Signal Processing Toolbox™

cheb1ap - Chebyshev Type I analog lowpass filter prototype

Syntax

[z,p,k] = cheb1ap(n,Rp)

Description

[z,p,k] = cheb1ap(n,Rp) returns the poles and gain of an order n Chebyshev Type I analog lowpass filter prototype with Rp dB of ripple in the passband. The function returns the poles in the length n column vector p and the gain in scalar k. z is an empty matrix, because there are no zeros. The transfer function is

Chebyshev Type I filters are equiripple in the passband and monotonic in the stopband. The poles are evenly spaced about an ellipse in the left half plane. The Chebyshev Type I passband edge angular frequency is set to 1.0 for a normalized result. This is the frequency at which the passband ends and the filter has magnitude response of 10^-Rp/20.

References

[1] Parks, T.W., and C.S. Burrus. Digital Filter Design,New York: John Wiley & Sons, 1987. Chapter7.

See Also

besselap, buttap, cheby1, cheb2ap, ellipap

cfirpm

cheb1ord