Hi, I found two simulations models IBIS and S-Parameters. What is the difference between them ? I know they are different then SPICE which we use to simulate the analog ICs in circuit but if we talk about IBIS and S-Parameters then how do we differentiate them ? I know that IBIS stands for "Input/output Buffer Information Specification" and is used primary for digital IC switching or digital I/O modelling. What are S-Parameters ? and how they differ then IBIS models ?