abcyin said:
But I use p-sub, and there is no nwell in the process, what do you mean by "large body effect with NMOS because of nwell process", however, I got a message from your reply, the large body effect will increase the threashold voltage of the NMOS load, then compress the swing, am I right?
and any other reasons?
theoretically, they are both diode connected and identical.
but in fact, it's a really bad design having your source voltage varying with signal (if using NMOS load).
That means if your Vout goes up and down, body effect will change the NMOS threshold voltage, which changes gm also. That's a disaster for AC operation.
If it's used for DC operation only, I don't see any difference between them.