- 25th March 2009, 03:59 #1

- Join Date
- Sep 2006
- Posts
- 190
- Helped
- 9 / 9
- Points
- 2,702
- Level
- 12

## chebyshev filter

what's the basic differences between butterworth & chebyshev filter ?

- 25th March 2009, 03:59

- 25th March 2009, 06:07 #2pauloynskiGuest
## butterworth chebyshev filter

Here is a comparison. Please google for a while to find many others. http://en.wikipedia.org/wiki/Chebyshev_filter

Added after 1 hours 42 minutes:

Download and install FilterPRO to simulate them http://focus.ti.com/docs/toolsw/fold...filterpro.html

- 25th March 2009, 06:07

- 25th March 2009, 08:55 #3

- Join Date
- May 2008
- Location
- Germany
- Posts
- 4,918
- Helped
- 1423 / 1423
- Points
- 36,280
- Level
- 46

## butterworth and chebyshev filters

In words:

Butterworth low pass exhibits a maximally flat response within the pass region;

Chebyshev response has some ripple within this region, however, in the transition region it is somewhat steeper.

- 25th March 2009, 08:55

- 28th March 2009, 00:12 #4

- Join Date
- Mar 2005
- Location
- USA
- Posts
- 1,323
- Helped
- 270 / 270
- Points
- 11,332
- Level
- 25

## chebyshev butterworth

desperado1,

The Butterworth filter is maximally flat It optimal is in the sense that of all possible filters with a monotonic passband and a monotonic stop band, it has the minimum attenuation in the pass band.

.

The Chebychev filter is optimum in the sense that of all filters with a monotonic stop band (ripple allowed in the passband), it has the steepest transition region.

Regards,

Kral

- 29th March 2009, 16:03 #5

- Join Date
- Jun 2008
- Posts
- 1,180
- Helped
- 35 / 35
- Points
- 8,202
- Level
- 21

## butterworth chebyshev

ALSO THINK WHAT PHASE SHIFT EACH FILTER GIVES.AND THE LEVEL OF DISTORTION (sorry about caps)

- 30th March 2009, 06:04 #6

- Join Date
- May 2008
- Location
- Pakistan
- Posts
- 403
- Helped
- 51 / 51
- Points
- 4,634
- Level
- 16

## chebyshev butterworth filters

both r basically mathematical function,butterworth is flat in it pass band but it's transition band is not much abrupt,where chabyshev has ripples in pass band but its transition band is abrupt so it signal dies out quickly,

it is basically trade off b/w passband n transition band

- 30th March 2009, 14:14 #7

- Join Date
- Mar 2005
- Location
- USA
- Posts
- 1,323
- Helped
- 270 / 270
- Points
- 11,332
- Level
- 25

## butterworth and chebyshev filter

The phase linearity of the Butterworth is better than that of the Chebyshev. In other words, the group delay (derivative of phase with respect to frequency) is more constant with respect to frequency. This means that the waveform distortion of the Butterworth is lower. Of course, with a single input frequency, there is no waveform dostortion in either filter.

Regards,

Kral

Added after 4 minutes:

Another point to consider; the Butterworth filter is completely defined mathematically by 2 parameters: Cutoff frequency and number of poles. The Chebyshev filter has a third parameter: Passband Ripple.

Regards,

Kral