Ripples in filter

Ripples are the fluctuations (measured in dB) in the pass band, or stop band, of a filter's frequency magnitude response curve. Elliptic and Chebyshev-based filters have constant ripple across their pass bands. While Bessel and Butterworth derived filters have no ripple in their pass band responses.

1. Which type filter has ripples in the response?
2. What is ripple in low pass filter?
3. Why is there ripple in a Chebyshev filter?
4. Is ripple and attenuation same?

Which type filter has ripples in the response?

Chebyshev Filter: It is also called an equal ripple filter. It gives a sharper cut-off than Butterworth filter in the passband. It has a ripple response in the passband and flat response in the stopband.

What is ripple in low pass filter?

Any realizable filter's passband will be only approximately flat; the deviation from flatness is called the ripple, and is often specified by giving the ratio between the highest and lowest gain in the passband, expressed in decibels. The ideal low-pass or high-pass filter would have a ripple of 0 dB.

Why is there ripple in a Chebyshev filter?

A ripple of 0.5% is a often good choice for digital filters. This matches the typical precision and accuracy of the analog electronics that the signal has passed through. FIGURE 20-1 The Chebyshev response. Chebyshev filters achieve a faster roll-off by allowing ripple in the passband.

Is ripple and attenuation same?

the ripple is a certain amount of amplification or attenuation tolerated in the pass band of the filter. So it depends if those effects are critical for your application or not. if you are doing a FFT and the amplitude of the spectrum is key, then a low or no ripple low pass filter is required.