{HEAD ~ An output} of {TAIL ~ the operational amplifier} is fed back to an input of the operational amplifier through 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 ~ An output } of { TAIL ~ the operational amplifier } is fed back to an input of the operational amplifier through 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 REL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH