{HEAD ~ An output} of the operational amplifier is fed back to an input of the operational amplifier through {TAIL ~ a current varying element} that varies current levels of the input of the operational amplifier to remove a level shift of an output signal of the differential amplifier 
is fed back through
{ HEAD ~ An output } of the operational amplifier is fed back to an input of the operational amplifier through { TAIL ~ a current varying element } that varies current levels of the input of the operational amplifier to remove a level shift of an output signal of the differential amplifier
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH