Sunday, April 23, 2017

Design of Chebyshev Filter

    Chebyshev filters have steeper roll-off and more passband/stopband ripples than Butterworth filters. Chebyshev filters minimize the error between idealized and actual filter characteristic over the range but with ripples in passband. There is a defnite ZERO at -1, number of poles gives the ordef of filter. Magnitude spectrum is equiripple in passband and monotonic in stop band.
  We observed that as we increase the order of filter, the ripples in passband reduce and we get more idealized characteristics. As all poles were inside the unit circle, the filter designed was stable.


9 comments:

  1. Chebyshev filter has ripple in its response while Butterworth does not

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  2. The ripples in passband of Chebyshev-1 filters can prove as a disadvantage as it introduces differences in gain for the passband signal.

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  3. Poles are inside the unit circle thus filters are stable(HPF and LPF)

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  4. The magnitude response is monotonic in stop band, i.e. flat without ripples, and equiripple in pass band, i.e. ripples have equal magnitude.

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  5. The transition period for Chebyshev filter is less than that of butterworth filter.

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  6. Chebyshev is preferred over Butterworth as the order of the filter is smaller for the same filter specifications so hardware requirement is less

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  7. A lower order means less hardware(delay blocks) required which lowers cost. The trade off is with quality.

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  8. The minimum order of Chebyshev filter is 2.

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