12 Apr
2013
12 Apr
'13
10:26 a.m.
On Apr 12, 2013, at 1:18 PM, Allison <ajp166 at verizon.net> wrote:
I use spice, XFTD, NEC2, and on and on...
They are all nice tools if you keep one thing in mind.
GIGO
For those that have forgotten of never heard that
"Garbage In produces Garbage Out". To avoid that
don't put garbage in. What is garbage? Simulations
with far to many unknown and parasitic items
unaccounted for.
If one takes the time and efffort to correlate and qualify the
results then the answers should be valid and often are.
That means if you use a mbt2222 transistor in spice
the first task is that spice realization a valid one!
Like anything computer simulation and test can be
good or bad and as a designer you can control that.
Absolutely. All I'm saying is that I work with (or rather
clean up after) a lot of people who use simulators, whether
SPICE or a logic simulator or whatever, as a DESIGN tool.
They end up with fragile code that looks like garbage
because e.g. they'll iteratively tweak their design by
simulating it and throwing in pipeline delays until it all
"works", at least under the specific conditions of the sim.
So yes, like any good tool, you have to be using it the
right way. Just because you CAN use a circular saw in
place of a pencil or a hammer doesn't mean you SHOULD.
It's important to do the math BEFOREHAND, ideally on paper
or paper equivalent, and simulate AFTERWARD. That is,
sadly, a lesson I'm still occasionally relearning.
- Dave