The Element library was updated to support automatic fitting of digital filter coefficients (FIR and IIR), allowing for convenient setup and accurate simulation of frequency dependent complex transmission s-parameters in the time domain. The new IIR filter fitting functionality allows for the direct fitting of the required time-domain filter impulse response spectrum to an arbitrarily shaped s-parameter curve in such a manner that the quality of the fit is excellent over the required simulation bandwidth.
Following are the parameters for the Digital Filter in the S Parameter elements:
|
Property |
Default Value |
Description |
|---|---|---|
|
digital filter type |
[single tap, FIR, IIR] |
digital filter types |
|
number of taps estimation |
[disabled, fit tolerance, group delay] |
estimation types |
|
filter fit tolerance |
0.05 |
filter fit error tolerance |
|
filter fit number of iterations |
50 |
filter fit number of iterations, this parameter is enabled when the filter type is "IIR" |
|
filter fit rolloff |
0.05 |
filter fit roll off value, this parameter is enabled when the filter type is "IIR" |
|
window function |
[rectangular, hamming, hanning] |
filter function types, this parameter is enabled when the filter type is "FIR" |
|
number of fir taps |
256 |
number of FIR filter taps, this parameter is enabled when the filter type is "FIR" |
|
number of iir taps |
4 |
number of IIR filter taps, this parameter is enabled when the filter type is "IIR" |
|
maximum number of iir taps |
20 |
number of maximum IIR filter taps, this parameter is enabled when the filter type is "IIR" |
|
initialize filter taps |
[false, true] |
choose whether or not to initialize filter taps |
|
fractional delay |
[true, false] |
choose whether or not to do fractional delay, this parameter is enabled when the "number of taps estimation" is "group delay" |
|
delay compensation |
0 |
delay compensation value, this parameter is enabled when the "number of taps estimation" is "group delay" |
The estimation status (fitting error) will be updated in the "output" window while the simulation is running at each step. The error value and the error tolerance can be used as a guideline to judge the estimation