Butterworth low pass filter

[zawminoo]

Hi,

I amnot clear these.
Effect of dB and cutoff frequency in noise removeing?
How remove noise by this filter?
second order and fourth order different? Advantages?
What are importance in design filter?

Royal

 

[Miguel Gaspar]

1st Cutt off frequency
2nd Flatness of the bandpass region
3rd Order of the filter that means -20dB/dec, -40dB/dec, -60dB/dec, first, orde, second order, third order etc

The more high the order the most look like an idela filter

 

[starfish]

Below Cuttoff Frequency all the frequencies pass through the filter . Above it as frequency increases more the attenuation in decibels for a low pass filter.

Attenuation in dB is 20 log10 ( x )

Higher the order of a filter more sharper the transition is and hence more closer to ideal filter.

Added after 6 minutes:

Importance in Filter Design

1. The order the filter. The more the order the higher the cost and the complexity in analog designs.

2. Filter should satisfy your requirments. If u want to remove 10k + frequencies then it can be achieved by using low pass with higher and lower order. So there is a compromise b/w the complexity / cost and ur objective.

3. Filter should produce stable output for all valid inputs. No poles should lie on unit circle.