CHAPTER 6. OPERATIONAL AMPLIFIERS110RBRFRIFigure 6.6: Inverting ampliﬁer with bias compensation.6.2.3Mathematical OperationsCurrent Summing AmpliﬁerConsider the current-to-voltage converter shown in ﬁgure 6.7. Applying our ideal ampliﬁerrules givesRFVoutVinFigure 6.7: Current-to-voltage converter.V+ = V− =0⇒ 0− Vout = IRF .(6.15)Therefore Vout =−IRF and the circuit acts as a current-to-voltage converter.Figure 6.8 shows several current sources driving the negative input of an inverting am-pliﬁer. Summing the current into the node givesRFR3R2R1V3V2V1VoutFigure 6.8: Current summing ampliﬁer.