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Need Info on Op-Amp Noise

A

AZ2NV

Jan 1, 1970
0
For a report i need:


Overall definition of what noise is and what cause it

Ways To reduce noise.



Anyweb sites or info would be great
 
I

Ian Stirling

Jan 1, 1970
0
AZ2NV said:
For a report i need:


Overall definition of what noise is and what cause it

Ways To reduce noise.

Google for
shannon noise

For many usefull results.
 
W

Winfield Hill

Jan 1, 1970
0
AZ2NV wrote...
For a report i need:
Overall definition of what noise is and what cause it
Ways To reduce noise.

There's a good discussion in the Art of Electronics, check
out a copy from your school library.

The OMU (One-Minute University) quick and incomplete answer:
Noise density, two types: current noise and voltage noise.
For the former, see shot noise, reduce by lowering current.
For the latter, Johnson / Nyquist noise, reduce by raising
the current (and for FETs, also by increasing the area).

Thanks,
- Win

whill_at_picovolt-dot-com
 
A

Active8

Jan 1, 1970
0
For a report i need:


Overall definition of what noise is and what cause it

Ways To reduce noise.

Google for
shannon noise

For many usefull results.
[/QUOTE]
and thermal (johnson/nyquist), shot, flicker, solar, sky, atmospheric,
galactic, white gaussian, galactic...

shielding, grounding, filtering...
 
L

Linear

Jan 1, 1970
0
Hello Win,

Does popcorn noise fall into current or voltage noise? Or is it a third
type? Any insight?

Regards,,,,, Linear

AZ2NV wrote...
For a report i need:
Overall definition of what noise is and what cause it
Ways To reduce noise.

There's a good discussion in the Art of Electronics, check
out a copy from your school library.

The OMU (One-Minute University) quick and incomplete answer:
Noise density, two types: current noise and voltage noise.
For the former, see shot noise, reduce by lowering current.
For the latter, Johnson / Nyquist noise, reduce by raising
the current (and for FETs, also by increasing the area).

Thanks,
- Win

whill_at_picovolt-dot-com
 
W

Winfield Hill

Jan 1, 1970
0
Linear wrote...
Hello Win,

Does popcorn noise fall into current or voltage noise?
Or is it a third type? Any insight?

I don't think popcorn noise, or 1/f noise for that matter,
fits into the 1-minute university's curriculum, but if it
did, I'd guess it'd be a fifth type. :>)

As for the manifestation of popcorn noise in the old classic
opamps, wasn't it primarily seen as a type of voltage noise?
Winfield wrote ...

The OMU (One-Minute University) quick and incomplete answer:
Noise density, two types: current noise and voltage noise.
For the former, see shot noise, reduce by lowering current.
For the latter, Johnson / Nyquist noise, reduce by raising
the current (and for FETs, also by increasing the area).

Thanks,
- Win

whill_at_picovolt-dot-com
 
L

Linear

Jan 1, 1970
0
I don't think popcorn noise, or 1/f noise for that matter,
fits into the 1-minute university's curriculum, but if it
did, I'd guess it'd be a fifth type. :>)

Hmmm. Lets see

Type 1 - current, shot
Type 2 - voltage, noise
Type 3 - i/f ?
Type 4 - ??
Type 5 - popcorn


As for the manifestation of popcorn noise in the old classic
opamps, wasn't it primarily seen as a type of voltage noise?

I think you are right about popcorn noise being primarily a voltage noise.
Any ideas how to minimize it?

Regards.... Linear
 
J

Jim Thompson

Jan 1, 1970
0
I don't think popcorn noise, or 1/f noise for that matter,
fits into the 1-minute university's curriculum, but if it
did, I'd guess it'd be a fifth type. :>)

Hmmm. Lets see

Type 1 - current, shot
Type 2 - voltage, noise
Type 3 - i/f ?
Type 4 - ??
Type 5 - popcorn


As for the manifestation of popcorn noise in the old classic
opamps, wasn't it primarily seen as a type of voltage noise?

I think you are right about popcorn noise being primarily a voltage noise.
Any ideas how to minimize it?

Regards.... Linear

Popcorn noise comes from an extra random carrier traversing the base
region, usually seen in "super-beta" devices with push-ahead emitters,
thus an ultra-narrow base region.

So I'd rend to lump it in with shot noise.

...Jim Thompson
 
J

Jim Thompson

Jan 1, 1970
0
On Sat, 11 Oct 2003 11:33:00 -0700, Jim Thompson

[snip]
Popcorn noise comes from an extra random carrier traversing the base
region, usually seen in "super-beta" devices with push-ahead emitters,
thus an ultra-narrow base region.

So I'd rend to lump it in with shot noise.

...Jim Thompson

Change "rend" to "tend"... it's dangerous to trust spell-checkers :-(

...Jim Thompson
 
B

Bill Sloman

Jan 1, 1970
0
Jim Thompson said:
Popcorn noise comes from an extra random carrier traversing the base
region, usually seen in "super-beta" devices with push-ahead emitters,
thus an ultra-narrow base region.

So I'd tend to lump it in with shot noise.

So how come the old 709's and 741's were notorious for pop-corn noise?

They pre-dated super-beta transistors by a few years, and some 741
parts were still demonstrating the problem in 1988.

Back in 1970, one of my co-workers was actually using the super-beta
LM308 as a low noise front end in a sonar system, where pop-corn noise
might have been embarassing.
 
M

Mike

Jan 1, 1970
0
Popcorn noise comes from an extra random carrier traversing the base
region, usually seen in "super-beta" devices with push-ahead emitters,
thus an ultra-narrow base region.

So I'd rend to lump it in with shot noise.

...Jim Thompson

Hmmm... I thought popcorn noise was due to trap sites in the base region,
which explained why it was particularly prevalent in some of the old
gold-doped RF transistors.

In MOS devices, one theory holds that flicker noise is the result of traps
in the oxide. Given a realistic trap density, it can be shown that the sum
of all the resulting popcorn noise sources produces a 1/f spectrum.

In any event, the spectrum of popcorn noise is Lorentzian, not white, so be
careful if you lump popcorn noise with shot noise.

-- Mike --
 
Y

YD

Jan 1, 1970
0
Google for
shannon noise

For many usefull results.
and thermal (johnson/nyquist), shot, flicker, solar, sky, atmospheric,
galactic, white gaussian, galactic...

shielding, grounding, filtering...[/QUOTE]

Wife, teenage daughter...

- YD.
 
A

Active8

Jan 1, 1970
0
On Sun, 12 Oct 2003 01:11:49 -0300, YD, said...
Wife, teenage daughter...

- YD.
gag, gun, send 'em shopping...

i was thinking along those lines, too.

mike
 
A

Active8

Jan 1, 1970
0
On Sat, 11 Oct 2003 11:33:00 -0700, Jim Thompson

[snip]
Popcorn noise comes from an extra random carrier traversing the base
region, usually seen in "super-beta" devices with push-ahead emitters,
thus an ultra-narrow base region.

So I'd rend to lump it in with shot noise.

...Jim Thompson

Change "rend" to "tend"... it's dangerous to trust spell-checkers :-(

...Jim Thompson
can i rend you a hand?

mike
 
A

Active8

Jan 1, 1970
0
On 11 Oct 2003 16:04:40 -0700, Bill Sloman, said...
Back in 1970, one of my co-workers was actually using the super-beta
LM308 as a low noise front end in a sonar system, where pop-corn noise
might have been embarassing.
"con, sonar. contact bearing 174 degrees. sounds like whales making
popcorn."

"galley, con. slow down. the movie doesn't start for 2hrs., and, er, did
we take on any KFC popcorn chicked at our last port of call?"

mike
 
I

Ian Buckner

Jan 1, 1970
0
Bill Sloman said:
Popcorn noise comes from an extra random carrier traversing the base
region, usually seen in "super-beta" devices with push-ahead emitters,
thus an ultra-narrow base region.

So I'd tend to lump it in with shot noise.

So how come the old 709's and 741's were notorious for pop-corn noise?

They pre-dated super-beta transistors by a few years, and some 741
parts were still demonstrating the problem in 1988.

Back in 1970, one of my co-workers was actually using the super-beta
LM308 as a low noise front end in a sonar system, where pop-corn noise
might have been embarassing.
[/QUOTE]

I used a lot of LM308's back then to do active filters at 1/30Hz and
1/7Hz in a
system where any popcorn noise would have been _very_ obvious. I never
saw any signs of that kind of noise with that part.

As to how to minimise it, change manufacturers.

Regards
Ian
 
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