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

commom centroid geomentry

Status
Not open for further replies.

swathi0356

Junior Member level 1
Joined
Dec 13, 2005
Messages
15
Helped
2
Reputation
4
Reaction score
0
Trophy points
1,281
Activity points
1,441
centroid matching

what is actually the common centroid geomentry and where is it used
 

steve_mac

Junior Member level 2
Joined
Nov 22, 2005
Messages
23
Helped
3
Reputation
6
Reaction score
0
Trophy points
1,281
Activity points
1,450
common centroid layout technique

common centroid geometry is often used in instances like current mirror or any form of mirroring.

split the fingers of the transistors evenly in order for both sides of the mirror to achieve matching

see attached article for more info
 

Attachments


muralikrishma

Newbie level 2
Joined
Dec 22, 2005
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,314
common centroid technique is used for matching purposes. Where, two transistors that need matching .matching means,, the process gradients should be equally felt by the two transistors that need to be matched. For this to be achieved ,, especially in the case of Differential pair matching, common centroid layout techniques are used. Common centroid is analogous to centre of mass. ie,,
if M1 and M2 are two transistors that needed to be matched, then they are digitated to fingers. And the fingers of M1 and fingers of M2 are placed in such a fashion that , the centre of mass of M1 and centre of mass of M2 are both same. This is analogous to common centroid. While providing the interconnects with metals and poly, care has to be taken to ensure that even the mass of the metals also have the same centre of masss. This kind of architecture gives a good matching.

To know what are the various styles of putting it,, refer Alan Hastings Art of Analog Lyout
 

vbhupendra

Full Member level 4
Joined
May 11, 2005
Messages
235
Helped
15
Reputation
30
Reaction score
8
Trophy points
1,298
Location
GOA, INDIA
Activity points
3,219
this technique is used for matching transitors such that the process variations cancels in either direction. For more information read Alan Hastings book.
 

YESH_23

Member level 4
Joined
Dec 20, 2005
Messages
78
Helped
8
Reputation
16
Reaction score
4
Trophy points
1,288
Location
INDIA
Activity points
1,951
as the name implies this technique constructs two devices symetrically about a common centre in the layout

the effect of process gradients is cancelled ib both x & y directions

while manufacturing is done due o the accuracy of the tool there exists a problem of mismatch btween the transistors.

so in the case of differential pair the should be matched
 

banihashemi

Newbie level 5
Joined
Dec 25, 2005
Messages
8
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
1,316
it is used for matching purpose for any alements in an IC.
because mismatch is due to different things that the most
important of them is ingrediants.
 

swathi0356

Junior Member level 1
Joined
Dec 13, 2005
Messages
15
Helped
2
Reputation
4
Reaction score
0
Trophy points
1,281
Activity points
1,441
thank you very much to every one
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top