RE: [IBIS-Users] Rising falling waveform timestep

Anshul,
 
You may rely on your SPICE simulator's dynamic time step
algorithm to generate the points for you as necessary,
but I prefer to set the simulation time step to a low
number and then extract the 100/1000 best points from
that.
 
For example, depending on the edge rate of the buffer,
I like to simulate at 1 ps )or even lower if the buffer
is really fast) and then use IBIS Center's "Best 100/1000
points" algorithm to reduce the total number of points
from several thousand to 100 or 1000.
 
You can look at how IBIS Center picks the best points
in my presentation:
 
http://www.vhdl.org/pub/ibis/training/IBIS_class_2003.zip
 
on pg. 29.  I hope this helps.
 
Arpad
========================================================

________________________________

From: owner-ibis-users@server.eda.org [mailto:owner-ibis-users@server.eda.org] On Behalf Of Anshul Bansal
Sent: Tuesday, November 04, 2008 10:45 AM
To: ibis-users@server.eda.org
Subject: Re: [IBIS-Users] Rising falling waveform timestep


Hello All,

Thanks to everyone for replying to my previous post on the usage of unequal timesteps for rising/falling waveform. I understand that usage of unequal timesteps is preferred in most cases. What I wanted to know now is that is there an automated method/program/scripts that exists that most people use in creation of the rising/falling waveforms with unequal timesteps?

We at Cypress Semiconductor have come up with a methodology for creation of rising/falling waveforms with unequal timesteps and I was thinking of submitting a paper for the Asian IBIS Summit at Japan. Before I do so, I wanted to know what other methods do people use.

Any help would be greatly appreciated.

Thanks,

Anshul

al davis wrote: 

	On Monday 27 October 2008, Anshul Bansal wrote:
	  

		I had a question regarding the timesteps for the
		rising/falling waveform. Is it legal to use unequal timestep
		for the rising or falling waveforms? 
		    

	
	The use of unequal timestep is preferred.  You should use more 
	points where they are needed to express detail and less points 
	in relatively flat sections.
	
	It actually makes a difference.  If your data looks like steps, 
	with groups of consecutive values that are the same, you are 
	using too many steps.  It does matter.
	
	You may not see a problem because files like that are common so 
	simulators will drop steps to make the waveform smooth and 
	simulateable.
	
	  


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