Hi Mahesh Please refer to Figure 63. DDC Details Block Diagram in the ADC12J1600 datasheet. The NCO setting changes the frequency of the oscillator (digital Numerically Controlled Oscillator) which feeds into the complex mixer section. Changing the NCO frequency shifts the ADC output spectrum that is input to the decimation filter. Some portion of the spectrum centered around DC will be passed and output in the data. Frequencies outside the DDC bandwidth are eliminated. The decimation factor is determined separately by the Decimation register setting. This adjusts the output sample rate and resulting output bandwidth, but does not select what portion of the ADC Nyquist zone is output. Best regards, Jim B
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