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