HyperLynx Basic Knowledge of IBIS-AMI Simulation in HyperLynx SI

HyperLynx Marketing SI/PI


This is the recording with questions and answers of a webinar broadcast on 14 MAR 2024


Q: Can you model decision feedback equalization (DFE) with Init-only models (in the AMI_Init function)?
    video time-point 29:40

A: Some models might use some tricks to approximate DFE in the AMI_Init function, but this is not the most accurate method. Time-dependent equalization like DFE or FFE should be modeled in the AMI_GetWave function.

Q: Do you need to extract a 3D area into an S-parameter model to connect the transmitter and receiver to accurately simulate your channel?
    video time-point 27:00

A: It is not necessary to export a net model to LineSim or to an S-parameter file. You can assign a complete IBIS component model to a part in BoardSim and simulate the connected nets directly. For high-speed SerDes nets (above about 5 Gbps) you might want to make 3D models of the areas around vias and pins. Even with these 3D areas, you can still simulate the nets directly in BoardSim.

Q: For a SerDes interface from a driver to a receiver and there is a re-driver in between, can this be simulated end to end? How about doing simulations with retimer IBIS-AMI models?
    video time-point 25:10

A: The current implementation for redriver and retimer IBIS-AMI models uses a script in an Excel file.

Q: How do you use the termination and package files that come with some IBIS-AMI models when using HyperLynx BoardSim (post-layout) vs. using LineSim (pre-layout)?
    video time-point 32:00

A: To simulate one net with this model, you can export the net from BoardSim to LineSim and connect the IC model sections in LineSim. If you plan to use the IBIS-AMI model on multiple nets, it is worth the time to construct a complete IBIS component and model to reference the AMI files.

Q: Very often in the past I have encountered a situation when the channel characterization results in a non-linear channel, even though I don't have any active circuits in it. The channel is comprised of multiple S-parameter models linked together as blocks. Is there a requirement on the frequency stepping for these S-parameter models given they all have the same max frequency as the channel characterization frequency?
    video time-point 38:30

A: This issue is most likely not an issue of IBIS-AMI. It is most likely a problem in the S-parameter data. You should always check S-parameter data to confirm that they are passive and causal.

Q: How do I know if my channel is LTI?
    video time-point 39:15

A: In the channel characterization dialog there is an option to evaluate LTI quality of the channel. In the IBIS-AMI SerDes Wizard, disable the checkbox for automatic channel characterization and click the Advanced button next to that checkbox. In the Advanced Channel Characterization dialog, select the Step/Puls Response radio button. Then select the Check channel linearity checkbox at the bottom of the dialog.

Q: How would you use IBIS-AMI to simulate the PCI Express channel on an add-in card since there is no model for the edge connector?
    video time-point 37:40

A: You could create an extra model for the connector and system board with an IBIS-AMI model included. That would be a lot of work. Another option that fits this scenario is to use the SerDes Compliance Wizard in HyperLynx SI.


KB Article ID# KB000130405_EN_US



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