Subject: [IBIS-Users] IBIS model for FET switch
From: Haque, Moshiul (mhaque@ti.com)
Date: Fri Sep 06 2002 - 10:27:35 PDT
IBIS Gurus,
I am trying to model a switch with parallel NMOS and PMOS. I am kind of
confused about the description of Series Mosfet keyword in IBIS Version 4
specification. The description says that either of the FET's could be
removed. Thus this model covers all four conditions , off, single NMOS,
single PMOS and parallel NMOS/PMOS.
1) Does that mean that I have to model NMOS, PMOS and off condition
separately? Or only one Series Mosfet keyword with different VDS is
sufficient to model the switch.
2) How to model the off condition? I thought to model off condition series
current keyword with off sub parameter is necessary.
3) What would be appropriate keyword to model parallel FET switches, series
current or series mosfet?
I have tried to model the switch with series switch keyword. One problem
with this type of model is the error generated due to decreasing current. In
the IBISCHK3.2.9 version the error has been changed to warning. But lot of
the simulator uses the older version of IBISCHK and my concern is that will
this error prevent the simulator from simulating?
Appreciate any suggestions.
Regards
Moshiul Haque
Standard Linear and Logic Marketing
Texas Instruments Incorporated
Ph: (903) 868-7153
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