Analog transfer function

Syntax
Ha=analogtf(ANum, ADen, AGain, DFormat)

Description
Define an analog filter object. Where, the ANum and ADen vectors are the Laplace transfer function coefficients in descending order.

Examples
A first order analog lowpass filter may be designed by an RC network:

analog low pass filter

Choosing R=100k\(Omega\) and C=100nF, gives cut-off at 100rad/s or ≈ 15.9Hz. The analog transfer function may be simply implemented in FilterScript (output shown below) as:
[code lang=”java”] Main()

wc=100; // 1/(R*C);
ANum={0,1};
ADen={1,wc};
AGain=wc;
Ha=analogtf(ANum,ADen,AGain,"symbolic");

[/code]

This analog filter object may be now transformed into a digital filter via the Bilinear or Match Z-transform methods. See the example script AnalogRCfilter.afs for more information.