Requirement : generation of frequency from 120 to 230 MHz with min 100Hz step size.
Will AD9911 be sufficient for that?
what is frequency resolution for AD9911 in Hz?
The frequency resolution equation of the DDS is (FTW/2^32 * system clock) where FTW is the decmal equivalent of the 32-bit frequency tuning word. So, for a 500MHz system clock, the frequency resolution is 116mHz well below the requirement of 100Hz. However, the 230MHz requirement is getting close to the nyquist limit of 250MHz. As you approach the nyquist limit, the 1st image (500-230= 270MHz) will be harder filter. For that reason, you typically limit the DDS output to roughly 40% of the system clock. So, either have a good filtering scheme for the 1st image or go to a higher sampling DDS. The AD9910 or the AD9912 are both 1GHz DDSs.
As a side note, all of our DDS products are capable of better than 100 Hz of tuning resolution.
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