In this case a rectangular pulse is assumed to be input into a RC circuit. The sampled input is shown in red. Orange output is obtained using the difference equation equivalent to the Z transfer function.

The B Magenta output is obtained by taking the inverse DFT of the product of the DFT of the input and the transfer function.

For the Bilinear approximation, the Z transfer function is:-

BLTF = (1 + z^-1)/((2Tc/Ts + 1) + (1 - 2Tc/Ts)z^-1).

For the Back Difference approximation, the Z transfer function is:-

BDTF = (Ts/Tc)/((Tc + Ts)/Tc - z^-1).

COPYRIGHT © 2007 Cuthbert Nyack.