Hello

For redesign purposes I need to identify equivalent schema of test chip that was fabricated. For next tapeout I should change some parameters. This changes requires transient simulation of schema that includes a block that is passive, but influence considerably the behavior of circuit. So, I want to replace this block by equivalent schema that will consist of (as I suppose) from 2 components - nonlinear resistor and nonlinear capacitor, connected in parallel.

How identify such system. I envisage following testbench (please, see the picture). Generator V1 generates steps that are applied to chain, consisting from some resistor in serial with my device. Measuring step response in point out will allow to get frequency response of the chain R0-U_DUT, and then, derive the characteristic of U_DUT. But what tool/mathematical methods could be used for such transformation. From my university years I remember integral of Duhamel, that could help to do this job. If anybody met similar problem?

Thanks in advance.

Regards.

Pavel.