it needs to be pointed out that a typical mushroom-shaped electromagnetic bandgap structure periodic unit is as shown in the figure. Figure 1 In practical applications, such a periodic unit is periodically embedded between the power supply layer 11 and the ground layer 13, and an additional electromagnetic bandgap structure layer 12 is needed in between, and in each periodic unit, the electromagnetic bandgap structure layer 12 and the ground layer 13 are connected through a via hole 14. The equivalent circuit of such a mushroom-shaped electromagnetic bandgap structure periodic unit is as shown in the figure. Figure 2 Among them, the horizontal equivalent inductance 21 is introduced by the planar inductance of the square sheet in the power supply layer, the equivalent capacitance 22 is introduced by the substrate between the power supply layer and the electromagnetic bandgap structure layer, and the vertical equivalent inductance 23 is mainly introduced by the via hole connecting the electromagnetic bandgap structure layer and the ground layer. The structure behaves as a band-stop filter, and the resonant frequency is determined by the equivalent capacitance 22 and the vertical equivalent inductance 23. When the distance between the power supply 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 needs an additional metal layer, resulting in high cost and affecting the device layout and wiring on the circuit board.

[0059] Based on this, the embodiment of the application uses a decoupling capacitor with a large capacitance value to replace the equivalent capacitance 22 in the equivalent circuit to form a new type of power line filtering structure based on electromagnetic bandgap structure, and a three-dimensional schematic view of one periodic unit is as shown in the figure. Figure 3 The side view is as shown in the figure. Figure 4 Specifically, it includes a power supply line 31, a decoupling capacitor 32, a pad 33, a via hole 34, and a ground layer 35 in one periodic unit. The periodic unit is composed of a decoupling capacitor, a section of power supply line, and a corresponding ground plane, and the decoupling capacitor is welded on the power supply line at one end and on the pad at the other end, and the pad is connected with the ground plane through a via hole, realizing a -30dB power supply noise stopband spanning nearly 5 orders of magnitude in the frequency domain, realizing power supply noise suppression from about 20 kilohertz to nearly 10 gigahertz, and realizing the geometric flexibility of the structure through the folding of the linear structure.

[0060] Referring to Figure 3 and Figure 4 , Figure 3 is a schematic view of a power supply noise suppression structure based on electromagnetic bandgap structure provided by the embodiment of the application, referring to Figure 3The power supply noise suppression structure is composed of a plurality of electromagnetic bandgap structures through a preset periodic arrangement structure, the plurality of electromagnetic bandgap structures include a power supply line, a decoupling capacitor and a via, a first end of the decoupling capacitor is connected to the power supply line, a second end of the decoupling capacitor and one end of the via are grounded, and the other end of the via is connected to the other end of the power supply line.

[0061] The other end of the power supply line is connected to a power supply modulation module and a pin pad of an integrated circuit for power supply, and the power supply line is used to adjust the upper limit cut-off frequency of the bandwidth of the power supply noise stopband.

[0062] The decoupling capacitor is used to adjust the lower limit cut-off frequency of the power supply noise stopband.

[0063] The other end of the via is grounded.

[0064] In summary, the power supply noise suppression structure of the embodiment of the present application is composed of a plurality of identical electromagnetic bandgap structure periodic units arranged in one dimension, each periodic unit is composed of a power supply line, a decoupling capacitor and a via. The power supply line is connected to a power supply modulation module and a pin pad of an integrated circuit for power supply; one end of the decoupling capacitor is connected to the power supply line, the other end of the decoupling capacitor is connected to the via, and the via is connected to the capacitor and the ground plane. The arrangement mode of the periodic unit can be a straight line, or can be folded into a serpentine bending structure. By adjusting the width of the power supply line and the length of the unit period, the upper limit cut-off frequency of the bandwidth of the power supply noise stopband can be adjusted; by adjusting the capacitance value of the decoupling capacitor, the lower limit cut-off frequency of the power supply noise stopband can be adjusted; by adjusting the arrangement mode of the periodic structure, the geometric flexibility of the structure can be realized. The structure can be embedded in the power supply line of the circuit board, and can be designed in two-layer circuit boards or multi-layer circuit boards.

[0065] It should be noted that the preset periodic arrangement structure includes a straight line structure and a folding structure, wherein the straight line structure represents that the power supply lines in the plurality of electromagnetic bandgap structures are sequentially cascaded at both ends, the folding structure represents that the power supply lines in the plurality of electromagnetic bandgap structures are folded into a serpentine shape and then sequentially cascaded, and the decoupling capacitors are welded on the same side of the power supply lines.

[0066] 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 supply 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 via is represented by the fourth inductor.

[0067] 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 and the first end of the third inductor are connected, the second end of the third inductor and the first end of the fourth inductor are connected, the second end of the first equivalent capacitor and the second end of the fourth inductor are connected and grounded.

[0068] In summary, the equivalent circuit of the new EBG periodic cell composed of a decoupling capacitor and a section of power line is shown in Figure 5 The power line is equivalent to a T-model, as shown in the first inductance 51, the second inductance 52 and the first equivalent capacitance 53 in the figure, the values of the first inductance 51 and the second inductance 52 are determined by the product of the distributed inductance of the power line and one-half of the period length, and the value of the first equivalent capacitance 53 is determined by the product of the distributed capacitance of the power line and the period length; the second equivalent capacitance 54 is introduced by the patch decoupling capacitor, and the capacitance value is generally greater than 1uF; the third inductance 55 is mainly introduced by the equivalent series inductance of the patch decoupling capacitor, the solder pad, the connection between the capacitor and the solder pad, and the layout of the wiring, and the inductance value is about 0.7nH; the fourth inductance 56 is introduced by the via, and the inductance value is about 0.3nH. Among them, the value of the second equivalent capacitance 54 is much greater than the value of the first equivalent capacitance 53, so that the equivalent circuit of the periodic cell can be considered as a band-stop filter with a resonance frequency determined by the second equivalent capacitance 54, the third inductance 55 and the fourth inductance 56, thereby producing a power noise filtering effect in the frequency range near the resonance frequency.

[0069] Cascading a plurality of the equivalent circuit to form a periodic structure, thereby realizing a wider range of power noise filtering effect. The lower limit cutoff frequency of the periodic structure is dominated by the capacitance value of the decoupling capacitor, the greater 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 capacitance 53 of the power line, the smaller the capacitance value, the higher the upper limit cutoff frequency.

[0070] Cascading the proposed periodic cell structure through the power line in sequence can realize one-dimensional expansion of the structure in space, and obtain a power noise suppression structure. The top view of a structure containing six periodic cells is shown in Figure 6 In an embodiment, the structure is applied to a double-layer circuit board, the thickness of the top layer and the bottom layer metal is 0.035mm, the intermediate dielectric material is FR4 material with a dielectric constant of 4.4 and a thickness of 0.8mm, all the through-hole diameters are 0.3mm, and the disc-in-hole, resin plug and electroplating cap process is adopted. The length of the periodic structure unit is 1.4mm, the capacitance value of the patch decoupling capacitor is 1uF, and the package size is 0201; the width of the power line is 20mil.

[0071] In order to test the power noise suppression effect of the present application, two ports are selected at both ends of the structure, and the insertion loss is taken as the index of the power noise suppression effect. The insertion loss of a typical power line embedded with a single patch decoupling capacitor (the capacitance value and package of the decoupling capacitor are consistent with the selected structure) is compared with the insertion loss of the structure (containing six units) proposed in the present application in the frequency domain, as shown in Figure 7 The insertion loss of the structure (containing twelve units) proposed in the present application in the frequency domain is compared with the insertion loss of the structure (containing six units) proposed in the present application in the frequency domain, as shown inFigure 8 As 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 increasing the parallel capacitance by 6 or 12 times, 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 stop band 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 shows that the power line embedded with a single chip decoupling capacitor achieves a power supply noise stop band of 0.26 MHz to 270 MHz; the invention containing 6 units achieves a power supply noise stop band of 45.2 kHz to 6.38 GHz; Figure 7 The results show that the present invention, comprising 12 units, achieves a -30dB power supply noise stopband from 22.2 kHz to 8.15 GHz. This invention extends the upper cutoff frequency of the power supply noise suppression bandwidth by approximately two orders of magnitude, while the lower cutoff frequency extends by one order of magnitude. This demonstrates that the present invention overcomes the limitations of the decoupling capacitor's equivalent series inductance on the effective decoupling bandwidth, achieving an ultra-wide power supply noise suppression stopband.

[0072] 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 capacitance 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.

[0073] 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.

[0074] It should be noted that the above-mentioned structure is a linear structure formed by one-dimensional expansion of the periodic unit, which can not meet the design of some circuit boards with strict area or layout restrictions. Therefore, in order to design the geometric flexibility, the present application proposes a method of bending the linear structure into a serpentine shape while still maintaining good power supply noise suppression effect. In these folded structures, the power supply lines are folded into a serpentine shape, the arrangement of the periodic units is changed, and all the decoupling capacitors are welded on the same side of the power supply lines. Thus, the geometry of the broadband power supply line decoupling structure based on the electromagnetic bandgap structure can be changed from a narrow linear shape to a flexible rectangular shape.

[0075] In summary, the folded structure can be analyzed and designed by an equivalent circuit, as shown in Figure 9 wherein 91 represents the power supply lines of a periodic unit and its adjacent periodic units; 92 represents the equivalent circuit of the power supply lines of a periodic unit and its adjacent periodic units. In 92, the first inductance combination 93 is introduced by the distributed inductance of the power supply lines, the first inductance combination 93 including a fifth inductance and a sixth inductance; the first capacitance combination 94 is introduced by the distributed capacitance of the power supply lines, the first capacitance combination 94 including a first capacitance and a second capacitance; the third capacitance 95 is introduced by the patch decoupling capacitor; the first mutual capacitance combination 96 is introduced by the coupling capacitance of adjacent power supply lines, the first mutual capacitance combination 96 including a first mutual capacitance and a second mutual capacitance; the first equivalent inductance 97 is introduced by the equivalent series inductance of the patch decoupling capacitor, the pad, the connection between the capacitor and the pad, and the layout; the equivalent inductance 98 is introduced by the via; and the third equivalent capacitance 99 is introduced by the coupling capacitance between the pad and the adjacent power supply line. The periodic units can be cascaded to realize the periodic expansion of the structure in space. The equivalent circuit considers the coupling effect between the vias in the adjacent periodic units. Figure 9 In 92, the first mutual inductance 910 and the second mutual inductance 911 both represent the mutual inductance between the vias, wherein 910 represents the mutual inductance between two vias with one power supply line in between; and 911 represents the mutual inductance between two vias of two periodic units directly cascaded. The third mutual inductance 912 is introduced by the coupling between the first equivalent inductances 97 of the adjacent periodic units. The fourth mutual inductance 913 is introduced by the coupling inductance of the adjacent power supply lines. In actual design, the values of the above parameters can be extracted by electromagnetic simulation software.

[0076] According to the analysis of the equivalent circuit, a folded structure can be designed, as shown in Figure 10The folding type structure contains 12 periodic units arranged in 2 groups by 6 columns. The structure is still applied to a double-layer circuit board, and the circuit board manufacturing process is the same as above. The periodic structure unit length is 1 mm, the decoupling capacitance value is 1 uF, and the package size is 0201; the power line width is 20 mil, and the interval distance between adjacent power lines of the snake-shaped folding is 1 mm. The insertion loss of the structure is as shown in the following table: Figure 11 As shown in the following table, the results show that the folding type structure has similar double-V type insertion loss characteristics in the frequency domain as the straight line type structure, forming a power supply noise stop band of 21.3 kHz to 9.22 GHz.

[0077] In addition to the above-mentioned manner, the folding manner of the present application can also be changed as follows: for a structure containing 6 periodic units, 3 groups by 2 columns, as shown in the following table: Figure 12 For a structure containing 2 groups by 3 columns, as shown in the following table: Figure 13 For a structure containing 12 periodic units, 6 groups by 2 columns, as shown in the following table: Figure 14 For a structure containing 4 groups by 3 columns, as shown in the following table: Figure 15 For a structure containing 3 groups by 4 columns, as shown in the following table: Figure 16 The number of periodic units contained in the present application is not limited to 6 or 12, but can be appropriately selected. The more the number of periodic units, the better the power supply noise suppression effect, but correspondingly, the cost will be increased and the occupied area will be larger.

[0078] Referring to Figure 17 The application embodiment further 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. The method comprises the following steps:

[0079] S100, setting the resonant frequency of the power supply noise filter according to the actual application requirement, determining the upper limit cutoff frequency of the power supply noise filter and the lower limit cutoff frequency of the power supply noise filter according to the resonant frequency;

[0080] S200, determining the structure parameters, device parameters and electromagnetic bandgap structure periodic unit number of the power supply noise filter according to the upper limit cutoff frequency and the lower limit cutoff frequency;

[0081] It should be noted that in some embodiments, step S200 can include: S210, determining the capacitance value of the decoupling capacitor and the capacitance value of the equivalent capacitor between the power supply line and the ground layer according to the upper limit cutoff frequency and the lower limit cutoff frequency; S220, determining the width of the power supply line and the period length according to the capacitance value of the equivalent capacitor between the power supply line and the ground layer, and combining the capacitance value of the decoupling capacitor to obtain the structure parameters and device parameters of the power supply noise filter; S230, determining the number of periodic units of the electromagnetic bandgap structure according to the actual application requirements.

[0082] In some specific embodiments, the step of determining the structure parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter includes: estimating the values of and based on the given upper and lower limit cutoff frequencies according to the following expressions:

[0083]

[0084]

[0085] In the above expressions, and represent the upper limit and lower limit cutoff frequencies, respectively; represents the equivalent inductance of the via (unit: H), that is, the fourth inductance 56 in Figure 5 represents the capacitance value of the decoupling capacitor (unit: F), that is, the second equivalent capacitor 54 in Figure 5 represents the equivalent capacitance between the power supply line and the ground layer in one period unit (unit: F), that is, the first equivalent capacitor 53 in Figure 5 .

[0086] wherein, The determination step is: according to the PCB process, the height of the dielectric layer, the appropriate via diameter and pad size are determined, and the equivalent inductance of the via is extracted by electromagnetic simulation software, that is, Based on the determined value of , the appropriate power supply line width (unit: mm) and period length (unit: m) are determined according to the following formula:

[0087]

[0088] In the above expressions, is in pF, is the relative dielectric constant of the dielectric layer, is the height of the power supply line (unit: mm), ​​​​​is the height of the dielectric layer (unit: mm). The number of periodic units of the electromagnetic bandgap structure used by the power supply noise filter is generally not less than 6. The more the number of periodic units, the better the noise suppression effect.

[0089] S300, according to the structure parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure, and the area of the actual application, determine the periodic unit arrangement mode of the power supply noise filter;

[0090] In some embodiments, according to the determined structure parameters, the number of periodic units and the area of the actual application, a suitable periodic unit arrangement mode can be determined, which can use a linear type or a serpentine folding structure with different arrangement modes.

[0091] S400, according to the periodic unit arrangement mode of the power supply noise filter, and combining the structure parameters of the power supply noise filter, determine the equivalent circuit parameters;

[0092] In some embodiments, the equivalent inductance of the power supply line in half a period , that is, the first inductance combination 93 in Figure 9 ; the parasitic inductance introduced by the decoupling capacitor, the pad, the capacitor and the pad connection, and the layout of the wiring , that is, the first equivalent inductance 97 in Figure 9 ; the coupling capacitance of adjacent power supply lines , that is, the first mutual capacitance combination 96 in Figure 9 ; the coupling capacitance between the pad and the adjacent power supply line , that is, the third equivalent capacitance 99 in Figure 9 ; the mutual inductance of adjacent power supply lines , that is, the fourth mutual inductance 913 in Figure 9 ; the mutual inductance between the parasitic inductances of adjacent periodic units , that is, the third mutual inductance 912 in Figure 9 ; the via mutual inductance , that is, the first mutual inductance 910 in Figure 9 ; the via mutual inductance , that is, the second mutual inductance 911 in Figure 9 .

[0093] Wherein, based on the determined equivalent circuit parameters, the equivalent circuit simulation is carried out, and the steps are: based on the above determined , and the number of periodic units and the periodic unit arrangement mode determined, according to Figure 9 , the equivalent circuit is built and simulated.

[0094] S500, the equivalent circuit parameters are simulated by the equivalent circuit, the power supply noise filter parameters are determined according to the simulation results, and the power supply noise filtering of the target chip is realized;

[0095] It should be noted that in some embodiments, step S500 can include: S510, drawing a power supply line on the metal layer required by the circuit board; S520, arranging decoupling capacitors on the top layer or bottom layer metal layer of the circuit board according to the periodic unit arrangement mode of the power supply noise filter; S530, setting a via hole to establish an electrical connection between the ground end of the decoupling capacitor and the ground layer, and applying a power supply signal to the power supply noise filter according to the equivalent circuit parameters, to realize power supply noise filtering for the target chip.

[0096] In some specific embodiments, a power supply line is drawn on the metal layer required by the circuit board, decoupling capacitors are periodically arranged on the top layer or bottom layer metal layer according to a determined arrangement mode, a via hole is set to establish an electrical connection between the ground end of the decoupling capacitor and the ground layer, and a power supply signal is applied to the filter to achieve a wideband noise suppression effect.

[0097] In summary, the embodiment of the present application first designs the resonant frequency, upper limit and lower limit cutoff frequency of the power supply noise filter according to actual application requirements; determines the structure parameters, device parameters and electromagnetic bandgap structure periodic unit number of the power supply noise filter; determines the periodic unit arrangement mode of the power supply noise filter; extracts equivalent circuit parameters using simulation software based on the determined structure parameters; performs equivalent circuit simulation based on the determined equivalent circuit parameters to verify that the filtering characteristics meet the application requirements; and performs power supply noise filtering for the target chip using the filter when the parameter configuration of the power supply noise filter is completed.

[0098] Therefore, the embodiment of the present application has the following advantages:

[0099] 1) A periodic repeating structure similar to the electromagnetic bandgap structure is adopted, which greatly expands the upper limit cutoff frequency of the -30dB power supply noise stopband, breaking through the frequency range limitation of the power supply noise suppression scheme based on the traditional decoupling capacitor.

[0100] 2) A plurality of decoupling capacitors are connected in parallel, and the power supply noise filter structure exhibits the characteristics of a lumped capacitor when the frequency is low, expanding the lower limit cutoff frequency of the -30dB power supply noise stopband.

[0101] 3) A large decoupling capacitor value and a small periodic unit length are adopted, so that the periodic unit has a compact arrangement, and compared with other power supply noise filter structures, it has the advantage of small size.

[0102] 4) A foldable periodic unit arrangement mode is adopted, which has high geometric flexibility and is suitable for various layout-limited high-density circuit board occasions.

[0103] 5) The power line structure is adopted, compared with other planar-based power noise suppression schemes, manufacturing cost is saved, and a large-area circuit board does not need to be occupied, and the application range is extended.

[0104] It can be understood that the contents in the above method embodiments are applicable to the system embodiments, the system embodiments specifically implement the functions same as the above method embodiments, and achieve the same beneficial effects as the above method embodiments.

[0105] The preferred embodiments of the application are described above with reference to the accompanying drawings, and the scope of the right of the application embodiments is not limited by this. Any modification, equivalent replacement and improvement made by the person skilled in the art within the scope and essence of the application embodiments should be within the right scope of the application embodiments.

Claims

1. A filtering method of a power supply noise suppression structure based on an electromagnetic bandgap structure, characterized by, The method comprises the following steps: Setting the resonant frequency of the power supply noise filter, determining the upper limit cutoff frequency of the power supply noise filter and the lower limit cutoff frequency of the power supply noise filter according to the resonant frequency; According to the upper limit cutoff frequency and the lower limit cutoff frequency, the structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter are determined; According to the structural parameters, the device parameters and the number of periodic units of the electromagnetic bandgap structure, the arrangement mode of the periodic units of the power supply noise filter is determined; According to the arrangement mode of the periodic units of the power supply noise filter, the equivalent circuit parameters are determined in combination with the structural parameters of the power supply noise filter; The equivalent circuit parameters are simulated, and the power supply noise filter parameters are determined according to the simulation results to realize the power supply noise filtering of the target chip; Wherein, according to the upper limit cutoff frequency and the lower limit cutoff frequency, the structural parameters, device parameters and the number of periodic units of the electromagnetic bandgap structure of the power supply noise filter are determined, comprising: According to the upper limit cutoff frequency and the lower limit cutoff frequency, the capacitance value of the decoupling capacitor and the capacitance value of the equivalent capacitor between the power supply line and the ground layer are determined; According to the capacitance value of the equivalent capacitor between the power supply line and the ground layer, the width and the period length of the power supply line are determined, and the structural parameters and the device parameters of the power supply noise filter are obtained in combination with the capacitance value of the decoupling capacitor; The number of periodic units of the electromagnetic bandgap structure is determined; The calculation expression of the structural parameters and the device parameters of the power supply noise filter is: In the above formula, f H represents the upper limit cutoff frequency, f L represents the lower limit cutoff frequency, L v represents the via equivalent inductance, C represents the capacitance value of the decoupling capacitor, C L represents the equivalent capacitance between the power supply line and the ground layer in one period unit, w represents the width of the power supply line, p represents the period length of the power supply line, ∈ r represents the relative dielectric constant of the dielectric layer, t represents the height of the power supply line, and h represents the height of the dielectric layer.

2. The method of claim 1, wherein, The equivalent circuit parameters are simulated, and the power supply noise filter parameters are determined according to the simulation results to realize the power supply noise filtering of the target chip, comprising: Drawing the power supply line on the metal layer required by the circuit board; According to the arrangement mode of the periodic units of the power supply noise filter, arranging the decoupling capacitor on the top layer or the bottom layer metal layer of the circuit board; Setting a through hole to establish electrical connection between the ground end of the decoupling capacitor and the ground layer, and applying a power supply signal to the power supply noise filter in combination with the equivalent circuit parameters to realize the power supply noise filtering of the target chip.

3. A power supply noise suppression structure based on an electromagnetic bandgap structure, characterized by, The power supply noise suppression structure is filtered and controlled by the filtering method of any one of claims 1-2, and the power supply noise suppression structure is composed of a plurality of electromagnetic bandgap structures through a pre-set periodic arrangement structure, and the plurality of electromagnetic bandgap structures comprise a power supply line, a decoupling capacitor and a through hole, a first end of the decoupling capacitor is connected to the power supply line, and a second end of the decoupling capacitor is grounded through the through hole, wherein: One end of the power supply line is connected to a power supply modulation module, and the other end is connected to an integrated circuit pin pad for power supply, and the power supply line is used to adjust the upper limit cutoff frequency of the power supply noise stopband; The decoupling capacitor is used to adjust the lower limit cutoff frequency of the power supply noise stopband; The other end of the through hole is grounded.

4. The power supply noise suppression structure of claim 3, wherein, The preset periodic arrangement structure includes a straight line structure and a folded structure, wherein the straight line structure represents that power lines in the plurality of EBG structures are sequentially cascaded in turn, the folded structure represents that the power lines in the plurality of EBG structures are folded into a snake shape and then sequentially cascaded, and the decoupling capacitor is welded on the same side of the power lines.

5. The power supply noise suppression structure of claim 4, wherein, For the straight line structure, an equivalent circuit of the EBG 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 lines are 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 via hole is represented by the fourth inductor.

6. The power supply noise suppression structure of claim 5, wherein, A second end of the first inductor, a first end of the second inductor, a first end of the first equivalent capacitor and a first end of the second equivalent capacitor are connected, a second end of the second equivalent capacitor and a first end of the third inductor are connected, a second end of the third inductor and a first end of the fourth inductor are connected, a second end of the first equivalent capacitor and a second end of the fourth inductor are connected and grounded.

7. The power supply noise suppression structure of claim 4, wherein, For the folded structure, an equivalent circuit of the EBG structure includes a fifth inductor, a sixth inductor, a first capacitor, a second capacitor, a third capacitor, a first mutual capacitor, a second mutual capacitor, a first equivalent inductor, a second equivalent inductor and a third equivalent capacitor, wherein the fifth inductor and the sixth inductor are introduced by the distributed inductance of the power lines, the first capacitor and the second capacitor are introduced by the distributed capacitance of the power lines, the third capacitor is introduced by the decoupling capacitor, the first mutual capacitor and the second mutual capacitor 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, the wiring layout at the connection between the capacitor and the pad, the second equivalent inductor is introduced by the via hole, and the third equivalent capacitor is introduced by the coupling capacitance between the pad and the adjacent power line.

8. The power supply noise mitigation structure of claim 7, wherein, A first end of the fifth inductor, a first end of the first capacitor and a first end of the first mutual capacitor are connected, a second end of the fifth inductor, a first end of the sixth inductor and a first end of the third capacitor are connected, a second end of the sixth inductor, a first end of the second mutual capacitor and a first end of the second capacitor are connected, a second end of the first mutual capacitor, a second end of the second mutual capacitor and a second end of the third equivalent capacitor are connected, a second end of the third capacitor and a second end of the first equivalent inductor are connected, a second end of the first equivalent inductor, a first end of the second equivalent inductor and a first end of the third equivalent capacitor are connected, a second end of the first capacitor, a second end of the second capacitor and a second end of the second equivalent inductor are grounded.

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