Super duper hype fast FET driver?

[Joerg]

John Larkin wrote:

[...]

Is it still there somewhere?

The Louies got out of the business. Their cookies were delicious but
couldn't compete with imports. They found a Chinese food magnate in
Brazil who wanted the machines so they disassembled them, marked every
piece (sort of like the old London Bridge) and reassembled them in
Brazil. They left us with outrageous 3-phase power and natural gas
feeds.

At least his invention lives on and hopefully he got a nice vacation in
Brazil out of it.

[...]

We had Japanese for lunch, too, unagi and salmon rolls, but no beer
for me; puts me to sleep if I have beer with lunch.

But then how could I ever buy you burger and beer at Zeitgeist?

 

[Joerg]

John Larkin wrote: [...]

but the Louie family put them up, so I guess it was an inside joke or
something. Edward Louie invented the fortune-cookie making machine in
1974.

ftp://jjlarkin.lmi.net/Fortune_Cookie_Machine.jpg

Is it still there somewhere?
The Louies got out of the business. Their cookies were delicious but
couldn't compete with imports. They found a Chinese food magnate in
Brazil who wanted the machines so they disassembled them, marked every
piece (sort of like the old London Bridge) and reassembled them in
Brazil. They left us with outrageous 3-phase power and natural gas
feeds.

At least his invention lives on and hopefully he got a nice vacation in
Brazil out of it.

[...]

We had Japanese for lunch, too, unagi and salmon rolls, but no beer
for me; puts me to sleep if I have beer with lunch.

But then how could I ever buy you burger and beer at Zeitgeist?

Sleep after lunch, of course.

You da boss, so you can do that

At least that's what George Jefferson said after he opened his chain of
cleaning stores and moved into that ritzy apartement.

 

[Spehro Pefhany]

The Louies got out of the business. Their cookies were delicious but
couldn't compete with imports. They found a Chinese food magnate in
Brazil who wanted the machines so they disassembled them, marked every
piece (sort of like the old London Bridge) and reassembled them in
Brazil. They left us with outrageous 3-phase power and natural gas
feeds.

If I owned a fortune cookie factory that was about to be closed, I
think the temptation to put "special" fortunes in the final batches
would be irresistable..


Best regards,
Spehro Pefhany

 

[Spehro Pefhany]

There is (or used to be) a company in SF that specialized in "special" racy
fortunes. They were pretty much unknown until a batch made it to a school ;-)

...Jim Thompson

A group of us used to get togther from time to time to eat inexpensive
meals at a faux Chinese restaurant where they handed out fortune
cookies (that was a few years ago when they were not sealed in
plastic). They had lucky numbers and a "learn Chinese" bit on the back
that was a bit error-prone, but I digress.. I made up a very
authentic-looking fortune with Photoshop and a color laser printer and
snuck it into one physicist's cookie and made sure he got the special
one. It said something like "(really obscure specialty) will cause you
nothing but misery". It had been a technically frustrating morning for
him.. and the somewhat delayed reaction was priceless. ;-)


Best regards,
Spehro Pefhany

 

[Joerg]

[...]

Near Huntsville? You've got to be kidding ...

The University of Alabama at Huntsville (UAH) has a certain fame amongst
people who are persuaded by the evidence for anthropogenic global warming.
Two of the researchers there - Spencer and Christy - were a bit slow to
correct their satellite data for orbital decay, and for a while their
uncorrected figures deviated from the predictions of the climate models.

http://en.wikipedia.org/wiki/Satellite_temperature_measurements

Roy Spencer is a card-carrying fundamentalist, and John Christy has spent
time as a bi-vocatiinal mission-pastor. This may - in part - explain why
they are two of the nine top climate scientists (out of the top 300) who
aren't persuaded by the evidence for anthropogenic global warming. Maybe
they think a loving God couldn't be that mean.

http://www.sourcewatch.org/index.php?title=Roy_Spencer

http://www.sourcewatch.org/index.php?title=John_R._Christy

Their kind of expertise can't entirely be relied on

You seem to be rather desparate to get yet another AGW debate going,
aren't you? Forget it, since climategate nobody is interested much anymore.

BTW, it's not a university that matters, it's the employers that are
already in the area.

Unfortunately, that kind of belief can gnaw at the foundations as well as
shaking the rafters.

My faith is my foundation and it is unshakeable. Nothing you can do
about that

 

[Joerg]

BillSlomanwrote:

On 20/08/2011 3:34 AM, Joerg wrote:
BillSlomanwrote:
On 20/08/2011 2:46 AM, Joerg wrote: [...]

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 ...
The University of Alabama at Huntsville (UAH) has a certain fame amongst
people who are persuaded by the evidence for anthropogenic global warming.
Two of the researchers there - Spencer and Christy - were a bit slow to
correct their satellite data for orbital decay, and for a while their
uncorrected figures deviated from the predictions of the climate models.
http://en.wikipedia.org/wiki/Satellite_temperature_measurements
Roy Spencer is a card-carrying fundamentalist, and John Christy has spent
time as a bi-vocatiinal mission-pastor. This may - in part - explain why
they are two of the nine top climate scientists (out of the top 300) who
aren't persuaded by the evidence for anthropogenic global warming. Maybe
they think a loving God couldn't be that mean.
http://www.sourcewatch.org/index.php?title=Roy_Spencer
http://www.sourcewatch.org/index.php?title=John_R._Christy
Their kind of expertise can't entirely be relied on

You seem to be rather desperate to get yet another AGW debate going,
aren't you?

Far from it. It was just a handy fact to drop on krw in reaction to
him calling me ignorant, which counts as gratuitous abuse in my book.

So why did you do it in response to my post? Not that I'd mind, just
curious.

Climategate just illustrated that climate scientists get upset when
some denialist saboteur manages to smuggle a totally inadequate paper
into the peer-reviewed literature. When it turned out that the action
editor had ignored four peer reviews telling him that the paper was
crap, and the publisher refused to dump the - denialist - action
editor, most of the editorial board of the journal resinged in
protest.

The denialist lobby seized on the e-mails that covered the nuts and
bolts of the University of East Anglia finding out what had been done
and telling people about it, as if it was some sort of evil
conspiracy, when in fact it was just the peer-review mechanism in
error-correction mode.

It was just one more denialist campaign to persuade the general public
to distrust good scientific information which doesn't happen to suit
the financial interests of the fossil-carbon extraction industry. The
fact that you haven't realised that climategate was pure denialist
propaganda is a tribute to the effectiveness of the propaganda machine
- and a worrying indicator of the effectiveness of paid advertising in
moulding public opinion.

Read some of the more juicy emails again. Have you forgotten? Or purged
from your mind because it doesn't jibe with your mantra? It couldn't
have gotten any more damaging than that (for warmingists).

And the potential employees that they've got to work with.


It's not your foundations that I'm worried about, it's the foundations
of the science that you - indirectly - rely on to make your money. If
your sub-contradtors were to reject experimental evidence because they
thought that the results didn't fit with their - say, anti-abortion -
theology you could eventually find yourself in serious trouble with
the FDA.

For the record, I am against abortion and if someone wanted me to work
on some device that is used in that area I will refuse. It is my right
to do so.

 

[Joerg]

John Larkin loves posting about fet drivers - he can make implausible
claims about how fast and cheap his are, and pose as the expert
electronic engineer that he wants to be accepted as.

John posts actual scope plots. So when he says that a transition happens
in under one nanosecond and proves it with a scope plot I don't know
what you mean by "implausible". Just because some people or datasheets
say it can't be done does not mean it can't be done. Also, he can show
the proof in revenue Dollars.

Now if someone had the opposite sex of the 2N7002 or a PNP with 15V+ and
no "saturation hold" that would be great. The BSS84 and it's siblings
ain't that hot.

 

[Joerg]

Have you tried any pfets?

I did try the BSS84 a few years ago and the results were not enthusing.

I haven't played much with pfets as really fast switches. Right, a
complement to the 2N7002, push-pull against a 7002, with the same
12-cent gate drivers, would be interesting, and might solve your
problem. Just ignore the shoot-through maybe.

I'll put that on my slow-day experiment list. All I need now is a slow
day.

Why doesn't somebody make p-channel gaasfets? The world wonders.

A gold-doped BJT would be nice as well. However, I have not seen any
commercially successful gold or otherwise doped PNP transistors. And I
guess there ain't no market to write home about so I won't hold my breath.

Some day I'll have to see how the BFT92 and the BFG31 behave. But they
are intended as amplifiers so they won't are about saturation effects.
Trick to keep it out of saturation get old quickly when every pF and
every thenth of an inch count.

 

[Joerg]

[snip]

Now if someone had the opposite sex of the 2N7002 or a PNP with 15V+ and
no "saturation hold" that would be great. The BSS84 and it's siblings
ain't that hot.

If you find a useful complement to the 2N7002 please let me know. Thanks!

Oh I will. But don't hold your breath :-(

 

[[email protected]]

I did try the BSS84 a few years ago and the results were not enthusing.



A gold-doped BJT would be nice as well. However, I have not seen any
commercially successful gold or otherwise doped PNP transistors. And I
guess there ain't no market to write home about so I won't hold my breath.

Hell, just some cheap NPN arrays would be really nice. I can get cheap FET
arrays but not bipolar, anymore. Cheap current source/sinks would be nice,
too.

 

[Joerg]

Hell, just some cheap NPN arrays would be really nice. I can get cheap FET
arrays but not bipolar, anymore. ...

Voila:

http://www.fairchildsemi.com/ds/FF/FFB3904.pdf

At around 50c not very cheap. If it needs to be cheaper you've got to
shop in Asia.

http://www.kexin.com.cn/pdf/KC846S.pdf
http://www.rohm.com/products/discrete/transistor/complex/#03

All those aren't fast though.

... Cheap current source/sinks would be nice, too.

That'll be a challenge, I don't think there's a market for those.

[...]

 

[[email protected]]

Voila:

http://www.fairchildsemi.com/ds/FF/FFB3904.pdf

At around 50c not very cheap. If it needs to be cheaper you've got to
shop in Asia.

$.50 wouldn't make me too happy (FETs arrays I'm using are $.10) but I could
make it work. HOWEVER, "NPN Multi-Chip General Purpose Amplifier" says it
all.

http://www.kexin.com.cn/pdf/KC846S.pdf

No useful specs.

http://www.rohm.com/products/discrete/transistor/complex/#03

"Very small package with two transistors."

All those aren't fast though.

Me? I don't need fast. ;-)

That'll be a challenge, I don't think there's a market for those.

Evidently there isn't a market for transistor arrays, either. Perhaps not
even a 2N7002 with a sex change. ;-)

 

[Nico Coesel]

For the record, I am against abortion and if someone wanted me to work
on some device that is used in that area I will refuse. It is my right
to do so.

Perhaps, but given a certain situation you may choose different. There
are many grey areas when it comes to these sort of decisions. The
bottom line is that you are in no position to choose what is best for
someone else.

Last month my grandfather asked the doctors to end his suffering.
After carefull consideration they decided to grant his wish. If there
is one thing I've learned from how my all of my grandparents passed
away is that becoming very old is not some holy grail or a pot of gold
at the end of the rainbow. I didn't like the idea ofcourse but I could
understand his desire so I did not ask him to reconsider. It still is
very strange to say goodbye to someone who will die shortly
afterwards.

Life is what you make of it, but if you have nothing to begin with
then there is no life at all.

 

[Joerg]

My mental model of a mosfet is an infinitely fast piece of silicon
with some capacitance and wire bonds. So the limit on fast switching
is mostly how hard you can drive the gate. Most fets can switch way
faster than the datasheets suggest if you slam them hard enough.
Unfortunately, my 600 ps mystery driver is only good for 6.5 volts
maybe, which that will drive a 2N7002 to an amp or so, fast, but pfets
usually need more drive to turn on hard. But I bet there's one out
there somewhere.

A little DC pre-bias, just below threshold, can buy another volt or
two of enhancement.


My experience using bjt's as this sort of fast switch has been
disappointing. I even tried some 45 GHz SiGe parts, and they switched
slow. Mosfets are much better, phemts are radically better.

RF transistors are also a problem if they can't get to an amp or more.
Usually you'll need that to swish charges around in a capacitive load.
LDMOS can pulse nicely but the price tag is usually prohibitive. NPX
isn't very useful there either because they won't release SPICE model.
But PolyFet in Camarillo does.

Yeah. I'd experiment with finding a 2N7002 complement. Now you've got
me interested.

I have the gear (pulsers, drivers, sampling scope) to experiment, if
you come up with some candidate parts.

This one could be a contender but it's Infineon and seems close to
unobtanium, in which case it would not do too much good:

http://www.infineon.com/dgdl/BSA223...90004&fileId=db3a304412b407950112b42ae5834414

 

[Joerg]

$.50 wouldn't make me too happy (FETs arrays I'm using are $.10) but I could
make it work. HOWEVER, "NPN Multi-Chip General Purpose Amplifier" says it
all.

Well, you didn't say monolithic

No useful specs.

That is normal with many Asian suppliers, got to get used to it and test
a lot for yourself. You can sometimes obtain additional data from them
but sometimes you'd have to be married to the CEO's cousin's daughter or
something like that.

"Very small package with two transistors."


Me? I don't need fast. ;-)

Lucky you

Almost all my stuff is RF nowadays.

Evidently there isn't a market for transistor arrays, either. Perhaps not
even a 2N7002 with a sex change. ;-)

No, there sure ain't :-(

 

[Joerg]

Perhaps, but given a certain situation you may choose different. There
are many grey areas when it comes to these sort of decisions. The
bottom line is that you are in no position to choose what is best for
someone else.

I didn't say that. I said I am personally against it. So, naturally, I
wish my tax Dollars not be used for that either. If someone commits a
sin it is not up to me to judge them but it is up to me not to support
that. Just like I do not support free drug use.

Of course there will always be triage type situations where there are
only two choices, between the yet unborn's survival and the mother's
survival. That's very different. What I meant was "doing it" and then,
whoops, "got to get rid of it". That is a grave sin.

Last month my grandfather asked the doctors to end his suffering.
After carefull consideration they decided to grant his wish. If there
is one thing I've learned from how my all of my grandparents passed
away is that becoming very old is not some holy grail or a pot of gold
at the end of the rainbow. I didn't like the idea ofcourse but I could
understand his desire so I did not ask him to reconsider. It still is
very strange to say goodbye to someone who will die shortly
afterwards.

I won't judge anyone who does that, that's not up to me. Personally I
would not do it because it is squarely against biblical teaching, and I
try to live by that.

Life is what you make of it, but if you have nothing to begin with
then there is no life at all.

You mean abortion with that? Ever looked at an ultrasound before "legal"
abortion deadline? I have, I design part of those machines.

 

[Joerg]

That looks really nice. Low capacitances, dynamite transfer curve,
nice pulsed current. Let's try some.

Tough to get though. Once I tried to cajole Infineon into samples of
another FET, explicitly telling them that I don't want them for free,
would also pay S&H and all that. They didn't afford me as much as a
courtesy call back. Ditched them.

This looks similar:

http://www.fairchildsemi.com/pf/FD/FDV304P.html

The Fairchild gumdrop parts are mostly excellent.

This looks promising, too:

http://www.vishay.com/docs/71411/tp0610k.pdf

I had looked at those a long time ago. The turn-off times are sluggish
yet they are driving them with gusto, for example Rgen 10V/10ohms for
the Vishay. They are smacking a whopping amp into the gate. 10pF and
150ohms load doesn't explain 35nsec turn-off and I bet their marketing
guys would razz them for being too conservative.

But one never knows with FETs.

 

[[email protected]]

Well, you didn't say monolithic



That is normal with many Asian suppliers, got to get used to it and test
a lot for yourself. You can sometimes obtain additional data from them
but sometimes you'd have to be married to the CEO's cousin's daughter or
something like that.

"Test a lot?" What does that tell me? It went against my grain to use a
green LED (GaN) at 3.3V. "Because one works..." Well, at least if the next
lot doesn't work we'll know.

Lucky you

Almost all my stuff is RF nowadays.

We buy modules for all that stuff. I wouldn't attempt it with the shoestring
capital budget we're on (we're down a scope and it doesn't appear that they're
going to even replace it).

No, there sure ain't :-(

....not that I have anything for the '7002, mind you.

 

[Joerg]

[...]

That is normal with many Asian suppliers, got to get used to it and test
a lot for yourself. You can sometimes obtain additional data from them
but sometimes you'd have to be married to the CEO's cousin's daughter or
something like that.

"Test a lot?" What does that tell me? It went against my grain to use a
green LED (GaN) at 3.3V. "Because one works..." Well, at least if the next
lot doesn't work we'll know.

I didn't mean a lot as in production lot, but as in "a lot of testing"

Meaning some of the properties have to be measure. In some designs that
is the only way to succeed because there are no parts that can
"formally" do what you need them to do.

We buy modules for all that stuff. I wouldn't attempt it with the shoestring
capital budget we're on (we're down a scope and it doesn't appear that they're
going to even replace it).

A scope? That's scary. I hope that doesn't mean any bad news. You can
nowadays get a lotta scope for $1-2k.

[...]

 

[Joerg]

Looking at the 2N7002 data sheets, one would never expect the sorts of
speeds I'm seeing. All you can do is get some parts and try them.

I have seen very zippy transitions from a 2N7002 myself. Not like yours
but then again the fastest scope I have rolls off at 1GHz. Never seen a
P-channel come anywhere close to that. There used to be a BSS83
P-channel that was very good. But it seems to be gone. Believe it or
not, there is also a BSS83 N-channel from another European manufacturer.
Whoops ...

The ones that switch fast seem to have low Cg, modest Rds-on, and peak
drain current ratings under an amp (which doesn't stop me from going
above an amp.)

I recall Win Hill getting kilovolt edges in a couple of ns from fets
that, from the data sheets, shouldn't do that.

Was that shortly before this happened?

http://www.flickr.com/photos/36342938@N02/4808112575/