Question

An ideal operational amplifier has:

• A. Infinite input impedance and zero output impedance
• B. Zero input impedance and infinite output impedance
• C. Infinite gain and infinite output impedance
• D. Finite gain and finite bandwidth

Hint:

Always remember: Ideal op-amp assumptions include infinite gain, infinite input impedance, zero output impedance, and infinite bandwidth.

Answer 1

The Correct Option is A

Step 1: Understanding the concept of an ideal operational amplifier.
An ideal operational amplifier (op-amp) is a theoretical device used to simplify circuit analysis. It is assumed to have perfect characteristics that are not fully achievable in practical op-amps but are useful for understanding circuit behavior.
Step 2: Key characteristics of an ideal op-amp.
An ideal op-amp draws no input current, which means its input impedance must be infinite. This ensures that the op-amp does not load the input signal source. Additionally, it should be able to supply any required output current without any voltage drop, which implies zero output impedance.
Step 3: Analyzing the options.
(A) Infinite input impedance and zero output impedance: Correct — These are fundamental assumptions of an ideal op-amp and ensure maximum signal transfer and perfect output behavior.
(B) Zero input impedance and infinite output impedance: This is opposite to ideal behavior and would severely load the input signal.
(C) Infinite gain and infinite output impedance: Although infinite gain is an ideal assumption, infinite output impedance is incorrect for an ideal op-amp.
(D) Finite gain and finite bandwidth: These are characteristics of practical op-amps, not ideal ones.
Step 4: Conclusion.
An ideal operational amplifier is characterized by infinite input impedance and zero output impedance, making option (A) the correct answer.