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