[IBIS-Users] RE: [IBIS] Multi level IBIS model development (Ethernet)

Vishrant,

IBIS generally doesn't support multi-level signaling,

unless you use the language extensions (*-AMS or SPICE)

to make your models.

However, if you are lucky, you may be able to model this

particular device. The question is whether that "0" in

the middle is "driven" or high impedance. If the latter,

you can make the pullup reference your high level and

pull up to it with a pullup I-V table, and the pulldown

reference a negative voltage and pull down to it with

the pulldown I-V table, and let the model go 3-state

when it needs to output a 0 V level. Even if this 0 V

level is not high-Z, you could use the clamp tables to

hold it firm, and add that much more current to the PU/PD

I-V tables to make the signal go high or low.

This is a little tricky and may not work, but there might

be a possibility...

I hope this helps,

Arpad

===========================================================

From: owner-ibis@eda.org [mailto:owner-ibis@eda.org] On Behalf Of
Vishrant GOYAL
Sent: Wednesday, April 27, 2011 5:42 AM
To: ibis-users@eda.org; ibis@eda.org
Subject: [IBIS] Multi level IBIS model development (Ethernet)

Hello Expert,

I am trying to develop ibis model for Ethernet Phy for 100 BT mode.

In 100 BT mode there are 3 level possible at the output (TXP and TXN).

Means for every 1's at the input data, output will switch between three
levels

and for every 0's output will remain on the same level.

So for given below input data stream we got following output from the
driver (Similar but opposite output on TXN)

0 1 1 0 1 1 1 1 0 0 0 1 0 1 0 1 1 0 (Input DATA)

 vcm

- How could I develop the ibis for Multi level signals?

Can anyone give some light on this model development.

Thanks & Regards,

Vishrant Goyal

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