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AD9361 RX2A gain table

Question asked by dinc@coherentlogix.com on Oct 29, 2015
Latest reply on Oct 30, 2015 by dinc@coherentlogix.com

Hi,

 

I'm running some tests to generate some BER curves for ODFM based waveform using RX2A path  on the receiver. Basically the input power level is decreased 1 dB step at a time and the BER is calculated on certain amount of received frames. Previously I used RX2B and RX1C paths and had no issues with the gain index increasing up to 76 (d) (as the input power level decreases the gain index goes up to 76)

However with path  RX2A it looks like there's an issue with the internal LNA's last stage (Register addr  = 0x131 Value = 0x6X). When it's turned on, or supposed to be turned on the gain index gets stuck around the previous stage and doesn't move to higher index. I checked the tables and tried various gain tables and moved this to the later part of the table (as high as where gain table index = 74 ) but I still see the issue or the gain index stays around the previous index for a while although the input power level keeps decreasing.

Why would this happen?

Any help/suggestion would be appreciated.

 

Thank you,

Best Regards,

Asli

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