The voltage of the second node corresponds to {TAIL ~ a threshold voltage} of {HEAD ~ the control terminal} 
The voltage of the second node corresponds to { TAIL ~ a threshold voltage } of { HEAD ~ the control terminal }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD