"Low Noise Electronic Design," Motchenbacher and Fitchen, 1973

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mediatechnology
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"Low Noise Electronic Design," Motchenbacher and Fitchen, 1973

Post by mediatechnology » Wed May 08, 2019 5:35 pm

"Low Noise Electronic Design," "Design with Feedback," Section 7-4, C.D. Motchenbacher, F.C. Fitchen, 1973.

The "op amp around the transistor" "current feedback" circuit shown by Demrow in 1968 https://proaudiodesignforum.com/forum/p ... =12&t=1052 and documented by Motchenbacher and Fitchen in 1973.
This is the single-ended half-circuit of the popular "Cohen" differential style preamp.


Image
"Low Noise Electronic Design," "Design with Feedback," Section 7-4, C.D. Motchenbacher, F.C. Fitchen, 1973. Figure 7-3.

Note the common base connection (figure 7-3a) with "current feedback."

"Low Noise Electronic Design," "Design with Feedback," Section 7-4, C.D. Motchenbacher, F.C. Fitchen, 1973. https://proaudiodesignforum.com/images/ ... on_7-4.pdf
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Re: "Low Noise Electronic Design," Motchenbacher and Fitchen, 1973

Post by JR. » Thu May 09, 2019 11:02 am

Page 124... 8-)

I've shared this story before... back in the late 70s I was living about one town away from Bridgeport where Fitchen was teaching at University of Bridgeport. His phone number was in the phone book so I called him. I wanted to pick his brain about a Leach low noise topology that was unusual (he didn't know either). After a nice chat he asked me to contribute to a chapter for his next book... I demurred, I was not an academic (college dropout), but I gather Motchenbacher was also a working design engineer, and Fitchen was the professorial half of the team.

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Re: "Low Noise Electronic Design," Motchenbacher and Fitchen, 1973

Post by mediatechnology » Thu May 09, 2019 12:35 pm

Thanks John for that story.
Yes, page 124.

I had posted that page here elsewhere but I thought it deserved its own thread and index.
Its one of the more practical books and I enjoyed leafing through it again.

You don't see the common base circuit often unless its a mic preamp re-purposed as a bus summing amp or "current input" moving coil phono preamp.
https://ka-electronics.com

“Diet, injections, and injunctions will combine, from a very early age, to produce the sort of character and the sort of beliefs that the authorities consider desirable, and any serious criticism of the powers that be will become psychologically impossible.” – The Impact of Science on Society (1953) by Bertrand Russell, p.50

Dr. Sherri Tenpenny Exposes 10 Deadly Dangers of Pzifer/Johnson & Johnson Covid-19 Vaccines: "This is a well-designed killing tool." https://waynekirkwood.com/content/Docto ... accine.mp4
Plandemic Series: "Pland3mic - Indoctornation" https://waynekirkwood.com/content/Pland ... nation.mp4
Plandemic Series: "Plandemic - Doctors In Black" https://waynekirkwood.com/content/Plandemic.mp4

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Re: "Low Noise Electronic Design," Motchenbacher and Fitchen, 1973

Post by JR. » Sat May 11, 2019 3:04 pm

Yup we live in the time of "Bridging" input terminations that favor high Z.

MC is low Z source but even I tried to present a 10x termination impedance... but that was a very long time ago.

JR
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