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

systematic offset & Random offset

Status
Not open for further replies.

surianova

Advanced Member level 1
Joined
Sep 1, 2004
Messages
411
Helped
30
Reputation
60
Reaction score
8
Trophy points
1,298
Location
ASIA
Activity points
3,276
systematic offset

hi!

just want to check between random offset and systematic offset in opamp for the below statements.. pls comment:

1. systematic offset can be simulated in normal simulation without doing any mismatch. It no need marte carlo simulation. Basically just get the output-vdd/2.

2. systematic offset basically just want to get the output vdd/2.

3. but systematic offset is not that important bcoz sometimes our output might be lower or higher than vdd/2 to bias other stage. Although output at vdd/2, can get the best gain from the opamp. Or in other word, purposely introduce systematic offset to get the desired output.


4. Random offset is cause by mismatch in the layout for the transistor need to be matched like current miror and input transistor.


5. Random offset must run with morte carlo analysis or mismatch the transistor manually.

pls comment statement above! thanks
 

hr_rezaee

Advanced Member level 3
Joined
Oct 6, 2004
Messages
751
Helped
109
Reputation
218
Reaction score
24
Trophy points
1,298
Location
Iran-Mashhad
Activity points
4,036
op amp systematic offset tutorial

Hi
sytematic offset is depend on architecture
but mismatch can generate random offset in any architecture.
regards
 

rajanarender_suram

Full Member level 4
Joined
Jan 20, 2006
Messages
215
Helped
22
Reputation
44
Reaction score
9
Trophy points
1,298
Activity points
2,375
random offset

1. systematic offset can be simulated in normal simulation without doing any mismatch. It no need marte carlo simulation. Basically just get the output-vdd/2..

its true that it is simulated in normal simulation.

2. systematic offset basically just want to get the output vdd/2.

i didnot understant this comment

3. but systematic offset is not that important bcoz sometimes our output might be lower or higher than vdd/2 to bias other stage. Although output at vdd/2, can get the best gain from the opamp. Or in other word, purposely introduce systematic offset to get the desired output.

You cant say this because its not much important in Vds mismatches of current mirror, but you cant neglect this mismatch in the input diffpair of an Op-amp

4. Random offset is cause by mismatch in the layout for the transistor need to be matched like current miror and input transistor.

yes.

5. Random offset must run with morte carlo analysis or mismatch the transistor manually.

yes
 

abcyin

Full Member level 4
Joined
Apr 15, 2005
Messages
237
Helped
12
Reputation
24
Reaction score
3
Trophy points
1,298
Activity points
2,855
analysis of systematic mismatch in current mirror

1, System offset:
System offset occures duo to the non-idealities of a circuit even when all the elements of the circuit are perfently matched.
2, Random offset
Random offset occures duo to mismatches in supposedly matched devices.
 

surianova

Advanced Member level 1
Joined
Sep 1, 2004
Messages
411
Helped
30
Reputation
60
Reaction score
8
Trophy points
1,298
Location
ASIA
Activity points
3,276
random mismatches in layout

rajanarender_suram said:
1. systematic offset can be simulated in normal simulation without doing any mismatch. It no need marte carlo simulation. Basically just get the output-vdd/2..

its true that it is simulated in normal simulation.

2. systematic offset basically just want to get the output vdd/2.

i didnot understant this comment

3. but systematic offset is not that important bcoz sometimes our output might be lower or higher than vdd/2 to bias other stage. Although output at vdd/2, can get the best gain from the opamp. Or in other word, purposely introduce systematic offset to get the desired output.

You cant say this because its not much important in Vds mismatches of current mirror, but you cant neglect this mismatch in the input diffpair of an Op-amp

4. Random offset is cause by mismatch in the layout for the transistor need to be matched like current miror and input transistor.

yes.

5. Random offset must run with morte carlo analysis or mismatch the transistor manually.

yes


how to check Systematic offset in normally simulation?
 

leohart

Full Member level 4
Joined
Nov 10, 2006
Messages
226
Helped
14
Reputation
28
Reaction score
1
Trophy points
1,298
Activity points
2,718
systematic offsets

surianova said:
rajanarender_suram said:
1. systematic offset can be simulated in normal simulation without doing any mismatch. It no need marte carlo simulation. Basically just get the output-vdd/2..

its true that it is simulated in normal simulation.

2. systematic offset basically just want to get the output vdd/2.

i didnot understant this comment

3. but systematic offset is not that important bcoz sometimes our output might be lower or higher than vdd/2 to bias other stage. Although output at vdd/2, can get the best gain from the opamp. Or in other word, purposely introduce systematic offset to get the desired output.

You cant say this because its not much important in Vds mismatches of current mirror, but you cant neglect this mismatch in the input diffpair of an Op-amp

4. Random offset is cause by mismatch in the layout for the transistor need to be matched like current miror and input transistor.

yes.

5. Random offset must run with morte carlo analysis or mismatch the transistor manually.

yes


how to check Systematic offset in normally simulation?
just use ideal component in spice and simulate output with zero input.It roots from the biasing of your circuit.
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top