Loading Filters into SigmaStudio

This page describes how to load FIR and IIR filters from FIR Designer M, FIR Designer and FIR Creator EX into Analog Devices’ “SigmaStudio®” design software.

FIR Filters

In the Export tab, select the “Text file (column, decimal)” format and press Save: FIR.

FIR Designer FIR filter export.

In SigmaStudio, add a FIR filter block as follows:

  • Add a FIR filter to the schematic.
  • Edit the number – here 10 – to be the number of taps or coefficients in the FIR filter file.

 

Adding a Sigma Studio FIR filter block.

 

  • Click Table to open the coefficient table editor.

Updating the tap length of a Sigma Studio FIR filter block.

The Table Editor window of a Sigma Studio FIR filter block.

  • Click Load table values and select the FIR filter text file.

The Table Editor of a Sigma Studio FIR filter block with loaded coefficients.

  • The coefficients from the file appear in the table.
  • Click Update, then close the Table Editor window.

IIR Filters

In the IIR Filters tab, select the “Text file (Annotated TF)” format and press Save.

Saving IIR filter coefficients from the FIR Designer IIR filters tab.Load the text file into a text editor.

IIR Mode: Generic

Sample Rate: 48000 Hz

HPF_BUTTERWORTH, 100.000 Hz, Order 6
b0:0.9965809104771632 b1:-1.9931618209543265 b2:0.9965809104771632
a0:1.0000000000000000 a1:-1.9930764377925365 a2:0.9932472041161169
b0:0.9907866979404248 b1:-1.9815733958808497 b2:0.9907866979404248
a0:1.0000000000000000 a1:-1.9814885091445693 a2:0.9816582826171302
b0:0.9874719843176635 b1:-1.9749439686353270 b2:0.9874719843176635
a0:1.0000000000000000 a1:-1.9748593658907694 a2:0.9750285713798850
BAND_PASS, 417.606 Hz, BW 2.000 (Q 0.667), -4.523 dB
b0:0.9794999029624512 b1:-1.8961485068242627 b2:0.9194851766671880
a0:1.0000000000000000 a1:-1.8961485068242627 a2:0.8989850796296390
LPF_LR, 2466.867 Hz, Order 4
b0:0.0211063588451854 b1:0.0422127176903708 b2:0.0211063588451854
a0:1.0000000000000000 a1:-1.5490465855020836 a2:0.6334720208828251
b0:0.0211063588451854 b1:0.0422127176903708 b2:0.0211063588451854
a0:1.0000000000000000 a1:-1.5490465855020836 a2:0.6334720208828251
BAND_PASS, 759.481 Hz, BW 0.784 (Q 1.817), 3.839 dB
b0:1.0119312519164967 b1:-1.9474042503524402 b2:0.9451363720783881
a0:1.0000000000000000 a1:-1.9474042503524402 a2:0.9570676239948847

Each pair of lines, starting with b0 and a0, make up the coefficients of a biquad. SigmaStudio runs each biquad as a separate processing block. Before loading the coefficients into SigmaStudio, each pair needs to be separated into a unique text file. (In the future, FIR Designer will automate this process, but for now this has to be done manually.)

For each biquad, using a text editor, create new files as follows. (The coefficients are placed in columns and the a0 coefficients are not used, so each file has 5 coefficients, not 6.)

Text file 1

0.9965809104771632
-1.9931618209543265
0.9965809104771632
-1.9930764377925365
0.9932472041161169

Text file 2

0.9907866979404248
-1.9815733958808497
0.9907866979404248
-1.9814885091445693
0.9816582826171302

Text file 3

0.9874719843176635
-1.9749439686353270
0.9874719843176635
-1.9748593658907694
0.9750285713798850

Text file 4

0.9794999029624512
-1.8961485068242627
0.9194851766671880
-1.8961485068242627
0.8989850796296390

Text file 5

0.0211063588451854
0.0422127176903708
0.0211063588451854
-1.5490465855020836
0.6334720208828251

Text file 6

0.0211063588451854
0.0422127176903708
0.0211063588451854
-1.5490465855020836
0.6334720208828251

Text file 7

1.0119312519164967
-1.9474042503524402
0.9451363720783881
-1.9474042503524402
0.9570676239948847

In SigmaStudio, for each biquad, add an IIR filter block as follows:

  • Add a General (2nd order) filter – either single or double precision – from the toolbox to the schematic.

Adding a Sigma Studio IIR filter block.

  • Click on the blue icon in the middle of the cell to access the options.

Selecting the IIR filter type in a Sigma Studio IIR filter block.

  • In the drop-down menu, select IIR Coefficient.

Selecting the IIR Coefficient option in a Sigma Studio IIR filter block.

  • Click the Load button and select one of the (column) text files, created above.

The default coefficients in a Sigma Studio IIR filter block.

  • The coefficients list updates with the values from the text file.

The Sigma Studio IIR filter block with custom filter coefficients.

  • Repeat the above for each of the biquads, and in the schematic, connect them in order as required.