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