Lecture 11 - Signal Amplification and Op-Amps

Question 1

What is signal amplification?

Answer 1

Increasing the amplitude of an electrical signal (voltage or current) by a scalar factor

Question 2

What are the four examples of the applications for amplification?

Answer 2

1) Analog to digital conversion
2) Radio transmission (transmitted power)
3) Audio amplification
4) Video amplifiers

Question 3

What is a transfer function H(w)?

Answer 3

A ratio of output (response) to the input (source) of a circuit

Question 4

What effect does indcuctive reactance have on an alternating current?

Answer 4

Delays current changes (not in sync with the coltage change)

Question 5

What effect does capacitive reactance have on an alternating current?

Answer 5

Leads current change; current changes before the voltage changes

Question 6

Define ‘impedence’

Answer 6

The impedence of a component indicated how the component can change the current in a circuit

Question 7

What are the 6 steps for a nodal analysis?

Answer 7

1) Identify all nodes and select a reference node
2) Identify all known voltages
3) At each node with a unknown voltage, write a KCL equation
4) Replace currents in terms of node voltages
5) Solve for unknown voltages as needed
6) Use voltages to solve for any desired values

Question 8

What were operational amplifiers originally designed to do?

Answer 8

They were originially designed to perform mathematical operations such as addition, substraction, differentiation, and integration

Question 9

Other than mathematical operations, what can op-amps be implemented to perform?

Answer 9

Voltage amplification, current to voltage conversion and etc.

Question 10

What is op-amp short for?

Answer 10

Operational Amplifiers

Question 11

What are operational amplifiers?

Answer 11

Voltage amplifying devices which can be used to perform various mathematical operations

Question 12

What are the connectors on the side of the op-amps utilized for?

Answer 12

They are used to connect the op-amp to supply/source

Question 13

What are the three points which make the ideal op-amp?

Answer 13

1) Infinite open-loop gain
2) Infinite input resistance
3) Zero output resistance

Question 14

What are the two ‘golden rules’ that the ideal op-amp will obery?

Answer 14

1) No currents enter or leave the op-amp inputs
2) The op-amp output will do whatever it can (within its limitations) to make the voltage difference between the two inputs zero

Question 15

What is a formula to represent the first golden rule?

Answer 15

i(+) = i(-) = 0

Question 16

What is a formula to represent the second golden rule?

Answer 16

V(+) = V(-)

Question 17

What should be the sign of the voltage gain for an inverting amplifier?

Answer 17

It should be negative; so that it will invert the voltage (amplitude will stay the same but invert the sign)

Question 18

In an op-amp, what is the non-inverting input?

Answer 18

The non inverting input is the same thing as the positive input terminal of the op-amp.

Question 19

In an op-amp, what is the inverting input?

Answer 19

The non inverting input is the same thing as the negative input terminal of the op-amp.

Question 20

What is the gain of an op-amp?

Answer 20

Represents how much larger the output voltage will be compared to the input voltage difference; Gain = V3 / (V2 - V1)

Question 21

What is the employment of open-loop op-amps?

Answer 21

Employed to create comparators

Question 22

What is the employment of closed-loop op-amps?

Answer 22

Employed to do signal amplification and mathematical operations.

Question 23

What are the three types of op-amps?

Answer 23

1) Unit gain buffer (no resistors)
2) Non-inverting op-amp
3) Inverting op-amp (grounded input(s) or switched polarity)

Question 24

What is V(s) equal to in the context of op-amps?

Answer 24

V(s) equals to either V(+) or V(-) (depending on which value we have since they are the same) as it’s the input voltage