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Old 30th March 2007, 03:19 PM   #1
roender is offline roender  Romania
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Default Another feedback compensation method

Hello all,

This is my new test poweramp which have differential VAS, compensated with shunt capacitor from output to ground.
The loop gain is 86dB and phase margin 36dB.
In the searching of a solution to decrease VAS capacitive load, I came to this schematic which have the same loop gain but more phase margin (49dB)
What is your opinion about this compensation type ?

Unmodified amp
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Old 30th March 2007, 03:21 PM   #2
roender is offline roender  Romania
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The new compensation methode
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Old 30th March 2007, 06:26 PM   #3
AndrewT is offline AndrewT  Scotland
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Hi,
that 150pF from VAS to inverting input is quite conventional.
used by many British designers (JLH, Crimson, Sugden that I know about) for reputedly improved sound quality.
The phase of your connection seems reversed from the norm.

Can you eliminate C8 & C9 completely and use 150pF//(R+C) to stabilise and tune the phase margin?
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Old 24th February 2013, 02:50 PM   #4
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Very similar to Bob Cordell amps compensation scheme. In Your amp C8 and C9 plays role C3 and R14 in Bob amp (which is better, because less VAS loading).

And no furher posta thoroug so many years ....?
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Old 24th February 2013, 05:40 PM   #5
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If this is correct image, then forgot my previous post. (image copied from anothere thread)
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