Lecture 9

Question 1

What is an operational amplifier?

Answer 1

An operational amplifier (op-amp) is an integrated circuit amplifier containing many transistors and resistors, used as a basic building block in analogue circuits.

Question 2

What are the functions of an operational amplifier?

Answer 2

Amplification/scaling of input signals
Sign changing (inversion) of input signals
Addition/subtraction/multiplication of multiple input signals
Integration/differentiation of input signals
Analogue filtering

Question 3

What are the main terminals of an op-amp?

Answer 3

V+ - positive DC supply pin
V- - negative DC supply pin
Non-inverting input (Vₚ)
Inverting input (Vₙ)
Output

Question 4

What is the typical open-loop gain of an op-amp?

Answer 4

Very high, usually >100,000

Question 5

What is the condition for linear operation of an op-amp?

Answer 5

The differential inout voltage (Vdiff) should be approximately zero, i.e. Vₚ ≈ Vₙ.

Question 6

What happens to the op-amp output with a large differential input. voltage?

Answer 6

The output voltage saturates at the supply voltage levels (e.g. +-15V)