Silent power supply design (noise<100uv)

[JuniorEE]

Hello

what is the best power supply design for low noise <100 uv
for analog circuit
LDO ? Opamp based PS ? Else ?
For example application:
Vin 5v
Vout 3v
Noise < 100uv for 0-200Mhz

It will be great also if you can forward me some links to read & learn about this topic

Thanks !

 

[KlausST]

Hi,

Look for "low noise linear regulator".
For sure you need proper PCB layout, proper bypassing your "noise sources" maybe filtering, maybe extra regulators for noisy and low noise parts of your system.

Documents:
Usually every regulator manufacturer provides datasheets and application notes with detailed and reliable informations for many use cases.

Klaus

 

[BigBoss]

Analog Devices have some very high performance ragulators for that.

Selection Table for LDO Plus | Parametric Search | Analog Devices

Analog Devices' Selection Table for LDO Plus lets you add, remove, and configure parameters to display; compare parts and choose the best part for your design.

www.analog.com

 

[ats2]

Hello

what is the best power supply design for low noise <100 uv
for analog circuit
LDO ? Opamp based PS ? Else ?
For example application:
Vin 5v
Vout 3v
Noise < 100uv for 0-200Mhz

It will be great also if you can forward me some links to read & learn about this topic

Thanks !

Hi,
Tps7a8300 ldo have 6uv noise according to datasheet. Maximum input voltage is 6.5v so you can use for 5 to 3.3v regulation. Also no external resistor for voltage set.

 

[dick_freebird]

While a regulator product may have uV of self-
generated noise, HF PSRR is a real differentiator
when it comes to output noise of the assembly.
And even this is subject to ohmic ground loop
conversion of ripple and switching noise current
waveforms to supply voltage noise.

Picking a good looking part is only the beginning
of cut-and-try, and/or PI/SI analysis.

For things like transistor noise measurement,
the done thing used to be batteries inside the
noise shield box and no external connections
at all. 3V happens to be a convenient stack-of-2
alkaline batteries.

 

[JuniorEE]

Thank you all for the replies.
Ive read about op amp with isolation resistor (RISO).
Is there any benefit to go with op amp over LDO ?

 

[danadakk]

Be aware some LDOs have a self defeating noise issue, the need for a minimum ESR
cap on their outputs.

Also be cognizant of capacitor technology and their ESR performance -

'
Regards, Dana.