Importance of MOS orientation in layout

[road_0506]

Hello...
Nowadays, is the orientation of MOS transistor important in layout designing?
I mean, if one transistor is vertically oriented, is it important for the others to follow? I have heard an idea that it is not important for all the transistors to be of the same orientation as long as "matched transistors" are. Does it depend on the process used?
Any idea would be appreciated...
Regards

 

[renwl]

Re: MOS orientation

the same is better, not depend on process.

 

[sengyee88]

Re: MOS orientation

When IC is big, it is very difficult to ensure all MOS having the same orientation due to area constraint. I would prefer the current to flow from top to down or from left to right or vice versa depending on how the power lines were constructed, especially high current paths, instead of lots of bending current paths to suit to same MOS orientation.

Of cause, matching MOS transistors should have same orientation and close to each other at any cost.

 

[cheny1982]

Re: MOS orientation

it is best to the same orientation,i think the most mos with centeral is the most important.

 

[muiyuen]

Re: MOS orientation

It is true that in some cases, the orientation of the MOS transistor may not be the same due to constraints in space and wiring length. However, in my layouts, i'd try to orientate them in the same direction where-ever possible...unless, it takes up too much space or too long wiring. If there can be reasonable trade off between the orientation with both the space and wiring length, then i'd make them the same orientation. Otherwise, it has to be oriented differently.

 

[road_0506]

Re: MOS orientation

Thanks for the comments..


Regards...

 

[truebs]

Re: MOS orientation

MOS orientations is a must for matching transistors and analog circuits to ensure good performance. However , it can be relaxed under sevevere cirumstances. Although its not usually recommended, iresspective of the process.