Prasad,
The numbers in an IBIS POWER_clamp curve will go from -VDD to 0V,
but this is because they are relative to VDD and inverted. They
are not absolute voltages. Basically, positive voltage values
in the POWER_clamp curve correspond to actual voltages below VDD,
and negative curve voltage values correspond to actual voltages
above VDD.
You can extend the data into the positive region to model a
terminator, and I believe any IBIS simulator will simulate the
entire curve as expected.
Mike
Prasad Rau wrote:
>
> Hi,
>
> I am modelling onchip termination for certain IO standards and unfortunately the [POWER_clamp] curve
> puts out information from -VDD to 0v. The region of interest( termination effects) is 0v to +VDD. Is there a way to input information
> ( without modifying the source code of the simulator ) such that the IBIS file spits out -VDD to +VDD in the
> [POWER_clamp] curve. By the way, the termination is modelled as a split termination ie 50 Ohms to VDD and
> 50 Ohms to GND. These are not passive devices but active( transistors) devices.
>
> Thanks in advance,
>
> Regards,
>
> Prasad Rau
> Xilinx
Received on Wed Jul 11 13:00:14 2001
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