Laplace TransformThe Laplace transform is a mathematical tool which is used to convert the differential equation in time domain into the algebraic equations in the frequency domain or s-domain.Mathematically, if $\mathit{x}\mathrm{\left(\mathit{t}\right)}$ is a time domain function, then its Laplace transform is defined as −$$\mathrm{\mathit{L}\mathrm{\left[\mathit{x}\mathrm{\left(\mathit{t}\right)}\right]}\:\mathrm{=}\:\mathit{X}\mathrm{\left(\mathit{s}\right)}\:\mathrm{=}\:\int_{-\infty }^{\infty }\mathit{x}\mathrm{\left(\mathit{t}\right)}\mathit{e^{-\mathit{st}}\:\mathit{dt}}\:\:\:\:\:\:...(1)}$$Equation (1) gives the bilateral Laplace transform of the function $\mathit{x}\mathrm{\left(\mathit{t}\right)}$. But for the causal signals, the unilateral Laplace transform is applied, which is defined as −$$\mathrm{\mathit{L}\mathrm{\left[\mathit{x}\mathrm{\left(\mathit{t}\right)}\right]}\:\mathrm{=}\:\mathit{X}\mathrm{\left(\mathit{s}\right)}\:\mathrm{=}\:\int_{\mathrm{0}}^{\infty }\mathit{x}\mathrm{\left(\mathit{t}\right)}\mathit{e^{-\mathit{st}}\:\mathit{dt}}\:\:\:\:\:\:...(2)}$$Time Scaling Property of Laplace TransformStatement - The time scaling property of Laplace transform states that if, $$\mathrm{\mathit{x}\mathrm{\left(\mathit{t}\right)}\overset{\mathit{LT}}{\leftrightarrow}\mathit{X}\mathrm{\left(\mathit{s}\right)}}$$Then$$\mathrm{\mathit{x}\mathrm{\left(\mathit{at}\right)}\overset{\mathit{LT}}{\leftrightarrow}\frac{1}{\left|\mathit{a}\right|}\mathit{X}\mathrm{\left( \frac{\mathit{s}}{\mathit{a}}\right )}}$$ProofFrom the definition of Laplace transform, we have, $$\mathrm{\mathit{L}\mathrm{\left[\mathit{x}\mathrm{\left(\mathit{t}\right)}\right]}\:\mathrm{=}\:\int_{\mathrm{0}}^{\infty ... Read More

Laplace TransformThe Laplace transform is a mathematical tool which is used to convert the differential equation in time domain into the algebraic equations in the frequency domain or s-domain.Mathematically, if $\mathit{x}\mathrm{\left(\mathit{t}\right)}$ is a time domain function, then its Laplace transform is defined as −$$\mathrm{\mathit{L}\mathrm{\left[\mathit{x}\mathrm{\left(\mathit{t}\right)}\right]}\:\mathrm{=}\:\mathit{X}\mathrm{\left(\mathit{s}\right)}\:\mathrm{=}\:\int_{-\infty }^{\infty }\mathit{x}\mathrm{\left(\mathit{t}\right)}\mathit{e^{-\mathit{st}}\:\mathit{dt}}\:\:\:\:\:\:...(1)}$$Integration in Time Domain Property of Laplace TransformStatement - The time integration property of Laplace transform states that if$$\mathrm{\mathit{x}\mathrm{\left(\mathit{t}\right)}\overset{\mathit{LT}}{\leftrightarrow}\mathit{X}\mathrm{\left(\mathit{s}\right)}}$$Then$$\mathrm{\int_{-\infty}^{\mathit{t}}\mathit{x}\mathrm{\left(\mathit{\tau }\right)}\mathit{d\tau}\overset{\mathit{LT}}{\leftrightarrow}\frac{\mathit{x}\mathrm{\left(\mathit{s}\right)}}{\mathit{s}}\:\mathrm{+}\:\int_{-\infty}^{\mathrm{0}}\frac{\mathit{x}\mathrm{\left(\mathit{\tau }\right)}}{\mathit{s}}\:\mathit{d\tau}}$$ProofConsider a function $\mathit{y}\mathrm{\left(\mathit{t}\right)}$ as, $$\mathrm{\mathit{y}\mathrm{\left(\mathit{t}\right)}\:\mathrm{=}\:\int_{-\infty }^{\mathit{t}}\mathit{x}\mathrm{\left(\mathit{\tau }\right)}\:\mathit{d\tau}}$$Taking differentiation on both sides with respect to time, we have, $$\mathrm{\frac{\mathit{d\mathit{y}\mathrm{\left(\mathit{t}\right)}}}{\mathit{dt}}\:\mathrm{=}\:\mathit{x}\mathrm{\left(\mathit{t}\right)}\:\:\:\:\:\:...(2)}$$Also, $$\mathrm{\mathit{y}\mathrm{\left(\mathrm{0}^{-}\right)}\:\mathrm{=}\:\int_{-\infty }^{\mathrm{0}}\mathit{x}\mathrm{\left(\mathit{\tau }\right)}\:\mathit{d\tau}\:\:\:\:\:\:...(3)}$$Taking the Laplace transform of equation (2), we get, $$\mathrm{\mathit{L}\mathrm{\left[ \frac{\mathit{d\mathit{y}\mathrm{\left(\mathit{t}\right)}}}{\mathit{dt}}\right ]}\:\mathrm{=}\:\mathit{L}\mathrm{\left [ \mathit{x}\mathrm{\left(\mathit{t}\right)} ... Read More

Z-TransformZ-transform is a mathematical tool which is used to convert the difference equations in time domain into the algebraic equations in the frequency domain.Mathematically, if $\mathrm{\mathit{x\left ( n \right )}}$ is a discrete-time sequence, then its Z-transform is defined as −$$\mathrm{\mathit{X\left ( z \right )\mathrm{\, =\, }\sum_{n\mathrm{\, =\, }-\infty }^{\infty }x\left ( n \right )z^{-n}\; \; \; \cdot \cdot \cdot \left ( \mathrm{1} \right )}}$$Where, z is a complex variable. The z-transform defined in eq. (1) is called bilateral or two-sided z-transform.The unilateral or one-sided z-transform is defined as −$$\mathrm{\mathit{X\left ( z \right )\mathrm{\, =\, }\sum_{n\mathrm{\, =\, }\mathrm{0}}^{\infty }x\left ( ... Read More

Laplace TransformThe Laplace transform is a mathematical tool which is used to convert the differential equation in time domain into the algebraic equations in the frequency domain or s-domain.Mathematically, if $\mathrm{\mathit{x\left ( t \right )}}$ is a time domain function, then its Laplace transform is defined as, $$\mathrm{\mathit{L\left [ x\left ( t \right ) \right ]\mathrm{\, =\, }X\left ( s \right )\mathrm{\, =\, }\int_{-\infty }^{\infty }x\left ( t \right )e^{-st}\:dt \; \; \cdot \cdot \cdot \left ( \mathrm{1} \right )}}$$Equation (1) gives the bilateral Laplace transform of the function $\mathrm{\mathit{x\left ( t \right )}}$. But for the causal signals, the ... Read More

Laplace TransformThe Laplace transform is a mathematical tool which is used to convert the differential equation in time domain into the algebraic equations in the frequency domain or s-domain.Mathematically, if $\mathrm{\mathit{x\left ( t \right )}}$ is a time domain function, then its Laplace transform is defined as −$$\mathrm{\mathit{L\left [ x\left ( t \right ) \right ]\mathrm{\, =\, }X\left ( s \right )\mathrm{\, =\, }\int_{-\infty }^{\infty }x\left ( t \right )e^{-st}\:dt }}$$Time Reversal Property of Laplace TransformStatement – The time reversal property of Laplace transform states that if a signal is reversed about the vertical axis at origin in the time ... Read More

Laplace TransformThe Laplace transform is a mathematical tool which is used to convert the differential equation in time domain into the algebraic equations in the frequency domain or s-domain.Mathematically, if $\mathrm{\mathit{x\left ( t \right )}}$ is a time domain function, then its Laplace transform is defined as −$$\mathrm{\mathit{L\left [ x\left ( t \right ) \right ]\mathrm{\, =\, }X\left ( s \right )\mathrm{\, =\, }\int_{-\infty }^{\infty }x\left ( t \right )e^{-st}\:dt\; \; \cdot \cdot \cdot\left ( \mathrm{1} \right ) }}$$Equation (1) gives the bilateral Laplace transform of the function $\mathrm{\mathit{x\left ( t \right )}}$. But for the causal signals, the unilateral ... Read More

The Inverse Z-TransformThe inverse Z-transform is defined as the process of finding the time domain signal $\mathrm{\mathit{x\left ( n \right )}}$ from its Z-transform $\mathrm{\mathit{X\left ( z \right )}}$. The inverse Z-transform is denoted as −$$\mathrm{\mathit{x\left ( n \right )\mathrm{\, =\, }Z^{-\mathrm{1}}\left [ X\left ( z \right ) \right ]}}$$Since the Z-transform is defined as, $$\mathrm{\mathit{X\left ( z \right )\mathrm{\, =\, }\sum_{n\mathrm{\, =\, }-\infty }^{\infty }x\left ( n \right )z^{-n}\; \; \; \cdot \cdot \cdot \left ( \mathrm{1} \right )}}$$Where, z is a complex variable and is given by, $$\mathrm{\mathit{z\mathrm{\, =\, }r\, e^{j\, \omega }}}$$Where, r is the radius of ... Read More

Laplace TransformThe Laplace transform is a mathematical tool which is used to convert the differential equation in time domain into the algebraic equations in the frequency domain or sdomain.Mathematically, if $\mathit{x}\mathrm{\left(\mathit{t}\right)}$ is a time domain function, then its Laplace transform is defined as −$$\mathrm{\mathit{L}\mathrm{\left[\mathit{x}\mathrm{\left(\mathit{t}\right)}\right]}\:\mathrm{=}\:\mathit{X}\mathrm{\left(\mathit{s}\right)}\:\mathrm{=}\:\int_{-\infty }^{\infty }\mathit{x}\mathrm{\left(\mathit{t}\right)}\mathit{e^{-\mathit{st}}\:\mathit{dt}}}$$Solution of Differential Equations Using Laplace TransformA linear time invariant (LTI) system is described by constant coefficient differential equations which are relating the input and output of the system. The response of the LTI system is obtained by solving these differential equations.The Laplace transformation technique can be used for solving the differential equation describing the ... Read More

Z-TransformThe Z-Transform is a mathematical tool which is used to convert the difference equations in time domain into the algebraic equations in the z-domain. Mathematically, the Z-transform of a discrete-time signal or a sequence $\mathit{x}\mathrm{\left(\mathit{n}\right)}$ is defined as −$$\mathrm{\mathit{X}\mathrm{\left(\mathit{z}\right)}\:\mathrm{=}\:\sum_{\mathit{n=-\infty }}^{\infty }\mathit{x}\mathrm{\left(\mathit{n}\right)}\mathit{z}^{-\mathit{n}}}$$Properties of Z-TransformThe following table highlights some of the important properties of Z-Transform −PropertyTime-Domainz-DomainRegion of Convergence (ROC)Notation$\mathrm{\mathit{x}\mathrm{\left(\mathit{n}\right)}}$$\mathrm{\mathit{X}\mathrm{\left(\mathit{z}\right)}}$$\mathrm{\mathit{R}}$$\mathrm{\mathit{x}_{\mathrm{1}}\mathrm{\left(\mathit{n}\right)}}$$\mathrm{\mathit{X}_{\mathrm{1}}\mathrm{\left(\mathit{z}\right)}}$$\mathrm{\mathit{R}_{\mathrm{1}}}$$\mathrm{\mathit{x}_{\mathrm{2}}\mathrm{\left(\mathit{n}\right)}}$$\mathrm{\mathit{X}_{\mathrm{2}}\mathrm{\left(\mathit{z}\right)}}$$\mathrm{\mathit{R}_{\mathrm{2}}}$Linearity and Superposition$\mathrm{\mathit{a}\mathit{x}_{\mathrm{1}}\mathrm{\left(\mathit{n} \right)}\:\mathrm{+}\:\mathit{b}\mathit{x}_{\mathrm{2}}\mathrm{\left(\mathit{n} \right)}}$$\mathrm{\mathit{a}\mathit{X}_{\mathrm{1}}\mathrm{\left(\mathit{z} \right)}\:\mathrm{+}\:\mathit{b}\mathit{X}_{\mathrm{2}}\mathrm{\left(\mathit{z}\right)}}$$\mathrm{\mathit{R}_{\mathrm{1}}\:\cap \mathit{R}_{\mathrm{2}}}$Time-Shifting$\mathrm{\mathit{x}\mathrm{\left(\mathit{n-k}\right)}}$$\mathrm{\mathit{z}^{-\mathit{k}}\mathit{X}\mathrm{\left(\mathit{z}\right)}}$$\mathrm{\mathrm{same\:as\:}\mathit{X}\mathrm{\left(\mathit{z}\right)}\:\mathrm{except}\:\mathit{z}\:\mathrm{=}\:\mathrm{0}}$$\mathrm{\mathit{x}\mathrm{\left(\mathit{n\mathrm{+}\mathit{k}}\right)}}$$\mathrm{\mathit{z}^{\mathit{k}}\mathit{X}\mathrm{\left(\mathit{z}\right)}}$$\mathrm{\mathrm{same\:as\:}\mathit{X}\mathrm{\left(\mathit{z}\right)}\:\mathrm{except}\:\mathit{z}\:\mathrm{=}\:\mathrm{\infty}}$Scaling in zdomain$\mathrm{\mathit{a}^{\mathit{n}}\mathit{x}\mathrm{\left(\mathit{n}\right)}}$$\mathrm{\mathit{X}\mathrm{\left( \frac{\mathit{z}}{\mathit{a}}\right )}}$$\mathrm{\left|\mathit{a}\right|\mathit{R}_{\mathrm{1}}Read More

Laplace TransformThe Laplace transform is a mathematical tool which is used to convert the differential equations in time domain into the algebraic equations in the frequency domain or s-domain.Mathematically, the Laplace transform of a time-domain function $\mathit{x}\mathrm{\left(\mathit{t}\right)}$ is defined as −$$\mathrm{\mathit{L}\mathrm{\left[\mathit{x}\mathrm{\left(\mathit{t}\right)}\right]}\:\mathrm{=}\:\mathit{X}\mathrm{\left(\mathit{s}\right)}\:\mathrm{=}\:\int_{\mathrm{0} }^{\mathrm{\infty} }\mathit{x}\mathrm{\left(\mathit{t}\right)}\mathit{e^{-\mathit{st}}\:\mathit{dt}}}$$Where, s is a complex variable and it is given by, $$\mathrm{\mathit{s}\:\mathrm{=}\:\sigma \:\mathrm{+}\:\mathit{j\omega}}$$And the operator L is called the Laplace transform operator which transforms the domain function $\mathit{x}\mathrm{\left(\mathit{t}\right)}$ into the frequency domain function X(s).Properties of Laplace TransformThe following table highlights some of the important properties of Laplace transform −PropertyFunction $\mathit{x}\mathrm{\left(\mathit{t}\right)}$Laplace Transform $\mathit{X}\mathrm{\left(\mathit{s}\right)}$Notation$\mathrm{\mathit{x}_{\mathrm{1}}\mathrm{\left(\mathit{t}\right)}}$$\mathrm{\mathit{X}_{\mathrm{1}}\mathrm{\left(\mathit{s}\right)}}$$\mathrm{\mathit{x}_{\mathrm{2}}\mathrm{\left(\mathit{t}\right)}}$$\mathrm{\mathit{X}_{\mathrm{2}}\mathrm{\left(\mathit{s}\right)}}$Scalar Multiplication$\mathrm{\mathit{k}\mathit{x}\mathrm{\left(\mathit{t}\right)}}$$\mathrm{\mathit{k}\mathit{X}\mathrm{\left(\mathit{s}\right)}}$Linearity$\mathrm{\mathit{a}\mathit{x}_{\mathrm{1}}\mathrm{\left( \mathit{t}\right)}\:\mathrm{+}\:\mathit{b}\mathit{x}_{\mathrm{2}}\mathrm{\left( \mathit{t}\right)}}$$\mathrm{\mathit{a}\mathit{X}_{\mathrm{1}}\mathrm{\left( \mathit{s }\right)}\:\mathrm{+}\:\mathit{b}\mathit{X}_{\mathrm{2}}\mathrm{\left(\mathit{s}\right)}}$Time Shifting$\mathrm{\mathit{x}\mathrm{\left(\mathit{t-t_{\mathrm{0}}}\right)}}$$\mathrm{\mathit{e}^{- ... Read More