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Explorer
Explorer
212 Views
Registered: ‎06-19-2014

ZCU111 board, eval tool gives 14 bit data instead of 12

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I am evaluating  ZCU111  through RF data converter Evaluation user interface TRD v1.3.

The ADC on chip is 12 bits hence maximum ADC values can be +- 2048. 

But as you can see, the attached graph shows ADC values of 14 bits. How is it possible that a 12 bit ADC is giving values of 14 bits ADC?

 

rf adc.PNG
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Observer sulemanzp
Observer
120 Views
Registered: ‎03-12-2017

Re: ZCU111 board, eval tool gives 14 bit data instead of 12

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As per my understanding.

FPGA Firmware for RF DC Evaluation tool uses  "Zynq UltraScale+ RFSoC RF Data Converter LogiCORE IP". According to the IP datasheet at page 9 in RF-ADC features its mentioned that (12-bit RF-ADC resolution, with 16-bit digital signal processing datapath). This tool is recieving 16 bit sample from ADC. If you increase the power of signal the graph will display values between +/- 32768 instead of 14bits value. Also figure at page 44 in ug1309 shows that amplidues (LSB) reaches 16 bits number. If you want 12 bit ADC data just drop the lower 4 bits after saving the raw ADC data. 

4 Replies
Explorer
Explorer
171 Views
Registered: ‎06-19-2014

Re: ZCU111 board, eval tool gives 14 bit data instead of 12

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Is it that difficult question? Guys can anyone reply?

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Explorer
Explorer
136 Views
Registered: ‎06-19-2014

Re: ZCU111 board, eval tool gives 14 bit data instead of 12

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Seems no one knows... 

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Observer sulemanzp
Observer
121 Views
Registered: ‎03-12-2017

Re: ZCU111 board, eval tool gives 14 bit data instead of 12

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As per my understanding.

FPGA Firmware for RF DC Evaluation tool uses  "Zynq UltraScale+ RFSoC RF Data Converter LogiCORE IP". According to the IP datasheet at page 9 in RF-ADC features its mentioned that (12-bit RF-ADC resolution, with 16-bit digital signal processing datapath). This tool is recieving 16 bit sample from ADC. If you increase the power of signal the graph will display values between +/- 32768 instead of 14bits value. Also figure at page 44 in ug1309 shows that amplidues (LSB) reaches 16 bits number. If you want 12 bit ADC data just drop the lower 4 bits after saving the raw ADC data. 

Visitor dbarker
Visitor
60 Views
Registered: ‎03-23-2018

Re: ZCU111 board, eval tool gives 14 bit data instead of 12

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This doesn't answer the question.  When I use the Eval Tool, I get 16-bit words from the A/D and the 14 MSB's of each word contain data, while the least significant 2 bits are always zero.  I have all the digital signal processing bypassed so I should be getting raw A/D data.  So why are the supposed 12-bit A/D's producing 14-bit data?

 

Thanks

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