[SI-LIST] Re: Simulation Question in Spectra Quest.
- From: Heiko Dudek <heikod@xxxxxxxxxxx>
- To: we_r_frendz@xxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Thu, 09 Aug 2001 12:01:08 +0200
Rahul,
>1) The technology that I simulate makes use of
>Differential strobes. Do I need to set up two strobes
>in my simulation or a single strobe sampling at both
>edges.
If your strobe line is layed out as a differential pair, you
definitely need to model this with a coupled trace element.
Same for driver / receiver (take care, often differential
drivers are used together with single receivers). You need
to use single or differential models, depending on what
you have in reality. No direct relation to sampling on
rising, falling or both edges. This again depends on
whatever technology you're simulating ... RAMBUS for
example samples on both edges. This way, a 400MHz
strobe results in 800MT/s.
>2) Does the tool sample at both the edges or only at
>the rising edges.
whatever you want it to. Select 'Set'->'Strobe Pins'. In
the 'Strobe Selection Window', you can set 'Active Edge'
to 'Both', 'Rising' or 'Falling'.
>3)When we make use of Custom measurements, In the IO
>cell Edit window there is a column for Freq. Does this
>frequency indicate the sampling frequency ( The rate
>at which the data is being sampled ). If so what does
>the Clock freq that appears in the Analysis
>preferences window indicate.
I assume you're talking about the I/O cell stimulus edit. You
do have the choice between different stimulus states ...
there's 'Rising', 'Falling', 'Pulse' and 'Custom' (and 'Quiet
hi', 'Quiet lo' and 'Tristate' as well). Whereas all I/O cells
with rising, falling or pulse waveforms are operating in
sync and with whatever you set in the analysis preference
window as clock frequency. If you decide an I/O cell to
have a custom stimulus, you can set the clock frequency
to whatever you want and individually for all custom I/Os.
The frequency set in the analysis prefs has no influence
on custom I/O stimulus.
Hope this helps.
- Heiko
Heiko Dudek
Technical Marketing Manager, High Speed Systems Design & IC Packaging
Cadence Design Systems, 270 Billerica Road, Chelmsford, MA 01824
ph (office Chelmsford, USA): (978) 262-6384
ph (office Feldkirchen, Germany): (089) 4563-0
fx (office Chelmsford, USA): (978) 446-6798
fx (office Feldkirchen, Germany): (089) 4563-1800
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email: heikod@xxxxxxxxxxx
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