 # Learn Z-Transform easily with examples

## Introduction to Z-Transform:

Z-transform of a signal provides a valuable technique for analysis and design of the discrete time signal and discrete-time LTI system.

Z-Transform of a discrete time signal has both imaginary and real part. The plot of the imaginary part versus real part is called as the z plane. The poles and zeros of the discrete time signals are plotted in the complex z plane. Pole-zero plot is the main characteristics of the discrete time signals. Using pole-zero plot we can check the stability of the system which we will see in the upcoming posts.

Following are some of the main advantages of the Z-Transform:

• We can simplify the solution of a differential equation using Z-Transform.

• By the use of Z-Transform, we can completely characterize given discrete time signals and LTI systems.

• The stability of the LTI system can be determined using a Z-Transform.

• Mathematical calculations can be reduced by using the Z-Transform. For example, the convolution operation is transformed into a simple multiplication operation.

### Z-Transforms:

There are two types of Z-Transform:

1. Single sided Z-Transform.

2. Double sided Z-Transform.

### Single sided Z-Transform:

Single sided Z-Transform can be defined as, ### Double sided Z-Transform:

Double sided Z-Transform can be defined as, In single sided Z-Transform only positive values of n are used (from 0 to 8) hence called single sided, whereas in the double sided values of n are ranging from -8 to +8.

### Representation of the Z-Transforms:

Z-Transform of the signal x(n) is represented as, The relation between x(n) and X(Z) is denoted as follows: Where X(Z) is the Z-Transform of the signal x(n). The arrow is bidirectional which indicates that we can obtain x(n) from X(Z) also, which is called as inverse Z-Transform.

x(n) and X(Z) is called as Z-Transform pair.

### Region of convergence (ROC):

"Region of convergence is defined as a set of all values of Z for which X(Z) has a finite value. It is very important to denote ROC every time when we find Z-Transform."

### Significance of ROC:

• ROC will decide whether the given system is stable or unstable.

• ROC is also useful for determining the type of sequence. i.e. whether the system is causal or non-causal, finite or infinite.

### Examples on Z-Transform:

[caption id="" align="alignnone" width="490"] Z-Transform[/caption]