The 9ZX21901B is a version of the Intel DB1900Z differential buffer with an adjustable external feedback path allowing the user to eliminate trace delays from their design. It is suitable for PCIe Gen 3 or QPI applications. The part is backward compatible with PCIe Gen 1 and Gen 2. And, the device maintains low drift for critical QPI applications. In bypass mode, the 9ZX21901 can provide outputs up to 400MHz. See the 9ZX21901C for a fixed external feedback path.