Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

How to reduce output noise for a LDO

Status
Not open for further replies.

hung_wai_ming@hotmail.com

Full Member level 6
Joined
Jan 5, 2004
Messages
383
Helped
52
Reputation
104
Reaction score
11
Trophy points
1,298
Activity points
2,464
output noise ldo

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

raduga_in

Full Member level 4
Joined
Aug 29, 2005
Messages
200
Helped
31
Reputation
66
Reaction score
10
Trophy points
1,298
Location
India's Silicon Vally
Activity points
2,359
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

Advanced Member level 4
Joined
Nov 19, 2005
Messages
1,347
Helped
219
Reputation
438
Reaction score
47
Trophy points
1,328
Location
EGYPT
Activity points
9,059
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

Full Member level 4
Joined
Aug 29, 2005
Messages
200
Helped
31
Reputation
66
Reaction score
10
Trophy points
1,298
Location
India's Silicon Vally
Activity points
2,359
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 ?
 

zyyang

Member level 3
Joined
Jan 19, 2006
Messages
55
Helped
3
Reputation
6
Reaction score
1
Trophy points
1,288
Location
P.R. CHINA
Activity points
1,560
Hi, raduga_in
the noise in amp and feedback network you refered is input noise or outputnoise?
 

krishnareddy

Junior Member level 1
Joined
Nov 26, 2007
Messages
16
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,348
feed back resistor noise can be reduced by bypassing them with capacitors
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top