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ADRF6820 frequency problem

Question asked by punk77 on Sep 22, 2015
Latest reply on Aug 15, 2016 by gyaliniz

Hello,

I have an official adrf6820  evaluation board. Regarding configuration software, I downloaded the official software from analog website

http://www.analog.com/media/en/evaluation-boards-kits/evaluation-software/ADRF6820_Software_010814.zip

I powered up the board with 6 DC volt
I used as REF, an external oscillator @ 20 MHz (attached photo)
I connected the evaluation board directly with USB interface to a windows 8.1 PC

I loaded the standard registry file, and I modified the REF frequency on the GUI according to my oscillator (20 MHz)
I set the LO Out Freq @ 1600 MHz

At this point, If I enable the LO out, and I measure the frequency using a spectrum analyzer, I realize that independently from which frequency I chose, the output is wrong and there is a frequency shift of about 20/30 MHz compared with my setup on the gui (the shift is different changing the frequency).

The LO carrier is also very noisy, and sometimes we found the pll auto-oscillating (unplugging the 20 MHz REF, on the spectrum analyzer the LO carrier still persists, until a reboot of the pll board)

The MuxOut flag, if configured as REFCLK, shows clearly the 20MHz clock (if measured with the spectrum analyzer on muxout pin on the board); if configured as lock_det, it shows just a very low lighting led and just few millivolt DC voltage on it (if measured on muxout pin on the board with a multimeter).

Let me know about these issues. Is there something wrong on my configuration or setup? In attachment I will provide various photos regarding my setup , registry files and software configurations.

 

thank you very much

 

FV

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