Photodiode amplifier noise

Spehro Pefhany · May 4, 2009

John said:
John said:

On Mon, 04 May 2009 09:32:54 -0700, Joerg

John Larkin wrote:
On Sun, 03 May 2009 15:22:14 -0400, Spehro Pefhany

On Sun, 03 May 2009 11:21:42 -0700, the renowned John Larkin

On Sun, 03 May 2009 09:53:37 -0700, Joerg

John Larkin wrote:
On Sat, 02 May 2009 21:29:47 GMT, James Arthur

John Larkin wrote:
On Sat, 02 May 2009 13:14:40 -0700, Joerg

John Larkin wrote:

[...]

This weekend I'm going to buy a tin of Danish sugar cookies, eat all
the cookies, and build a pA range diode-curve measuring setup into it.
I have a bunch of LMC6001s (Ib is 10 fA typ) to use. The datasheet
hints somewhere in one of the app circuits that Cin is big. But it's
not specified anywhere.

It's "Danish Butter cookies"

Make sure to _throughly_ clean it before you build anything into it,
until wiping shows no grease residue. Else you might experience an
impressive meeting of ants in there. BTDT.

The rule seems to be that if Cin is large, don't mention it on the
datasheet.

Cin is probably largish and usually not used directly:

http://www.postech.ac.kr/ee/paust/p...a Beam-Profile Monitor for Cyclotron MC50.pdf
Interesting; that's vaguely like what I'm tying to do. But I can't
find a datasheet on the JU421, even on the Vishay site, so I assume
it's another FormerFet.
www.vishay.com/docs/70248/70248.pdf

Cheers,
James Arthur
Cool. Vishay didn't recognize "JU421".

Nice part for leakage, but with En=30 nv/rthz and Gm=200 uS, it's sort
of the Marching Band of Noise. This guy adds a second one in
differential mode to add bonus noise and lower the gain to boot.

Well, good luck finding one

If you do it'll probably have "DoD pricing".

Why do these scientific types so love differential jfet front-ends?

In electronics they tend to hang on to stuff much longer than we do.

[...]
I hadn't paid much attention to discrete jfets in, well, some decades.
They have low transconductance, high capacitances, miserable matching,
and astounding datasheet parameter spreads, like 10:1 Idss limits.

But for really low noise (like, under 1 nV/rthz) amplification of
high-impedance signals, nothing can touch them. The best fet opamps
are, like, 5x as noisy as the best jfet.
True.

Pity that most people, at
least the scientists, trend to use them wrong.

John
What wrongness have you seen? The commercial stuff for research
applications looks pretty decent to me.

I see mostly botched circuit protection. Last one: A freaking expensive
laser diode driver with TEC in there was running. Janitor plugged vacuum
into same circuit, turned it on ... tzzzt ... phut ... *POP*

That isn't supposed to happen.

I've seen a lot of diffamps where it wasn't necessary, really rotten
second stages (the fets have low gain, so 2nd stage noise matters) and
circuits where the Johnson noise of gate bias resistors (and
occasionally drain load resistors!) overwhelmed the fet's noise. One
paper got around that by testing the amp with a grounded input!

Could it be that there just aren't a lot of good disctete circuit
designers around? I would hate to think that.

That is most definitely the case :-(

OTOH, this puts bread on the table around here ...

Most people can be adequate carpenters or painters or cooks. Not many
people, even with engineering or physics degrees, can be decent
circuit designers.

That's sort of weird. I guess circuit design is really more art and
instinct than science.

Click to expand...

It is, but include cooks as well. Had salmon at Sudwerks yesterday,
exquisite. But I had a very similar salmon dish in other restaurants and
it was bland. Good cooks must know how much a tad, a dash and a smidgen
is yet very few really know. Just like there are engineers who slap the
biggest hinking inductor they can fit onto an EMC problem, and later
many units go bzzzap ... *POOF* upon disconnecting power.

Click to expand...

Did you learn all those sound effects the hard way ?

...Jim Thompson

Are you accusing Joerg of being a *POOF*ter?

James Arthur · May 4, 2009

Joerg said:
There is, but in the analog world camouflaging is not easy at all. Other
than grinding off part numbers and potting the whole chebang there isn't
much more to obfuscate. The big kahuna of the particular marketplace
will surely notice when turf is invaded and try their utmost to find out
how yours works.

I've looked at a $1000 device from <insert name of major lab supplier
here> because an engineer came into the lab with it already open and
asked "How does this work? Could we do it that way?" All P/Ns were filed
off but within a few minutes I knew how it worked and what chips they
had most likely used. It was cheap alright, probably no more than $20
worth of parts in there (ain't that a nice fat profit margin?)

That's why engineering is too valuable to sell--if you wrap some
components around a few really cool idea you can sell those gadgets
over and over. The engineering, however, can only be sold once.

Cheers,
James Arthur

Clifford Heath · May 5, 2009

John said:
Graffiti is a nuisance.

Some areas here have had success with a strategy of painting over it
within 24 hours. If it's done aggressively and consistently, they mostly
stop doing it (and go elsewhere?).

Clifford Heath.

James Arthur · May 5, 2009

Joel said:
Some public canings of taggers -- as, e.g., Singapore does -- might
significantly reduce the problem.

If you're getting tagged regularly, I guess you just have a regular (e.g.,
monthly) schedule for re-painting? :-(

In the little dorf where I lived in Germany, two local teens thought
it would be neat to tag a bridge. Absolutely unheard of, IME.
Someone called the Polizei, but not to report them, to save them.

The villagers, you see, didn't appreciate their town being defaced.
A crowd gathered 'round the teens and proceeded to beat the living
daylight out of 'em. The Polizei hauled the kids off, saving their
teen-age tails.

Said teens, black and blue, were later seen on the same bridge,
scrubbing it clean.

They don't stand with that there.

James Arthur

James Arthur · May 5, 2009

John said:
John said:

On Sun, 03 May 2009 09:53:37 -0700, Joerg

John Larkin wrote:
On Sat, 02 May 2009 21:29:47 GMT, James Arthur

John Larkin wrote:
On Sat, 02 May 2009 13:14:40 -0700, Joerg

John Larkin wrote:

[...]

This weekend I'm going to buy a tin of Danish sugar cookies, eat all
the cookies, and build a pA range diode-curve measuring setup into it.
I have a bunch of LMC6001s (Ib is 10 fA typ) to use. The datasheet
hints somewhere in one of the app circuits that Cin is big. But it's
not specified anywhere.

It's "Danish Butter cookies"

Make sure to _throughly_ clean it before you build anything into it,
until wiping shows no grease residue. Else you might experience an
impressive meeting of ants in there. BTDT.

The rule seems to be that if Cin is large, don't mention it on the
datasheet.

Cin is probably largish and usually not used directly:

http://www.postech.ac.kr/ee/paust/p...a Beam-Profile Monitor for Cyclotron MC50.pdf
Interesting; that's vaguely like what I'm tying to do. But I can't
find a datasheet on the JU421, even on the Vishay site, so I assume
it's another FormerFet.
www.vishay.com/docs/70248/70248.pdf

Cheers,
James Arthur
Cool. Vishay didn't recognize "JU421".

Nice part for leakage, but with En=30 nv/rthz and Gm=200 uS, it's sort
of the Marching Band of Noise. This guy adds a second one in
differential mode to add bonus noise and lower the gain to boot.

Well, good luck finding one

If you do it'll probably have "DoD pricing".

Why do these scientific types so love differential jfet front-ends?

In electronics they tend to hang on to stuff much longer than we do.

[...]
I hadn't paid much attention to discrete jfets in, well, some decades.
They have low transconductance, high capacitances, miserable matching,
and astounding datasheet parameter spreads, like 10:1 Idss limits.

But for really low noise (like, under 1 nV/rthz) amplification of
high-impedance signals, nothing can touch them. The best fet opamps
are, like, 5x as noisy as the best jfet. Pity that most people, at
least the scientists, trend to use them wrong.

John

Click to expand...

I may have a wacky idea. What's your signal bandwidth (if you can say)?

Cheers,
James Arthur

Click to expand...

Pity, but I can't get too close to the actual application in public.
We can go private if you're interested. It is a fascinating and
important problem where good circuit design could affect the world, at
least some.

John

ps: tell S thanks for the PC! Everybody will be pleased except the
potatoes.

Rodger, I'll pass that along, & hope it's fun.

Cheers,
James

Tim Williams · May 5, 2009

But perhaps I just don't
understand the hooligan mindset well enough...

Well, I figure there are maybe three Types...
1. The real "honest" criminals (well, probably quite dishonest..):
murders, rapists...Enron execs...
2. The "situational" criminals, put there by culture (or rather, the
subculture they belong to), of which these hooligans are a subset, and
3. The non-criminal criminals, including drug offenders and music
pirates (victims of unjust laws -- depending on your meaning of
"just"...)

And intersecting these classes, there are also a few Mindsets:

1. The "I didn't mean to" type. Something like an everyday shmoe,
caught in a bad situation, of which s/he has acknowledged his/her
fault and learned his/her lesson. These are the people who might be
considered "prison successes", in the sense of prison as a reform
institution.
2. The "natural born killer" sort. These include hard core serial
killers, the kind of people who (by nature or nurture) have a magnet
sitting next to their moral compass. This especially goes by degree,
ranging from normal to homicidal. Presumably, most inmates have some
of this characteristic, since they willingly did something which went
against the law as we know it. One could argue that the "non-criminal
criminals" (NCC) class follows the same pattern, but in that case I
draw the distinction that 1. most people don't think the NCCs are all
that bad (they aren't arrested for violent crimes, for example), and
2. there is a tremendous quantity of NCCs.
3. Those who recognize that there are laws against their behavior, and
may even be morally opposed to it themselves, but who nonetheless
commit criminal acts out of survival. These include petty theft and
gang activity (and related enterprises, like drug supply). If the
conditions leading to these subcultures didn't exist (mainly, low
socioeconomic status), the people born into those conditions also
would be different. These people will tend to be repeat offenders,
because, even though they may recognize the law of the land, that law
is not the law of their environment, and it's not how they were
raised.

I recognize there may be considerable overlap in these six
categories. I haven't made a special analytical effort to seperate
them into an optimal, linearly independent set of attributes.

Now, as far as prison as a reform institution:

Those of Type #1 and Mindset #2 in particular represent the hardened
criminals, the kind which either don't want to change (prison is a
setback, regardless of any opportunities -- reform -- it may offer),
or cannot change (I suppose that, just like you "can't fix stupid",
you "can't fix Jeffrey Dahmer", for example). These prisoners
represent a baseline which cannot be reformed and will continue to
commit crimes, regardless of attempts to pacify them.

Mindset #1 prisoners (spanning all three Types) will almost always
return to society peacefully. They know what happened, and they know
better. Only if prison changed them for the worse (maybe they
accidentially dropped the soap?) might they start a criminal career.
With a fairly high reform rate regardless of prison style, this type
represents a baseline in reformability.

Those of Mindset #3 are the big variable which the prisons can (maybe)
control. If the prisons do nothing, these types will probably return
to the same city, same family and same friends which got them into
this problem in the first place. If the prisons were extremely
effective at reform (friendly atmosphere, heavy social, education and
work programs, etc.), most of these people would return with a new
look on life, seek out new friends and start anew.

So as far as prison success goes, I think there are a few levels to
the inmates. Many don't belong; some will (most likely) continue to
commit crimes; some will (most likely) never again commit a crime; and
many will either return, time and again, or start a new life, escaping
the evil cycle. It is the duty of the prisons (and/or legislators) to
minimize the first population, and reform the fourth as best they can.

Tim

P.S. I originally wanted this post fairly short, to complement your
brief comment. But since it's late, it seems to have turned into a
long expression of personal speculation. I really should find
something more useful to write about when I get all "writey" like this.

T · May 5, 2009

Phil said:
Phil said:

Joerg wrote:
[...]

You could carve out a niche catering to the fiber optics scientists,
an area where extreme profit margins are customary. But it depends
where you live. California is currently too biz-unfriendly for me to
start anything where I'd need employees or where sales are involved.
If you live in NY state it could be the same.

That thought has come up in conversation. Stay tuned.

Click to expand...

Interesting! BTW, it would be good if your web site states a few more
details about exactly what kinds of projects you feel competent to take
on, experiences and so on. If a client needs a consultant in the optics
area I would know where you'd be a good match but I found that a lot of
people come to my web site out of coincidence, and then call. No
referrals or anything. About half of those "inverse cold calls" result
in actual consulting. Some of them really interesting, the usual analog
stuff but totally new markets for me.

When you open a real brick-and-mortar kind of business which you almost
have to if you produce anything, watch out for overregulation,
over-fining and stuff like that. Even if it's just you and a couple of
techs some day they might hit you because one bathroom isn't 100%
compliant with some law or the lettering on some poster was too small.
Best to do that in a state that's very biz-friendly and also won't tax
your biz into oblivion.

Click to expand...

We haven't had a lot of interference, here in San Francisco. We're
across the street from the Building Inspection Department and four
blocks from City Hall.

The fire department inspects us once every year or two and checks the
fire extinguishers and tests the alarm system. The State Disability
folks check our paperwork every couple of years... no problems so far.
No hassle about bathrooms or posters or other nuisance stuff. Of
course, state and fed taxes are horrible.

Graffiti is a nuisance. The city writes us up if there stuff on our
building. We'll get a fine if we don't paint it over within something
like 60 days after the notice, which is silly since we get tagged a
couple of times a week. Of course, nobody arrests the taggers, because
if they do the judges dismiss them.

I don't blame companies who "offshore" their manufacturing to Alabama
or Mexico. That would export a lot of expensive problems.

John

How interesting. Here in Providence, RI all you have to do is pickup the
phone and call the Graffiti Control hotline. A week or so later a crew
comes out and scrubs, paints and gets rid of the graffiti.

Charlie E. · May 5, 2009

Some areas here have had success with a strategy of painting over it
within 24 hours. If it's done aggressively and consistently, they mostly
stop doing it (and go elsewhere?).

Clifford Heath.

Our town has that policy, and it helps, but it sure hasn't stopped it

We had one idiot that kept at it for years, always signing the same
handle. One local motel owner had put up video cameras, and caught
this guy tagging his sign (He had to climb a wall, walk along it (12
foot drop!) and shimmy along the roof to reach it. Motel owner is
also the head of the public safety commision...

One less tagger!

Charlie

Jim Thompson · May 5, 2009

Wikipedia sources it from this article:
http://www.pww.org/article/view/4786/1/202/ ... "Shortly after Arpaio took
office in 1993 he expanded the state's policy of housing prisoners in tents.
According to former department employees, he emptied an entire floor of one
jail to accomplish this. He is thus able to say, and does say, that he will
always be able to house anyone picked up or condemned to his jail system."

Anti-Joe sites such as arpaio.com have this to say:
"Sheriff Joe Arpaio: He built the tent city jail because of overcrowding in
the regular jails.

Truth: To insure there were enough inmates for the much publicized tent city
jail he closed an entire floor of the First Avenue Jail."

I of course don't know at all one way or the other.

But clearly a lot of people support Joe, and I'd definitely think twice before
committing a crime if I lived in his county!

---Joel

Ever know of an honest leftist weenie ?

Nemo · May 5, 2009

Joerg writes

I wanted to take Spanish in high school but was told that Latin was

mandatory and with all my elected math and physics courses there weren't
enough hours left to sign up for one more language. That really ticked
me off, having to learn a dead language.

Me too, (substitute German for Spanish). But returning to photodiodes...

Cin is probably largish and usually not used directly:

http://www.postech.ac.kr/ee/paust/paper_link/2007 Development of a%
20Beam-Profile%20Monitor%20for%20Cyclotron%20MC50.pdf

I've studied this circuit and I'm quite confused by it. Apart from the
issue of resistances being higher than they need to be, surely this
topology is not using the JFETs to their best advantage. According to
Phil Hobbs' excellent article hither -

http://www.electrooptical.net/www/frontends/frontends.pdf

the point of adding a cascode front end is to isolate the photodiode
from the summing junction. (I think J2A/J1A form a cascode current
source.) But these Korean researchers are connecting it to the
opamp-created virtual earth (ie where the feedback resistor goes back
to). I suppose they isolate the photodiode's capacitance from the actual
inverting input of the op amp and thus stop it oscillating, and the
input bias current of their chosen amp (OPA27) is tens of pA so the
differential JFET front end maybe compensates for thermal drift etc, but
they don't seem to be taking full advantage of the possibility of
buffering the photodiode from the op amp. They'll lose bandwidth...?!

It's kind of like they've taken the photodiode input to the wrong node.
They've added a bunch of components to the front end... and then
overlooked the advantages of bootstrapping.

[Another odd thing about this circuit is that the OPA27 they've chosen
is lowish voltage nose but current noise density is ~1pA/rt Hz, and I'd
expect them to use an amp with femtoamp level noise figures - like the
OPA656 I've been playing with - since the feedback resistor is 100M.]

Hmm.

Concerning criminal mentalities, the most interesting studies I've come
across have been by economists and psychologists morethan sociologists.
They ask questions like "why" and discover that young folk have
different perceptions of risk / reward to older people; that people who
are denied opportunities by society - say, because they have a criminal
record already - don't feel like stakeholders, etc. One study found that
gang members in New York's most violent areas figured they weren't going
to live to age 20 anyhow, so it made little difference how they lived
their lives.

Nemo · May 6, 2009

My opinion is that people who have done their time they should be taken

off the "stigma list", except maybe for sensitive jobs such as law
enforcement. Similar to the driving record in many states where an xyz
violation is removed from the database after x years but it remains on
the "hidden side" so a judge could still see it. Otherwise they'll
remain pariahs almost for the rest of their lives and that can turn
folks willing to become good citizens into desperados. And it does.

Absolutely. People change. I'm not the same person I was 10 years ago;
and major life experiences such as becoming a parent (and presumably,
going to jail) can be personality-altering.

Bob Larter · May 6, 2009

Phil said:
Jim said:

On Mon, 04 May 2009 09:32:54 -0700, Joerg

John Larkin wrote: [snip]
Could it be that there just aren't a lot of good discrete circuit
designers around? I would hate to think that.

That is most definitely the case :-(

OTOH, this puts bread on the table around here ...

Most people can be adequate carpenters or painters or cooks. Not many
people, even with engineering or physics degrees, can be decent
circuit designers.

That's sort of weird. I guess circuit design is really more art and
instinct than science.

John

Click to expand...

Absolutely! I was a circuit designer _before_ I trotted off to MIT.
The education only honed my capabilities.

...Jim Thompson

Click to expand...

Ditto. Except that I never took a circuits course.

The difference between an art and a science is that in science the
answer is out there waiting to be found, and we can all agree when we
find it (at least after all the people emotionally invested in incorrect
positions have decently died off).

In an art, there are different ways of doing things that are more or
less equally good, it's unclear whether there's really a single best
answer, and the results depend a lot on the personality of the artist.
Not all valid questions are scientific ones, by a long shot.

By these definitions, troubleshooting is a science and design is an art.

Them's fightin' words, Phil! I could argue the exact opposite, having
spent many years in the service side of the industry. You try teaching
people how to troubleshoot circuits some time, & you'll soon see how
much art is is required to do it well. ;^)

Bob Larter · May 6, 2009

Nemo said:
Absolutely. People change. I'm not the same person I was 10 years ago;
and major life experiences such as becoming a parent (and presumably,
going to jail) can be personality-altering.

Indeed. Now that I'm a dad, I'm a very different person to the one I was
before I became a father. And I expect that many other life experiences
can change a person just as much.

James Arthur · May 6, 2009

Joel said:
Wow.

Realistically you probably can't let the crowd get off without charging them
with assault too (well, OK, MAYBE JUST ONCE you might ), as police
departments can't allow vigilantism on a recurring basis either.

No one was arrested except the two teens. AFAIK, they never did that
again, and suffered no permanent harm. Instead they got a valuable,
clear lesson in civics and pride, as did any other would-be taggers.

In an earlier time in America, people and communities just solved their
own problems. If their Chicken McNuggets were too spicy or their
neighbor was too loud, they'd simply talk it over and fix things.

I lived in a tiny house in a poor neighborhood as a kid, but everyone
kept it clean. I remember being scolded by a neighbor "You pick that
up!" when my 5-year-old self accidentally dropped a piece of paper on
the street.

Now that govm't provides those services, people just call '911'.

Cheers,
James Arthur

Jim Thompson · May 6, 2009

I was told that I was arrogant & opinionated, because they eventually
found the problem if they changed enough parts. What a bunch of
maroons. That was the same place where a 'committee' showed up my forth
day on the job and told be that I better slow down, because I was making
everyone look bad.

Jim Thompson · May 7, 2009

Haha... nice.

I think it's unfortunately not all that uncommon to find places similar to
where Michael worked. At some point if someone said I was "too productive,"
I'd just cut back and spend the spare time trying to improve my own skills or
working on my resume to try to find someplace better! ;-)

Given your skills and personality, I doubt many people would contest that your
becoming a consultant wasn't the optimal scenario both for yourself as well as
as the clients you've worked for.

I think all my clients are happy, though they _still_ regularly
protest when I toss a design-in-progress and start over... my
perfectionist personality is my own worst enemy :-(

Personal finance wise I should have gone into manufacturing... that's
where the profit is.

I may design and build a product yet before I exit ;-)

Hmm... were your kids in scouting growing up?

My two girls were in Girl Scouts. Then all _five_ granddaughters.

I, personally, made it up to Life Scout rank in the Explorers; and
served as a Den Chief for several Cub Troops. Right now I'm an adult
member of the Girl Scouts, doing financial things like orchestrating
cookie sales.

My two sons and I were in Indian Guides, one-on-one father-son kind of
camping and projects.

(I know your wife does the girl
scout thing now.) It's interesting to picture you as a scoutmaster... I have
an uncle-in-law that was a scoutmaster back in the '70s, and in summer he'd
take his troop out to eastern Oregon, start hiking over some mountain pass on,
e.g., a Sunday with the arrangement that someone would come to pick them up at
a point, say, 30 miles away the following Saturday. One guy with a half-dozen
scouts, no cell phones or GPS, out in the woods for a week... hard to imagine
these days!

---Joel

I can remember hiking training with compass and glow-in-the-dark star
charts ;-)

I also had police crowd control training... my Explorer troop was
police-department-sponsored. That ought to rile up the leftists
amongst us ;-)

...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

Jim Thompson · May 7, 2009

A friend who is scoutmaster still does that with his team. They used to
spend Newyears up at Glacier Point in Yosemite National Park, a place
where nobody is allowed at that time other than rangers (road is
closed). He said that you have to say good-bye to pretty much anything
from civilization during those days.

Jim Thompson · May 7, 2009

message news:[email protected]... [snip]

I also had police crowd control training... my Explorer troop was
police-department-sponsored. That ought to rile up the leftists
amongst us ;-)

Click to expand...

The boy scout troop I was in was sponsored, early-on, by the local police
department too, but there wasn't any crowd control training that I received
(maybe before I joined?).

[snip]

Can't remember now for sure what it was called by the police, be we of
Scot ancestry would call it a cudgel... amazing how many people you
can drive back. I'll have to hone my training in case it's needed for
the coming war against the leftist weenies ;-)

...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

James Arthur · May 9, 2009

JosephKK said:
Never heard of an honest neocon either. Say Enron.

Can you say "wrong Prez?"

Enron folded in 2001. The principals were arrested and prosecuted
under Bush.

Their house of cards, however, was built under Clinton's watch.
Eron's stock peaked in 2000, along with the rest of the internet
bubble we had under Clinton.

The California energy market scam took place in 2000 and early
2001, pre-Bush.

Clinton was also tight with Kenneth Lay. As he should've been,
since Lay was thought to be an important guy doing new,
valuable stuff. And Lay donated $900k to Clinton's party,
making him an important contributor too.

Cheers,
James Arthur

Jim Thompson · May 11, 2009

Not so much about presidents as political character, Lay and the Enron
perps are neocons. You might recheck your dates as well, it was at
least 2003 when the Enron bubble burst. Bush and FERC at the time
steadfastly refused to do anything relieve Grey Davis' deregulation
errors.

Eh?

"Enron Creditors Recovery Corporation (formerly Enron Corporation,
former NYSE ticker symbol ENE) was an American energy company based in
Houston, Texas. Before its bankruptcy in late 2001..."

...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

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