Encoders and decoders are used for physical layer coding for Gigabit Ethernet, Fibre Channel, and other applications. The 8B/10B encoder takes byte inputs and generates a direct current (DC) balanced stream (equal number of 1s and 0s) with a maximum run length of 5. Some of the individual 10-bit codes have an equal number of 1s and 0s, while others have either four 1s and six 0s, or six 1s and four 0s. In the latter case, the disparity between 1s and 0s is used as an input to the next 10-bit code generation to reverse the disparity and maintain an overallbalanced stream. For this reason, some 8-bit inputs have two valid 10-bit codes, depending on the input disparity.
The Altera® 8B10B Encoder/Decoder MegaCore® function is a compact, high-performance intellectual property (IP) core capable of encoding and decoding in multi-gigabit applications.
Typical ApplicationThe 8B10B Encoder/Decoder MegaCore function can be used within generic framing procedure (GFP) applications.