# Inverting Amplifier

^{o}is called

**Inverting Amplifier**.

_{i}while its non-inverting terminal is grounded. Further the feedback necessary to stabilize the circuit, and hence to control the output, is provided through the feedback resistor R

_{f}.

Mathematically the voltage gain offered by the circuit is given as
Where,
However, it is to be noted that ideal Op-Amps have infinite input impedance due to which the currents flowing into its input terminals are zero i.e. I_{1} = I_{2} = 0. Thus, I_{i} = -I_{f}. Further, as the non-inverting terminal is grounded (V_{2} = 0), one gets V_{1} = 0 due to the fact that the voltages at the inverting and the non-inverting terminals of an ideal Op-Amp are equal. Hence,
Substitution V_{1} and I_{f} in equation of V_{o} yields
This indicates that the voltage gain of the inverting amplifier is decided by the ratio of the feedback resistor to the input resistor; with the minus sign indicating the phase-reversal. Further, it is to be noted that the input impedance of the inverting amplifier is nothing but R_{i}.

**Inverting amplifiers** exhibit excellent linear characteristics which make them ideal to be used as DC amplifiers. Moreover they are often used to convert input current to output voltage in the form of Transresistance or Transimpedance Amplifiers. Further these can also be used in audio mixers when used in the form of Summing Amplifiers.

**Comments/Feedbacks**

Closely Related Articles Op-amp | Working Principle of Op-ampOp amp 741 or Operational Amplifier 741 ICNegative Feedback in Op amp and Closed Loop Gain of Op ampIdeal OP AmpNon Inverting AmplifierSumming AmplifierDifference AmplifierIntegratorDifferentiatorDigital to Analog Converter or DACMore Related Articles Ohm's Law | Equation Formula and Limitation of Ohm's LawNodes, Branches and Loops of a CircuitKirchhoff Current Law and Kirchhoff Voltage LawResistances in Series and Resistances in ParallelSeries ResistanceVoltage in SeriesVoltage in ParallelElectric Current and Voltage Division RuleDelta - Star transformation | Star - Delta TransformationNodal Analysis in Electric CircuitsSingle and Multi Mesh AnalysisSuperposition TheoremThevenin Theorem and Thevenin Equivalent Voltage and ResistanceElectrical Source TransformationNorton Theorem | Norton Equivalent Current and ResistanceMaximum Power Transfer TheoremTellegen TheoremReciprocity TheoremCompensation TheoremSubstitution TheoremMillman TheoremPower in AC CircuitTrees and Cotrees of Electric NetworkWhat is Incidence Matrix?Cutset Matrix Concept of Electric CircuitTwo Port NetworkImpedance Parameters or Z ParametersAdmittance Parameters or Y ParametersHybrid Parameters or h Parameters New Articles Trees and Cotrees of Electric NetworkDifferentiatorIntegratorPhase Synchronizing Device or Controlled Switching DeviceDigital to Analog Converter or DACDifference Amplifier