digital design: analog vs digital circuits

Chapter 1

BASIC DIGITAL CONCEPTS

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 2

Lesson 2

Analog vs. Digital Circuits

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 3

Outline

•• Analog CircuitAnalog Circuit• Digital Circuit

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 4

Analog circuit Features• More close to physical system and

physical values• Capabilities of representing

directly a physical value. For example, the value of temperature, wind, speed or rotation by a corresponding voltage or current or frequency or phase angle.

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 5

Analog circuit Feature• Faster speed due to lesser number

of components needed to represent a physical value

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 6

Analog circuit Disadvantage• Noise in voltage or current does

matter because an output or input is measured in terms of a value of voltage or current or frequency or phase.

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 7

Analog circuit Disadvantage• Logical values are reflected by a

complex analog to digital conversion circuit

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 8

Analog circuit Disadvantage• A circuit shows the deviation with

time due to change in circuit temperature or changes in physical condition

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 9

Outline

• Analog Circuit• Digital Circuit

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 10

Digital circuit Features• More close to logic and number

systems and a logic state has a definiteness and thus the circuit inputs and outputs have preciseness and reliability

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 11

Digital circuit Feature• Capabilities of logical decisions

and arithmetic, logic and Boolean operations

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 12

Digital circuit Feature• Noise in voltage or current does not

matter because an output or input is measured in terms of its logic state(s), not in terms of a value of the Voltage or current or frequency

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 13

Digital circuit Disadvantage• The circuits have high

complexities. To represent a big decimal number, the large number of components needed.

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 14

Digital circuit Disadvantage• Physical values are reflected by a

complex digital to analog conversion circuit

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 15

Digital circuit Disadvantage• Slower speed due to greater

number of components needed to represent a state. For example, a bipolar junction transistor as inverter will act faster than a circuit in TTL inverter.

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 16

Summary

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 17

• Digital circuits are circuits for logic and number systems and a logic state has a definiteness and thus the circuit inputs and outputs have preciseness and reliability

•

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 18

• Analog circuits are affected by noise and surrounding physical conditions changes

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 19

End of Lesson 2 on

Analog vs. Digital Circuits

Ch01L1-"Digital Principles and Design", Raj Kamal, Pearson Education, 2006 20

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