Negative Feedback of Operational Amplifier vs. Positive Feedback of Operational Amplifier

Attribute	Negative Feedback of Operational Amplifier	Positive Feedback of Operational Amplifier
Definition	Feedback in which the output signal is fed back to the inverting input of the operational amplifier	Feedback in which the output signal is fed back to the non-inverting input of the operational amplifier
Effect on Gain	Reduces the overall gain of the amplifier	Increases the overall gain of the amplifier
Stability	Increases stability and reduces distortion	May lead to instability and oscillations
Bandwidth	Wider bandwidth due to reduced gain	Narrower bandwidth due to increased gain

Negative Feedback

Negative feedback in operational amplifiers is a technique where a portion of the output signal is fed back to the input in such a way that it opposes the input signal. This helps in stabilizing the amplifier's gain and reducing distortion. One of the key attributes of negative feedback is that it improves the linearity of the amplifier by reducing harmonic distortion. This is achieved by reducing the gain at higher frequencies, which helps in maintaining a flat frequency response.

Another advantage of negative feedback is that it increases the input impedance of the amplifier. This is beneficial as it reduces the loading effect on the input signal source, ensuring that the input signal is not significantly affected by the amplifier's input impedance. Additionally, negative feedback helps in improving the amplifier's bandwidth by reducing the effects of parasitic capacitances and inductances.

One of the drawbacks of negative feedback is that it can reduce the amplifier's speed. This is because the feedback loop introduces a delay in the signal path, which can limit the amplifier's ability to respond quickly to changes in the input signal. Another disadvantage is that negative feedback can increase the noise in the amplifier, as the feedback loop can amplify any noise present in the system.

In summary, negative feedback in operational amplifiers offers benefits such as improved linearity, increased input impedance, and enhanced bandwidth. However, it can also have drawbacks such as reduced speed and increased noise.

Positive Feedback

Positive feedback in operational amplifiers is a technique where a portion of the output signal is fed back to the input in such a way that it reinforces the input signal. This can lead to an increase in gain and can be used to create oscillators and other nonlinear circuits. One of the key attributes of positive feedback is that it can increase the gain of the amplifier, allowing for amplification of weak signals.

Another advantage of positive feedback is that it can be used to create hysteresis in the amplifier, which is useful in applications such as Schmitt triggers. This allows for the creation of circuits that have a well-defined switching threshold, making them suitable for digital applications. Additionally, positive feedback can be used to create oscillators by providing the necessary phase shift and gain for sustained oscillations.

One of the drawbacks of positive feedback is that it can lead to instability in the amplifier. This is because the feedback loop can introduce phase shifts that can cause the amplifier to oscillate uncontrollably. Another disadvantage is that positive feedback can increase the distortion in the amplifier, as it can amplify nonlinearities in the system.

In summary, positive feedback in operational amplifiers offers benefits such as increased gain, creation of hysteresis, and generation of oscillations. However, it can also have drawbacks such as instability and increased distortion.