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Q&A AD9375 DDS Scale to dbm

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AD9375 DDS Scale to dbm

Manikandan_M_M on May 9, 2022

Category: Hardware

I am working on AD9375 interfaced with Xilinx Ultrascale + FPGA.

While working with DDS scale, I found this in Driver Code and the scale is in micro units (i.e. 1*1000*1000 is 1.0)

axi_dac_dds_set_scale(dac, ((i*2)+0), 50*1000);
axi_dac_dds_set_scale(dac, ((i*2)+1), 50*1000);

How can i relative this with dBm? (micro units to dBm)

0 srimoyi

on May 9, 2022 2:34 PM
Moving to FPGA forum
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0 travisfcollins

on May 10, 2022 12:29 AM in reply to srimoyi
You would need to measure it at each DDS step with an instrument. The device itself is not calibrated so you cannot get to a calibrated/scientific unit like dBm.

-Travis
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0 Manikandan_M_M on May 21, 2022 1:22 PM in reply to travisfcollins

Thanks for your reply,

From the software code, I am able to find the DDS scale is getting Converted to 14- bit value (16384 - max )

In Eval Board, for 4.5GHz Band around 250,000 as DDS scale, the sample value (4912), maximum power is reached (-3dBm), (without spurious).

Kindly let me know the what is the Vref for DACs, as i am unable to find in the datasheet.

How to find the maximum power of individual Dac's, bcoz the resultant voltage of TX is sqrt(sqr(i)+sqr(Q))
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