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.Internally terminated differential CML inputs accept AC−coupled LVPECL (Positive ECL) or direct coupled CML signals. By providing internal 50 Ohm 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 Ohm terminations, and 400 mV output swings when externally terminated, 50 Ohm 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.