ultra low noise like 50uV from the psu for 80V 15A possibility? - diyAudio
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Old 13th March 2014, 06:44 PM   #1
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Default ultra low noise like 50uV from the psu for 80V 15A possibility?

Is there anyway to reduce the psu noise to substantial level yet providing the 80V 15A current?
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Old 13th March 2014, 06:54 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

Why ? The PSU is dominated by ripple and noise is not an issue.

You can regulate or use a capacitance multiplier to reduce ripple.
Both are generally not needed except for simple class A,
which you won't be doing at 80V and 15A.

rgds, sreten.

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Last edited by sreten; 13th March 2014 at 07:01 PM.
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Old 13th March 2014, 07:46 PM   #3
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Im more concerned with noise than ripple. For ripple no problem can use CLC circuits but for the noise thats the problem.
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Old 13th March 2014, 08:10 PM   #4
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Why the fear for noise? What is the application?
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Old 13th March 2014, 09:03 PM   #5
infinia is offline infinia  United States
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the short answer yes , but I doubt you need it for the whole power output section.
look at using a separate low power supply for the front end regulator using discrete transistors and LN references. several ways to do this, and still keep some decent efficiency rather than brute force.
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Old 13th March 2014, 09:31 PM   #6
sreten is offline sreten  United Kingdom
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Hi,

What noise ? Caused by what component ? What do
think the noise of the final capacitor is determined by ?

rgds, sreten.
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Old 14th March 2014, 03:06 AM   #7
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I found some regulator from TI for VAS stage which can give noise performances as much low as 50uV but for the output stage we dont have any choices as the voltage and current requirements are high.
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Old 14th March 2014, 03:11 AM   #8
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Low noise PSUs tend to be only such when a very constant current is drawn. Otherwise the load dependent current draw * the Zout gives rise to much more noise than 50uV. Output impedance is king in my experience.
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Old 14th March 2014, 03:12 AM   #9
kouiky is offline kouiky  United States
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I wonder if the regulators could be paralleled. Is your load dynamic or constant?
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Old 14th March 2014, 03:28 AM   #10
infinia is offline infinia  United States
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yes the idea is to split the supplies, clean up all gain stages. With the normal supply to the OP stage (gain <1). Then re measure the output noise into a very light load at O V ( see CMRR / PSRR measurement for power op amps ) compared to the unclipped Vo .
20 LOG (Vo RMS / 50uv ) is an unreasonable S/N
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Last edited by infinia; 14th March 2014 at 03:36 AM.
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