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SigmaStudio's Bessel filter coefficient operation inquiry

Question asked by Andrew.Choi on Mar 21, 2018
Latest reply on Mar 25, 2018 by KJBob

Hi all

 

One of the customers is developing the product by applying ADAU1452 to the product.

There are inquiries about Bessel filters in the filter.

 

If measure another manufacturer's equipment in the Bessel filter and simulate it with MATLAB, the signal will decrease -3 dB in cutoff frequency as shown below.

 

However, when we simulate with the filter coefficients provided by SigmaStudio, the signal size is reduced by -5 dB at the cutoff frequency. If you actually apply a filter and measure the signal with the instrument, -5dB will fall.

 

 

In general, I know that the -3 dB drop in cutoff frequency in a filter.

Other filters in SigmaStudio fall -3dB at the cutoff frequency.
Is there a reason why only the Bessel filter drops -5dB?

 

Thank you

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