How to reduce output noise for a LDO

[hung_wai_ming@hotmail.com]

output noise ldo

What kinds of tricks or techniques to reduce the total output noise for a LDO?
Any suggestion?

 

[raduga_in]

The noise components in LDO are basically the

1. Amp Noise
2. Resistor Noise
3. Buffer Noise
4. Pass transistor noise

Now if you see it is a negative feedback system and
hence, the noise added in feed forward path doesn't
change and it adds with the reference. Noise in feedback path is multiplied with the feedback factor.

Hence main noise components are in feed forward
path and hence you try and minimize the noise from
amp, pass device and buffer ..

Regards

Raduga

 

[safwatonline]

usually people don't care about output noise cause the transient response of the LDO due to load activity usually dominates the ripples at the output

 

[raduga_in]

Safwat .. if you consider that the load is a stable one
then your regulator should not introduce noise in the
circuit, isn't it ? Then why should we ignore such
a condition ?

 

[safwatonline]

sure, i meant in case of noisy load

 

[zyyang]

Hi, raduga_in
the noise in amp and feedback network you refered is input noise or outputnoise?

 

[krishnareddy]

feed back resistor noise can be reduced by bypassing them with capacitors