[SI-LIST] Re: Cin in IBIS models

HI! Thanks for all the help and I can conclude that if
I specify the pin parasitics for each pin and if
C_comp is specified in the input buffer model then
this will take care the total capacitance from the
input of the pin + everything that is on the die.
Thanks
Bob
--- "Muranyi, Arpad" <arpad.muranyi@xxxxxxxxx> wrote:
> 
> The current IBIS specification does not allow
> anything
> for the die other than C_comp.
> 
> Even though I am not the most experienced in this
> area,
> I haven't seen a  case where the on die inductance
> between
> the I/O buffer and its pad was larger then the
> package
> inductance.  Judging by the dimensions, I would
> think that
> it should be much smaller, and therefore negligible.
> 
> However, you can brake up your problem at a
> different
> boundary, if you still need to do this.  You could
> consider
> the on die interconnect being part of your package
> and
> include its parasitics in the package model.  That
> way
> the C_comp will only represent the buffer
> capacitance alone.
> There is nothing illegal about doing this, you may
> just
> want to write a bunch of comments to tell the IBIS
> model's
> user about what you did.
> 
> Arpad
>
==========================================================
> 
> -----Original Message-----
> From: Khederian, Bob
> [mailto:RKhederian@xxxxxxxxxxxx]
> Sent: Monday, December 17, 2001 11:57 AM
> To: 'perry.qu@xxxxxxxxxxx'; arpad.muranyi@xxxxxxxxx
> Cc: si_list
> Subject: RE: [SI-LIST] Re: Cin in IBIS models
> 
> 
> The IBIS V2.1 Specification says "C_comp defines the
> silicon die
> capacitance.  This value should not include
> capacitance of the package."
> 
> 
> -----Original Message-----
> From: Perry Qu [mailto:perry.qu@xxxxxxxxxxx]
> Sent: Monday, December 17, 2001 2:29 PM
> To: arpad.muranyi@xxxxxxxxx
> Cc: si_list
> Subject: [SI-LIST] Re: Cin in IBIS models
> 
> 
> 
> Hi!
> 
> Related to this question, is it good enough to
> represent the on-chip
> parasitics with just a C_comp ? How about R and L ?
> 
> I had a case with one vendor about their receiver
> model: for some of the
> pins, the on-chip parasitics are even bigger
> compared with packaging RLCs.
> I was told that these on-chip parastics represent
> routing parasitics from
> C4 pads to the actual receiver; Wondering how IBIS
> model take these into
> account ?
> 
> Thanks
> 
> Perry
> 
> "Muranyi, Arpad" wrote:
> 
> > Bob,
> >
> > The C_comp capacitance must represent what you see
> when you look into
> > the die at the die pad.  This includes the die
> pad, metal connections
> > on the die, the driver transistor's capacitance,
> the receiver (input)
> > capacitance, everything that is on the die. 
> Package, pin, ball, and
> > other stuff is modeled in the package model
> section of the IBIS model.
> >
> > Arpad Muranyi
> > Intel Corporation
> >
>
======================================================================
> >
> > -----Original Message-----
> > From: Bob Patel [mailto:whizplayer@xxxxxxxxx]
> > Sent: Monday, December 17, 2001 10:27 AM
> > To: si_list
> > Subject: [SI-LIST] Cin in IBIS models
> >
> > Hi! Is the input capacitance for a pin included in
> the
> > IBIS models, I know the pad capacitance is by
> using
> > C_comp. Also, when using output buffers do I have
> to
> > model the output capacitance as an external
> capacitor
> > and the input capacitance as an external
> capacitor.
> > Thanks in advance
> > Bob
> >
> > __________________________________________________
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> --
> Perry Qu
> 
> Product Integrity         |      600 March Road
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