Question

What is the problem with a single operational difference amplifier?

(a) High input resistance

(b) Low input resistance

(c) Low output resistance

(d) High output resistance

I have been asked this question in a national level competition.

My doubt is from Transistor Difference Amplifiers in division Low Frequency Transistor Amplifier Circuit of Electronic Devices & Circuits

Answer 1

The correct choice is (b) Low input resistance

The explanation: The problem with a single operational difference amplifier is its low input resistance. This low input resistance results in a loss of a major component of the signal. Operational Amplifier is internally a Differential Amplifier with features like High Input Impedance, Low Output Impedance.