At the inverting input of the operational amplifier Ao {HEAD ~ a virtual ground} is created by {TAIL ~ means} of feedback from the output node Vout through feedback resistor Rfb 
is created by
At the inverting input of the operational amplifier Ao { HEAD ~ a virtual ground } is created by { TAIL ~ means } of feedback from the output node Vout through feedback resistor Rfb
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH