The VSC8144 is a SONET/SDH compatible multi-rate transceiver with integrated clock generator for use in SONET/SDH systems operating at OC-48, OC-24, OC-12, OC-3, or Gigabit Ethernet data rates. The internal clock generator uses a Phase Locked Loop (PLL) to multiply either a 77.76MHz, 155.52MHz, or 622.08MHz reference clock for internal logic and output retiming. The 4-bit parallel LVDS interface incorporates an on-board FIFO to address loop timing design issues. Facility and Equipment Loopbacks can be configured separately or simultaneously. The device operates with 2.5 W maximum power and is packaged in a thermally enhanced 100-pin PQFP package.