Low audio noise JFETs?

datasheet.

Thanks, Pieter. This would be for business but I also still have a few dozen because I bought them before they became difficult to obtain. Lots of (mostly European) hobby shops actually still carry them. They are excellent parts for hobby electronics. Thing is, we need better LF noise than the BF245 could provide.

The Wikipedia entry matches my usage of the word pretty much exactly. For example, stating a "repeatability" specification in large print while the actual accuracy specification is elsewhere in small print and you have to add several error terms to *that* number to get the actual worst-case error.

Best regards, Spehro Pefhany

It's just a one-pager what I found but yes, the IF9031 and others do look nice. Might have to call them up to see how they are sold. The distributors I looked at don't carry that manufacturer.

Not allowed to tell ;-)

Fred Bartoli a écrit :

Forgot the Toshiba 2SK3320 (nice low noise dual in a small SMT package).

Yes, it does, thanks! We should be able to squeeze one TO92 in there for the first stage (it really only matters there).

Ampslabs has them, haven't found a mainstream distributor yet but as long as they can supply hundreds that'll be fine.

Arrow has the 2sk170

Aha, thanks. Nowadays it's more like that they claim low noise and then there isn't any noise spec at all in the datasheet.

Single-ended? I'm still surprised that you can't adequately filter the input of a bipolar opamp.

John

Must be a typo. Click on their datasheet link and the 2SK1739 comes up. It's a power MOSFET, just like their 2SK170 link says.

Oh, I could. Can't go into details but let's put it that way: It has to be extremely small and there can't be a lot of metal some areas. The input is single-ended by default. A low noise FET like the one Phil suggested could work.

Ah. Magnetic fields? Radioactive activation? A million G's on a centrifuge?

John

Number 3 comes close but my lips have to remain sealed. Again, it could be done but I'd have to be on the road a lot just to get there. Plus it would be really nice if I could call the guys, tell them to plop in something that has no b-e rectification issues, then go to the Thai place with my wife instead of sitting in a hotel.

datasheet.

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Without something to support the supposition, yes, I think it is. Many parts designed specifically for RF work have rather terrible audio noise figures. The 1/f noise may well start at 10kHz or even above. The equipment we build that covers to 100MHz and above often has rather poor low-audio-range noise performance, but then very few of our customers are looking with this equipment below 1MHz even.

Cheers, Tom

datasheet.

If you want the best of both worlds you'll have to design in two diplexers and two amp strips.

I attribute it to the California and Texas climate. Compare and .

Martin.