Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them.

From	Jan Panteltje <alien@comet.invalid>
Newsgroups	sci.electronics.design
Subject	Re: Drat. NTE is gone, and they took the last 5-GHz PNP with them.
Date	2024-09-06 06:44 +0000
Message-ID	<vbe8c2$26ha5$1@solani.org> (permalink)
References	(4 earlier) <60cd9dfe-42b7-8d6c-d101-8e771bc762e8@electrooptical.net> <7oakdjl3maqislrtoba0lunseakhroo22o@4ax.com> <vbdc8j$gsdh$1@dont-email.me> <uidkdj9krlovum2aee9fuuheqiavh1kt9e@4ax.com> <vbdh4h$hf8e$1@dont-email.me>

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On a sunny day (Fri, 6 Sep 2024 00:07:45 -0000 (UTC)) it happened Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote in
<vbdh4h$hf8e$1@dont-email.me>:

>john larkin <jl@650pot.com> wrote:
>> On Thu, 5 Sep 2024 22:44:36 -0000 (UTC), Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>> 
>>> john larkin <jl@650pot.com> 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?
>>>> 
>>>> 
>>> 
>>> Ive used them a fair amount in front ends, generally with a SiGe NPN
>>> cascode-slash-drain bootstrap.  Their transconductance is a few times
>>> higher than a CPH3910s, but not as good as the local-feedback circuits. 
>>> 
>>> pHEMTs have very low drain impedancethe late lamented ATF38143 had a
>>> voltage gain of ~0.7 as a follower, even with a current sink in the tail.  
>>> 
>>> Their amazing noise floor (~0.3 nV in 1 Hz) makes them well worth patching
>>> up, but they do take some patching. 
>>> 
>>> Cheers 
>>> 
>>> Phil Hobbs 
>> 
>> What is the Vdd in your circuit above?
>> 
>> I learned about jfet impact ionization from AoE. Keep the drain
>> voltage low!
>> 
>> 
>
>Yup. I run them between 2.5 and 3 V_DS. 

I run some on a few mV:
 https://panteltje.nl/pub/lighting_a_LED_with_a_candle_IMG_3604.GIF
 https://panteltje.nl/pub/lighting_a_LED_with_a_candle_setup_IMG_3607.GIF

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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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