Comments on spectre/spectreS difference
Quek Hong Cheang
I found that I could not really find a difference between Spectre and
SpectreS except that they use model files with different format and
that spectreS is simply a spice-language compatible version of
spectre.
Both are capable of using BSIM3 SPICE and are improvements over SPICE.
In fact, it was also mentioned in an article (comp.cad.cadence,
1995/09/29) by Alessandro Piovaccari that both simulators are the
same. If that is the case, then why create both when one is sufficient
???
Thanks
Quek
Andrew Beckett
In the past, many simulators (spectre included) did not have a strong native
parameterizable netlist format. cdsSpice however had a powerful macro language
that could be used to allow parameterisation etc - yet the cdsSpice simulator
is essentially based on Berkeley SPICE - and so is not a particularly powerful
simulator.
So, what used to happen when a simulator was integrated into the AnalogArtist
system was that it was integrated using the "cdsSpice Socket". This meant that
the netlists were produced in cdsSpice's language - which is an extended spice
syntax (it's not actually spice compatible though - the continuation characters
are different, for a start) - and then cdsSpice took care of producing a final
netlist for the integrated simulator.
spectre and hspice were integrated this way - and so there was a spectreS and
hspiceS interface.
Now, the problem was that integrating spectre this way really limited the access
to a number of its features - plus the fact that cdsSpice is rather long in the
tooth, and this approach is rather slow. So, in IC443, a new "spectre"
(sometimes referred to as "spectre direct") interface was created. The simulator
itself was enhanced to support more complete parameterisation (some of this
had already been done by then), plus implementing some things like monte-carlo
native in the simulator (previously this had been taken care of by cdsSpice as
the random number generator).
The resulting interface is considerably qucker, and now Artist talks directly in
spectre's netlist language, as well as communicating directly with the
simulator. This means that when a parameter gets changed, Artist can just tell
the simulator it changed and usually this means that spectre can change it in
memory without having to restart, get the license, re-read the netlist and so
on. So parametric sweeps are _much_ faster.
spectre itself supports both a limited spice-compatibility language, but has
a fuller spice compatibility via the spp (spice preprocessor) extension which
is invoked if you have spice-language include files.
So, to summarize. The simulator in both spectreS and spectre is the same,
but the spectre interface is the newer one. Many of the newer analyses are not
available in the spectreS interface, and also any new features are not being
added in the spectreS interface. In other words, spectreS is obsolete and is
only there for compatibility if you have old setups. You are strongly
recommended to use the spectre interface because it works so much better!
Regardsl
Andrew.
--
Andrew Beckett
Senior Technical Leader
Custom IC Solutions
Cadence Design Systems Ltd