Design IIR Bandpass Filters
In this post, I present a method to design Butterworth IIR bandpass filters. My previous post [1] covered lowpass IIR filter design, and provided a Matlab function to design them. Here, we'll do the same thing for IIR bandpass filters, with a Matlab function bp_synth.m
Summary
This article presents a practical method for designing Butterworth IIR bandpass filters and provides a MATLAB function (bp_synth.m) to synthesize them. Readers will learn the design steps from analog lowpass prototype through frequency transformation and bilinear mapping, plus verification techniques using MATLAB plots and examples.
Key Takeaways
- Implement the bp_synth.m MATLAB function to synthesize Butterworth IIR bandpass filters from specifications.
- Select filter order and cutoff frequencies to meet given passband/stopband amplitude specs.
- Apply lowpass-to-bandpass frequency transformation and the bilinear transform with prewarping for digital mapping.
- Verify filter performance by plotting frequency response, phase/group delay, and checking pole-zero stability.
Who Should Read This
DSP engineers, researchers, or advanced students with basic DSP and MATLAB experience who need a practical, code-backed method to design Butterworth IIR bandpass filters for audio, communications, or radar applications.
TimelessIntermediate
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