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Re: A SOT-89 with emitter in the middle

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From	Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de>
Newsgroups	sci.electronics.design
Subject	Re: A SOT-89 with emitter in the middle
Date	Fri, 22 Dec 2017 10:34:12 +0100
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Am 22.12.2017 um 04:51 schrieb John Larkin:
> On Thu, 21 Dec 2017 22:07:53 +0200, LM <sala.nimi@mail.com> wrote:
> 
>> Has anyone seen a NPN  bipolar transistor with emitter in the middle,
>> tab. Emitter is easier to ground in RF amplifiers.
> 
> Not me. But phemts usually have the center pin/tab as source, which is
> really handy.
> 
> The heat apparently comes out the collector of transistors but the
> source of phemts.

It is the substrate that naturally ends up on the tab.

That's why with JFETs, it is usually the gate. The channel is
in the middle between the top and bottom gate regions, and the
chip thickness plays a role in the channel height, which is
not so closely controlled. Hence the variation in Vgs in JFETs
for the "same effect".

The BFQ790 seems to be somewhat unusual with the emitter on the
substrate side, without that usual +++ doped collector well that
kills voltage ratings.

Note the 18 V Vcb for a 20 GHz SiGe transistor. That could be
interesting for large output voltage in a cascode.
And in a cascode, the emitter is relatively quiet, voltage-wise.

OK, the base on the tab would be even better for that. :-)

It seems, they did a lot of work to characterize that thing.
Much more than just abs. max. ratings and s-parameters as it
is common today.

cheers, Gerhard

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Thread

A SOT-89 with emitter in the middle LM <sala.nimi@mail.com> - 2017-12-21 22:07 +0200
  Re: A SOT-89 with emitter in the middle Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-12-21 21:55 +0100
    Re: A SOT-89 with emitter in the middle LM <sala.nimi@mail.com> - 2017-12-21 23:51 +0200
      Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-24 10:47 -0800
        Re: A SOT-89 with emitter in the middle Robert Baer <robertbaer@localnet.com> - 2017-12-24 18:27 -0800
          Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-25 08:41 -0800
    Re: A SOT-89 with emitter in the middle Winfield Hill <hill@rowland.harvard.edu> - 2017-12-21 13:54 -0800
      Re: A SOT-89 with emitter in the middle LM <sala.nimi@mail.com> - 2017-12-23 21:27 +0200
      Re: A SOT-89 with emitter in the middle Robert Baer <robertbaer@localnet.com> - 2017-12-23 22:05 -0800
  Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-21 19:51 -0800
    Re: A SOT-89 with emitter in the middle Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-12-22 10:34 +0100
      Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-22 08:56 -0800
        Re: A SOT-89 with emitter in the middle Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-12-23 08:01 -0500
        Re: A SOT-89 with emitter in the middle Winfield Hill <hill@rowland.harvard.edu> - 2017-12-26 05:34 -0800
          Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-26 08:43 -0800
            Re: A SOT-89 with emitter in the middle Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-12-26 13:03 -0500
              Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-26 10:36 -0800
            Re: A SOT-89 with emitter in the middle Winfield Hill <hill@rowland.harvard.edu> - 2017-12-27 05:50 -0800
              Re: A SOT-89 with emitter in the middle krw@notreal.com - 2017-12-27 09:34 -0500
              Re: A SOT-89 with emitter in the middle "John Miles, KE5FX" <jmiles@gmail.com> - 2017-12-27 13:42 -0800
                Re: A SOT-89 with emitter in the middle krw@notreal.com - 2017-12-27 19:58 -0500
                Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-27 19:11 -0800
                Re: A SOT-89 with emitter in the middle krw@notreal.com - 2017-12-27 22:44 -0500
                Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-27 20:08 -0800
                Re: A SOT-89 with emitter in the middle krw@notreal.com - 2017-12-27 23:29 -0500
                Re: A SOT-89 with emitter in the middle whit3rd <whit3rd@gmail.com> - 2017-12-28 03:34 -0800
                Re: A SOT-89 with emitter in the middle krw@notreal.com - 2017-12-28 08:42 -0500
                Re: A SOT-89 with emitter in the middle John Larkin <jjlarkin@highlandtechnology.com> - 2017-12-28 08:16 -0800
                Re: A SOT-89 with emitter in the middle boB <boB@K7IQ.com> - 2017-12-28 10:11 -0800
                Re: A SOT-89 with emitter in the middle krw@notreal.com - 2017-12-28 20:03 -0500
                Re: A SOT-89 with emitter in the middle Winfield Hill <hill@rowland.harvard.edu> - 2017-12-28 17:08 -0800
                Re: A SOT-89 with emitter in the middle krw@notreal.com - 2017-12-28 20:28 -0500
  Re: A SOT-89 with emitter in the middle mpm <mpmillard@aol.com> - 2017-12-23 17:12 -0800

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