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AD9371 - Questions

Question asked by Shay.L on Jul 26, 2016
Latest reply on Jul 28, 2016 by Vinod


  I have few questions about the AD9371 User Guide UG-992:


  1. In the past when we worked with the AD9361 we used registers in order to control the RFIC.
    When we changed a register value the effect took place immediately.
    Now in the AD9371 we are using API functions so, for example if I want to change Tx1 attenuation using an API  function: 
    MYKONOS_setTx1Attenuation(mykonosDevice_ t *device, uint16_t tx1Attenuation_mdB)
    My question is what is the time duration from this API function till the Tx1 attenuation change ? 

    Is this time duration constant for all API functions ?
  2. Page 120:
    "The SnRx internal attenuator is similar to the ORx and Rx internal attenuators. However, the valid range of internal  attenuator index values extends from 0 to 19 (5-bit control) on the SnRx."
    If this attenuator has 5-bit control the index values should be 0 – 31 and not 0 – 19 as written in the data sheet is this  correct ?
    What is the formula to calculate the attenuation of the SnRx internal attenuator ?
  3. Page 204:
    Table 105:   GP_Interrupt Configurations
    What is the meaning of Tx1 PA protection and Tx2 PA protection ?
  4. On page 86:

"In summary, for Tx calibrations to run successfully:
1.   The ORx must be assigned to internal calibrations by the user for 400ms of transmit time every 2sec.
2.   Assign this time in batches of at least 800 μs, or multiples thereof."
My question is:   how can we work with TD-LTE signal and keep the ORx assigned to internal calibration for such a  long period ?

    5.  On page 87: (Rx QEC Initial Calibration)
         "For optimal Rx path calibration performance, ensure a maximum signal power of −92dBm/MHz is present at the Rx             input. In addition, it is recommended that the Rx input be properly terminated while the calibration is running, as test               tones are output from the receive port."
          My question is:   In this test the Rx input is terminated with 50Ohm. How can I ensure a maximum signal power of               −92dBm/MHz is present at the Rx input ?

    6.  On page 106: (Tx Power Control)
        "Note that transmitter performance may degrade at attenuation settings greater than 20dB."

My questions are: 
a.   Can you explain this sentence ? 20dB is it related to both Tx attenuators or for one of them ?
b.   performance may degrade – What is that means ?

Shay L.