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AD9371 JESD inteface output issue

Question asked by JunHu on Apr 11, 2017
Latest reply on Apr 12, 2017 by sripad

hi, all,

 

recently, we are using single tone to test AD9371 JESD output spectrum, the tone is located at +3.84MHz offset compared to 3.5GHz. After JESD interface output, we saw the image tone at -3.84MHz is quite large (seems only 8~10dB image rejection, gain imbalance ~=0.5dB, phase imbalance >30 degree) which is quite abnormal

 

i have asked my colleague whether he enables IQ calibration, and he mentions that with his understandings and local check, it had been enabled.

 

I think I need to take a look at this part, so can anyone point out the the most important parts or key configurations that I should double check to make sure that IQ calibration and QEC inside AD9371 are correctly enabled ??

 

besides, by checking the JESD output tone, I found that it seems the IRR is damaged mainly due to I / Q cosine and sine wave has large phase imbalance (phase imbalance >30 degree, far away from expected orthogonality), I am just wondering whether i missed something or certain configurations that leads to I / Q path has large delay difference ??

 

thanks !

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