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