The cascoding of NFET Qf2 630 and NFET Qf1 632 extends the range of Vds because NFET Qf1 632 is in the triode region for {HEAD ~ a small range} of {TAIL ~ voltage} 1, and NFET Qf2 630 is in the triode region for a small range of voltage 2 
The cascoding of NFET Qf2 630 and NFET Qf1 632 extends the range of Vds because NFET Qf1 632 is in the triode region for { HEAD ~ a small range } of { TAIL ~ voltage } 1 , and NFET Qf2 630 is in the triode region for a small range of voltage 2
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH