[time-nuts] Simulation

[jimlux]

Bob Camp wrote:
> Hi
> 
> Simply a few stories I thought I would share.
> 
> Simulate design. Use manufacturer's published models. Build design. Note differences. Call manufacturer. Answer - switched die three years ago, Ft is now " much better " ( now 3x old parts ).
> 
> Odd they never mentioned that to people who work for the same company.
> 
> Simulate design, Build design, verify design, ship it for a few years. Odd things start to happen. Look at some parts. Package looks different. Ask around..... Line got moved to other side of big ocean. Process got " tweaked" beta is now 4x what it was.
> 
> Again all inside the same company. Both cases were excused by industry standard specs that had no upper limit.
> 
> We had whole departments devoted to tracking this sort of stuff. It still happened on a regular basis. 30 years later the specs on the devices and their published models are still the " old version " ones.
> 


there are also designs that depend on "non-data-sheet" performance of 
particular devices.  There's a very low noise, very low leakage fet 
popular in charge amplifiers.  It has a JEDEC 2N number (which I can't 
remember off hand), but only the ones from one particular company (in 
England) actually work in the circuits, and even then, there's some hand 
selection involved.