[SI-LIST] Re: Question about Simulation in Spectraquest
- From: Carlos Moll <cmoll@xxxxxxxxxxx>
- To: we_r_frendz@xxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Tue, 07 Aug 2001 09:47:59 -0400
Rahul:
All simulator computed values are only as useful as the parameters
established by the user during the initial simulation setup.
These include models (checks), field solver cutoff frequency for
interconnect and vias, buffer delay measurements, corners, cycle
measurement (set to >1 for settling), simulation granularity, etc..
These parameters should be set in the analysis-simulation preference section.
IBIS min, typ, max definitions maps into SQ as slow, typ, fast for flight
time calculations.
At times, vendor device model characterization processes/ behavior is
difficult to emulate unless the user and vendor understand/participate in
all stages involved during device characterization process. There can also
be some documentation provided by the model company on how the
characterization process was defined and provide useful data that may
include Tco, buffer delay measurements to standard load (value), min, typ,
max (slow, typ, fast) flight time at preset thresholds and so on and the
overall process used to derive the data used for the ibis parameters. With
this said....
The mapping results for slow, typ, fast calculations can be easily modified
(and hence the statement above) to comply with the manufactures device
characterizations process.
Again, go to simulation preference section->Fast/Typical/Slow Definitions
and change the parameters to match the required process.
By default, the following conventions are used to derive at flight time
(fast, typ, slow) calculations;
inputhighfast Minimum
inputhightypical Typical
inputhighslow Maximum
inputlowfast Maximum
inputhightypical Typical
inputlowslow Minimum
vmeasfast Minimum
vmeastyp Typical
vmeasslow Maximum
You could change in the ui to
inputhighfast Maximum
inputhighslow Minimum
inputlowfast Minimum
inputlowslow Maximum
vmeasfast Maximum
vmeastyp Minimum
vmeastyp Typical
vmeasslow Minimum
You could easily generate a script and replay it as need to support various
manufacturing processes. Also, the default values above are stored in a
file named cds_signoise.cfg, which is located in the
install_directory/share/pcb/signal. The can be change to always read in
the same setup for any flight time calculations or you can copy file and
store in pcbenv directory and change as required.
Carlos Moll
Cadence
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