At the non inverting input, {TAIL ~ a reference voltage Vref} is applied thru {HEAD ~ a resistor Rx} 
At the non inverting input , { TAIL ~ a reference voltage Vref } is applied thru { HEAD ~ a resistor Rx }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD