The TLK2208A is the third generation of Gigabit Ethernet transceivers from Texas Instruments combining high port density and ultralow power in a small form-factor footprint. The TLK2208A provides for high-speed full-duplex point-to-point data transmissions based on the IEEE 802.3z 1000-Mbps Ethernet specification. The TLK2208A supports data rates from 1.0 Gbps through 1.3 Gbps. The primary application of this device is to provide building blocks for developing point-to-point baseband data transmission over controlled impedance media of 50 . The transmission media can be printed circuit board traces, copper cables or fiber-optical interface modules. The ultimate rate and distance of data transfer is dependent upon the attenuation characteristics of the media and the noise coupling to the environment. The TLK2208A performs the data encoding, decoding, serialization, deserialization, clock extraction, and clock tolerance compensation functions for a physical layer interface device. Each channel operates at up to 1.3 Gbps providing up to 8.32 Gbps of aggregate data bandwidth over copper or optical-media interfaces. The TLK2208A supports two selectable reduced-pin-count double-data-rate (DDR) timing interfaces, nibble mode and multiplexed channel mode, to a protocol device. In the nibble interface mode, the parallel interface accepts nibble-wide unencoded or 8b/10b encoded data aligned to both the rising and falling edges of the transmit clock. In the multiplexed channel mode, the parallel interface accepts 8-bit-wide unencoded or 10-bit-wide 8b/10b encoded data with channels A, C, E, and G aligned to the falling edge of the source synchronous transmit clock and channels B, D, F, and H aligned to the rising edge of the transmit clock. The receive path interface is done in the same manner.