FreeLists / si-list / [SI-LIST] Re: Validation of XTK results for clock skews

[abe riazi <ariazi@xxxxxxxxxxxxxxx>]

Suchitha Wrote:

In your previous reply to the statement,

**********Because the minimum net segment length that XNS/TLC
can simulate and the time step are related by:

      min_length =3D velocity * timestep***************

1) I am not clear what 3D means. Can you please explain this?

The 3D does not have any meaning in above formula and should not be there. It 
must been inserted (after the equal sign) by the editor used.

2)   In regard to GTL simulation, you have said that a time step = 3D 0.005 ns
has been used frequently at Serverworks.
     Do you control the minimum segment length(physical etch length) while
actually routing the GTL signals on your board?

Again, the 3D in the 3D 0.005 ns is meaningless (has been inserted by the 
editor program after the equal sign) and should have been just 0.005 ns. 

As mentioned in my previous email, higher accuracy is  achievable by reducing 
time step; but at the expense of simulation speed. 

The time of step of 0.005 ns used in GTL simulations is frequently a  good 
compromise between accuracy and speed.  Of course, if you see a XTK warning 
that time step is too large (which I
have not yet seen when using the 0.005 ns ), a 
smaller time step can then be appropriate.

3)   *****************When analysis of overshoot/undershoot is of concern, the
following rule may be used:
     1. Determine the signal rise time and take time step as 10% of rise
time.******************

     To calculate the time step as 10% of rise time, can i use the rise time
given in the buffer model?

I usually determine the rise time by looking at the driver waveform on XNS GUI, 
when driving a realistic load (since the rise time varies with the load).

The time step equal to 1/10th the rise time should be considered as an upper 
limit value, that is a smaller time step can be also used.

Best Regards,

Abe Riazi
ServerWorks.




------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field

List archives are viewable at:     http://www.freelists.org/archives/si-list 
Old list archives are viewable at: http://www.qsl.net/wb6tpu