Notes on Digital Signal Processing: Practical Recipes for Design, Analysis and Implementation

Note 39. Characterizing Analog Filters

Several of the most popular techniques for designing IIR filters are based on transformations or mappings of analog prototype filters into digital filters. Often these prototype filters are classic filter designs such as Butterworth, Chebyshev, or elliptic. These classical filters are usually presented in the literature as normalized lowpass filters that must be denormalized and possibly transformed into other band configurations before they can be used as protoypes for IIR filters. This note covers techniques that are used to characterize and frequency-scale classical analog filters.

Neglecting imperfections in the components used to implement them, classical analog filters are considered to be time-invariant, ...