Electronics > Projects, Designs, and Technical Stuff

ultra low noise power supply design

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ogden:

--- Quote from: tggzzz on October 16, 2018, 12:57:47 am ---
--- Quote from: GigaJoe on October 15, 2018, 10:42:38 pm ---"  Power Designs 2020B " - when it was done, 1960 ?
I'm no in doubt it was advanced in this time ...   Like, want a programming: learn ENIAC :)

LT3045 - a microvolt RMS noise ...

--- End quote ---
I'm not quite sure what point you are trying to make, nor how you expect it to help the OP, but you sound.... very young.

--- End quote ---

When you show your frustration regarding LT low noise regulators you sound .... very old ;)

He suggested to study modern approach of building low noise supplies by suggesting to learn from LT3045 which has two orders of magnitude better noise performance than supply suggested by you. Very relevant and helping.


--- Quote ---However, I fail to see why you think processor families are relevant.

--- End quote ---

Both - ENIAC and voltage reference circuit of the 2020B are extinct

OM222O:
I also found that LDOs have quite a bit of noise on their own (best ones are about 100uV rms!) Are they rated like that due to the power supply noise and perform without noise if the PSU has no noise, or will they create their own noise?

ogden:

--- Quote from: OM222O on October 16, 2018, 09:33:45 am ---I also found that LDOs have quite a bit of noise on their own (best ones are about 100uV rms!)

--- End quote ---

Best ones like LT3045 have 1uV rms. Yes, generic regulators are noisy indeed. That's why there are "low noise" regulators and also "high output current voltage references".


--- Quote ---Are they rated like that due to the power supply noise and perform without noise if the PSU has no noise, or will they create their own noise?

--- End quote ---

LDO noise is always own noise, measured using "clean supply". If you want to know supply noise filtering performance, then look for PSRR figure.

Mechatrommer:

--- Quote from: OM222O on October 16, 2018, 09:33:45 am ---I also found that LDOs have quite a bit of noise on their own (best ones are about 100uV rms!)

--- End quote ---
noise psrr
why people always talk like they know what thee know?

P_Doped:
LDO noise is typically dominated by the internal reference designed into the LDO.  This noise contribution can propagate 2 ways:
1) The reference might be gained up to bring to the error amp.
2) The output of the LDO may have a feedback divider to feed the error amp.  That also gains of the reference noise seen at the error amp input, referred to the LDO output.

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