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simonlindberg
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Registered: ‎01-22-2019

DC coupling mode ADC on ZCU111

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I want to DC-couple the outputs from the ADC:s on the Zync UltraScale+ RFSoC ZCU111. For this I need the common voltage output (VCM) from the ADC which I have extracted from the plug-in board. However, I don't get the 1.2 V output which I expect. In ug583 it is stated that "The VCM output buffer is only enabled in DC coupled mode.", but I have not been able to figure out how to change from AC coupled mode to DC coupled mode. The only thing I have found is how to read out the current state using the XRFdc_GetLinkCoupling function. Does anyone know how to configure the ADC to work in DC coupled mode?

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pthakare
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Registered: ‎08-08-2017

@simonlindberg 

There is no API to set the link coupling.  You need to set it in RF data converter IP

Capture.PNG

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pthakare
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Registered: ‎08-08-2017

@simonlindberg 

There is no API to set the link coupling.  You need to set it in RF data converter IP

Capture.PNG

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klumsde
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Registered: ‎04-18-2011

Hi @simonlindberg 

You'll have to set this in the IP I think. 

I don't think it makes sense to be able to switch between AC and DC coupled mode on the fly. Hence there is only a "Getter" for the Link Coupling mode in the driver API. 

To enable the VCM output you need to set the link coupling to DC in the IP. link_coupling.JPG

 

 

Also take note of the PCB Design Guidelines hererfadc_dccoupling.JPG

 

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simonlindberg
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Registered: ‎01-22-2019

Thank you for the help.

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