[IBIS-Users] Correlating Tco of IBIS to SPICE


Subject: [IBIS-Users] Correlating Tco of IBIS to SPICE
From: Timothy Coyle (timothy.coyle@sun.com)
Date: Wed May 21 2003 - 08:25:20 PDT


Hello,
I am trying to correlate the rising Tco of IBIS file to original SPICE file. To obtain the rising waveform for IBIS, I applied a PWL
source to the input, starting at time 0ns, and 300ps later reaching Vcc. (300ps is the slew rate of the device) Since this is a clocked
output, I then apply a PWL to the clock input. So at about 1ns, I get my rising waveform. When I run the SPICE file into the standard load (Vref, Rref, Cref) and get the Tco number, it is 800ps, where the IBIS Tco is 1.53ns. I apply the same signal to both the SPICE and IBIS input, with no delay and rise/fall times of 300ps. So depending on how I set up my clock input, that is where my rising waveform will
start, and hence my IBIS Tco number. Is it acceptable to get rid of leading zero's to match up IBIS to SPICE? Or should I be able to handle
this with the way I set up my inputs?

Regards,
Tim
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