KR20080072505A - Electromagnetic Bandgap Structures and Printed Circuit Boards - Google Patents

Abstract

Disclosed are an electromagnetic bandgap structure and a printed circuit board which solve a mixed signal problem between an analog circuit and a digital circuit. The electromagnetic bandgap structure includes a first metal plate on which a first metal layer, a first dielectric layer, a second dielectric layer, and a second metal layer are stacked, and formed between the first dielectric layer and the second dielectric layer; A second metal plate formed on the same plane as the first metal plate and accommodated in a hole formed in the first metal plate and electrically connected to the first metal plate through a metal wire; and the second metal plate and the first metal plate. And vias connecting any one of the metal layer and the second metal layer. Such an electromagnetic bandgap structure may have a small size but a low bandgap frequency.

Description

Electromagnetic bandgap structure and printed circuit board

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board, and more particularly, to an electromagnetic bandgap structure and a printed circuit board which solve a mixed signal problem between an analog circuit and a digital circuit.

Recently, as mobility is important, various devices such as mobile communication terminals, PDAs (Personal Digital Assistants), notebook computers, and DMB (Digital Multimedia Broadcasting) devices capable of wireless communication are being released.

These devices include printed circuit boards that consist of a combination of analog circuits (eg RF circuits) and digital circuits for wireless communication.

1 is a cross-sectional view of a printed circuit board including an analog circuit and a digital circuit. Although the printed circuit board 100 having a four-layer structure is illustrated, a printed circuit board having various structures, such as two layers and six layers, is also applicable. Here, it is assumed that the analog circuit is an RF circuit.

The printed circuit board 100 may include a metal layer 110-1, 110-2, 110-3, 110-4, hereinafter abbreviated as 110, and a dielectric layer stacked between the metal layer 110. (120) (divided into 120-1, 120-2, and 120-3), a digital circuit 130 mounted on the uppermost metal layer 110-1, and an RF circuit 140.

Assuming that the metal layer 110-2 is a ground layer and the metal layer 110-3 is a power layer, a via connected between the ground layer 110-2 and the power layer 110-3. Current flows through the 160, and the printed circuit board 100 performs a predetermined operation or function.

Here, the electromagnetic wave (EM wave) 150 due to the operating frequency of the digital circuit 130 and the harmonics components are transmitted to the RF circuit 140 to generate a mixed signal problem. The mixed signal problem means that electromagnetic waves in the digital circuit 130 interfere with the correct operation of the RF circuit 140 because they have frequencies within the frequency band in which the RF circuit 140 operates. For example, when the RF circuit 140 receives a signal of a predetermined frequency band, since the electromagnetic wave 150 including the signal in the frequency band is transmitted from the digital circuit 130, the accurate signal within the corresponding frequency band may be lost. Reception can be difficult.

The mixed signal problem is difficult to solve as the operating frequency of the digital circuit 130 increases as the electronic device becomes complicated and becomes more complicated.

The decoupling capacitor method, which is a typical solution of power noise, is not an appropriate solution at high frequencies. Therefore, a study of a structure that blocks high frequency noise between RF circuits and digital circuits is required.

2 is a cross-sectional view of an electromagnetic bandgap structure for solving a mixed signal problem between an analog circuit and a digital circuit according to the prior art, and FIG. 3 is a plan view showing a metal plate arrangement structure of the electromagnetic bandgap structure shown in FIG. 4 is a perspective view of the electromagnetic bandgap structure shown in FIG. 2, and FIG. 5 is an equivalent circuit diagram of the electromagnetic bandgap structure shown in FIG. 2.

The electromagnetic bandgap structure 200 may include a first metal layer 210-1, a second metal layer 210-2, a first dielectric layer 220a, a second dielectric layer 220b, a metal plate 232, Via 234 is included.

The first metal layer 210-1 and the metal plate 232 are connected through the via 234, and the metal plate 232 and the via 234 form a mushroom type structure 230 (FIG. 4). Reference).

When the first metal layer 210-1 is a ground layer The second metal layer 210-2 is a power layer, and when the first metal layer 210-1 is a power layer, the second metal layer is a power layer. 210-2 becomes a ground layer.

That is, by repeatedly forming the mushroom-like structure 230 formed of the metal plate 232 and the via 234 between the ground layer and the power layer (see FIG. 3), a band that does not pass a signal included in a specific frequency band It has a gap structure.

Functions that do not pass signals in a particular frequency band include resistance (R _E , R _P ), inductance (L _E , L _P ), capacitance (C _E , C _P , C _G ) And the conductance (G _P , G _E ) components, which are expressed by approximating an equivalent circuit as shown in FIG. 5.

BACKGROUND OF THE INVENTION Representative electronic devices in which digital circuits and RF circuits are implemented and used on the same substrate are mobile communication terminals. In order to solve the mixed signal problem in the mobile communication terminal, noise shielding is required in the region of 0.8 to 2.0 GHz, which is an operating frequency of the RF circuit, and the size of the mushroom structure must be small to be used in the mobile communication terminal. However, when using the above-described electromagnetic bandgap structure there is a problem that does not satisfy both at the same time.

As the size of the mushroom structure decreases, the bandgap frequency at which the noise is shielded increases, which is not effective in the 0.8 to 2.0 GHz range of the operating frequency of the RF circuit.

Accordingly, the present invention provides an electromagnetic bandgap structure and a printed circuit board having a small size and low bandgap frequency.

In addition, the present invention provides an electromagnetic bandgap structure and a printed circuit board that solves a mixed signal problem in an electronic device (eg, a mobile communication terminal, etc.) in which an RF circuit and a digital circuit are implemented in the same substrate.

The present invention also provides an electromagnetic bandgap structure and a printed circuit board that do not pass noise of a specific frequency.

Other objects of the present invention will be readily understood through the following description.

According to one aspect of the present invention, an electromagnetic bandgap structure is provided that prevents signal transmission in a predetermined frequency band.

According to one embodiment, an electromagnetic bandgap structure in which a first metal layer, a first dielectric layer, a second dielectric layer, and a second metal layer are stacked, comprising: a first metal plate formed between the first dielectric layer and the second dielectric layer; A second metal plate formed on the same plane as the first metal plate and accommodated in a hole formed in the first metal plate and electrically connected to the first metal plate through a metal wire; and the second metal plate and the first metal plate. An electromagnetic bandgap structure is provided that includes a metal layer and a via connecting one of the second metal layers.

The metal line may be formed on the same plane as the first metal plate and the second metal plate.

In addition, the inner wall of the hole may be spaced apart from the second metal plate at a predetermined interval.

The metal wire may have a straight or curved shape or a spiral shape surrounding the second metal plate.

According to another embodiment, the first metal layer; A first dielectric layer stacked on the first metal layer; A metal plate stacked on the first dielectric layer; A via connected at one end to the first metal layer; A second dielectric layer stacked on the metal plate and the first dielectric layer; And a second metal layer stacked on the second dielectric layer, wherein the other end of the via is connected to a via land located in a hole formed in the metal plate, and the via land is connected to the metal plate through a metal line. An electromagnetic bandgap structure is provided. The metal line may have a straight, curved or spiral form.

According to another aspect of the present invention, there is provided a printed circuit board comprising an analog circuit and a digital circuit to prevent signal transmission of a predetermined frequency band from the digital circuit to the analog circuit.

According to an embodiment, a printed circuit board may include: a first metal plate formed between the first dielectric layer and the second dielectric layer; A second metal plate formed on the same plane as the first metal plate and accommodated in a hole formed in the first metal plate and electrically connected to the first metal plate through a metal wire; and the second metal plate and the first metal plate. An electromagnetic bandgap structure comprising a metal layer and a via connecting one of the second metal layers is disposed between the analog circuit and the digital circuit.

Here, the first metal layer may be either a ground layer or a power layer, and the second metal layer may be the other.

The analog circuit may be an RF circuit including an antenna for receiving a radio signal from the outside.

The metal line may be formed on the same plane as the first metal plate and the second metal plate.

In addition, the inner wall of the hole may be spaced apart from the second metal plate at a predetermined interval.

The metal wire may have a straight or curved shape or a spiral shape surrounding the second metal plate.

In addition, a plurality of electromagnetic bandgap structures may be disposed between the analog circuit and the digital circuit.

According to another embodiment of the present invention, a printed circuit board includes: a first metal layer, a first dielectric layer stacked on the first metal layer, a metal plate stacked on the first dielectric layer, and vias connected to one end of the first metal layer; An electromagnetic bandgap structure comprising a second dielectric layer stacked on the metal plate and the first dielectric layer and a second metal layer stacked on the second dielectric layer is disposed between the analog circuit and the digital circuit, the vias of the via The other end is connected to a via land located in a hole formed in the metal plate, and the via land is connected to the metal plate through a metal wire.

The first metal layer may be either a ground layer or a power supply layer, and the second metal layer may be the other. The analog circuit may be an RF circuit including an antenna for receiving a radio signal from the outside. The metal line may have a straight, curved or spiral form.

The electromagnetic bandgap structure and the printed circuit board according to the present invention may have a small size but a low bandgap frequency.

In addition, there is an effect of solving a mixed signal problem in an electronic device (for example, a mobile communication terminal, etc.) in which an RF circuit and a digital circuit are implemented in the same substrate.

In addition, there is an effect of suppressing signal transmission at a specific frequency or reducing noise at a specific frequency.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component. The term and / or includes a combination of a plurality of related items or any item of a plurality of related items.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as having meanings consistent with the meanings in the context of the related art, and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. Do not.

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described in detail.

FIG. 6 is a cross-sectional view of an electromagnetic bandgap structure for solving a mixed signal problem between an analog circuit and a digital circuit according to an embodiment of the present invention, and FIG. 7 is an electromagnetic bandgap structure according to AA ′ shown in FIG. 6. It is a top view which shows the metal plate arrangement structure of this. FIG. 8 is a perspective view of the electromagnetic bandgap structure shown in FIG. 6.

Electromagnetic bandgap structure 300 comprising a first metal layer 210-1, a second metal layer 210-2, a first dielectric layer 220a, a second dielectric layer 220b, a metal plate 332, and a via 334. Is a cross-sectional view of FIG. 6.

The first metal layer 210-1 and the metal plate 332 are connected through the via 334. The dielectric layer 220 is stacked between the first metal layer 210-1 and the second metal layer 210-2. The dielectric layer 220 is divided into a first dielectric layer 220a and a second dielectric layer 220b according to the formation time based on the metal plate 332.

The first metal layer 210-1, the second metal layer 210-2, the metal plate 332, and the via 334 may be a metal material (eg, copper (Cu), etc.) to which power is supplied and a signal may be transmitted. It is composed of

The first dielectric layer 220a and the second dielectric layer 220b may be made of the same dielectric material or dielectric materials having different dielectric constants.

When the first metal layer 210-1 is a ground layer The second metal layer 210-2 is a power layer, and when the first metal layer 210-1 is a power layer, the second metal layer is a power layer. Reference numeral 210-2 is a ground layer. That is, the first metal layer 210-1 and the second metal layer 210-2 are composed of a ground layer and a power layer adjacent to each other with the dielectric layer 220 interposed therebetween.

The metal plate 332 is illustrated as having a square shape in FIG. 7, but may be in various forms such as polygons, circles, and ellipses.

A hole 320 is formed in the metal plate 332, and the via 334 is located in the hole 320. The via 334 and the metal plate 332 are connected through the metal wire 310 (see FIGS. 7 and 8).

The method of forming the via 334 is as follows.

The first metal layer 210-1, the first dielectric layer 220, and the metal plate 332 are sequentially stacked. The via land 340 is formed at the position where the via 334 is to be formed to be electrically connected to the first metal layer 210-1 of the metal plate 332. The via land 340 is to overcome the position error in the drilling process for forming the via 334, and is formed larger than the cross-sectional area of the via 334.

The via land 340 is formed in the hole 320 penetrating the metal plate 332, and the via land 340, the hole 320, and the like may be masked after the metal plate 332 or at the same time as the metal plate 332 is formed. It is formed by a general printed circuit board manufacturing process such as exposure, etching, and development.

In addition, a via penetrating the via land 340 and the first dielectric layer 220 is formed through a drilling process. Alternatively, vias may be formed through the via land 340, the first dielectric layer 220, and the first metal layer 210-1.

After the formation of the via, a plating process is performed such that a plating layer is formed on an inner wall of the via for electrical connection between the first metal layer 210-1 and the via land 340. Depending on the plating process, the center portion of the inside of the via is empty, and a plating layer may be formed only on the inner wall of the via, or the inside of the via may be filled. When the central portion of the interior of the via is empty, the central portion may be filled with dielectric material or air. The formation of such vias is obvious to those skilled in the art, and detailed descriptions thereof will be omitted.

One end 334b of the via 334 is connected to the first metal layer 210-1, and the other end 334a of the via 334 is located inside the hole 320 formed in the metal plate 332. Is connected to the land 340. One end 310a of the metal line 310 is connected to the via land 340, and the other end 310b of the metal line 310 is connected to the metal plate 332.

The metal line 310 is positioned on the same plane as the metal plate 332 and may be formed simultaneously in the same process of the manufacturing process of the electromagnetic bandgap structure 330.

The metal wires 310 shown in FIGS. 6 to 8 have a straight line shape, but may also have various shapes such as a curved line and a spiral shape.

The inner wall of the hole 320 is spaced apart from the via land 340 connected to the other end 334a of the via 334 and spaced apart from the rest of the metal wire 310 except for the portion connected to the metal plate 332. It is.

In the mushroom structure 330 including the metal plate 332 and the via 334, one or more may be formed between the first metal layer 210-1 and the second metal layer 210-2.

The metal plate 332 of the mushroom structure 330 may be disposed on the same plane or on different planes between the first metal layer 210-1 and the second metal layer 210-2. In addition, although the via 334 of the mushroom structure 330 is illustrated as being connected to the first metal layer 210-1 in FIG. 6, it may be connected to the second metal layer 210-2.

In addition, the plurality of mushroom structures 330 are all connected to the first metal layer 210-1 or the second metal layer 210-2 through the vias 334, or some mushroom structures 330 may be formed. The first metal layer 210-1 may be connected, and the remaining mushroom structure 330 may be connected to the second metal layer 210-2.

Referring to FIG. 7, the mushroom structure 330 is repeatedly arranged at predetermined intervals. Since the mushroom structure 330 is repeatedly formed, it is possible to shield a signal in a frequency domain corresponding to an operating frequency region of an analog circuit (for example, an RF circuit) among electromagnetic waves traveling from a digital circuit to an analog circuit. Do.

By forming the structure of the metal plate 332 connected to the via 334 in the mushroom structure 330 as shown in Figures 6 to 8, the capacitance between the metal plate 332 and the second metal layer 210-2 The value C _E decreases to be negligible. In addition, the inductance value L _E connected in series between the metal plate 332 and the first metal layer 210-1 corresponding to the via 334 may be sufficiently secured.

Therefore, even if the size of the mushroom-like structure 330 can be reduced without increasing the band gap frequency. The bandgap frequency refers to a frequency at which transmission of electromagnetic waves from one side of the electromagnetic bandgap structure 300 to the other side is suppressed. In the embodiment of the present invention, the 0.8 to 2.0 GHz region, which is an operating frequency region in the RF circuit of the mobile communication terminal, corresponds to the band gap frequency region.

Computer simulation results using the electromagnetic bandgap structure 300 according to an embodiment of the present invention and the electromagnetic bandgap structure 200 according to the related art are shown in FIG. 9.

Referring to FIG. 9, the structure size of the conventional electromagnetic bandgap structure 200 (that is, the size of the metal plate 232) is 49 mm 2 (7 × 7) (see 910), and 324 mm 2 (18 × 18). Is illustrated (see 920).

When the structure size is 49 mm2 (7x7) (see 910), the frequency with a noise level of -50 dB or less is 2 to 3.6 GHz, and its center frequency bandgap frequency is 2.8 GHz.

When the structure size is 324 mm2 (18x18) (see 920), the frequency with a noise level of -50 dB or less is 0.7 to 1.3 GHz, and the band gap frequency, which is its center frequency, is 1.0 GHz.

That is, in the case of the conventional electromagnetic bandgap structure 200, the noise must be shielded by placing a bandgap frequency in a region of 0.8 to 1.0 GHz, which is an operating frequency of an RF circuit used in a mobile communication terminal. (18 × 18) (see 920).

However, in the case of the electromagnetic bandgap structure 300 according to an embodiment of the present invention, when the structure size (that is, the size of the metal plate 332) is 49 mm2 (7 × 7) (see 930) A frequency with a level below -50 dB is 0.8-1.2 GHz, and its center frequency bandgap frequency is 1.0 GHz.

This is shown in Table 1 below.

That is, when the electromagnetic bandgap structure 300 according to an embodiment of the present invention has the same bandgap frequency as the electromagnetic bandgap structure 200 according to the prior art, its size can be reduced by 1/6 or more. (324 mm 2 → 49 mm 2) can be confirmed.

In addition, even in the case of the same structure size, the bandgap frequency is more than 1/3 low (2.8 GHz → 1 GHz) can be confirmed.

FIG. 10 is a three-dimensional perspective view of an electromagnetic bandgap structure according to another embodiment of the present invention, and FIG. 11 is a plan view showing a structure in which the number of metal plates of the electromagnetic bandgap structure shown in FIG. 10 is arranged. 12 is a three-dimensional perspective view of an electromagnetic bandgap structure according to another embodiment of the present invention, Figure 13 is a plan view showing a structure in which the number of metal plate drums of the electromagnetic bandgap structure shown in FIG.

The electromagnetic bandgap structure 400 may include a first metal layer 410, a second metal layer 420, a first dielectric layer 430a, a second dielectric layer 430b, a first metal plate 440a, a second metal plate 440b, Vias 450.

The mushroom structure 460 includes a first metal plate 440a having a predetermined size, a second metal plate 440b accommodated in the hole 445 formed in the first metal plate 440a, and one end of the mushroom-shaped structure 460. And a via 450 connected to the other end of the second metal plate 440b. The first metal plate 440a and the second metal plate 440b are located on the same plane. The inner wall of the hole 445 of the first metal plate 440a and the outer outer wall of the edge of the second metal plate 440b are spaced apart from each other by a predetermined distance and are electrically connected only through the metal wire 442.

The first dielectric layer 430a is stacked on the first metal layer 410, and the first metal plate 440a and the second metal plate 440b are stacked on the first dielectric layer 430a. The second dielectric layer 430b is stacked on the first metal plate 440a, the second metal plate 440b, and the first dielectric layer 430a. The dielectric layer 430 is divided into a first dielectric layer 430a and a second dielectric layer 430b according to a formation time based on the first metal plate 440a and the second metal plate 440b.

The first metal layer 410, the second metal layer 420, the first metal plate 440a, the second metal plate 440b, and the via 450 may be a metal material to which power is supplied to which a signal may be transmitted (for example, Copper (Cu) and the like).

The first dielectric layer 430a and the second dielectric layer 430b may be formed of the same dielectric material or a dielectric material having the same or different dielectric constants.

When the first metal layer 410 is a ground layer, the second metal layer 420 is a power layer, and when the first metal layer 410 is a power layer, the second metal layer 420 is a ground layer. That is, the first metal layer 410 and the second metal layer 420 are composed of a ground layer and a power supply layer adjacent to each other with the dielectric layer 430 interposed therebetween.

Although the first metal plate 440a is illustrated as having a square shape, the first metal plate 440a may have various shapes such as polygons, circles, and ellipses. Although the second metal plate 440b is also illustrated as having a square shape, the second metal plate 440b may have various shapes such as polygons, circles, and ellipses.

The method of forming the electromagnetic bandgap structure 400 is as follows.

The first metal layer 410 and the first dielectric layer 430a are stacked.

Thereafter, a via 450 penetrating the first dielectric layer 430a is formed through a drilling process so that the second metal plate 440b to be stacked on the first dielectric layer 430a and the first metal layer 410 are electrically connected. do.

After the via 450 is formed, a plating process is performed such that a plating layer is formed on an inner wall of the via 450 for electrical connection between the first metal layer 410 and the second metal plate 440b. Depending on the plating process, the center portion of the inside of the via is empty, and a plating layer may be formed only on the inner wall of the via, or the inside of the via may be filled. When the central portion of the interior of the via is empty, the central portion may be filled with dielectric material or air. The formation of such vias is obvious to those skilled in the art, and detailed descriptions thereof will be omitted.

After the metal layer is stacked, the first metal plate 440a, the second metal plate 440b, and the metal wire 442 are formed by patterning. The patterning operation uses a method of masking, exposure, etching, development, etc., which is generally used when forming a circuit pattern on a printed circuit board, and thus a detailed description thereof will be omitted.

In addition, the electromagnetic bandgap structure 400 is formed by sequentially stacking the second dielectric layer 430b and the second metal layer 420.

The mushroom structure 460 including the first metal plate 440a, the second metal plate 440b, the metal wires 442, and the vias 450 may include at least one between the first metal layer 410 and the second metal layer 420. It may be formed. The metal plates of the plurality of mushroom-like structures 460 may be disposed on the same plane or on different planes. In addition, although the vias 450 of the mushroom structure 460 face the first metal layer 410, they may also face the second metal layer 420.

In addition, the vias 450 of the plurality of mushroom structures 460 may all face the first metal layer 410 or toward the second metal layer 420, or the vias 450 of some mushroom structures 460 may be used. ) May face the first metal layer 410 and the vias 450 of the remaining mushroom-like structure 460 may face the second metal layer 420.

The metal line 442 may have a straight form (see FIG. 10) or a spiral form (see FIG. 12). Alternatively, the present invention may have various forms such as curved shapes, and one end is connected to the first metal plate 440a and the other end is connected to the second metal plate 440b.

Referring to FIG. 11 or 13, the mushroom structure 460 is shown to be repeatedly arranged on the first metal layer 410 at a predetermined interval. The mushroom structure 460 is repeatedly formed to more effectively shield signals in the frequency domain corresponding to the operating frequency range of the analog circuit (for example, RF circuit) among electromagnetic waves traveling from the digital circuit to the analog circuit. It is possible.

In the mushroom structure 460, the band gap frequency is reduced even when the size of the mushroom structure 360 is reduced by connecting the second metal plate 440b and the first metal plate 440a connected to the via 450 with the metal wire 442. Has a low value without increasing it.

The results of computer simulations using the electromagnetic bandgap structure 400 according to another embodiment of the present invention and the electromagnetic bandgap structure 200 according to the related art are shown in FIG. 14.

Referring to FIG. 14, the structure size of the conventional electromagnetic bandgap structure 200 (that is, the size of the metal plate 232) is 4 mm 2 (2 × 2) (see 1410), and 64 mm 2 (8 × 8). Is shown (see 1420).

When the structure size is 4 mm2 (2x2) (see 1410), frequencies with noise levels below -50 dB are above 5.5 GHz.

And when the structure size is 64 mm2 (8x8) (see 1420), the frequency with noise level below -50 dB is 1.5-1.8 GHz, and the frequency with the lowest noise level is 1.7 GHz.

That is, in the case of the conventional electromagnetic bandgap structure 200, the noise must be shielded by placing the bandgap frequency in the 0.8 to 2.0 GHz region, which is an operating frequency of the RF circuit used in the mobile communication terminal, and the structure size is 64 mm2. (8x8) (see 1420).

However, in the case of the electromagnetic bandgap structure 400 according to another embodiment of the present invention, the structure size (ie, the size of the first metal plate 440a) is 4 mm 2 (2 × 2) (see 1430). The frequency with noise level below -50 dB is 1.2 to 3.2 GHz, and the frequency with the lowest noise level is 1.7 GHz.

This is shown in Table 2 below.

That is, when the electromagnetic bandgap structure 400 according to another embodiment of the present invention has the same bandgap frequency as the electromagnetic bandgap structure 200 according to the prior art, the size can be reduced by 1/16 or more (64 mm 2 → 4 mm 2) can be confirmed.

In addition, even in the same structure size it can be seen that the bandgap frequency is more than 1/4 low (7.5 GHz → 1.7 GHz).

The printed circuit board according to the present invention includes an analog circuit and a digital circuit. The analog circuit may be an RF circuit such as an antenna that receives a radio signal (RF signal) from the outside.

In the printed circuit board, the electromagnetic bandgap structure 300 according to one embodiment shown in FIGS. 6 to 8 or the electromagnetic bandgap structure 400 according to another embodiment shown in FIGS. 10 to 13 may be connected to an analog circuit. Disposed between the digital circuits. That is, the electromagnetic bandgap structure 300 or 400 is disposed between the RF circuit 140 and the digital circuit 130 of the printed circuit board shown in FIG. 1.

The electromagnetic bandgap structure 300 or 400 is disposed such that electromagnetic waves transmitted from the digital circuit 140 to the RF circuit 130 necessarily pass through the electromagnetic bandgap structure 300 or 400. That is, the electromagnetic bandgap structure 300 or 400 may be arranged in the form of a closed curve around the RF circuit 130, or the electromagnetic bandgap structure 300 or 400 may be arranged in the form of a closed curve around the digital circuit 140.

Alternatively, the electromagnetic bandgap structure 300 or 400 may be disposed in every printed circuit board from the digital circuit 140 to the RF circuit 130.

Since the above-described electromagnetic bandgap structure 300 or 400 is disposed therein, a printed circuit board in which an analog circuit and a digital circuit are simultaneously implemented and used is a specific frequency region (for example, electromagnetic wave transmitted from a digital circuit to an analog circuit). 0.8 ~ 2.0 GHz) can prevent the transmission of electromagnetic waves.

That is, despite the small structure size, it is possible to solve the mixed signal problem described above by preventing the transmission of electromagnetic waves in a specific frequency region corresponding to noise in the RF circuit.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art to which the present invention pertains without departing from the spirit and scope of the present invention as set forth in the claims below It will be appreciated that modifications and variations can be made.

1 is a cross-sectional view of a printed circuit board including an analog circuit and a digital circuit.

2 is a cross-sectional view of an electromagnetic bandgap structure that solves the mixed signal problem between analog and digital circuits in accordance with the prior art.

3 is a plan view showing a metal plate arrangement structure of the electromagnetic bandgap structure shown in FIG.

4 is a perspective view of the electromagnetic bandgap structure shown in FIG.

FIG. 5 is an equivalent circuit diagram of the electromagnetic bandgap structure shown in FIG. 2. FIG.

6 is a cross-sectional view of an electromagnetic bandgap structure that solves the mixed signal problem between analog and digital circuits in accordance with one embodiment of the present invention.

7 is a plan view showing a metal plate arrangement structure of the electromagnetic bandgap structure according to AA ′ shown in FIG. 6.

8 is a perspective view of the electromagnetic bandgap structure shown in FIG. 6.

9 is a result of computer simulation using the electromagnetic bandgap structure according to an embodiment of the present invention and the electromagnetic bandgap structure according to the prior art.

10 is a three-dimensional perspective view of an electromagnetic bandgap structure according to another embodiment of the present invention.

FIG. 11 is a plan view showing a structure in which the number of metal plate drums of the electromagnetic bandgap structure shown in FIG. 10 is arranged;

12 is a three-dimensional attempt of an electromagnetic bandgap structure according to another embodiment of the present invention.

FIG. 13 is a plan view showing a structure in which the number of metal plate drums of the electromagnetic bandgap structure shown in FIG. 12 is arranged; FIG.

Figure 14 is a computer simulation results using the electromagnetic bandgap structure according to another embodiment of the present invention and the electromagnetic bandgap structure according to the prior art.

<Description of the symbols for the main parts of the drawings>

100: printed circuit board

130: digital circuit 140: analog circuit

200, 300, 400: electromagnetic bandgap structure

210-1, 210-2, 410, 420: metal layer

220a, 220b, 430a, 430b: dielectric layer

232, 332: metal plate

234, 334, 450: Via

310, 442: metal wire

320, 445: hole

440a: first metal plate 440b: second metal plate

Claims (19)

An electromagnetic bandgap structure in which a first metal layer, a first dielectric layer, a second dielectric layer, and a second metal layer are stacked, A first metal plate formed between the first dielectric layer and the second dielectric layer; A second metal plate formed on the same plane as the first metal plate and accommodated in a hole formed in the first metal plate and electrically connected to the first metal plate through a metal wire; And And an via connecting the second metal plate to any one of the first metal layer and the second metal layer. The method of claim 1, And the metal wire is formed on the same plane as the first metal plate and the second metal plate. The method of claim 1, The inner wall of the hole is an electromagnetic bandgap structure, characterized in that spaced apart from the second metal plate. The method of claim 1, Electromagnetic bandgap structure, characterized in that the metal line has a straight or curved form. The method of claim 1, And said metal wire has a spiral shape surrounding said second metal plate. In a printed circuit board comprising an analog circuit and a digital circuit, A first metal plate formed between the first dielectric layer and the second dielectric layer; A second metal plate formed on the same plane as the first metal plate and accommodated in a hole formed in the first metal plate and electrically connected to the first metal plate through a metal wire; and And an electromagnetic bandgap structure including the second metal plate and vias connecting one of the first metal layer and the second metal layer to the analog circuit and the digital circuit. The method of claim 6, And the first metal layer is either a ground layer or a power layer, and the second metal layer is the other. The method of claim 6, The analog circuit is a printed circuit board, characterized in that the RF circuit including an antenna for receiving a wireless signal from the outside. The method of claim 6, The metal line is a printed circuit board, characterized in that formed on the same plane as the first metal plate and the second metal plate. The method of claim 6, The inner wall of the hole is spaced apart from the second metal plate by a predetermined interval. The method of claim 6, Printed circuit board, characterized in that the metal line has a straight or curved form. The method of claim 6, The metal line has a spiral shape surrounding the second metal plate. The method of claim 6, The electromagnetic bandgap structure is a printed circuit board, characterized in that a plurality is disposed between the analog circuit and the digital circuit. A first metal layer; A first dielectric layer stacked on the first metal layer; A metal plate stacked on the first dielectric layer; A via connected at one end to the first metal layer; A second dielectric layer stacked on the metal plate and the first dielectric layer; And A second metal layer laminated on the second dielectric layer, And the other end of the via is connected to a via land located in a hole formed in the metal plate, and the via land is connected to the metal plate through a metal wire. The method of claim 14, Electromagnetic bandgap structure, characterized in that the metal line has a straight, curved or spiral form. In a printed circuit board comprising an analog circuit and a digital circuit, The first metal layer, A first dielectric layer laminated on the first metal layer, A metal plate laminated on the first dielectric layer, A via connected at one end to the first metal layer; A second dielectric layer laminated on the metal plate and the first dielectric layer; An electromagnetic bandgap structure comprising a second metal layer stacked on the second dielectric layer, disposed between the analog circuit and the digital circuit, The other end of the via is connected to the via land located in the hole formed in the metal plate, the via land is connected to the metal plate via a metal line. The method of claim 16, And the first metal layer is either a ground layer or a power supply layer, and the second metal layer is the other. The method of claim 16, The analog circuit is a printed circuit board, characterized in that the RF circuit including an antenna for receiving a wireless signal from the outside. The method of claim 16, Printed circuit board, characterized in that the metal line has a straight, curved or spiral form.

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