I am implementing a USB 3.x signal redriver to help with signal integrity issues. I understand that a redriver provides equalization to the signal path but what losses are affected by this equalization?
In general there are two concepts that need to be taken into account to understand what losses are affected by your USB 3.x signal redriver, Pre-channel loss and Post-channel loss. “Pre-channel” loss refers to any loss that occurs before USB 3.x signal redriver’s receiver. “Post-channel” loss refers to the loss that occurs after the USB 3.x signal redriver’s transmitter. Trace length and trace width heavily influence the Pre-channel and Post-channel loss. USB 3.x signal redriver equalization function, primarily, takes place at the receiver and compensates for the all the Pre-channel loss and a small portion of the Post-channel loss. Keep in mind that for dual channel devices, like TUSB1002A, the Pre-channel and Post-channel losses are not the same for channel one versus channel two. For Pre-channel and Post-channel length recommendations, please refer to your specific USB Host design guidelines and TI USB 3.x redriver design guidelines.
