{HEAD ~ means} for comparing {TAIL ~ the extracted components} with a reference voltage to derive an error signal, 
for comparing
{ HEAD ~ means } for comparing { TAIL ~ the extracted components } with a reference voltage to derive an error signal ,
HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH