method, on the AD9739/AD9739A?
There is no calibration feature on either the AD9739 or the AD9739A. The
AD9739/AD9739A datasheets refer to the fact that a customer could choose to
cancel the spur, which is caused by DAC non-linearities, using any of various
methods, including linear correction by destructive interference, for example.
The customer could create an algorithm to create a destructive signal that is
equal in amplitude and opposite in phase to the undesired component, add it to
the signal prior to the DAC, and watch the fs/4 spur become reduced at the DAC
output. Or, a more complicated method using feedback of the output signal could
be used, like in power amplifier digital pre-distortion (DPD). Either of these
or others can be used to correct the undesired spurious.