Patent Application
20240332765
This application claims the benefit under 35 U.S.C. 119 (a) of Korean Patent Application No. 10-2023-0043627 filed on Apr. 3, 2023 with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes.
The following description relates to ultra-high speed digital signal integrity improving structures that can autonomously recover a distorted phase while rejecting a common-mode signal in a frequency band up to 40 GHz or more.
An ultra-high speed digital signal transmission is required for the transmission of high-capacity digital data for the 5th generation and the next-generation communications. Up to now, a differential line has been used as a transmission line for a high-speed digital signal. However, it is extremely difficult, if not impossible, to use the differential line in a frequency band of 10 GHz or more due to various problems, including a signal skew phenomenon by a length difference between two signal lines, uneven electromagnetic interference (EMI) due to adjacent lines, a non-linear phase distortion phenomenon due to electromagnetic (EM) coupling between signal lines of a differential line when a phase difference in which two signal lines deviate from 180° occurs, phase difference occurrence by fiber weave effects in an FR4 substrate, etc.
Further, the above-mentioned problems in a differential line cause a common-mode signal, which degrades the performance of digital circuit operations. The common-mode signal consists of frequency components that are generally higher than the frequency spectrum of a differential signal, becomes a main cause of electromagnetic interference (EMI) and adversely affects the operation of a circuit receiving a signal. Therefore, for an unflawed operation of a digital circuit, it is necessary to suppress the magnitude of the common-mode signal, and to this end, a filter for rejecting the common-mode signal is required.
Most commercial common-mode signal rejection filters have a way that winds two signal lines of a differential line around a ferrite core and rejects the common-mode signal through a magnetic field generated by the ferrite core. However, since the impedance of an inductor generated by winding two signal lines around the ferrite core is affected by parasitic components as frequencies increase above a specific frequency, the frequency band of the common-mode signal rejection is limited to approximately 10 GHz or less.
In addition, common-mode signal rejection filters published in papers so far mostly adopt a scheme using various types of resonance structures that modify the ground surface under the differential line. However, the reported common-mode signal rejection filters do not provide enough frequency bandwidth, having a maximum frequency of about 15 GHz or less, which is not suitable for use for the next-generation ultra-high speed digital communication.
Therefore, the common-mode signal rejection filter, which has been proposed or in use so far, has a limited frequency bandwidth within approximately 15 GHz, so the improvement of an ultra-wideband common-mode signal rejection performance is required for the ultra-high speed digital signal transmission of dozens or hundreds of Gbps in the future.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
An object of the present disclosure is to provide ultra-high speed digital signal integrity improving structures which can reject or suppress a common-mode signal in a frequency band of a predetermined range or more (i.e., 40 GHz or more) while minimizing an influence applied to a differential signal required for ultra-high speed digital signal transmission and, at the same time, autonomously recovering a distorted phase.
Another object of the present disclosure is to provide ultra-high speed digital signal integrity improving structures which enable common-mode signal rejection and phase recovery to enable ultra-high speed digital communication when a common-mode signal is generated due to distortion of a digital signal which passes through a differential line-based circuit and a non-linear phase distortion phenomenon occurs due to a length difference between two signal lines and electromagnetic coupling between signal lines.
The technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.
In one general aspect, ultra-high speed digital signal integrity improving structures are structures that are arranged to face each other on the left and right sides along a longitudinal direction of a balanced line, centered around a first-type balanced line or a second-type balanced line formed on a substrate, to reject a common-mode signal and recover a distorted phase while minimally affecting a differential signal. The structures include a first unit structure and a second unit structure, which may be identical or different in shape. At least one of the first unit structure and the second unit structure includes a first side close to the balanced line and having a linear or curve shape; a second side facing the first side; and left and right sides connecting the first side and the second side. A width of the first side is less than or equal to a width of the second side, the left and right sides have a linear or non-linear slope, and a width from the first side to the second side is configured to change continuously or discontinuously. The first-type balanced line is a coplanar stripline (CPS), and the second-type balanced line is a parallel stripline (PSL).
The structures may be formed entirely from a conductor.
The structures may be configured in a state in which a portion of an internal conductor is removed.
A first side of the first unit structure and a first side of the second unit structure may be spaced apart at a predetermined interval.
A second side of the first unit structure and a second side of the second unit structure may be connected to or spaced apart from a ground formed on the substrate.
The unit structures may be arranged along the longitudinal direction of the balanced line, with at least one or more structures. The arranged structures may have either identical or different shapes.
The unit structures may be arranged along the longitudinal direction of the balanced line periodically or aperiodically.
In another general aspect of ultra-high speed digital signal integrity improving structures, the structures comprise a transition structure connecting a balanced line to a differential line and are arranged to face each other on the left and right sides along a longitudinal direction of the balanced line to reject a common-mode signal and recover a distorted phase while minimally affecting a differential signal. The structures include a first unit structure and a second unit structure, which may be identical or different in shape. At least one of the first unit structure and the second unit structure includes a first side close to the balanced line and having a linear or curve shape; a second side facing the first side; and left and right sides connecting the first side and the second side, a width of the first side is less than or equal to a width of the second side, and the left and right sides have a linear or non-linear slope, and a width from the first side to the second side is configured to change continuously or discontinuously.
The structures may be formed either entirely from a conductor or with a portion of an internal conductor removed.
A first side of the first unit structure and a first side of the second unit structure may be spaced apart at a predetermined interval.
A second side of the first unit structure and a second side of the second unit structure may be connected to or spaced apart from a ground formed on the substrate.
The unit structures may be arranged along the longitudinal direction of the balanced line, with at least one or more structures. The arranged structures may have either identical or different shapes. The unit structures may be arranged along the longitudinal direction of the balanced line periodically or aperiodically.
In another general aspect, surface-mounted digital signal integrity improving structures includes a first substrate with a differential line; a second substrate with a balanced line. On the second substrate, the structures are arranged to face each other on the left and right sides along a longitudinal direction of the balanced line, centered around the balanced line. The structures include a first unit structure and a second unit structure, which may be identical or different in shape. At least one of the first unit structure and the second unit structure includes a first side close to the balanced line and having a linear or curve shape; a second side facing the first side; and left and right sides connecting the first side and the second side. A width of the first side is less than or equal to a width of the second side, the left and right sides have a linear or non-linear slope, and a width from the first side to the second side is configured to change continuously or discontinuously.
The structures may be formed either entirely from a conductor or with a portion of an internal conductor removed.
A first side of the first unit structure and a first side of the second unit structure may be spaced apart at a predetermined interval.
A second side of the first unit structure and a second side of the second unit structure may be connected to or spaced apart from a ground formed on the substrate.
The unit structures may be arranged along the longitudinal direction of the balanced line, with at least one or more structures. The arranged structures have either identical or different shapes. The unit structures are arranged along the longitudinal direction of the balanced line periodically or aperiodically.
According to an example of the present disclosure, the common-mode signal can be suppressed or rejected in a frequency band of up to 40 GHz or more, and at the same time, the distorted phase can be autonomously recovered, so there is an effect of significantly improving the quality of the digital signal, and the digital signal can be transmitted according to an ultra-high transmission speed.
According to an example of the present disclosure, an effect can be expected in which the ultra-high speed digital signal integrity improving structures can be applied to high-speed interfaces and chips, so the ultra-high speed digital signal integrity improving structures can also be easily applied to next-generation communication technology in addition to 5th generation communication technology, requiring high performance and super-wide frequency bandwidth.
According to an example of the present disclosure, since a phase difference generated by a length difference between differential lines and a phase difference by a configured fiber weave structure can be recovered even in a general FR4 substrate, ultra-high speed digital signal transmission can be significantly improved compared to the related art made by an inexpensive PCB process.
According to an example of the present disclosure, when the ultra-high speed digital signal integrity improving structures are applied to a differential line-based digital circuit board, the quality of the digital signal can be improved, and in particular, when the ultra-high speed digital signal integrity improving structures are combined by an ultra-wideband transition structure of connecting a balanced line to the differential line, the frequency band of up to 40 GHz or more can be secured, which enables ultra-high speed digital signal transmission.
The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent after an understanding of the disclosure of this application. For example, the sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent after an understanding of the disclosure of this application, with the exception of operations necessarily occurring in a certain order. Also, descriptions of features that are known in the art may be omitted for increased clarity and conciseness.
Although terms such as “first,” “second,” and “third” may be used herein to describe various members, components, regions, layers, or sections, these members, components, regions, layers, or sections are not to be limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or section from another member, component, region, layer, or section. Thus, a first member, component, region, layer, or section referred to in examples described herein may also be referred to as a second member, component, region, layer, or section without departing from the teachings of the examples.
The terminology used herein is for describing various examples only, and is not to be used to limit the disclosure. The articles “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “includes,” and “has” specify the presence of stated features, numbers, operations, members, elements, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, members, elements, and/or combinations thereof.
The spatially relative terms below, beneath, lower, above, upper, and the like may be used to facilitate the description of the relationship of one element or component to another element or component as shown in the drawings. Spatially relative terms should be understood to include different orientations of an element in use or operation in addition to the orientations shown in the drawings. For example, an element described as being “below” or “beneath” another element may be “above” or “upper” another element when the elements shown in the drawing are inverted. Thus, the exemplary term below may include both below and above orientations. Elements may also be oriented in other directions, and accordingly, spatially relative terms may be interpreted according to their orientation.
An expression representing a part of the terms such as “part” or “portion” used in the present disclosure may be used herein to describe a device that may include a specific function, software that may include a specific function, or a combination of devices and software that may include a specific function, and is not to be used to limit the described function. This is provided to help a more general understanding of the present disclosure, and various modifications and variations may be made from these descriptions by those of ordinary skill in the field to which the present disclosure belongs.
Additionally, it should be noted that all electric signals used in the present disclosure, as an example, may be reversed in signs of all electric signals to be described below when an inverter or the like is additionally provided in the circuit of the present disclosure. Therefore, the scope of the claims of the present disclosure is not limited to the direction of the signal.
The features of the examples described herein may be combined in various ways as will be apparent after an understanding of the disclosure of this application. Further, although the examples described herein have a variety of configurations, other configurations are possible as will be apparent after an understanding of the disclosure of this application.
Hereinafter, the present disclosure is described in more detail based on the example illustrated in the drawings.
Before explaining the present invention, the non-linear phase distortion phenomenon, which occurs due to the length difference between two signal lines of a differential line and the electromagnetic coupling between two signal lines, is described. The reason is that the phase unbalance causes the common-mode signal, and the common-mode signal becomes the main cause of the electromagnetic interference (EMI), which adversely affects the circuit operation.
When a length difference between two signal lines occurs as illustrated in
Referring to this, it can be seen that when a length difference of 30 mil or more occurs, the phase is distorted by 20 degrees or more after 20 GHz. Further, it can be seen that when a length difference of 60 mil or more occurs, the phase is distorted by 20 degrees or more after 11.7 GHz when the distance up to the length compensation structure is 1000 mil.
As described above, it can be seen that when the length difference between two signal lines of a differential line occurs, the non-linear phase distortion phenomenon of the differential lines becomes more significant as the frequency increases, so it is impossible to recover the distorted phase simply by applying the length compensation structure.
Meanwhile, when an FR4 substrate generally used as a commercial digital circuit board in
Characteristics of the balanced line provide features in which ultra-wideband differential signal transmission is possible, EMI from other lines in proximity may be suppressed, when the phase difference which deviates from 180° between two signal lines occurs, the phase may be autonomously recovered, and main design parameters may be calculated through analytical formulas considering the electric field distribution and a dielectric constant of a substrate, and performance enhancement is possible through a characteristic impedance change. In addition, the second-type balanced line PSL may maintain signal integrity even in a bent line.
As illustrated in (a) and (b) of
Specifically, in a CPS line 10 of (a) of
In addition, in a PSL line 20 of (b) of
Referring to (a) of
In the case of the balanced line, a common-mode signal should be suppressed at any degree due to structural characteristics, and there is strong electromagnetic coupling between two signal lines to recover a phase of a distorted signal.
The present invention proposes a method for placing structures that may suppress or reject the common-mode signal while minimizing the influence of the differential signal on the balanced line, are capable of transmitting the digital signal at an ultra-high speed, and autonomously recover the distorted phase on the balanced line.
Referring to
In
Respective unit structures, exemplified as the first to fourth structures 200, 300, 400, and 500, may be variously formed but may be designed according to the following rules. Since the same rules can be applied to all structures, the first structure 200 is described as an example.
Referring to any one exemplified unit structure 200a or 200b of the first structure 200, the unit structure 200a or 200b may be formed to include a first side (upper side) 201 close to the balanced line 110 and having a linear or curve shape, a second side (lower side) 202 facing the first side 201, and left and right sides 203 and 204 connecting the first side 201 and the second side 202. The first side 201 may be formed to have a smaller width than or the same width as that of the second side 202. Further, there may be a structure in which the left and right sides 203 and 204 have a linear or non-linear slope, and the width is continuously changed or discontinuously changed from the first side 201 to the second side 202. A continuous shape may be a linear or curve shape, and a discontinuous shape may be a step shape.
Meanwhile, as in
The unit structure manufactured according to such a design rule may be arranged on the balanced line according to the following rule.
As illustrated in
One or multiple unit structures continuously placed in the longitudinal direction of the balanced line 110 may be placed periodically or aperiodically, and different-shaped structures may be placed jointly, and the structures may be placed to overlap with each other. For example, in
Various examples in which the structures of the present invention are arranged around the balanced line 110 may be seen in
Referring to (a) of
Structures 700a and 700b of (b) of
Structures 800a and 800b of (c) of
(d) of
In the above description, the examples in which the structures are arranged on the substrate only with the balanced line according to the predetermined rule are described.
However, the present invention may also be applied to a line with both the differential line and the balanced line, so the present invention will be continuously described with reference to
Therefore, the balance line combined with an ultra-wideband transition structure for ultra-high speed digital signal transmission provides characteristics of common-mode signal rejection and phase recovery in an ultra-wideband, and a common-mode signal rejection performance may be approximately 5 to 10 dB in an operating frequency band of up to dozens of GHz or more. In other words, there is an advantage in that the structures of the present invention are additionally placed around the balanced line, including the transition structure, to significantly enhance the common-mode signal rejection performance in an ultra-wideband frequency band.
Referring to (a) to (d) of
As such, in a structure in which the differential line and the balanced line of the circuit board are connected with optimal performance, the structures of the present invention may be applied around the balanced line, and accordingly, common-mode signals may be significantly rejected, thereby improving the quality of the digital signal.
Referring to this, the surface-mounted digital signal integrity improving structure includes a first substrate 1100 with a differential line 1000 and a second substrate 1300 connected through a via 1200. In the second substrate 1300, a structure of the via 1200 is used, so the balanced line 2000 connected to the differential line 1000 of the digital signal circuit board is formed, and structures 200 of the present invention are placed to face each other around the balanced line 2000.
That is, in the second substrate 1300, the balanced line 2000 and the structure 200 are jointly configured in a module form, which is possible to be compatible with a general digital transmission line.
The structure applied to the second substrate 1300 may adopt all structures having various shapes described above in addition to the structure illustrated in
Continuously, performance evaluation for the structure of the present invention is described.
In the performance evaluation, a common-mode signal suppression performance and a phase recovery performance are evaluated through a 3D EM simulation with respect to a case of the structures of the present invention combined by the transition structure for the ultra-high speed digital signal transmission filed by the present applicant. Furthermore, the structures of the present invention are implemented using the corresponding substrate and measured by a commercial 4-port network analyzer to confirm a similar performance to the simulation.
Referring to (a) of
In respect to the phase recovery level of (b) of
Referring to (a) of
In respect to the phase recovery level of (b) of
As described above, it can be seen that when the structures of the present invention are applied around the balanced line, common-mode signal rejection and autonomous phase recovery are possible in the ultra-wideband, and accordingly, the integrity of the digital signal can be improved, and next-generation ultra-high speed digital signal transmission becomes possible.
In addition, when the structures of the present invention are also applied to the general FR4 substrate, the phase difference generated by the length difference between two signal lines of a differential line can be recovered without the influence of the configured fiber weave structure of the substrate, so ultra-high speed digital signal transmission, which is significantly improved compared to the related art, can be made even by using an inexpensive PCB process.
Further, when the structures of the present invention are applied to the differential line-based digital circuit board, the integrity of the digital signal can be improved.
Further, when the structures of the present invention are combined by the ultra-wideband transition structure connecting the balanced line to the differential line, high-integrity ultra-high speed digital signal transmission is possible in the frequency band of 40 GHz or more.
While this disclosure includes specific examples, it will be apparent after an understanding of the disclosure of this application that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0043627 | Apr 2023 | KR | national |
