It seems that the first CIC Decimator output is always zero and I don’t understand its behavior.
I generated the input data and construct signed 12-bit data.
len_data = 100;
in = randi([-2048 2047], len_data, 1);
a = fi(in,1,12,0)

Then I created CIC filter object with decimation factor of 20, number of stages of 4, and internal bit width of 30-bit, and output bit width of 30-bit.

cicDecimOut = dsp.CICDecimator(DecimationFactor=20,…
NumSections=4,…
FixedPointDataType="Specify word lengths",…
SectionWordLengths=30,…
OutputWordLength=30)

Then I checked the output of the CIC filter.
out = cicDecimOut(a)

My question is the first output of the CIC filter is always zero no matter the input is and I don’t know why.It seems that the first CIC Decimator output is always zero and I don’t understand its behavior.
I generated the input data and construct signed 12-bit data.
len_data = 100;
in = randi([-2048 2047], len_data, 1);
a = fi(in,1,12,0)

Then I created CIC filter object with decimation factor of 20, number of stages of 4, and internal bit width of 30-bit, and output bit width of 30-bit.

cicDecimOut = dsp.CICDecimator(DecimationFactor=20,…
NumSections=4,…
FixedPointDataType="Specify word lengths",…
SectionWordLengths=30,…
OutputWordLength=30)

Then I checked the output of the CIC filter.
out = cicDecimOut(a)

My question is the first output of the CIC filter is always zero no matter the input is and I don’t know why. It seems that the first CIC Decimator output is always zero and I don’t understand its behavior.
I generated the input data and construct signed 12-bit data.
len_data = 100;
in = randi([-2048 2047], len_data, 1);
a = fi(in,1,12,0)

Then I created CIC filter object with decimation factor of 20, number of stages of 4, and internal bit width of 30-bit, and output bit width of 30-bit.

cicDecimOut = dsp.CICDecimator(DecimationFactor=20,…
NumSections=4,…
FixedPointDataType="Specify word lengths",…
SectionWordLengths=30,…
OutputWordLength=30)

Then I checked the output of the CIC filter.
out = cicDecimOut(a)

My question is the first output of the CIC filter is always zero no matter the input is and I don’t know why. cic decimator, cic MATLAB Answers — New Questions

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