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The easiest way to design a Digital Filter


COMING SOON: an implementation re-design with plugins for extended development by the comunity.

Software Description

WinFilter is a software tool provided as freeware to design digital filter. A Window interface makes it very user friendly.
This software can design as well IIR filters as FIR filters and can generate the C and VHDL code. The digital filters models are:
  • Butterworth
  • Chebyshev I
  • Bessel
  • Raised Cosine
  • Rectangular 
  • All IIR filters are a transformation from the S domain to the Z domain with the Bilinear Transformation and the aliasing error
    correction (not the matched Z transform).

    Screen Shots

    The WinFilter is composed of a dialogue box at left and a document window where the digital filter description and performance are displayed.


    As you can see, radio buttons and boxes are the filter parameters. The button "Calculate" takes the selected parameters and displays the graphical results in the window document. The Frequency Response, Phase and Group Delay are calculated. The Zeros and Poles are plotted on a Z plan. The Impulse and Step Response are also show.

    The graph's value pointed by the mouse is displayed in the right side of the status bar.

    The C code can be generated and the filter graphical results can be exported in a GIF format file.

    VHDL code can be generated in 2 models : Size or Speed Optimized. Both designs run over 160 MHz  in a Virtex2 (grade -4) FPGA.

    System Requirements

    • IBM PC compatible computer running Microsoft Windows 98/2000, NT, or XP


    Why should you donate? If you think this little tool is useful to you, then it's a good reason to do a donation. Your gratitude and finance help will motivate me to continue WinFilter project development.


    Releases Description Software Download Link
    next release
    VHDL code for IIR filter.
    Add/Remove Pole/Zero possibilities
    Filter conversion from S domain to Z domain.
    not yet available
    December 6th, 2004
    NEW! Version 0.7 Bug fixes.    Windows95, 98, Me, NT, 2K and XP (206 KB)
    July 26th, 2004
    The filter coefficients are now quantizied in float, 16-bit or 8-bit. Synthezis in VHDL (speed or size optimization) with a Resources Usage Estimation for FIR filter.
    Version 0.1 Bug fixes.
       Windows95, 98, Me, NT, 2K and XP (205 KB)
    March 12th, 2003  
    This first release software can design IIR and FIR filter with Butterworth, Chebyshev I, Bessel, Raised Cosine and Rectangular models.
    The C code can be generated and the graphical results saved in GIF format file.
       Windows95, 98, Me, NT, 2K and XP (440 KB)


    This software was created by Adrian Kundert, B.Eng. (Electrical Engineering). I wanted to increase my digital signal processing knowledge. This web page is for the free distribution and further development of WinFilter.

    Please report any WinFilter software bugs or new ideas here (use winfilter keyword in the subject). All reported problems will help me to continue the development of this digital filter design tool.

    Last Update: May 16th, 2012

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