# Noise Equivalent Bandwith of IIR and FIR Filters?

How do you calculate the noise equivalent bandwidth for an IIR or FIR filter?

$$B_\text{eq} = \frac{1}{|H(e^{j\omega_0})|^2} \int_0^\infty |H(e^{j\omega})|^2 d\omega$$
where $H(e^{j\omega})$ is the frequency response, and $\omega_0$ is the max-abs frequency. For FIR filters, you can just use e.g. freqz in MATLAB/Octave. For IIR filters, you'd have to do analysis or take measurements (or see if you can get away with truncating)
• Shouldn't the denominator term be $|H(e^{j\omega_0})|^2$ ? onmyphd.com/?p=enbw.equivalent.noise.bandwidth – Peter K. Nov 11 '13 at 22:15