Lecture 10

Question 1

What are the basic characteristics of an ideal op-amp?

Answer 1

Infinite open-loop voltage gain, infinite input resistance, zero output resistance.

Question 2

What is the purpose of negative feedback in op-amps?

Answer 2

Allows amplification of larger signals without saturation, ensures operation in the linear region and provides controllable gain.

Question 3

What is the closed-loop gain formula for an inverting amplifier?

Answer 3

ACL = Vₒᵤₜ / Vᵢₙ = -Rբ / Rᵢ

Question 4

What is the closed-loop gain formula for a non-inverting amplifier?

Answer 4

ACL = 1 + (Rբ / Rₛ)

Question 5

What is the virtual ground in an inverting amplifier circuit?

Answer 5

The node at the inverting input (Vₙ) that behaves as if connected to ground due to the op-amp’s properties.

Question 6

What are the two main ‘golden rules’ for ideal op-amps?

Answer 6

AOL → ∞, therefore V(diff) = 0
Rᵢₙ → ∞, therefore Iᵢₙ = 0

Question 7

Name two applications of op-amp circuits.

Answer 7

Summing amplifier (inverting configuration) and voltage comparator (non-inverting configuration).