Laplace & Ztransform

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  • 8/11/2019 Laplace & Ztransform

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    Table of Laplace and Z-transforms

    X(s) x(t) x(kT) orx(k) X(z)

    1. Kronecker delta0(k)

    1 k= 0

    0 k01

    2.

    0(n-k)

    1 n= k

    0 nkz

    -k

    3.s1 1(t) 1(k)

    111

    z

    4.as +

    1 e

    -ate

    -akT11

    1 ze aT

    5.2

    1

    s t kT

    ( )211

    1

    z

    Tz

    6.3

    2

    s t

    2 (kT)2 ( )

    ( )31112

    1

    1

    +

    z

    zzT

    7.4

    6

    s t3 (kT)3

    ( )( )41

    2113

    1

    41

    ++

    z

    zzzT

    8. ( )assa

    + 1

    e

    -at

    1

    e

    -akT ( )( )( )11

    1

    11

    1

    zez

    zeaT

    aT

    9.( )( )bsas

    ab

    ++

    e

    -at e

    -bte

    -akT e

    -bkT ( )( )( )11

    1

    11

    zeze

    zeebTaT

    bTaT

    10.( )2

    1

    as + te

    -at kTe-akT

    ( )211

    1

    ze

    zTe

    aT

    aT

    11.( )2as

    s

    + (1 at)e-at (1 akT)e-akT

    ( )

    ( )211

    1

    11

    +

    ze

    zeaT

    aT

    aT

    12.( )3

    2

    as + t

    2e

    -at (kT)2e-akT ( )

    ( )31112

    1

    1

    +

    ze

    zzeeT

    aT

    aTaT

    13.

    ( )ass

    a

    +2

    2

    at 1 + e-at akT 1 + e-akT ( ) ( )[ ]

    ( ) ( )12

    1

    11

    11

    11

    ++

    zez

    zzaTeeeaT

    aT

    aTaTaT

    14.22

    +s sin t sin kT

    21

    1

    cos21

    sin

    + zTz

    Tz

    15.22

    +s

    s cos t cos kT

    21

    1

    cos21

    cos1

    +

    zTz

    Tz

    16.( ) 22

    ++ as e-atsin t e-akTsin kT

    221

    1

    cos21

    sin

    + zeTze

    TzeaTaT

    aT

    17.( ) 22 ++

    +

    as

    as e

    -atcos t e-akTcos kT

    221

    1

    cos21

    cos1

    +

    zeTze

    TzeaTaT

    aT

    18. ak11

    1 az

    19. ak

    k= 1, 2, 3, 1

    1

    1

    az

    z

    20. kak-1

    ( )211

    1

    az

    z

    21. k2ak-1 ( )

    ( )3111

    1

    1

    +

    az

    azz

    22. k3ak-1 ( )

    ( )412211

    1

    41

    ++

    az

    zaazz

    23. k4ak-1 ( )

    ( )51332211

    1

    11111

    +++

    az

    zazaazz

    24. akcos k11

    1+ az

    x(t) = 0 for t< 0x(kT) =x(k) = 0 for k< 0Unless otherwise noted, k= 0, 1, 2, 3,

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    Definition of the Z-transform

    Z{x(k)}

    =

    ==0

    )()(k

    kzkxzX

    Important properties and theorems of the Z-transform

    x(t

    ) orx

    (k

    ) {x

    (t

    )} or {x

    (k

    )}1. )(tax )(zaX

    2. )t(bx)t(ax 21 + )()( 21 zbXzaX +

    3. )Tt(x + or )k(x 1+ )(zx)z(zX 0

    4. )Tt(x 2+ )T(zx)(xz)z(Xz 022

    5. )k(x 2+ )(zx)(xz)z(Xz 1022

    6. )kTt(x + )TkT(zx)T(xz)(xz)z(Xz kkk K10

    7. )kTt(x )z(Xz k

    8. )kn(x + )k(zx)(xz)(xz)z(Xz kkk 1110 1 K

    9. )kn(x )z(Xz k

    10. )t(tx )z(Xdz

    dTz

    11. )k(kx )z(Xdz

    dz

    12. )t(xe at )ze(X aT

    13. )k(xe ak )ze(X a

    14. )k(xak

    a

    zX

    15. )k(xkak

    a

    zX

    dz

    dz

    16. )(x 0 )(lim zXz

    if the limit exists

    17. )(x )(1lim1

    1zXz

    z

    if ( ) )z(Xz 11 is analytic on and outside the unit circle

    18. )k(x)k(x)k(x 1= ( ) )z(Xz 11

    19. )k(x)k(x)k(x += 1 ( ) )(zx)z(Xz 01

    20. =

    n

    k

    )k(x0

    )z(Xz

    11

    1

    21. )a,t(xa

    )a,z(Xa

    22. )k(xkm )z(X

    dz

    dz

    m

    23. =

    n

    k

    )kTnT(y)kT(x0

    )z(Y)z(X

    24.

    =0k

    )k(x )(X 1