This document may be of some help. These are the lowest noise resistors I know about. The resistors cost about $10 each, and are available from Texas Components Corp.
If you used a string of water-clear LED's as the photo-emitters and receptors you would waste less energy as heat -- by matching up the emission spectra. You could also flatten the lens and polish them, glue emitter and receptor together with something like Duco cement, cover with aluminum foil etc., etc.....getting a little OT here.
I don't know if the output and ground are mixed, or if the circuit simply floats as needed.
As for the Vishay marketing stuff, howcomeisit nobody ever shows the circuits they used to make the measurement so other people can duplicate and validate it? Kinda like the people that sell fancy capacitors for a high price but can't show any way to verify the amount of fancy. Not that I'm saying the Vishay parts aren't excellent- I know they are for various other reasons, but I want the noise test circuit and conditions.
As for the Vishay marketing stuff, howcomeisit nobody ever shows the circuits they used to make the measurement so other people can duplicate and validate it? Kinda like the people that sell fancy capacitors for a high price but can't show any way to verify the amount of fancy. Not that I'm saying the Vishay parts aren't excellent- I know they are for various other reasons, but I want the noise test circuit and conditions.
Here's a link to the 86 page book on Vishay's website:
http://images.vishaypg.com/vpgdocs/49789VMN-PL0373.pdf
Conrad -- I would guess if you had a quiet/shielded room and a Stanford SR785 or an Agilent HP35670A you could cross-correlate the FFT's.
Best I can do here is about 0.9 nV/RtHz. That's using an oreo cookie tin inside a danish cookie tin on a Saturday morning before the air conditioners and hair blowers start up.
I recall Scott speaking (typing) of one set up for which he put "device under test" on a bench in the middle of the room.
http://images.vishaypg.com/vpgdocs/49789VMN-PL0373.pdf
Conrad -- I would guess if you had a quiet/shielded room and a Stanford SR785 or an Agilent HP35670A you could cross-correlate the FFT's.
Best I can do here is about 0.9 nV/RtHz. That's using an oreo cookie tin inside a danish cookie tin on a Saturday morning before the air conditioners and hair blowers start up.
I recall Scott speaking (typing) of one set up for which he put "device under test" on a bench in the middle of the room.
Have a look at the test circuitry, and test results in this paper, and in particular the Vishay S102K.
Resistor Current Noise Measurements
The author Frank Seifert is a research engineer working on the development of a quantum-noise limited power stabilization for a high-precision laser system.
Ron
Briliant post going to copy this to my post in Salas Simplistic tread
Hope you dont mind
Tanks
Regarding the original question: why do you worry more about the input terminating resistor than about all other resistors in the circuit? The other resistors seem more critical to me, as they have DC bias voltages across them.
Had a look at the Vishay PDF and it didnt take long to turn me off.
So they have changed the laws of physics and made noise free components, have they?
All the noise related graphs on page 12 have no numbers so there kinda useless.
So they have changed the laws of physics and made noise free components, have they?
All the noise related graphs on page 12 have no numbers so there kinda useless.
- Status
- Not open for further replies.