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INACCURACY IN RX STEP ATTENUATION of AFE7950

dharani vykuntam
Prodigy 60 points

Part Number: AFE79xx

Tool/software:

Hello, I am trying to implement step attenuator using LATTE, and i have setting like sysParams.defaultRxDsa =[0,0,0,0], sysParams.defaultFbDsa = [0,0] ,sysParams.defaultTxDsa =[0,0,0,0] .

  1. AFE.DSA.setRxDsa(chNo,dsaSetting)
  2. AFE.DSA.setTxDsa(chNo,dsaSetting)    

 I am using these 2 functions in order to attenuate the TX,RX power .What i observed is TX attenuation is working fine i.e., the output attenuated power of TX has mostly 0 -1 dB difference, But when it comes to RX POWER ATTENUATION.Let's say the output power at 0 dB is 0.If i gave  AFE.DSA.setRxDsa(0,5), The output i am getting -4.20 dB, If i gave  AFE.DSA.setRxDsa(0,10), The output i am getting (-7.86) dB, If i gave AFE.DSA.setRxDsa(0,15), The output i am getting -12. 37 dB .So the attenuation is not happening accurately for  the RX SIDE , What could be the reason for it ? Do i need to change any setting on the latte ? 

anticipating positive response.

  • 0
    TI__Genius 14961 points

    Hi Dharani,

    The AFE RX DSA has a gain and phase correction block to reduce error in gain and phase for each DSA settings, as described in section 8.3.2.2 in the datasheet. The calibration procedure is detailed in a guide 'AFE79xx_RxDSACalibrationProcedure', which is available in the AFE79xx secure folder under 'Application_Notes'. 

    Regards,

    David Chaparro