Good, people are still introducing jfets.
Good Gm, 15 cents, and "low noise", whatever they mean by that.
Good, people are still introducing jfets.
Good Gm, 15 cents, and "low noise", whatever they mean by that.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Looks like a CPH3910 selected for high I_DSS.
Nice part--it's about 1 dB quieter than a BF862 in my typical applications, but doesn't like to run at I_DSS, which complicates some things.
Cheers
Phil Hobbs
"High Breakdown Voltage" ... WRT 5V? Make a JFET with 40V (or more) breakdown, then and only ten that would be meaningful. AFAIK they all are rated at 5V, so "High Breakdown Voltage" is BS.
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** The -25V "breakdown voltage" is gate to drain.It's intended for a +12V supply environment. No BS.
..... Phil
Does it make a good diode?
It's also intended as a first-RF antenna amplifier for an automotive antenna - they claim it has high ESD protection. I don't see how though.
Clifford Heath.
Jfets have impact ionization excess gate current above a few volts on the drain, so it's best to run them at a low voltage. Cascode with a bipolar if needed.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Not especially. Lots of capacitance, lots of series resistance, and probably more leakage than other options.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
That makes it easy to bootstrap away C_dg as well. I like to run them at about 2-3V D-S.
Cheers
Phil Hobbs
Idss looks like about 35 mA. Is that a problem?
Does noise figure translate directly to nv/rthz? You never know what sort of tuned circuit they may have used.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The noise bottoms out around 10 mA, increasing gently between there and I_DSS. So ine is constantly running them with V_GS ~ -500 mV. On the plus side, the noise minimum and the zero-TC point aren't that far apart.
Their e_N is about 0.7 nV.
Cheers
Phil Hobbs
Noise figure is usually specified relative to a specified source impedance... dB's relative to the source noise. ...Jim Thompson
-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | STV, Queen Creek, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | Thinking outside the box... producing elegant solutions. "It is not in doing what you like, but in liking what you do that is the secret of happiness." -James Barrie
That one was introduced a while ago. Did you find them featuring it someplace?
-- Thanks, - Win
Right, but I didn't see that impedance specified. And sometimes there's a tuned network that optimizes the match.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
I was just prowling the "new product" pages of various semi companies. I do that now and then to see what's happening.
The electronics mags are literally disappearing, approaching see-through, so one has to do other things to keep up.
Digikey has a periodic new products mailing that is nice.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
Thank you *so* much for that, John. As a lapsed Catholic, I'd simply despaired of this world up until reading your post.
What do you know, the SPICE model includes package parasitics.
It's not clear what they're measuring noise figure on. It's not the AM preamp circuit, that's for sure (which, speaking of, is clearly made with a very poor match: s11 is near 0dB across the band, so could be greatly improved).
Tim
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