An SerDes system is capable of serializing and deserializing digital communication signals. Deserializing, or demultiplexing, involves receiving a signal from a high-speed medium (usually a fiber optical cable), then demultiplexing the signal into several lower frequency channels. Serializing, or multiplexing, involves taking several lower frequency signals and multiplexing them into a high-speed channel, which is transmitted onto a high-speed medium.
