Inverting vs Non-Inverting Op-Amp: A Comparison

Inverting Op-Amp:

  1. Principle of Operation:

    • The inverting op-amp configuration uses a negative feedback loop where the input signal is applied to the inverting terminal (-) and the feedback is connected from the output to the inverting terminal.

  2. Gain Calculation:

    • The voltage gain of the inverting op-amp configuration is determined by the feedback resistor (Rf) and the input resistor (Rin) using the formula: $$A_v = -\frac{Rf}{Rin}$$.

  3. Phase Shift:

    • The inverting op-amp configuration introduces a 180-degree phase shift between the input and output signals due to its negative feedback nature.

  4. Input Impedance:

    • The input impedance of the inverting op-amp configuration is equal to the input resistor Rin.

Non-Inverting Op-Amp:

  1. Principle of Operation:

    • The non-inverting op-amp configuration utilizes a positive feedback loop where the input signal is applied to the non-inverting terminal (+) and the feedback is connected from the output to the non-inverting terminal.

  2. Gain Calculation:

    • The voltage gain of the non-inverting op-amp configuration is calculated using the formula: $$A_v = 1 + \frac{Rf}{Rin}$$, where Rf is the feedback resistor and Rin is the input resistor.

  3. Phase Shift:

    • The non-inverting op-amp configuration maintains the same phase as the input signal, resulting in 0-degree phase shift between the input and output signals.

  4. Input Impedance:

    • The input impedance of the non-inverting op-amp configuration is high and is primarily determined by the bias resistors in the feedback network.

Comparison:

  • Gain:

    • Inverting configuration produces an inverted output signal with a gain determined by the ratio of two resistors, while the non-inverting configuration provides a non-inverted output with a gain slightly above unity.

  • Phase Shift:

    • Inverting configuration introduces a 180-degree phase shift, whereas non-inverting configuration maintains the same phase as the input signal.

  • Input Impedance:

    • Inverting has an input impedance equal to the input resistor, while non-inverting has a higher input impedance due to the bias resistors in the feedback network.

  • Feedback Mechanism:

    • Inverting uses negative feedback, while non-inverting uses positive feedback, influencing the amplification behavior and stability of the circuits.

Understanding these differences helps in choosing the appropriate op-amp configuration based on the specific requirements of the circuit design and desired signal processing characteristics.

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