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Visitor jmcoreymv
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Registered: ‎04-22-2019

ZCU111 RFSoC - Data Converter Eval Tool - How to correctly use inverse sinc compensation?

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Hi,

I'm evaluating the Zync RFSoC using the ZCU 111 eval kit with the RF Dataconverter Eval Tool.  I'm taking some preliminary measurements by sweeping a CW across a 500 MHz band of interest, in the DACs second nyquist zone.  The setup is:

DAC Clk = 6389.8 MHz

Nyquist Zone = 2

Interpolation = 1x (bypass)

I generate a CW tone and sweep from 3.3 to 3.9 GHz and measure the results via an ADC cabled to it.

The ADC setup is:

ADC Clk = 3194.9 MHz

Calibration Mode 2

Nyquist Zone 1

Decimation = 1x (bypass)

I have QMC and the mixers disabled and 2nd Nyquist Zone selected in the DAC Generation window.  I took CW measurements comparing the RX ADC Amplitude (dBFS) across my band of interest and see ~5 dB of drop over 500 MHz without inverse sinc compensation (which was more than I expected), but with it compensation I see closer to 6-7 dB of variation, plus pretty strong spurs.  From looking at the docs, I think I might need to put the DAC into mix-mode to use the inverse sinc compensation in this Nyquist zone, but when I do that, it forces the interpolator to 2x+ and I can't seem to generate tones > 3.2 GHz anymore.

Can someone provide guidance?

Thanks!

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Community Manager
Community Manager
77 Views
Registered: ‎08-30-2011

回复: ZCU111 RFSoC - Data Converter Eval Tool - How to correctly use inverse sinc compensation?

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Hi @jmcoreymv 

Yes, set the Nyquist Zone to 2 turns on the Mixer-mode.

You can see the DAC output response in Figure 43.

image.png

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Community Manager
Community Manager
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Registered: ‎08-30-2011

回复: ZCU111 RFSoC - Data Converter Eval Tool - How to correctly use inverse sinc compensation?

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Hello,

inverse sinc is used for compensating the signal roll off in the first Nyquist Zone. If you signal is located in the second Nyquist Zone, it only needs to set the mixer mode on.

I take a quick look in the GUI. Below is my setting with the same as yours. I can see nothing strange. Would you mind have a check and may be a screen shot may help align us.

image.pngimage.pngimage.pngimage.png

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Visitor jmcoreymv
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Registered: ‎04-22-2019

回复: ZCU111 RFSoC - Data Converter Eval Tool - How to correctly use inverse sinc compensation?

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Hi Zhendon,

Thank you for the response.  Can you clarify the statement 'It only needs to set the mixer-mode on'?  In the screenshots from your post it looks like the Mixers are all in Bypass mode, but maybe by setting to Zone 2, that turns mixer-mode on?

Is your setup using the 'non-MTS 8x8' provided design?

How much variation in RX ADC amplitude should I expect to see with a CW loopback over the band from ~3.3 to 3.9 GHz on this eval kit?

I will re-run with the configuration you have to try and replicate and provide screenshots.

Thank you.

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Community Manager
Community Manager
78 Views
Registered: ‎08-30-2011

回复: ZCU111 RFSoC - Data Converter Eval Tool - How to correctly use inverse sinc compensation?

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Hi @jmcoreymv 

Yes, set the Nyquist Zone to 2 turns on the Mixer-mode.

You can see the DAC output response in Figure 43.

image.png

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如果提供的信息能解决您的问题,请标记为“接受为解决方案”。
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