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Butterworth
and Chebyshev filters with sharp
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cutoffs
(high order) carry a penalty that is
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evident
from the positions of their poles in
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the s
plane. Bringing the poles closer to the
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j axis
increases their Q, which degrades the
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filter's
transient response. Overshoot or
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ringing
at the response edges can result.
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The
Bessel filter represents a trade-off in the
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opposite
direction from the Butterworth. The
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Bessel's
poles lie on a locus further from the
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j
axis. Transient response is improved, but
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at
the expense of a less steep cutoff in the
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stop-band.
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