[sdiy] Sic Transit OTA Mundi

[Don Tillman]

   > From: Grant Richter <grichter at asapnet.net>
   > Date: Fri, 27 May 2005 13:21:45 -0500
   > 
   > > Or would Intersil consider introducing an improved 21st century
   > > version of the the CA3280, made in a modern fab?
   > >
   > 
   > Thank you for fighting the good fight.

Hey Grant,

You're welcome.  I'm implicitly encouraging others to do something
similar.

   > I believe the problem is that "modern" fab processes do not like
   > 30 volts across a die.

I don't believe that.  While there are more chips at lower supply
voltages now than ever before, certainly, many current analog
processes for opamps and similar devices can easily handle 30 volts.
Some handle significantly higher voltages.  There's no reason the
modern 3280 couldn't just use the current 30 volt opamp processes.

   > At least thats what the reps tell me. The move to low voltage
   > ANALOG is motivated by greed. Low voltage parts are much more
   > profitable than high voltage parts.

Sure, if they've invested a lot of money, they deserve to make a
profit.  Otherwise there'd be no incentive to invest the money in the
first place.

I'm guessing the profit really comes from volume sales.  If they can
sell Madonna quantities of OTA's, they'll be happy.  That would
suggest that the best way to get 3280's back into production is to
come up with lots of killer applications.

And heck, if it performs better, I'm not convinced a low supply
voltage 3280 would be a bad thing.  My QuadTrap VCO intentionally runs
its 3280's at 16 volts as a performance tweak.

A 21st century OTA should just use whatever the regular opamp process
is and abide by its limitations.

  -- Don

-- 
Don Tillman
Palo Alto, California
don at till.com
http://www.till.com