Max Frequency Characterized in Datasheet

Question

Hi, 
 The AD9744 is specified to clock to 210MHz, making the Nyquist frequency 105MHz. However the datasheet only characterises for a maximum output frequency of 69MHz. Is there a reason for characterising only up to 69MHz and not up to 105MHz? 
 I plan to use the DAC up to 90MHz and would like to know if there is a "hidden" limitation on maximum output frequency or will the device work till 90MHz (i.e work till it's theoretical limit of 105MHz) or not. 
 Thanks 
 Regards

JMMina · Accepted Answer

Hi ThomasFunk , 
 The AD9744 can output a 100MHz signal, but we usually recommend getting a DAC with a sampling rate (Fclk) at least 4x the desired Fout. With the max sampling rate of 210 MSPS, the Fout was swept from 0 to 65 MHz. You could still use AD9744 to generate a waveform up to 90 MHz but I would recommend a DAC with a higher sampling frequency such as MAX5890 or AD9781 . 
 Best regards, Marco)

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Max Frequency Characterized in Datasheet