{HEAD ~ a gate electrode} of said {TAIL ~ third N channel MOS transistor} receives a reference potential at said second potential level 
{ HEAD ~ a gate electrode } of said { TAIL ~ third N channel MOS transistor } receives a reference potential at said second potential level
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH