Active cables are

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

cables used for data transmission that use an

electronic circuit An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or Conductive trace, traces through which electric current can flow. It is a t ...

to boost their performance. Without an electronic circuit, a cable is considered passive. Unlike passive cables, which can suffer from data degradation due to issues such as

attenuation In physics, attenuation (in some contexts, extinction) is the gradual loss of flux intensity through a Transmission medium, medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and ...

crosstalk In electronics, crosstalk (XT) is a phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, ...

, and

group velocity The group velocity of a wave is the velocity with which the overall envelope shape of the wave's amplitudes—known as the ''modulation'' or ''envelope (waves), envelope'' of the wave—propagates through space. For example, if a stone is thro ...

distortion, active cables contain one or more

integrated circuit An integrated circuit (IC), also known as a microchip or simply chip, is a set of electronic circuits, consisting of various electronic components (such as transistors, resistors, and capacitors) and their interconnections. These components a ...

s to address these problems. This active boosting allows cables to be more compact, thinner, and longer, and to transmit data faster than passive cables. Active cables are used in

enterprise networks Enterprise (or the archaic spelling Enterprize) may refer to: Business and economics Brands and enterprises * Enterprise GP Holdings, an energy holding company * Enterprise plc, a UK civil engineering and maintenance company * Enterprise ...

to connect

consumer A consumer is a person or a group who intends to order, or use purchased goods, products, or services primarily for personal, social, family, household and similar needs, who is not directly related to entrepreneurial or business activities. ...

devices such as

camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

gaming console A video game console is an electronic device that outputs a video signal or image to display a video game that can typically be played with a game controller. These may be home consoles, which are generally placed in a permanent location connect ...

s, and

HDTV High-definition television (HDTV) describes a television or video system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since at least 1933; in more recent times, it ref ...

s. Embedding circuitry in cables can allow less copper to be used in cable production while retaining performance. This reduces weight and offers longer reach and lower power consumption. Active cables use one or more integrated circuits to boost the signal passing through the cable. This helps to compensate for issues that can degrade data, such as attenuation, crosstalk, and group velocity distortion. There are two main types of active cables: Active Electrical Cables (AECs) and Active Optical Cables (AOCs). Both types have pluggable transceivers that are permanently connected to multiple strands of copper or fiber cable. Passive cables are copper cables that do not have an electronic circuit, and are prone to data degradation. Passive cables are also typically bi-directional, while active cables that convert a signal usually only work in one direction. There are two main types of signal conditioning used in active electrical cables: re-driver-based and re-timer. Re-driver-based AECs use a simpler signal amplification, while re-timer AECs use a clock and data recovery (CDR) based signal conditioning.

Consumer electronics

Active cables are used with products such as smartphones, HDTVs, gaming consoles, and DV cameras.

DisplayPort DisplayPort (DP) is a digital interface used to connect a video source, such as a Personal computer, computer, to a display device like a Computer monitor, monitor. Developed by the Video Electronics Standards Association (VESA), it can also car ...

is the latest consumer electronics standard to support active cables by allocating power supply pins inside the connector. Enabling ultra-thin (32 AWG and thinner) and long-reach interconnects which are particularly valuable for the use with the miniature

Mini DisplayPort The Mini DisplayPort (MiniDP or mDP) is a miniaturized version of the DisplayPort audio-visual digital interface. It was announced by Apple, Inc., Apple in October 2008, and by early 2013 all new Apple Macintosh computers had Mini DisplayPort, ...

form factor.

Enterprise and storage applications

Active cables are used in enterprise and storage applications, where space and air-flow requirements in

data centers A data center is a building, a dedicated space within a building, or a group of buildings used to house computer, computer systems and associated components, such as telecommunications and computer data storage, storage systems. Since IT opera ...

are considerations. The thinner gauge of active cables allows for a tighter bend radius, which helps facilitate cable management and airflow. As of 2010, half of the SFP+ interconnect volume are active cables (as opposed to passive copper cables and optical transceiver modules). In addition to this, the advent of

QSFP file:SFP board 2.jpg, Small Form-factor Pluggable connected to a pair of fiber-optic cables Small Form-factor Pluggable (SFP) is a compact, hot-pluggable network interface module format used for both telecommunication and data communications a ...

(Quad SFP) interconnects for

40 Gigabit Ethernet 40 Gigabit Ethernet (40GbE) and 100 Gigabit Ethernet (100GbE) are groups of computer networking technologies for transmitting Ethernet frames at rates of 40 and 100 gigabits per second (Gbit/s), respectively. These technologies offer significant ...

and

InfiniBand InfiniBand (IB) is a computer networking communications standard used in high-performance computing that features very high throughput and very low latency. It is used for data interconnect both among and within computers. InfiniBand is also used ...

has led to increased use of active cables in this form factor.

Standards

Serial Attached SCSI In computing, Serial Attached SCSI (SAS) is a point-to-point serial Communications protocol, protocol that moves data to and from Computer storage, computer-storage devices such as hard disk drives, solid-state drives and tape drives. SAS replac ...

(SAS) *

PCI Express PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a high-speed standard used to connect hardware components inside computers. It is designed to replace older expansion bus standards such as Peripher ...

HDMI High-Definition Multimedia Interface (HDMI) is a proprietary digital interface used to transmit high-quality video and audio signals between devices. It is commonly used to connect devices such as televisions, computer monitors, projectors, gam ...

USB Universal Serial Bus (USB) is an industry standard, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical ...

Thunderbolt A thunderbolt or lightning bolt is a symbolic representation of lightning when accompanied by a loud thunderclap. In Indo-European mythology, the thunderbolt was identified with the 'Sky Father'; this association is also found in later Hel ...

Criticism

Some critics of active cable technology criticize the fact that the electronics in an active cable design could be placed inside the connected devices instead, and an inexpensive passive cable used to connect the devices. Digital alternatives to using analogue equalizers and impedance-matching circuits to improve cable performance also exist, such as

channel estimation In wireless communications, channel state information (CSI) is the known channel properties of a communication link. This information describes how a signal propagates from the transmitter to the receiver and represents the combined effect of, for ...

link adaptation Link adaptation, comprising adaptive coding and modulation (ACM) and others (such as Power Control), is a term used in wireless communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditi ...

. Another criticism of active cables is that manufacturers may patent the electronics inside an active cable or even utilize on-chip

cryptography Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...

to prevent competitors or consumers from producing their replacement cables, and therefore enable manufacturers to monopolize the market for cables and charge consumers higher prices. Active cables are typically priced 5 to 10 times higher than passive cables. Some active cables are only produced by a single manufacturer and sold through a single distributor. Some critics argue that active cables do not provide power savings for signal processing reasons; in an active cable design, there is at least one extra integrated circuit (IC) compared to passive cable designs. This extra IC must be powered separately when, in a passive cable design, the signal processing can be integrated onto a single chip.

References

{{Reflist Signal cables

Consumer electronics

Enterprise and storage applications

Standards

Criticism

See also

References