"W3JDR" writes:

From what I've seen in the data sheets, the closer you operate the RF output
to the Nyquist limit (Fref/2), the cleaner the spurs get. I've seen numbers
of -90 dB or better on even some of the cheapo Analog Devices parts.

Joe
W3JDR

It has to do with where the spurs end up. If you are close to Fref/2,
lots of the spurs alias down to base band. Worst case is Fref/3. With
the proper choice of filters, and band choice you can find areas where
spurs are almost non-existent. If you have a narrow band application,
your frequency planning can find those holes. Make sure you have your
peak detector turned on.

There are lots of sources of spurs-- phase truncation, amplitude
truncation, noise, etc.

--
Steven D. Swift, , http://www.novatech-instr.com
NOVATECH INSTRUMENTS, INC. P.O. Box 55997
206.301.8986, fax 206.363.4367 Seattle, Washington 98155 USA