Field Guide · algorithm

Also known as: CIC filter

A CIC filter (cascaded integrator–comb) is a digital filter built from only integrators and combs — no multipliers — making it very efficient for large-ratio decimation or interpolation.1

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A CIC filter uses only adders and delays (no multipliers), making it a cheap high-ratio decimator.

How it works

Integrator stages run at the high rate and comb stages at the low rate, changing the sample rate cheaply. Its gentle passband is usually followed by a short compensation FIR filter.

Relevance to SDR

CIC filters are common in the front of an SDR channeliser, where huge decimation ratios must be done with minimal computation.

Sources

  1. Cascaded integrator–comb filter — Wikipedia, on Hogenauer’s multiplier-free decimation/interpolation structure. ↩

See also

Learn it step by step

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