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Groups > sci.electronics.design > #725875
| From | Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> |
|---|---|
| Newsgroups | sci.electronics.design |
| Subject | Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them. |
| Date | 2024-09-08 00:02 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <vbipiq$1k0jo$1@dont-email.me> (permalink) |
| References | (2 earlier) <vbbmn9$8mib$1@dont-email.me> <j2fjdjhn1e4uht19jlundnl45mtanlsghq@4ax.com> <60cd9dfe-42b7-8d6c-d101-8e771bc762e8@electrooptical.net> <7oakdjl3maqislrtoba0lunseakhroo22o@4ax.com> <NHknlWwLIQIumCNTcOxTkFklwQHMrNgK@bonus.frugalusenet.com> |
bitrex <user@example.net> wrote: > On 9/5/2024 6:06 PM, john larkin wrote: >> On Thu, 5 Sep 2024 10:49:42 -0400, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> 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 >> >> The CPH3910 is a jfet. Might an un-assisted PHEMT be better? >> > > What about a PFET/JEFT cascode buffer kinda like: > > <https://imgur.com/a/5fBR8Gb> > There aren’t any decent discrete pfets left, and there never was a 5 GHz one. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics
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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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