Drain aligned cable for next generation speeds

A dual axial cable is provided with adjacent and substantially parallel first and second wires. Each wire is formed from electrical conductor surrounded by a respective first and second electrical insulator having lengthwise drain alignment groove on outward side and having respective first and second inward sides of interlocking structure. First and second inward sides of interlocking structure of first and second electrical insulators mutually engage to prevent relative transverse displacement of first and second wires. The interlocking structure maintains the planar alignment of lengthwise drain alignment grooves and electrical conductors of first and second wires. First and second drain conductors are received respectively in lengthwise drain alignment grooves of first and second electrical insulators and run adjacent and substantially parallel to first and second electrical conductors. Drain conductors are maintained in parallel alignment to electrical conductors to provide shielding benefits.

BACKGROUND

1. Technical Field

The present disclosure relates in general to communication cables in an information handling system (IHS), and more particularly to dual drain, dual axial communication cables in an IHS.

2. Description of the Related Art

In many applications, one or multiple IHSs configured as servers may be installed within a single chassis, housing, enclosure, or rack. Communication between components internal to the servers, as well as communication between two or more servers and/or between enclosures, are often accomplished via communication cables. Within a server, for example, cables can electronically connect one of more printed circuit boards (PCBs). Cables provide a lower loss mode for signal propagation compared to PCBs which makes cables a frequent design choice. Thus, communication cables are an integral part of conventional server design.

Generally-known single drain and dual drain dual-axial cables are satisfactory to support current signal/data transfer speeds within a conventional IHS. However, the signal/data speeds within newer generations of IHS are increasing significantly (e.g., doubling with each generation). Higher signal speeds result in a corresponding increase in signal integrity sensitivity to parasitic effects. With fifteenth generation (15G), Peripheral Component Interconnect Express (PCIe) is going to speeds of 16 Gbps (gigabits per second). Sixteenth generation (16G) can be expected to be at 32 Gbps speeds. Subtle effects that did not impact the signal performance of conventionally utilized dual axial cables become significant at next generation signal speeds.

BRIEF SUMMARY

In accordance with the teachings of the present disclosure, a dual axial cable includes adjacent and substantially parallel first and second wires. Each wire is formed from an electrical conductor surrounded by a respective first and second electrical insulator. Each electrical insulator is formed with a lengthwise drain alignment groove on an outward side and respective first and second inward sides of an interlocking structure. The first and second inward sides of the interlocking structure of corresponding first and second electrical insulators mutually engage to prevent a relative transverse displacement of the first and second wires. The interlocking structure maintains planar alignment of the lengthwise drain alignment grooves and electrical conductors of the first and second wires. First and second drain conductors are received respectively in the lengthwise drain alignment grooves of the respective first and second electrical insulators and run adjacent and substantially parallel to the first and second electrical conductors.

In accordance with the teachings of the present disclosure, an information handling system (IHS) includes a communication interconnect comprising a dual axial cable that is attached between first and second functional components. The dual axial cable includes adjacent and substantially parallel first and second wires. Each wire is formed from an electrical conductor that is surrounded by a respective first or second electrical insulator. Each electrical insulator has a lengthwise drain alignment groove on an outward side and has one of a first and second inward sides of an interlocking structure. The first and second inward sides of the interlocking structure of the first and second electrical insulators mutually engage to prevent a relative transverse displacement of the first and second wires. The interlocking structure maintains planar alignment of the lengthwise drain alignment grooves and electrical conductors of the first and second wires. First and second drain conductors are received respectively in the lengthwise drain alignment grooves of the first and second electrical insulators. The first and second drain conductors run adjacent and substantially parallel to the first and second electrical conductors.

In accordance with the teachings of the present disclosure, a method includes forming first and second wires respectively by surrounding a length of an electrical conductor with a respective one of a first and second electrical insulator. Each insulator is formed having a lengthwise drain alignment groove on an outward side and having one side of first and second inward sides of an interlocking structure. The method includes mutually engaging the first and second inward sides of the interlocking structure of the first and second electrical insulators to prevent a relative transverse displacement of the first and second wires. Engaging the interlocking mechanism maintains planar alignment of the lengthwise drain alignment grooves and electrical conductors of the first and second wires. The first and second wires are adjacent and substantially parallel to each other. The method includes inserting first and second drain conductors respectively in the lengthwise drain alignment grooves of the first and second electrical insulators. The first and second drain conductors run adjacent and substantially parallel to the first and second electrical conductors, respectively, forming a dual axial cable.

The above presents a general summary of several aspects of the disclosure in order to provide a basic understanding of at least some aspects of the disclosure. The above summary contains simplifications, generalizations and omissions of detail and is not intended as a comprehensive description of the claimed subject matter but, rather, is intended to provide a brief overview of some of the functionality associated therewith. The summary is not intended to delineate the scope of the claims, and the summary merely presents some concepts of the disclosure in a general form as a prelude to the more detailed description that follows. Other systems, methods, functionality, features and advantages of the claimed subject matter will be or will become apparent to one with skill in the art upon examination of the following figures and detailed written description.

DETAILED DESCRIPTION

According to aspects of the present disclosure, a dual axial cable, an information handling system (IHS), and a method provide for differential signal communication having electrical performance capable of next generation speeds. The dual axial cable includes adjacent and substantially parallel first and second wires. Each wire is formed from an electrical conductor surrounded by a respective first and second electrical insulator having a lengthwise drain alignment groove on an outward side and having one side of respective first and second inward sides of an interlocking structure. The first and second inward sides of the interlocking structure mutually engage to prevent a relative transverse displacement of the first and second wires. The interlocking structure maintains planar alignment of the lengthwise drain alignment grooves and of the electrical conductors of the first and second wires. First and second drain conductors are received respectively in the lengthwise drain alignment grooves of the first and second electrical insulators and respectively run adjacent and substantially parallel to the first and second electrical conductors.

The drain alignment grooves provide a mechanism to lock the drain conductor or wire in position by creating a small groove or ridge in dielectric insulation medium of the first and second electrical insulators around the electrical conductors. By creating the groove with a depth of approximately half of the diameter of the drain conductor, the drain conductor is locked in position and will not move during the cable manufacturing and assembly and subsequent usage. The drain alignment groove can be created during an extrusion process, ensuring consistent positioning of drain wire relative to the conductor in order to achieve optimized electrical characteristics. The amount of electrical current carried by the drain conductor is small and can be served by a small diameter wire. Generally-known drain wires are physically larger than electrically necessary in order to be assembled into a cable assembly. The physical support to the drain conductors provided by the present innovation allows the diameter of the drain conductors to be reduced. Moreover, the drain wire size can be reduced to a fraction of the conventional size, such as a half or two thirds size reduction, without impact to the electrical performance. The drain alignment groove has dimensions that are scaled proportionately to receive and secure the reduced size drain conductor. The interlocking structure further aligns the electrical conductors with the drain conductors to optimize the dual drain cable. The two wires become a single assembly, maintaining alignment of the electrical conductors with the drain alignment grooves providing alignment for the drain wires.

FIG. 1Aillustrates a block diagram representation of example information handling system (IHS)100having dual drain cable102with mechanical and electrical dual-axial properties that support next generation (and beyond) differential signaling speeds to high-speed functional component(s)104. Within the general context of IHSs, IHS100may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, IHS may be personal computer, personal digital assistant (PDA), consumer electronic device, network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. IHS100may include random access memory (RAM), one or more processing resources such as central processing unit (CPU) or hardware or software control logic, ROM, and/or other types of nonvolatile memory. Additional components of IHS may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/O) devices, such as keyboard, mouse, and video display. IHS100may also include one or more buses operable to transmit communications between various hardware components.

Referring again toFIG. 1A, IHS100has processor subsystem112that is coupled to system memory114via system interconnect116, which includes dual drain cable102. System interconnect116can be interchangeably referred to as system bus, in one or more embodiments. Also coupled to system interconnect116is non-volatile storage, e.g., non-volatile random-access memory (NVRAM) storage118, within which can be stored one or more software and/or firmware modules and one or more sets of data that can be utilized during operations of IHS100. These one or more software and/or firmware modules can be loaded into system memory114during operation of IHS100. Specifically, in one embodiment, system memory114can include therein a plurality of such modules, including one or more of application(s)120, operating system (OS)122, basic input/output system (BIOS) or Uniform Extensible Firmware Interface (UEFI)124, and firmware (F/W)126. These software and/or firmware modules have varying functionality when their corresponding program code is executed by processor subsystem112or secondary processing devices within IHS100. For example, application(s)120may include a word processing application, presentation application, and management station application, among other applications.

IHS100further includes one or more input/output (I/O) controllers130, which support connections by and processing of signals from one or more connected input device/s132, such as keyboard, mouse, touch screen, or microphone. I/O controllers130also support connection to and forwarding of output signals to one or more connected output devices134, such as monitor or display device or audio speaker(s). Additionally, in one or more embodiments, one or more device interfaces136, such as optical reader, universal serial bus (USB), card reader, Personal Computer Memory Card International Association (PCMCIA) slot, and/or high-definition multimedia interface (HDMI), can be associated with IHS100. Device interface(s)136can be utilized to enable data to be read from or stored to corresponding removable storage device(s)138, such as compact disk (CD), digital video disk (DVD), flash drive, or flash memory card. In one or more embodiments, device interface(s)136can further include general purpose I/O interfaces such as inter-integrated circuit (I2C), system management bus (SMB), and peripheral component interconnect (PCI) buses.

IHS100comprises network interface controller (NIC)140. NIC140enables IHS100and/or components within IHS100to communicate and/or interface with other devices, services, and components that are located external to IHS100. These devices, services, and components can interface with IHS100via external network, such as example network142, using one or more communication protocols that can include transport control protocol/internet protocol (TCP/IP) and network block device (NBD) protocol. Network142can be local area network, wide area network, personal area network, and the like, and connection to and/or between network142and IHS100can be wired, wireless, or a combination thereof. For purposes of discussion, network142is indicated as single collective component connected to automated manufacturing system144that communicates via network interface146.

Automated manufacturing system144controls fabrication and assembly of dual drain cable102. Processor148executes assembly utility150to make dual drain cable102that includes adjacent and substantially parallel first and second wires152a-b. Each wire152a-bis formed with electrical conductor154a-bsurrounded by respective first and second electrical insulator156a-bhaving lengthwise drain alignment groove158a-bon outward side and having respective first and second inward sides160a-bof interlocking structure162. First and second inward sides160a-bof interlocking structure162of first and second electrical insulators156a-bmutually engage to prevent relative transverse displacement of first and second wires152a-b. Interlocking structure162maintains planar alignment of lengthwise drain alignment grooves158a-band electrical conductors154a-bof first and second wires152a-b. First and second drain conductors164a-bare received respectively in lengthwise drain alignment grooves158a-bof first and second electrical insulators156a-band run adjacent and substantially parallel to first and second electrical conductors152a-b. A shield166of foil conductive material is helically wrapped around exterior perimeter of the assembly of first and second wires152a-band first and second drain conductors164a-b.

Dual drain cable102can be used for short to medium reach (e.g., less than 10-20 meters) in standards, including, but not limited to, Serial Attached Small Computer System Interface (SAS), InfiniBand, Serial Advanced Technology Attachment (SATA), Peripheral Component Interconnect Express (PCIe), Double Speed Fibre Channel, Synchronous Optical Networking (SONET), Synchronous Digital Hierarchy (SDH), and 10 Gigabit Ethernet (10 GbE). The present disclosure provides an approach to constructing dual axial cables that ensure that the electrical performance is not compromised by displacement of drain conductors164a-b. Maintaining electrical performance allows expected higher communication speeds for use in PCIe fifth generation (Gens) and SAS 4.0 solutions in sixteenth generation (16G) and beyond.

FIG. 1Billustrates a generally-known dual-axial cable170having first end172that is ideally manufactured with left drain conductor174, left signal conductor176of left differential signal wire178, right signal conductor180of right signal wire182, and right drain conductor184all in planar alignment. Each of left and right drain conductors174,184and left and right signal wires178,182have a respective circular cross section that contact only at a small areas. Thus, left and right drain conductors174,184and left and right signal wires178,182can twist or otherwise move relative to each other during assembly at a second end186of generally-known dual-axial cable170. At second end186, left signal wire178includes a relative transverse displacement188upward from right signal wire182, creating a nonplanar alignment with the combination of right signal wire182and right drain conductor184. In response to the relative transverse displacement188, left drain wire174has a relative displacement190downward and to the right. Relative displacement190takes left drain wire174out of planar alignment with any combination of left and right signal wires178,182and right drain conductor184. For example, an outer layer192that provides electrical shielding and protection to the dual-axial cable170can urge the left drain conductor174with relative displacement190. Electrical performance is degraded when left drain conductor174, left signal conductor176, right signal conductor180, and right drain conductor184are not all in planar alignment.

The present disclosure recognizes how conventional dual-axial cables can be improved.FIG. 2illustrates a cross-sectional view of conventional dual axial cable200having wires202a-beach including central conductor wire204surrounded by cylindrical insulator206. In one embodiment, central drain wire208(shown in dashed line) represents one known approach to improve shielding when assembled within spiral wrap shield210as a central drain dual-axial cable. However, center drain dual-axial cables have a resonance or suck-out effect due to the spiral wrapping of the shield210around the assembly of two conductor wires202a-band central drain wire208. The spiral wrap shield210creates a periodic return path discontinuity resulting in a resonance, which degrades performance, as described below with regard toFIG. 3.

Dual-drain dual-axial cables, represented by aligned drain wires212a-b(shown in dashed lines) and without central drain wire208, do not have resonance and thus support very high speeds and long lengths. Helical foil wrap214has been properly applied during manufacturing. A polyester (e.g., polyethylene terephthalate (PET)) sheath (not shown) covers the entire assembly. However, dual drain dual-axial cables also have a problem which can cause performance issues at high speeds. The location of the two drain wires212a-bcan be off-set by a few mils, depending on the spiral wrapping and depending on the cable formation, such as due helical foil wrap214′ (shown in dashed lines). For example, left drain wire212a′ is upwardly off-set and right drain wire212b′ is downwardly offset from the ideal positions of left and right drain wires212a-b.

FIG. 3is a graphical representation300of frequency versus impedance plots302a-dthat illustrate impedance changes that result from an offset between drain wires for a conventional dual drain, dual-axial cable. A plot302afor an aligned drain wire (“0 mil) generally has lower impedance than impedance plots302b-drespectively for drain wires with 2, 5 and 7 mils of offset. Lower impedance is related to propagation delay and mode conversion impacts. Any mismatch in propagation delay results in resonance at high speeds. Mismatch in propagation delay also results in common-mode conversion from differential mode which increases crosstalk. Conventional dual drain, dual-axial cables can have degraded performance represented by302b-din addition to a subset that are manufactured with 0 mil offset as given by impedance plot302a. The conventional dual drain, dual-axial cable does not maintain a uniform performance across lengths of cable or between certain specimens. Thus, the conventional dual drain, dual axial cable is inadequate for higher communication speed requirements. By contrast, a dual-drain cable manufactured according to aspects of the present innovation avoids having non-zero offsets from the ideal. Instead, all drain wires uniformly have an ideal 0 mil offset as given by impedance plot302a. Without any drain wires in a manufacturing sample that deviate with non-zero offsets such as impedance plots302b-d, a dual-drain cable according to the present disclosure is adequate for higher communication speed requirements. Dual-drain cables that maintain drain wires with ideal 0 mil offsets is a significant improvement over conventional dual drain, dual-axial cables.

FIGS. 4A-4Bare perspective views of example first and second wires400a-bthat are identically formed with an electrical conductor402a-bsurrounded by a respective first and second electrical insulators404a-b. First and second electrical insulators404a-beach has lengthwise drain alignment groove406a-bon an outward side. First and second electrical insulators404a-bhave respective first and second inward sides408a-bof interlocking structure410. Second wire400bis rotated 180° about a longitudinal axis relative to the first wire400ato orient the second inward side408binto contacting opposition with the first inward side408a. First and second inward sides408a-binclude male and female interlocking surfaces412,414symmetrically spaced about a midpoint.

FIGS. 4C-4Dare perspective views of assembled first and second wires400a-b. First and second inward sides408a-bof the interlocking structure410of the first and second electrical insulators404a-bmutually engage to prevent a relative transverse displacement of the first and second wires400a-b. Thus, interlocking structure410maintains planar alignment of the lengthwise drain alignment grooves406a-band electrical conductors402a-bof the first and second wires400a-b.FIG. 4Cillustrates first and second drain conductors416a-bdisassembled from the first and second wires400a-b.FIG. 4Dillustrates first and second drain conductors416a-badjacent and substantially parallel to first and second wires400a-band received in respective drain alignment grooves406a-b.

In the construction illustrated byFIG. 4D, while some return current may flow on shield (166,FIG. 1A), the largest portion of such return current may flow through dual drain conductors416a-b. The current through dual drain conductors416a-bthus avoids the periodic impedance discontinuity of the shield (166,FIG. 1A), and thereby reduces the occurrence of undesired resonance. Unlike generally-known dual-drain cables, the cable size (e.g., width) is not appreciably increased. Generally-known dual-drain cables have a width that is directly increased by the diameter of the two drain wires. By contrast, first and second wires400a-bincrease about half as much by fitting about half of the diameter of first and second drain conductors416a-bwithin respective first and second wires400a-b. The grooves provide physical support to first and second drain conductors416a-ballowing sizing of the drain conductors416a-baccording to an amount of required electrical conductivity. Thus supported, the diameter of the first and second drain conductors416a-bcan be reduced by at least half, enabling use in applications that require smaller width cables.

FIGS. 5A-5Bare perspective views of example first and second wires500a-bthat are correspondingly formed with an electrical conductor502a-bsurrounded by respective first and second electrical insulators505a-b. First and second electrical insulators505a-bhave lengthwise drain alignment groove506a-bon an outward side. First and second electrical insulators505a-bhave respective first and second inward sides508a-bof interlocking structure510. First inward side508aincludes a central male interlocking surface512between two female interlocking surfaces514. Second inward side508bincludes a central female interlocking surface516between two male interlocking surfaces518.

FIGS. 5C-5Dare perspective views of assembled first and second wires500a-b. First and second inward sides508a-bof interlocking structure510of the first and second electrical insulators504a-bmutually engage to prevent a relative transverse displacement of the first and second wires500a-b. Thus, interlocking structure510maintains planar alignment of the lengthwise drain alignment grooves506a-band electrical conductors502a-bof first and second wires500a-b.FIG. 5Cillustrates first and second drain conductors516a-bdisassembled from the first and second wires500a-b.FIG. 5Dillustrates first and second drain conductors516a-bthat are adjacent and substantially parallel to first and second wires500a-band received in respective drain alignment grooves506a-b.

FIG. 6is a cross-section view of a ribbon cable600formed from two dual drain cables602a-battached in parallel alignment by a ribbon substrate604. Each dual drain cable602a-bincludes example first and second wires606a-bthat are correspondingly formed with an electrical conductor608a-bsurrounded by a respective first and second electrical insulator610a-b. First and second electrical insulators610a-bhave respective first and second inward sides612a-bof interlocking structure614that include correspondingly sized male and female interlocking surface616,618on respective sides about a midpoint.

FIG. 7is a flow diagram illustrating a method700of making a dual-drain, dual axial cable that maintains planar alignment during shield wrapping to ensure high communication performance. Method700begins at block702and includes providing lengths of electrical conductor and drain wire (block702). Method700includes extruding a dielectric insulation material, such as polyethylene (PE), through a die opening to form first wire of PE each surrounding a length of an electrical conductor. Each die imparts a selected one of a first or second electrical insulator with a lengthwise drain alignment groove on an outward side and one side of first or second inward sides of an interlocking structure (block704). Method700includes similarly forming the second wire (method706). Method700includes mutually engaging the first and second inward sides of the interlocking structure of the first and second electrical insulators to prevent a relative transverse displacement of the first and second wires (block708). Engaging the interlocking structure maintains planar alignment of the lengthwise drain alignment grooves and electrical conductors of the first and second wires. The first and second wires are adjacent and substantially parallel to each other.

In one or more embodiments, the first and second inward sides of the interlocking structure of the first and second electrical insulators comprise corresponding male and female interlocking surfaces. In one or more embodiments, the first and second electrical insulators are identical with the first and second inward sides of the interlocking structure comprising symmetric male and female features.

Method700includes inserting first and second drain conductors respectively in the lengthwise drain alignment grooves of the first and second electrical insulators (block710). The first and second drain conductors run adjacent and substantially parallel to the first and second electrical conductors, respectively, forming a dual axial cable. Method700includes helically wrapping foil around an exterior perimeter of the assembly of the first and second wires and the first and second drain conductors to form a shield of electrically conductive material (block712). Method700includes encasing the shield and assembly of drain conductors and wires with a polyester (polyethylene terephthalate (PET)) cover (block714). Then method700ends.

In one or more embodiments, method700includes making another dual axial cable. Method700includes attaching the dual axial cable to the other axial cable with a ribbon substrate that maintains planar alignment of the lengthwise drain alignment grooves and electrical conductors of the first and second wires of the dual axial cables.

In the above described flow chart ofFIG. 7, one or more of the methods may be embodied in an automated manufacturing controller that performs a series of functional processes. In some implementations, certain steps of the methods are combined, performed simultaneously or in a different order, or perhaps omitted, without deviating from the scope of the disclosure. Thus, while the method blocks are described and illustrated in a particular sequence, use of a specific sequence of functional processes represented by the blocks is not meant to imply any limitations on the disclosure. Changes may be made with regards to the sequence of processes without departing from the scope of the present disclosure. Use of a particular sequence is therefore, not to be taken in a limiting sense, and the scope of the present disclosure is defined only by the appended claims.

One or more of the embodiments of the disclosure described can be implemented, at least in part, using a software-controlled programmable processing device, such as a microprocessor, digital signal processor or other processing device, data processing apparatus or system. Thus, it is appreciated that a computer program for configuring a programmable device, apparatus or system to implement the foregoing described methods is envisaged as an aspect of the present disclosure. The computer program may be embodied as source code or undergo compilation for implementation on a processing device, apparatus, or system. Suitably, the computer program is stored on a carrier device in machine or device readable form, for example in solid-state memory, magnetic memory such as disk or tape, optically or magneto-optically readable memory such as compact disk or digital versatile disk, flash memory, etc. The processing device, apparatus or system utilizes the program or a part thereof to configure the processing device, apparatus, or system for operation.