Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > sci.electronics.design > #462161

Re: Running out of ideas: stability, bootstrap

Show all headers | View raw

On 2017-05-28 13:09, Gerhard Hoffmann wrote:
> Am 28.05.2017 um 18:46 schrieb John Larkin:
>
>>
>> Over what frequency range is the Zin negative?
>
> The network analyzer starts officially at 300 KHz,
> non-guaranteed at 150KHz. At 150 KHz Zin is already
> negative. It seems, at about 10 MHz everything is
> running out of steam, so it stops being offensive.
>
> Every impedance inside the circle that goes through 0
> has a positive real part. Everything on the circle
> through 0 has zero Ohms, only LC.
> Everything outside of that circle has a negative
> real part.
> The Smith diagram is in the same photo album.
>
> There are no complaints by LTspice.
> In a very old version of Genesys, I get about the same
> behavior regarding Zin. But I could not make the
> bias loop converge, so setting the operating point
> is clumsy.
>
>
>> Where does GATE_BIAS come from?
>
> That comes from an integrator. I have added that
> part of the circuit. Since the 30uF input capacitance
> * 66Meg bias resistor takes an eternity to settle,
> I have added a window comparator & analog switch to
> reduce the bias resistor by paralleling 4Meg7.
> That works.
>
>>
>> How is this physically assembled?
>
> It is all on a small dual-sided circuit board.
> Pic included. It does no longer look that tidy.  :-)
>
> < https://www.flickr.com/photos/137684711@N07/albums/72157682404684680 >
>
> and the pics left/right of it.
>

The 17.6pF cap could perform better if it had a flag in the Borussia 
Dortmund colors black and yellow :-)

Just curious, shouldn't there be a cap to ground at the base of Q3 and 
maybe also Q2?

-- 
Regards, Joerg

http://www.analogconsultants.com/

Back to sci.electronics.design | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 17:11 +0200
  Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-28 12:09 -0400
    Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 23:01 +0200
      Re: Running out of ideas: stability, bootstrap Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-28 14:30 -0700
        Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 23:56 +0200
          Re: Running out of ideas: stability, bootstrap Jim Thompson <To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> - 2017-05-28 15:08 -0700
  Re: Running out of ideas: stability, bootstrap John Larkin <jjlarkin@highlandtechnology.com> - 2017-05-28 09:46 -0700
    Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-28 22:09 +0200
      Re: Running out of ideas: stability, bootstrap Joerg <news@analogconsultants.com> - 2017-05-29 07:13 -0700
        Re: Running out of ideas: stability, bootstrap dagmargoodboat@yahoo.com - 2017-05-29 20:56 -0700
          Re: Running out of ideas: stability, bootstrap Winfield Hill <hill@rowland.harvard.edu> - 2017-05-30 03:55 -0700
            Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-30 15:53 +0200
              Re: Running out of ideas: stability, bootstrap dagmargoodboat@yahoo.com - 2017-05-30 10:42 -0700
  Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 08:38 -0400
    Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 08:40 -0400
    Re: Running out of ideas: stability, bootstrap Gerhard Hoffmann <ghf@hoffmann-hochfrequenz.de> - 2017-05-30 16:51 +0200
  Re: Running out of ideas: stability, bootstrap Winfield Hill <hill@rowland.harvard.edu> - 2017-05-29 07:36 -0700
    Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 11:20 -0400
      Re: Running out of ideas: stability, bootstrap Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-29 15:36 +0000
        Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 11:44 -0400
          Re: Running out of ideas: stability, bootstrap bitrex <bitrex@de.lete.earthlink.net> - 2017-05-29 11:53 -0400
          Re: Running out of ideas: stability, bootstrap Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-29 17:01 +0000
        Re: Running out of ideas: stability, bootstrap Winfield Hill <hill@rowland.harvard.edu> - 2017-05-29 08:46 -0700
          Re: Running out of ideas: stability, bootstrap Jan Panteltje <pNa0nStpealmtje@yahoo.com> - 2017-05-29 16:56 +0000
      Re: Running out of ideas: stability, bootstrap dagmargoodboat@yahoo.com - 2017-05-29 21:12 -0700

csiph-web