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Altera_Forum's avatar
Altera_Forum
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11 years ago

DC in the CIC-FIR filter result

Hi All, I have attached a figure showing my filter issue. Please subtract 28 MHz from the x axis values (it was a typo). It is apparent that there is a strong DC peak in the plot. My question i...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

I think you are confused.

dBm has no meaning here, you probably mean dB. Even dB depends on how you see spectrum. Don't worry about these figures.

Why you mention nco cosine only? I expect nco to be cos/sin

what matters is this:

Your input signal is centred at 28.05MHz and is real only I assume. Ok what s your nco frequency? that is the key to any dc. if your nco is -28.05 or +28.05 then you are pushing signal to dc