The operational amplifier also includes {HEAD ~ source transistors} for pushing {TAIL ~ the output and sink transistors} for pulling the output to obtain particular output voltage swing 
for pushing
The operational amplifier also includes { HEAD ~ source transistors } for pushing { TAIL ~ the output and sink transistors } for pulling the output to obtain particular output voltage swing
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH