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Re: Fast buffer idea

Subject Re: Fast buffer idea
Newsgroups sci.electronics.design
References (2 earlier) <XnsA7759BED550Bidtokenpost@69.16.179.22> <auchhcp4h0898t9hatrh3017esf6dve1n5@4ax.com> <ofbmuh$s3t$1@gioia.aioe.org> <dpcjhclpajjafaf2nq0q7l7nt17jl40spo@4ax.com> <ofce8n$9ia$1@gioia.aioe.org>
From bitrex <bitrex@de.lete.earthlink.net>
Message-ID <cnlSA.15485$Qg.3753@fx14.iad> (permalink)
Organization frugalusenet - www.frugalusenet.com
Date 2017-05-15 13:15 -0400

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On 05/15/2017 10:33 AM, Jan Panteltje wrote:
> On a sunny day (Mon, 15 May 2017 07:01:06 -0700) it happened John Larkin
> <jjlarkin@highlandtechnology.com> wrote in
> <dpcjhclpajjafaf2nq0q7l7nt17jl40spo@4ax.com>:
>
>> On Mon, 15 May 2017 07:56:01 GMT, Jan Panteltje
>> <pNa0nStpealmtje@yahoo.com> wrote:
>>
>>> On a sunny day (Sun, 14 May 2017 12:54:12 -0700) it happened John Larkin
>>> <jjlarkin@highlandtechnology.com> wrote in
>>> <auchhcp4h0898t9hatrh3017esf6dve1n5@4ax.com>:
>>>
>>>> If the object is to buffer a logic level, some 13-cent TinyLogic gate,
>>>> like an NL37WZ16US or something.
>>>>
>>>> If it needs to be linear, there are tons of opamps to consider:
>>>> THS4222, AD8007, whatever.
>>>
>>> THS4222 datasheet says open loop gain 0dB at 100 MHz?
>>
>> Where does it say that?
>>
>>> With a free 80 degrees phase shift?
>>> Fig 17, see also Fig 1 for 500 Ohm load.
>>>
>>> It won't drive a 50 Ohm coax either..
>>> Maybe good for a 5 to 10 MHz wide video amp...
>>>
>>
>> BW is 230 MHz as a unity-gain buffer. Each half of the dual will
>> source and sink 88 mA. And there are lots of faster THS-series parts.
>>
>>>
>>> But indeed you can do that with a few NPNs of the old days,
>>>
>>
>> Post it.
>
> Did not I ;-)?
>
> Actually when I did read that OP, I scribbled this on my 'desk':
>  http://panteltje.com/pub/maybe_this_amp_IMG_6183.JPG
>   that is a dual complementary emitter follower.
>
> The reason I did not jump into the discussion with that, is that _in this form_
> I am not sure about zero temp drift, it may need some resistors.
> But it should have zero output offset versus input, low output impedance,
> high input impedance, temp tracking, and I do not have spice running
> to give an idea, so not a tested thing.
> So if it melts you mega $ trannies so be it.
>

It's a regular "diamond buffer" topology. Without emitter degeneration 
resistors in the output emitters it's asking for thermal runaway, and 
the output waveform won't be particularly linear.

Try adding 10 ohm degeneration resistors, and check the quiescent 
current on that bad boy with 10/-10 rails. Yikes!

Taking feedback from the tops of the degeneration resistors to the input 
collectors makes it more linear by reducing Early effect variations. 
It's an even better idea with a MOSFET input stage, as ideally if the 
Vds is near constant you wont have the gm compromised due to 
channel-length modulation.

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Thread

Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 13:50 -0400
  Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 11:27 -0700
    Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 19:19 +0000
      Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 15:24 -0400
      Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 12:54 -0700
        Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:02 -0400
          Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 13:10 -0700
            Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:16 -0400
              Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:18 -0400
              Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 14:14 -0700
              Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:51 +0100
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:17 -0700
                Re: Fast buffer idea Clifford Heath <clifford.heath@gmail.com> - 2017-05-17 09:14 +1000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 16:26 -0700
                Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-17 02:04 -0500
        Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 20:26 +0000
          Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:31 -0400
          Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:43 -0400
          Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 14:17 -0700
            Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-14 21:53 +0000
              Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 16:14 -0700
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 19:59 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:06 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 00:16 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:10 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 03:28 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:48 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 04:17 +0000
        Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 07:56 +0000
          Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 06:58 -0400
            Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 12:59 +0000
          Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 07:01 -0700
            Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 10:09 -0400
              Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 10:18 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 08:56 -0700
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:02 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 10:33 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:15 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 14:25 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 14:26 -0400
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 16:24 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 16:36 +0000
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 17:18 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:30 -0400
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:07 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:19 +0000
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 19:45 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:33 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:13 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:33 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:16 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 22:10 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:10 +0000
              Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-15 08:55 -0700
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 12:51 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 12:56 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:05 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 10:28 -0700
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:38 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 11:29 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 18:41 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:19 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 20:46 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:56 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 21:00 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 16:46 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 01:22 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 11:16 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 18:55 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 12:21 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 20:33 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 14:00 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 21:21 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 16:15 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-16 23:58 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-16 17:51 -0700
                Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-16 16:30 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-17 00:16 +0000
                Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-16 18:05 -0700
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:05 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-25 01:13 +0000
                Re: Fast buffer idea Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-05-24 21:43 -0400
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-30 03:16 +0000
                Re: Fast buffer idea Ralph Barone <ralph@invalid.com> - 2017-05-17 02:26 +0000
                Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-17 08:34 +0200
                Re: Fast buffer idea Ralph Barone <ralph@invalid.com> - 2017-05-17 14:31 +0000
                Re: Fast buffer idea Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-05-17 10:39 -0400
                Re: Fast buffer idea Reinhardt Behm <rbehm@hushmail.com> - 2017-05-17 23:02 +0800
                Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-16 21:24 +0200
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:12 -0700
                Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 04:38 -0700
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-25 07:28 -0700
                Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-26 08:54 -0500
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-26 14:14 +0000
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-26 07:21 -0700
                Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-16 20:27 +0100
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:05 -0400
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:19 -0400
                Re: Fast buffer idea John Larkin <jjlarkin@highland_snip_technology.com> - 2017-05-15 13:21 -0700
                Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 20:56 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 17:37 -0400
              Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:50 +0100
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:25 +0000
                Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-16 20:19 +0100
            Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 14:33 +0000
              Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 13:15 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-15 19:05 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-15 15:38 -0400
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 08:12 +0000
                Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 18:47 +0000
                Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 21:52 -0400
                Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 05:05 -0700
                Re: Fast buffer idea pcdhobbs@gmail.com - 2017-05-25 05:42 -0700
                Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-25 05:49 -0700
                Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-25 08:10 -0700
                Re: Fast buffer idea Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-25 15:01 +0200
      Re: Fast buffer idea "John Miles, KE5FX" <jmiles@gmail.com> - 2017-05-14 18:53 -0700
        Re: Fast buffer idea Steve Wilson <no@spam.com> - 2017-05-15 02:45 +0000
    Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 15:23 -0400
  Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-14 20:28 +0100
    Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:00 -0400
    Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 16:10 -0400
      Re: Fast buffer idea Winfield Hill <hill@rowland.harvard.edu> - 2017-05-14 17:58 -0700
        Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-14 23:13 -0400
        Re: Fast buffer idea Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-16 17:27 -0700
          Re: Fast buffer idea Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-16 17:34 -0700
      Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-14 20:14 -0700
        Re: Fast buffer idea "Kevin Aylward" <kevinRemovAT@kevinaylward.co.uk> - 2017-05-15 19:42 +0100
  Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-16 03:29 -0500
    Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 06:57 -0700
      Re: Fast buffer idea bitrex <bitrex@de.lete.earthlink.net> - 2017-05-16 22:47 -0400
        Re: Fast buffer idea John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-16 20:18 -0700
          Re: Fast buffer idea "Tim Williams" <tiwill@seventransistorlabs.com> - 2017-05-17 02:22 -0500
    Re: Fast buffer idea Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-16 14:05 +0000

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