In PCIe, USB 3.0, and SATA systems, the most common technique is downspreading, via frequency modulation with a lower-frequency source. Spread-spectrum clocking, like other kinds of dynamic frequency change, can also create challenges for designers. Principal among these is clock/data misalignment, or clock skew. A phase-locked loop on the receiving side needs a high enough bandwidth to correctly track a spread-spectrum clock.