Hi,
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.
Bill....WB6BNQ
d0ct0r wrote:
Hello,
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
http://www.tentec.com/products/Universal-Low%252dNoise-Broadband-DC-to-1-GHz-RF-Preamp-%252d-Model-1001.html
Is it normal to have that kind of distortions for the signal, or
something wrong with design ?
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