Inverting Operational Amplifier | Inverting Op AmpPublished on 24/2/2012 & updated on 5/9/2018
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Mathematically the voltage gain offered by the circuit is given as Where,
However, we know that an ideal op amp has infinite input impedance due to which the currents flowing into its input terminals are zero i.e. I1 = I2 = 0. Thus, Ii = If. Hence, We also know that in an ideal op amp the voltage at inverting and non-inverting inputs are always equal.
As we have grounded the non - inverting terminal, zero voltage appears at the non - inverting terminal. That means V2 = 0. Hence, V1 = 0, also. So, we can write From, above two equations, we get,
The voltage gain of the inverting operational amplifier or inverting op amp is, 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 Ri.
Inverting amplifiers exhibit excellent linear characteristics which make them ideal as DC amplifiers. Moreover, they are often used to convert input current to the 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.
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