bigsheng
Newbie level 2
I am designing a typical cascode high swing NMOS current mirror. Trying to determine on the transistor size here. In my opinion, the bottom transistor can be minimum length because its Vds doesn't change much due to the buffer of cascode transistor above, while the cascode transistor should use longer length because it can see large Vds change. But what I found out is many people are actually doing the opposite way: using a large L for the bottom NMOS and min L for cascode NMOS. Is there any reason for doing that? Thanks.