Lecture 11

Question 1

What are the characteristics of open-loop op-amp operation?

Answer 1

There is no feedback, high uncontrolled gain, saturation behaviour, non-linear response and limited applications.

Question 2

What are the characteristics of closed-loop op-amp operation?

Answer 2

There is feedback control, lower controlled gain, stable behaviour/high precision, linear operation, wide range of applications.

Question 3

What are the two main types of closed-loop op-amp amplifiers?

Answer 3

Inverting amplifier and non-inverting amplifier.

Question 4

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

Answer 4

ACL = Vₒᵤₜ / Vᵢₙ = -Rբ / Rᵢ

Question 5

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

Answer 5

ACL = 1 + (Rբ / Rₛ)

Question 6

How does an op-amp comparator operate?

Answer 6

It operates in open-loop, compares two input voltages and outputs saturates at power supply levels (+V or -V). It is used for binary decisions.

Question 7

What should be identified when assessing an op-amp circuit?

Answer 7

Open-loop or closed-loop, inverting or non-inverting, operating in linear mode or saturation mode.

Question 8

What calculations are typically performed for closed-loop op-amps?

Answer 8

Calculate the closed-loop voltage gain.

Question 9

What should be sketched for both open and closed-loop op-amps?

Answer 9

Input and output voltage waveforms, indirecting voltage levels.