http://www.spisim.com/blog/ibis-model-how-does-ibis-work/ EDA Experts in Signal, Power Integrity and Simulation Thu, 13 Dec 2018 22:56:33 +0000 hourly 1 https://wordpress.org/?v=5.3.2 http://www.spisim.com/blog/ibis-model-how-does-ibis-work/#comment-4165 Thu, 13 Dec 2018 22:56:33 +0000 http://www.spisim.com/?p=805#comment-4165 […] In previous post, we explained how IBIS model’s data are used in a circuit simulation. Simply speaking, the “VT” data is considered as “target” while “IV” data are used to compute “switching coefficients” so that appropriate amount of current will be injected or withdrawn from the buffer to achieve the nodal voltage specified by that VT table at that particular time point. Because there are switching coefficients for both pull-up and pull-down structures… need two equations to solve for two unknowns, thus two set of VT, each under different test loads, are required. Based on this algorithm, an IV data and calculated coefficients are actually “paired” and affect each other. If current in IV table is larger, than the calculated coefficients will become smaller so that overall injected/withdrawn current will still be the same. In this sense, the actual IV data is not that important as it will always be “adjusted” or weighted by the parameters. […]

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