Small Form-factor Pluggable (SFP) Transceiver

Small form-factor pluggable is the full name of SFP, a prevailing type of fiber optic transceivers
in the market. The transceiver can be simply regarded as the upgraded version of the GBIC module.  SFP module is the half size of GBIC, but the numbers of ports configured on the same panels are double. Because the small-factor pluggable transceiver is the same function with GBIC, SFP transceivers is also called as mini-GBIC.

By placing the CDR and electrical dispersion compensation outside the modules, SFP transceiver modules greatly compressed the size and power consumptions.
Google currently are purchasing a large amount of SFP + modules to design and produce its own Gigabit Ethernet switches to meet the needs of the data center database system.

SFP Standard
SFP transceiver is regulated by a competition the Multilateral Agreement (MSA) between the manufacturers. The SFP is designed according to GBIC interface, allowing ratio the GBIC greater port density (the motherboard edge of the number of transceivers per inch), the SFP is also known as “mini-GBICs”. Compared with this small package transceivers (SFF transceiver), which is smaller than the SFP, but the SFF is soldered to the motherboard as a pin through-hole device, but not plugged into the edge.

SFP Type
SFP transceivers have a variety of different transmission and receiving type, the user can select the appropriate transceiver for each link, to provide the optical performance can be achieved based on the available fiber type (such as a multimode fiber or single mode fiber). Optical SFP module available are generally divided into the following categories:
10 km distance of the wavelength of 850 nm / 550 meters distance MMF (SX)
1310 nm wavelength SMF (LX)
1550 nm wavelength / 40 km distance XD
80 miles from ZX
120 km distance from the EX or EZX
DWDM
SFP optical module configuration are: lasers (including transmitter TOSA with the receiver ROSA) and board composition IC and external accessories and external accessories, there are housing, base, PCBA, pull ring, clasps, unlock, rubber stopper composition, In order to facilitate the identification generally pull ring color discrimination module parameter type. SFP optical modules also have copper interface, making the host device designed primarily for fiber optic communication can communicate through the UTP network cable. There are also WDM (CWDM) and single fiber bi-directional “(1310/1490 nm wavelength uplink / downlink), SFP. Commercial SFP transceivers can provide a rate of 4.25 Gbps. Several packages of 10 Gbps transceivers are XFP, SFP+ and the updated version of SFP.

Figure 1 SFP Transceiver Module (Fiber-Optic LC Connector)

 

SFP Application

A compact, hot plug fiber optic transceiver, the Small Form-Factor pluggable (SFP) transceiver is used in fiber optic communications for telecommunication and data communications applications. SFP is the interface between a network device mother board and a fiber optic or copper cable network cable.

The SFP transceiver is able to support Gigabit Ethernet, fiber channel, SONET, and a number of other communications standards. For your information that in the near future, SFP will expand to the SFP+. At the time, the data rate in 10 Gbit/s is achievable, including 8 billion fiber channel. Compared to Xenpack or XFP type of modules, all of their circuitry inside, an SFP+ module leaves some of its circuitry to be implemented on the host board.

Actually available, the  SFP transceiver has the capability transfer rates of up to 4.25 Gbit/s. XFP, a form factor which is virtually identical to the SFP type, increases this amount by nearly three times, at 10Gbit/s. The SFP transceiver is specified and made compatible via a multi-source agreement (MSA) between manufacturers, so that different users who may use equipment from different manufacturers and provides can work effectively and smoothly without worrying about errors and inconveniences.

There is a huge change in the optical transceiver is available, each with different transmitter or receiver. This allows the user configure and customize the transceiver to get the proper optical reach with either a multi-mode fiber or single-mode fiber type. In addition, the optical SFP module comes in four categories -SX, which is 850nm, LX, which is 1310nm, ZX, which is 1550nm and DWDM. All of them have an interface of a copper cable which permits a mother board to communicate via USTP (unshielded twisted-pair) cable network. There are also a coarse wavelength division multiplexing and two-way optical fiber cable, single mode 1310/1490 nm upstream and downstream.