## Modelica_LinearSystems2.WorkInProgress.Tests.Filters

### Package Content

Name | Description
--- | ---
plotFilter |
plotFilter2 |
plotFilter3 |
compareBaseFiltersWithTietzeSchenk | Compare normalized base filters with the table of Tietze/Schenk Halbleiterschaltungstechnik
plotAlphaForPassBand |

## Modelica_LinearSystems2.WorkInProgress.Tests.Filters.plotFilter

### Inputs

Name | Description
--- | ---
analogFilter | Analog filter characteristics (CriticalDamping/Bessel/Butterworth/Chebyshev)
filterType | Type of filter (LowPass/HighPass)
f_cut | Cut-off frequency [Hz]
A_ripple | Pass band ripple for Chebyshev filter (otherwise not used) [dB]
f_min | Band of pass band filter is f_min (-3db) .. f_cut (-3db) [Hz]
normalized | = true, if amplitude at f_cut decreases/increases 3 db (for low/high pass filter), otherwise unmodified filter

## Modelica_LinearSystems2.WorkInProgress.Tests.Filters.plotFilter2

### Inputs

Name | Description
--- | ---
filterType | Type of filter (LowPass/HighPass)
f_cut | Cut-off frequency [Hz]
A_ripple | Pass band ripple for Chebyshev filter (otherwise not used) [dB]
f_min | Band of pass band filter is f_min (-3db) .. f_cut (-3db) [Hz]
normalized | = true, if amplitude at f_cut decreases/increases 3 db (for low/high pass filter), otherwise unmodified filter

## Modelica_LinearSystems2.WorkInProgress.Tests.Filters.plotFilter3

### Inputs

Name | Description
--- | ---
f_cut | Cut-off frequency [Hz]
A_ripple | Pass band ripple for Chebyshev filter (otherwise not used) [dB]
f_min | Band of pass band filter is f_min (-3db) .. f_cut (-3db) [Hz]
normalized | = true, if amplitude at f_cut decreases/increases 3 db (for low/high pass filter), otherwise unmodified filter

## Modelica_LinearSystems2.WorkInProgress.Tests.Filters.compareBaseFiltersWithTietzeSchenk

Compare normalized base filters with the table of Tietze/Schenk Halbleiterschaltungstechnik

### Information

This function compares the filters with the ones from

Tietze U., and Schenk C. (2002):
  Halbleiter-Schaltungstechnik. Springer Verlag, 12. Auflage, pp. 815-852.

In tables Abb. 13.14 on pages 828-834 of (Tietze/Schenk 2002), the filter coefficients are given with respect to normalized filters for a cut-off angular frequency of 1 rad/s. The normalization is performed in such a way that at the cut-off frequency the transfer function has an amplitude of -3db (= 10^(-3/20) = 0.7079457..). In the tables, not the exact -3db value is used but the approximation sqrt(2)/2 (= 0.707106...). Due to "historical" reasons, function baseFilter from the Modelica_LinearSystems library uses -3db for Bessel and Chebyshev filters and sqrt(2)/2 for CriticalDamping and Butterworth filters. Furthermore, the table gives the values only up to 4 significant digits. For these reasons, in this test function the comparison is performed up to 3 significant digits.

### Inputs

Name | Description
--- | ---
outputFile |

## Modelica_LinearSystems2.WorkInProgress.Tests.Filters.plotAlphaForPassBand

### Inputs

Name | Description
--- | ---
a |
b |
w |