It would be better to study it from many well-written text books about cmos circuit design e.g. from Allen and Holberg. Some lecture notes of these authers can be found from here. (**broken link removed**) You will see how to do it from the begining. Another way you can try to search it from google, for example, this article is interesting www.bmas-conf.org/2001/papers/bmas01-gathercole.pdf .