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Compound Pair vs Darlington Pair
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Lucky-Luka:
Hi all
I've read that Sziklai pair are more thermically stable than Darlington ones.
Is it because since Q5 has half Q10 voltage bias it dissipates half the heat and the configuration is in such a way more thermically stable?
Is that so? Anything else?

Happy holidays
edavid:
Douglas Self ("Audio Power Amplifier Design Handbook, 5th Ed") says:


--- Quote ---The CFP topology is generally considered to show better thermal stability than the EF, because the
Vbe of the output devices is inside the local NFB loop, and only the driver Vbe has a major effect on
the quiescent conditions. The true situation is rather more complex, and is explored in Chapter 15.
--- End quote ---

So, I suggest you get a copy and read Chapter 15!
exe:
Check this one: https://sound-au.com/articles/cmpd-vs-darl.htm . Explains topic quite in in-depth.
Lucky-Luka:
I've also read that Szikai configuration should behave better against distortion... Is it true?
I've tried a comparison but it looks like that Darlington behaves better. Am i wrong?
 
Kleinstein:
The Szikai configuration likes an addition base to emitter resistor with the larger transistor.
Another point to look for it that the  Szikai configuration is more prone to oscillation, especially if the driving side is higher impedance.

The distortion in the class AB power stage depends on the standing current - both types tend to prefer a slightly different current.  Better thermal stability leads to a more stable standing current and could this way cause less distortion. The simulation tends to no include that thermal effect.
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