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General First Order

Hello. I am using frequency filter in Sigma studio. Some parts were not explained in the calculations and I was not sure. I do the calculations but it doesn't work. Can you help with the calculations? What values do A1,B0,B1 correspond to first?

https://wiki.analog.com/resources/tools-software/sigmastudio/toolbox/filters/general1storder

The calculations given on the site and the calculations of sigma studio are different. What is the problem? Can you help me?

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  • Hello, great question.

    The issue is that SigmaStudio is doing A1 = 2.7^(-2 * pi * 100/48000)  instead of e^(-2 * pi * 100/48000)

    I have no idea why!

    So in this case A1 = 2.7^(-2 * pi * 100/48000) = 0.987082520837763

    Now, when you convert that to 8.24 format i.e. floor(A1*2^24)*2^-24 = 0.987082481384277 which is the exact value you are showing!

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  • Hello, great question.

    The issue is that SigmaStudio is doing A1 = 2.7^(-2 * pi * 100/48000)  instead of e^(-2 * pi * 100/48000)

    I have no idea why!

    So in this case A1 = 2.7^(-2 * pi * 100/48000) = 0.987082520837763

    Now, when you convert that to 8.24 format i.e. floor(A1*2^24)*2^-24 = 0.987082481384277 which is the exact value you are showing!

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