1. The user manual Page 34 and 23 shows that the DDS output sampling rates is 1/4 fSYSCLK when AD9910 operates in RAM modulation mode, For example, if the system clock is 1G, then DDS_clk only to 250MHz, according to Nyquist rate, it will only produce maximum 125MHz IF carrier?
2. If the above-mentioned circumstances, then the signal from the DDS output reach the input of DAC ,which part makes four times interpolation? From the functional block diagram I cannot find it out.
3.If the above-mentioned circumstances, A DDS with 250MHz sampling rate is equal to AD9910 ?