J
Joerg
Guest
Bill Sloman wrote:
Near Huntsville? You've got to be kidding ...
They can make the rafters shake.
--
Regards, Joerg
http://www.analogconsultants.com/
On 20/08/2011 2:46 AM, Joerg wrote:
John Larkin wrote:
On Fri, 19 Aug 2011 09:07:39 -0700, Joerg<invalid@invalid.invalid
wrote:
John Larkin wrote:
On Fri, 19 Aug 2011 07:28:18 -0700, Joerg<invalid@invalid.invalid
wrote:
Jim Thompson wrote:
On Thu, 18 Aug 2011 18:06:13 -0700,
Joerg<invalid@invalid.invalid> wrote:
John Larkin wrote:
On Thu, 18 Aug 2011 14:01:41 -0700, Joerg<invalid@invalid.invalid
wrote:
John Larkin wrote:
On Thu, 18 Aug 2011 12:59:05 -0700,
Joerg<invalid@invalid.invalid
wrote:
Folks,
Have to drive around a hundred pF or so in parallel with
maybe a few
hundred ohms blazingly fast. 10-12V amplitude, transitions
ideally
sub-nanosecond from 10-90% both directions. Not too
boutiquish or
unobtanium (which excludes certain companies ...) and not
more than a
few Dollars. Shouldn't introduce noise when low. Low
quiescent current,
preferably under 20mA.
Looked around and the fastest one I could see is this dude:
http://www.diodes.com/datasheets/ZXGD3003E6.pdf
Not too much data but it gets into the 2nsec range. Anyone
aware of a
driver with even more testosterone?
The rise/fall times are mediocre. A little series inductive
peaking
would help.
Mediocre? At high capacitive load maybe but at low loads I
think they
are amazing for a 25c part. Most others including its other
ZXGD300x
brethren peter out towards 10nsec for one of both slopes
towards zero
capacitance.
Gate driver chips are cool, though. They have lots of
off-label uses.
Oh yeah
Of course the ideal scenario would be a push-pull MMIC with
15V or more
supply voltage but that ain't going to happen. Same with RF
switches,
even if they could take 12V they are surprisingly slow in
switch action.
Ok, could roll my own, of course. But that gets to be
involved and a bit
too big for this project.
What's the load? Need DC coupling/long pulses?
Pulses are under 100nsec length and duty cycle is well under
5%. Getting
DC across would be great but I am afraid I'll have to clamp
that ...
somehow ... because it's a high voltage I'll have to move with
that. Or
I'll let this whole thing ride on the rail. Woe to dose who
toucha wid
da fingahs
I know how to get 6 or 7 volts of brutal sub-ns swing cheap,
at zero
Iq. Could be doubled, depending. Not for public release.
7V would be a bit low, and I'd need zippy in both directions.
If you need high-side drive, a pair of my drivers could feed
opposite
ends of a 1:1 transmission line transformer (or maybe a balun) to
double the swing. 12 volts for 100 ns would be no problem,
edges well
below a ns.
RF parts such as baluns or obscure directional couplers with a
voodoo
coefficient never scared me.
At below 5% duty cycle, you probably don't need to DC restore.
Not sure yet if I do. This high voltages acts as kind of a
reference
somewhere. It's one of those circuits that most people won't
even touch
with a 10ft pole.
It'll cost you a burger and a couple of beers. Zeitgeist has
about 40
on tap.
I am game. But I have no idea when I get to S.F. the next time.
A lot of
my clients are no longer in California, for reasons we all know,
and
Villaraigosa has just made that loud and clear to companies once
more :-(
Now if you ever get into this area we have a very nice Japanese
restaurant. Blue Moon and Sapporo on tap.
If pulse width is fixed, there's another way to do it: a really
fast
open-drain mosfet feeding a 1:1 transformer, 12 volts or
whatever you
like. The magnetizing current powers the falling edge. Also cheap.
It must remain adjustable.
Never turn down an offer from Larkin. He's promised you a
half-fast solution,
and I'm sure he can deliver ;-)
I am sure he can. Fast stuff is what his company mostly does and
if they
didn't earn megabucks per year with this they would hardly be able to
buy a large building smack dab in the middle of a metropolis.
It was a working fortune cookie factory. 1930's (ie, terrible)
concrete side walls, wooden floors and roof, a perfect candidate for
pancaking in the next good earthquake. It's sitting on sand, at the
edge of a liquefaction zone. We added a bunch of concrete footings and
steel frames and plywood and bolts.
You can see our place in the default Google Earth view of San
Francisco. For some odd reason, Google thinks "San Francisco" is in
the middle of the interesction of Market and Van Ness, one block away.
And we haven't had a sandstorm for as long as we've been here.
http://www.panoramio.com/photo/57596123
Those cherubim were on there before you bought it? They are amazingly
well preserved. I can't imagine the salty air down there to be too
friendly to concrete and plaster. The almond below probably has some
cultural meaning as well.
They are original, and we just cleaned them up and repainted. No
architect would dare do anything this cool any more.
The salty fog is out west, near the ocean. Everything rusts out there.
The bummer is that it's a wooden building that looks up at Sutro
Tower, 22 megawatts of AM/FM/TV/whatever. The EMI is ghastly.
Look at the bright side: If you'd need a sensor somewhere out of reach
of power you can just add a loop, some diodes, and it'll be supplied
with power until Sutro Tower keels over
If I'd needed a quiet lab place I'd find something in the outbacks of
Alabama or similar states. Then you are neither bothered by RF fields
nor by biz-hostile politicians.
On the other hand, the chances of being able to hire locally resident
expert help wouldn't be that great.
Near Huntsville? You've got to be kidding ...
Baptists and Lutherans get along quite well, and I love their choirs.
They can make the rafters shake.
--
Regards, Joerg
http://www.analogconsultants.com/