The VN16218 is a low power single chip, 2.5GBd transceiver. It provides a 2.5GBd serial link interface in the physical layer and includes a Serialize/Deserialize (SERDES) capability. Other functions include clock generation, clock data recovery, and word synchronization. In addition, an internal loopback function is provided for system debugging. The VN16218 is ideal for 2.5 Gigabit, serial backplane and proprietary point-to-point applications. The device supports both fiber-optic and copper media. The transmitter section of the VN16218 accepts 20-bit wide TTL data and latches it on the rising edge of the incoming Transmit Byte Clock (TBC) and serializes the data onto the TX differential outputs, at a baud rate that is twenty times the TBC frequency. The data is converted to a high-speed serial data stream. The transmit PLL locks to the 125 MHz TBC. This clock is then multiplied by 20 to supply a 2.5 GHz serial clock for parallel-to-serial conversion. The high-speed serial outputs can interface directly with copper cables or PCB traces. Where optical transmission is required, the outputs can connect to a separate optical module. When copper lines are the medium, equalization is available for improved performance. The receiver section of the VN16218 accepts a serial data stream of 2.5 GBd and recovers 20 bit parallel data. The receiver PLL locks on to the incoming serial signal and recovers the high-speed incoming clock and data. The serial data is converted back into 20-bit parallel data format. Byte alignment is accomplished by optional recognition of the K28.5+ comma character. The recovered parallel data is sent to CMOS outputs, together with two 125 MHz clocks, RBC and RBCN, that are 180 degrees out of phase from each other.