I have an application where a DDS is ideal in many ways, but I can't tolerate the close-in frequency spurs which result from certain combinations of reference clock and output frequency. I see some numerically controlled oscillators in communication ICs have what they call phase dither to eliminate these spurs at the expense of a slightly elevated noise floor. This isn't a selection parameter in the Analog Devices DDS table, though, so I'd need to wade through all the data sheets to see if any have phase dither. Unless, of course, someone here can recommend something! :-) My ref ck is about 65 MHz and I'd like as many bits of resolution as possible.