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Tx Quad Calibration

Question asked by Manas@98 on Dec 17, 2017
Latest reply on Dec 18, 2017 by srimoyi

We are using AD9361 with FMCOMM3 & ZC702 setting.We wanted to do  IQ imbalance correction and DC offset calibration.

We are setting TX LO frequency to 800MHz, sampling rate to 10 MHz and sending an exponential signal of 0.5Mhz. Please find below the attached screen shot of the spectrum analyzer. We see a  peak at 800MHz(-60bm). Is this because of the IQ imbalance or LO leakage?  How do we eliminate this ? We tried changing the phase offset value which is passed  into the ad9361_do_calib() function from 0 to 31, but there is no change in the attenuation value which is constantly near -60dbm. (Our main peak is at -20dbm. refer to the screen-shot)

 

FIR filter configuration was not changed from the default values and we are using the same values in default_init_param.

We are using the below functions for calibration :

 

 ad9361_set_rx_rfdc_track_en_dis(ad9361_phy, ENABLE);
 ad9361_set_rx_bbdc_track_en_dis(ad9361_phy, ENABLE);

  ad9361_do_calib(ad9361_phy,TX_QUAD_CAL,31);
 ad9361_do_calib(ad9361_phy,RFDC_CAL,0);

 

What else should be set for IQ imbalance correction? (other than calling the above functions)

How do we set the optimal phase offset value in the ad9361_do_calib() function?

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