ncauer {gsignal}

ncauer analog filter design

Description

Compute the transfer function coefficients of a Cauer analog filter.

Usage

ncauer(Rp, Rs, n)

Arguments

Rp

dB of passband ripple.

Rs

dB of stopband ripple.

n

filter order.

Details

Cauer filters have equal maximum ripple in the passband and the stopband. The Cauer filter has a faster transition from the passband to the stopband than any other class of network synthesis filter. The term Cauer filter can be used interchangeably with elliptical filter, but the general case of elliptical filters can have unequal ripples in the passband and stopband. An elliptical filter in the limit of zero ripple in the passband is identical to a Chebyshev Type 2 filter. An elliptical filter in the limit of zero ripple in the stopband is identical to a Chebyshev Type 1 filter. An elliptical filter in the limit of zero ripple in both passbands is identical to a Butterworth filter. The filter is named after Wilhelm Cauer and the transfer function is based on elliptic rational functions.Cauer-type filters use generalized continued fractions.[1]

Value

A list of class Zpg with the following list elements:

zero

complex vector of the zeros of the model

pole

complex vector of the poles of the model

gain

gain of the model

Author(s)

Paulo Neis, [e-mail].
Conversion to R Tom Short,
adapted by Geert van Boxtel, [e-mail].

References

[1] https://en.wikipedia.org/wiki/Network_synthesis_filters#Cauer_filter

See Also

Zpg, filter, ellip

Examples

zpg <- ncauer(1, 40, 5)
freqz(zpg)
zplane(zpg)