[time-nuts] DDS on AD9852
wb6bnq at cox.net
Sat Jan 17 02:33:49 EST 2015
I am not clear about the little sawtooth riding on the signal, but it
looks like you are running out of headroom on the Ten-Tec preamp. The
Ten-Tec preamp would not be my first choice for the job. One of the
Minicircuits MMIC's would probably be a better choice depending upon
your frequency range requirements.
> I would like to ask some advise about the signal distortion I get from
> my DDS project.
> The T-Bolt GPSDO is in use as a REF signal source (10Mhz) for AD9858
> DDS. This chip has two COS analog outputs which opposite to each
> other. I am using 20x reference multiplier in my project. And I am
> using Low Pass filter and RF amplifier connected to ONE of the COS
> output. The other output has no filter or op-amp on it. Attached is
> four files with OSC screen shots, where the signal which goes through
> the filter and amplifier somehow distorted. In contrary, the signal
> from another output (without filter and op-amp) has near perfect
> curve. I am using the same cable for connection to Oscilloscope.. And
> I set 5 Mhz output on DDS as an example. In this my project I am using
> Ten-Tec broadband pre-amp. The filter is standard Chebyshev Low Pass
> filter made by MINI-CIRCUITS. Model PLP-90 (81 Mhz).
> Here is the link to Ten-Tec
> Is it normal to have that kind of distortions for the signal, or
> something wrong with design ?
More information about the time-nuts