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| Subject | Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. |
|---|---|
| Newsgroups | sci.electronics.design |
| References | <6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net> <vbbia5$25sla$1@solani.org> <vbbmn9$8mib$1@dont-email.me> <j2fjdjhn1e4uht19jlundnl45mtanlsghq@4ax.com> |
| From | Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> |
| Message-ID | <60cd9dfe-42b7-8d6c-d101-8e771bc762e8@electrooptical.net> (permalink) |
| Date | 2024-09-05 10:49 -0400 |
On 2024-09-05 10:14, john larkin wrote:
> On Thu, 5 Sep 2024 07:30:50 -0000 (UTC), Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>> Jan Panteltje <alien@comet.invalid> wrote:
>>> On a sunny day (Wed, 4 Sep 2024 17:54:19 -0400) it happened Phil Hobbs
>>> <pcdhSpamMeSenseless@electrooptical.net> wrote in
>>> <6b1217f0-f55b-95b4-6516-6914d18d0e91@electrooptical.net>:
>>>
>>>> The NTE2403, similar to the BFT92, but a bit better overall. Dunno who
>>>> actually made them. (I saw the news on s.e.repair today.)
>>>>
>>>> Rochester claims to have 1,500,000 of the 2SA1462 (1.8 GHz) for 20
>>>> cents, but that's all she wrote.
>>>>
>>>> I have a couple of reels of BFT92s and one of BFG31s, so I'm good for
>>>> protos and small production, but I can't use PNP wraparound bootstraps
>>>> for customer designs anymore. :(
>>>>
>>>> Barstids.
>>>>
>>>> Cheers
>>>>
>>>> Phil Hobbs
>>>
>>> Lots if RF snall signal low noise stoff in LNBs:
>>> https://www.infineon.com/dgdl/Infineon-Design_guide_for_RF-transistors_and_diode_in_Low-Noise-Block-ApplicationNotes-v01_00-EN.pdf?fileId=8ac78c8c7e7124d1017f01f071aa5b8f
>>> Does that help?
>>>
>>>
>>> Complete LNBs inclusive transistors and peeseebees are 5 dollies on ebay.
>>>
>>>
>>
>> Thanks. It’s not a 50-ohm system, so using those would be hard. I have
>> thousands for personal use, but can’t put them in licensed designs, which
>> is what I’m moaning about.
>>
>> Cheers
>>
>> Phil Hobbs
>
> Can you use mmics? There are some really cool, fast, cheap, low-noise
> things around. Just because the RF boys test everything at 50 ohms
> doesn't mean we have to use them at 50 ohms.
>
For the wraparound topology, which is the second-best follower I know of,
VDD 0------*---------*
| |
R |
R |
R /
| |V
*-------| BFT92
| |\
|--* \
In 0-->| CPH3910 |
|--* |
| |
| |
*---------*----0 Follower output
|
V (tail current source)
the BJT needs to be a PNP.
It's a nice circuit, because the PNP reduces the output impedance a lot
without adding much noise at all--way better than an NPN follower after
the FET.
Because of the local feedback, the transistors need to be fairly
different in speed to maintain stability. The FET is about a 750-MHz
device, so a 5-GHz PNP is great. The alternative would be a 100-MHz
PNP, which would be too depressing to contemplate. :(
The very best follower topology I know about is a fancy bootstrapped
version of the White cathode follower, where the feedback is applied via
the tail source. That's much harder to stabilize, because there are
three transistors in the local feedback loop, but on the other hand its
gain is 0.9997 at baseband and above 0.995 at 10 MHz. (You can't
readily measure those sorts of numbers directly, so I inferred them from
its performance as a bootstrap.)
The reason I care about getting such accurate bootstraps is a bit
subtle--probably I'd have enough bandwidth improvement with a gain of
0.9, but that extra 10% shows up as a gnarly settling transient at late
times, which screws up measurements. 0.9997 is dramatically better.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510
http://electrooptical.net
http://hobbs-eo.com
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Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-04 17:54 -0400
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. john larkin <jlarkin_highland_tech> - 2024-09-04 19:50 -0700
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-05 07:22 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Jan Panteltje <alien@comet.invalid> - 2024-09-05 06:15 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-05 07:30 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. john larkin <jlarkin_highland_tech> - 2024-09-05 07:14 -0700
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-05 10:49 -0400
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. john larkin <jl@650pot.com> - 2024-09-05 15:06 -0700
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-05 22:44 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. john larkin <jl@650pot.com> - 2024-09-05 15:55 -0700
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-06 00:07 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Jan Panteltje <alien@comet.invalid> - 2024-09-06 06:44 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. bitrex <user@example.net> - 2024-09-07 23:40 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-08 00:02 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-08 00:16 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Gerhard Hoffmann <dk4xp@arcor.de> - 2024-09-06 01:43 +0200
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. john larkin <jl@650pot.com> - 2024-09-05 16:58 -0700
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-06 00:13 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Bill Sloman <bill.sloman@ieee.org> - 2024-09-05 21:15 +1000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. bitrex <user@example.net> - 2024-09-05 14:24 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-05 18:17 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Gerhard Hoffmann <dk4xp@arcor.de> - 2024-09-05 20:57 +0200
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-05 19:58 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Chris Jones <lugnut808@spam.yahoo.com> - 2024-09-06 22:47 +1000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Gerhard Hoffmann <dk4xp@arcor.de> - 2024-09-06 17:31 +0200
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-06 13:33 -0400
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Joerg <news@analogconsultants.com> - 2024-09-06 15:59 -0700
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-07 21:46 +0000
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Joerg <news@analogconsultants.com> - 2024-09-09 14:02 -0700
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-09 21:59 -0400
Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2024-09-09 22:12 -0400
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