Subject: [IBIS-Users] IBIS Model for SSTL differential output buffer
From: Ranjan Kumar Sahoo (rek@cypress.com)
Date: Mon Dec 29 2003 - 05:29:12 PST
Hi all,
I am trying to generate IBIS model for SSTL diiferential Output buffer.
Input swing is 500 mv ( VDD-500mv to VDD) .Output swing is 0 to Vdd.
s2ibis2 is used for IBIS file generation. The problem is output never
falls below
Vdd value in case of Falling wave form and always close to Vdd in case
of rising wave form
But when I do an Antrim Simulation (with R_fixture=50ohm connected to
Vdd) the swing is
proper.
In case of differntial output buffer how the input stimulus is applied
and how R_fixture is connected. The relevent input information and pin
details
are given below.
Thanks & regards,
Ranjan
[temperature range] 27 140 0
[voltage range] 1.8 1.7 1.9
[sim time] 9ns
[vil] 1.3 1.2 1.4
[vih] 1.8 1.7 1.9
[Tr] 1ns 0.9ns 1.10ns
[Tf] 1ns 0.9ns 1.10ns
[C_comp] 2pf 1.8pf 2.2pf
[rload] 50
[Pin]
1 d_core_p d_core_p dummy_in
2 d_core_n d_core_n dummy_in
3 pad1 pad1 diff_output
-> 1
4 pad2 pad2 diff_output
-> 2
5 vgnd vgnd GND
6 vpwr vpwr POWER
Non-inv_pin inv_pin vdiff tdelay_typ tdelay_min tdelay_max
1 2 250mv 0ns NA NA
|Differential output pin is indicated by keyword Diff Pin
|
[Diff Pin]
|Non-inv_pin inv_pin vdiff tdelay_typ tdelay_min tdelay_max
3 4 0v 0ns NA NA
[Model] diff_output
[Model type]Output
[Polarity] Non-inverting
[Model file] typ.mod typ.mod typ.mod
[Rising waveform] 50 0 0 0 NA NA NA NA NA
[Falling waveform] 50 1.8 1.7 1.9 NA NA NA NA NA
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