[SOLVED] Common centroid cross coupled for five MOS transistors

[Junus2012]

Hello

Kindly could you suggest me please how to match five equal MOS transistors (A,B,C,D,E) to have a good matching.
my idea is to devide each transistor in to five fingers.

thank you
Regards

 

[erikl]

...my idea is to devide each transistor in to five fingers.

Hello Senan ;-)
you probably meant ... into five multiple transistors? If you really want full common centroid, you have to use an even number. In this case you can create a 6x6 array, from which you dismiss one of the transistors as dummy (e.g. F).

ABCDEF
BCDEFA
CDEFAB
BAFEDC
AFEDCB
FEDCBA

This will also result in the most possible complex routing :-(

 

[Junus2012]

Hello erikl
kindly, could you please suggest me the case where it is just five and satisfying the full centroid . because five transistors with five fingers are also lead to square arra [5*5], why the even is the condition of full symmetry ????

thank you in advance

 

[erikl]

... why the even is the condition of full symmetry ????

Point symmetry, and all equal transistors. Just think twice. (Or read Umberto Eco's book about mirrors ;-))

 

[Junus2012]

sorry erikl, but could you please give me just a method if I still it not full symmetrical with only five transistors

 

[erikl]

Not fully symmetrical: Are you content with this one? Only E is fully symmetrical.

ABCDE
BCDEA
CDEAB
AEDCB
EDCBA

 

[Junus2012]

thank you very much erikl