The signal can be converted from time domain into z domain with the help of z transform (ZT). Similar way the signal can be converted from z domain to time domain with the help of inverse z transform(IZT). The inverse z transform can be obtained by using two different methods.

1) Partial fraction expansion Method (PFE) / Application of residue theorem

2) Power series expansion Method (PSE)

1. Partial Fraction Expansion Method

In this method X(z) is first expanded into sum of simple partial fraction.

Solve Using Partial Fraction Expansion Method (Pfe)

Residue Theorem Method

Power-Series Expansion Method

The z transform of a discrete time signal x(n) is given as