PMA said:
Well I certainly did the drawing. But I don't recall the context. I dug up the original on my drive and saw that I named it "poison.gif."
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PMA said:
Ah! Thanks, Pavel!
I'd put my memories of that place in a dusty old trunk buried deep in the cellar. 😀
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jacco vermeulen said:You mean transistors can do both current and voltage gain at the same time ?
Mmmmm. You mean a single transistor cannot provide power gain?
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scott wurcer said:Where are the SOTA circuits?
Ok, I'll get it started.
The rest of you can tack on the other bits.
An externally hosted image should be here but it was not working when we last tested it.
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Interesting circuit. The input signal modulates Ic3, but X1 tries to keep that constant by modulating Ic4. Looks like the load current is provided by Q4, and that Q3's only purpose is to make the offset equal to zero, depending on the matching of I1 and I2.
Of course, I could be totally wrong 😉 .
Jan Didden
Of course, I could be totally wrong 😉 .
Jan Didden
The opamp drives Q4 such that collector current of Q3 never drops below I1. It works like linearized EF buffer, with quite low distortion.
Robert J. Widlar — The Genius, The Legend, The Bohemian, Springer Berlin Heidelberg, 2007, ISBN 978-3-540-34257-1
dimitri said:
Widlar was notorious for hating FET's. I mean he REALLY thought they were useless to the point of designing at least one pico-amp input bi-polar op-amp that was an embarassment to NS.
john curl said:Now, there is genius! Why?
symmetrical power supply and load coupling. Disallows for specific harmonic content to emerge? as well, it kinda reminds me of the mechanical equivalent of an offset tension system to prevent 'float' noise/distortion near the 'used to be' zero point from adding distortion. In civil engineering terms, it's called: '3 to 15'. After all, its the modulated signal you want, nothing else. Feel free to laugh at my musing, if it spurs a bit more actual content.
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