IBIS (Input/output Buffer Information Specification) model was originally developed by Intel Corporation as a model for digital signal integrity analysis for PCB board and system level.
Now managed by the IBIS Open Forum and becoming the official industry standard, the IBIS model uses U/I and U/T tables to describe the characteristics of digital integrated circuit I/O cells and pins.
Since the IBIS model does not need to describe the internal design of the I/O unit and the transistor manufacturing parameters, it has been welcomed and supported by semiconductor manufacturers.
Now major digital IC manufacturers are able to provide the corresponding IBIS models while providing chips.
