I generally don't use op amp SPICE models, because IME when the results aren't obvious, they're usually wrong. so I'm kind of out of date on this point.
Do manufacturers' op amp models account properly for noise and input capacitance these days? Which ones are good/bad/indifferent?
Thanks,
Phil Hobbs
Some do, some don't. Unfortunately most OpAmp models are done using macros rather than at device-level, so the results are dubious at best.
I've seen a few that, at least, have the input stage modeled at device-level.
You just need to look over every subcircuit carefully to be sure.
Some simulators can handle encrypted models, allowing device-level modeling without showing competitors what the schematic actually looks like.
Unfortunately the models are simulator-specific... for instance, PSpice can't read an HSpice-encrypted model :-(
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | | | | America: Land of the Free, Because of the Brave | | | | Due to excessive spam, googlegroups, UAR & AIOE are blocked! |
Thanks, but I'm being much much lazier than that. ;)
Any specifics?
Thanks,
Phil Hobbs
No. Because I rarely use them. Most of the time _I'm_ designing the OpAmp ;-)
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | | | | America: Land of the Free, Because of the Brave | | | | Due to excessive spam, googlegroups, UAR & AIOE are blocked! |
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
What's the likelihood that the manufacturers would consent to letting you post the schematics of those you did, say, ten years ago in a public forum?
I'm assuming that most of the op-amp improvements in the past few decades have come from the transistors themselves and not any fundamentally new/not-well-known architecture. :-)
I haven't done an off-the-shelf OpAmp since the early '70's. Everything has been customer-specific.
...Jim Thompson
-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | | | | America: Land of the Free, Because of the Brave | | | | Due to excessive spam, googlegroups, UAR & AIOE are blocked! |
To be honest since the quality of some datasheets and lots of app notes have gone downhill starting some times in the 90's my faith in SPICE models has shrunk proportionately.
To be really honest, my faith in opamps in general has shriveled up a little as well so I use more discrete stuff. "Hey, here's this great amplifier" ... "Oh yeah, can I buy, say, a reel?" ... "Err, not right now, maybe next year or so, we just messed up the foundry."
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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