Digital Signal Processing Reference
In-Depth Information
6.5 CONCLUSION
In this chapter we investigated three different methods of generating digital IIR
filters from analog transfer functions. In each case we found that there is no
perfect match to the original analog function, primarily because there is a strict
limit on the frequency range of a digital filter. However, the bilinear transform
method does provide good overall response characteristics, and for that reason it
was chosen to be implemented in C code. (Details of this code are provided in
Appendix G.) The frequency response characteristics of the IIR filter were also
considered, and the calculation of the response was implemented in C code.
Finally, we used WFilter to design an IIR filter and display the complete
magnitude response including the multiple replications of the original response.
The implementation of IIR filters is discussed in Chapter 8.
