[SI-LIST] Re: Purpose of Cref,Rref and Vref parameters in IBIS files
- From: steve weir <weirsi@xxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 28 Mar 2014 00:16:29 -0700
Cref and Rref are there to so that the timing effects between of the
test fixture used to generate the IBIS file can be deembedded.
Steve
On 3/27/2014 11:19 PM, Mallikarjun K wrote:
> Hi,
> from IBIS spec
> "The Cref and Rref subparameters correspond to the test load
> | that the semiconductor vendor uses when specifying the
> | *propagation delay and/or output switching time of the model*.
> | The Vmeas subparameter is the reference voltage level that the
> | semiconductor vendor uses for the model. Include Cref, Rref,
> | Vref, and Vmeas information to facilitate board-level timing
> | simulation. The assumed connections for Cref, Rref, and Vref
> | are shown in the following diagram:
> |
> | _________
> | | |
> | | |\ | Rref
> | |Driver| \|------o----/\/\/\----o Vref
> | | | /| |
> | | |/ | === Cref
> | |_________| |
> | |
> | GND
> "
> Correct me if i am wrong,
> IBIS model Output switching curves (V-T curves) were generated by Buffer
> having Rload/Rfixture to Vfixture or GND.
>
> I-V Curves were generated by connecting a variable voltage source and
> measuring current entering Buffer.
>
> In these 2 data measurements, Vref,RRef and Cref were never used.
>
> What is the purpose and usage of these models.
>
>
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