How do I place transistors of folded cascode amp.?

[yousoo]

Hi all.

Now, I am just about to layout folded cascode for the firs time in my life
How do i place components? these transistor`s size is almost 1um/1um and i use 0.35um
so, too small to use common multifinger and common centroid at the input stage

Considerin about critical matching
How I place components?

 

[acbalbason]

hi!

still aim for common centroid. use the usual guidlines. separate pmos from nmos, guard rings, no routing over gates, etc... you can refer to the stick diagram forum if you like...

- al