Hogenauer filters are sometimes better known as CIC filters. This begs the question: What on earth are CIC filters? CIC stands for “cascaded integrator-comb “. These filters are used very often as sigma – delta A/D decimation filters and the inverse ( interpolators ) are also used in image processing and other applications. These are examples of multirate filters.

Eugene B. Hogenauer published the principles of these filters in his paper entitled:
” An Economical Class of Digital Filters for Decimation and Interpolation”, IEEE Transactions on Acoustics, Speech and Signal Processing, Vol ASSP-29, No. 2, April 1981.

These filters came to be known as Hogenauer filters. CIC is just another name for the structure he proposed. That I believe answers the fundamental question posed in the title of this post.

We decided to investigate these filters a little more in an attempt to demystify the mathematics and the structures so they would become more friendly to us practising engineers. In the attempt perhaps also come up with a few useful formulas or graphs or tricks for usage.

The result of this work is detailed in our wesbite at www.signalpro.biz>engineering pages>hogenauer filters. Interested readers may peruse this interesting paper at their convenience.