What is signal intergrity Analaysis? And where it is used?

Signal Integrity Analysis is used to explore the quality of signals in a PCB as they pass from Driver to Receiver through the PCB Interconnect and terminations. Models, typically IBIS, are used for the Driver and Receiver, SPICE models are typically used for passive components, and the Interconnect, tracks and vias, is extracted from the board for post route analysis, this lot ends up in a Topology file and the tools allow the topology to be simulated and signal quality observed. There is also pre-route analysis where Drivers and Receivers, terminations, and some "more ideal" Interconnect models are used to determine topology requirements, as Constraints, which can then be applied to the board design to control physical design. In terms of products, SigXplorer is the Topology Viewer and Simulator, SigWave displays the resulting waveforms, there is also a license option, PCB SI, to allow Allegro to run in a "Signal Integrity" mode for more advanced investigation. In common designs, multi-Gigahertz serial links and DDR memory structures require analysis to ensure that signal quality requirements are designed in as Constraints before routing and verify that requirements are met post routing and then verified by testing and measuring the completed PCB design. Signal quality, or lack of, might also affect the reliability of designs where frequencies are not necessarily high but drivers with fast edge rates are used.