The signaling schemes for SuperSpeed USB and PCI-Express are quite different. SuperSpeed USB does not use a common clock architecture. It requires spread spectrum on both sidebands and requires equalization at the receiving end. The processing of time jitter also takes a different approach. At the same time, this solution does not provide sideband pins for connection/disconnection detection, link reset, power management control or wake-up.
The increase in transmission speed poses a challenge to existing USB 2.0 cables. SuperSpeed USB requires a shielded differential pair (SDP) cable to ensure signal integrity and minimize electromagnetic interference. At the same time, the maximum cable length has been reduced from 5m for USB 2.0 to 3m for SuperSpeed USB. The physical layer's electronic signaling scheme has also evolved from a simple two-wire system to a dual-simplex data path. This is achieved through a completely separate connection and is no longer a two-wire interface in existing USB 2.0. The purpose of this is to be able to achieve a 5Gb/s transmission rate on a 3m cable. In addition, although changes are required to meet the electronic signaling scheme, the host does not have to provide a new form factor plug or socket; if possible, no changes are required on the peripheral.
