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Can you describe the signal you are sampling (its amplitude and frequency), and the ADC you are using? Sampling at 25MHz seems like too much oversampling.
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In the designed system , 100KHZ and 200KHZ signals are sampled by ADC through 25MHZ sampling rate ( its amplitude is MV level ), by system processing , FIR IP filter final input includes a DC signal(which is generated after system processing) and three high-frequency signal(100KHZ , 200KHZ ,300KHZ) and maybe some high frequency noise signal.
what I want is only the DC signal , so I'm confused how to set the FIR IP filter's parameter ( Fs and Fc ) ???
thank you very much for your reply !