Spectrum analysis with Eclypse Z7 and Zmod DAC 1411

[Ale]

I have a Zmod DAC 1411 connected to an Eclypse Z7 board. The Eclypse board is powered by its original power supply, housed in its enclosure, and the DAC is connected to a spectrum analyzer with a BNC cable. When connecting the DAC output to the spectrum analyzer, I observe an interference between 16 and 19 kHz. In this case, the FPGA on the Eclypse is programmed only to send a constant signal to the DAC. Is the disturbance at 16-19 kHz a known issue? Do you know what might be causing it?

[zygot]

The Zmod DAC Reference Manual uses a ZMOD ADC to create what it publishes as the board's "spectral characteristics". This should tell you something.

What you are measuring over the usable published bandwidth of the AWG is almost all below 100 dBm. Is this anomaly really a problem for your needs?

Anyone who's spent some time reading over the "spectral characteristics" of DAC and ADC converter devices... not complete converter circuits with high/low range and multiple variables... can see what lengths and games the vendors go to to make their devices appear to be as "pretty" as possible. It's really a long running game.

Of course, it's possible that your application needs to take into consideration a very careful analysis of how the hardware and logic interface for your ZMOD behaves over a bandwidth of interest. Sounds like a good student project with lab and simulation exercises... and a lot of time. Start adjusting the variables and continue your tests. I'm pretty sure that you'll have more questions to ask about why you are surprised about your measurements.

This ADC/DAC stuff is complicated. Edited November 14, 2023 by zygot