The NB4N840M is a high-bandwidth fully differential dual 2 x 2 crosspoint switch with CML inputs/outputs that is suitable for applications such as SDH/SONET DWDM and high speed switching. Fully differential design techniques are used to minimize jitter accumulation, crosstalk, and signal skew, which make this device ideal for loop-through and protection channel switching applications. Each 2 x 2 crosspoint switch can fan-out and/or multiplex up to 2.7 Gb/s data and 2.7 GHz clock signals. Internally terminated differential CML inputs accept AC-coupled LVPECL (Positive ECL) or direct coupled CML signals. By providing internal 50 W input and output termination resistor, the need for external components is eliminated and interface reflections are minimized. Differential 16 mA CML outputs provide matching internal 50 W terminations, and 400 mV output swings when externally terminated, 50 W to VCC. Single-ended LVCMOS/LVTTL SEL inputs control the routing of the signals through the crosspoint switch which makes this device configurable as 1:2 fan-out, repeater or 2 x 2 crosspoint switch. The device is housed in a low profile 5 x 5 mm 32-pin QFN package.