SBASAP7 December 2024 ADC3664-SP
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The DDC blocks are equipped with a 32-bit NCOs for mixing in the complex decimation mode prior to the digital filtering. The NCOs provide a complex output of:
where the frequency ω is specified as a 32-bit signed number also known as the frequency control word (FCW).
The complex output is multiplied with the real input from the ADC to mix the desired carrier to a frequency equal to fIN ± fNCO. The NCO frequency can be tuned from –FS/2 to FS/2 and is processed as a signed, 2s complement number. After programming a new NCO frequency, either the NCO_RES (D5 & D1 of 0x26) or the SYNC pin have to be toggled for the new frequency to take effect.
The NCO FCW is calculated as follows: