1
\$\begingroup\$

What do you do when you want to simulate a signal (i.e with Hyperlynx) but you can't find the IBIS model of the receiver chip?

What parameters do you need? Where can you find them?

\$\endgroup\$

1 Answer 1

2
\$\begingroup\$

For a high impedance input, you can use a dummy probe (that's what Cadence calls it, can't remember the term for the Hyperlynx equivalent) which basically just looks at the voltages without affecting the signal.

Edit: In Hyperlynx you can find the models of probes, as the image shows.

enter image description here

A "real" IBIS input model will add some input capacitance, which you may also do as a separate ideal capacitor at the input. A few pF is common. Also a "real" IBIS input model will add pull-up/dn and pwr/gnd clamping diodes.

Since the pwr/gnd clamping tends to mask overshoot, I often use just an ideal input (dummy probe) and an estimated input capacitor for inputs when trying out different bus topologies and termination schemes.

Other than that, you may also be able to find the IBIS model for a 2nd source part (I guess you tried that already).

\$\endgroup\$
3
  • \$\begingroup\$ I'll try to find the equivalent for Hyperlynx \$\endgroup\$ Jun 5, 2013 at 12:45
  • \$\begingroup\$ I'm thinking in the same question but for drivers... Definitely we need a IBIS tags! \$\endgroup\$ Jun 5, 2013 at 13:05
  • 1
    \$\begingroup\$ Drivers are more difficult... You want something with the same voltage swing and the same rise/fall time (edge rate) as a minimum. \$\endgroup\$ Jun 5, 2013 at 18:10

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.