extremis wrote on Dec 17th, 2010, 2:42am:I am trying this OPAMP from P.E. Allen lectures, except that input is a differential PMOS pair.
If you change the input (differential pair) to PMOS, and leave the output the same, you can get into biasing problems. If u want PMOS in, PMOS out, go for the folded cascode.
You can also make a complete PMOS->NMOS translation: NMOS diffpair -> PMOS diffpair AND PMOS outputstage -> NMOS output stage.