# Difference between Analog and digital systems

## Introduction

Electronics systems are of two types- digital and analog.

Analog systems are those where voltages and currents vary continuously with respect to time.

For example, amplifier circuits, power supplies, diodes, transistors etc. are analog circuits.

Digital systems are those where the voltage levels are defined to a certain range. All modern digital circuits use two voltage levels, one is HIGH level and other is LOW level. The HIGH voltage level is +5V and the low voltage level is 0V. practically 0V to 0.8 V is considered as 0V or LOW level  and 2V to 5V is considered as 5V or HIGH level.

Digital circuits are also called as switching circuits, because in digital system voltage levels are switched from one state to another state. Switching circuits are of two types- combinational switching circuits and sequential switching circuits.

In combinational switching circuits the output depends on only the present inputs. On the other hand in sequential switching circuits the output depends on present inputs and also on the past inputs.

• Digital systems are easy to construct
• Storing of information is easy in digital systems
• These systems are less affected by noise
• Digital circuits can be fabricated in IC chips
• Digital systems are versatile
• Reliability is more

#### Limitations of digital systems:

There is only one drawback in a digital system, i.e. “The real world is analog”.

We can’t provide the real world entities directly to a digital system as input. We need to convert the real world entities into digital form and supply it to the digital circuit. This makes the circuit complex.

#### Functions of digital systems:

Digital systems can perform many operations by using logic circuits. The operations are –

##### Encoding

Encoding is a function of digital system that converts the inputs to binary codes. The inputs can be digits, alphabets or special symbols.

##### Decoding

Decoding is the reverse function of encoding. It converts the binary inputs into numbers or alphabets.

##### Multiplexing

Multiplexing is the function of viewing a series of information in a single line.

##### De-multiplexing

De-multiplexing is reverse operation of Multiplexing. It converts single line information into several lines.

##### Arithmetic Operation

The arithmetic operations of digital electronics are – Addition, Subtraction, Multiplication and Division.

##### Comparison

This function takes two inputs in, compares them and provides the result of comparison.

##### Storage

Digital system also has a storage device in it. The device used to store the data is called register.

##### Code Conversion

Code conversion is the function that converts one form of code to another form.

##### Counting

The counting function in digital system counts the number of pulses, so that it can go to a certain pulse when it is needed.

##### Frequency Division

Frequency Division in digital systems divides the frequency by the help of a counter.

##### Data Transmission

Data transmission function in digital system transfers the data from one place to another.

We will discuss these functions one by one in further studies.

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