Modern analog filter designs fit into two categories: cascade prototypes; and ladder prototypes. Although software programs for cascade filters are common, the same cannot be said for ladder filters. In order to teach advanced topics such as element frequency transformations, simulated passive elements, leapfrog implementations, and switched capacitor implementations, students must be comfortable with passive filter design. The use of tables for ladder filter design is very complex and only offers a black box approach to the problem. Although many algorithms exist, most are too computationally complex to use in a classroom. A software package for advanced analog filter design and simulation has been developed. This new package has many features, including polynomial manipulation, transfer function design, and post design simulation. This paper includes a description of LADDER, along with some example filter designs, which help demonstrate LADDER's usefulness in education.
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