Hi,

I'm doing the Rx test in AD9364 with KC705.

Based on your inputs I'm able to control the Rx gain manually and observe the RSSI in a periodic manner.

The observation is that mostly the increase in gain and RSSI are gradual but at some specific areas, RSSI is getting changed in an unexpected manner.

Below is the data collected for different values of the Rx gain. Please check the highlighted areas. Observed issues are below.

- When gain is changed from 2 to 3, there is a change of 4dB in the RSSI.
- For few Rx gain values like 61 and 67, the RSSI value gets reduced instead of increase.

Note: These observations are same in repeated runs of the scenario.

Could this be due to some saturation of gain in any of the gain location (LNA/ Mixer/ TIA)?

If so, can we get the status of these saturation/ overload from any registers?

Value of SPI Register 0x2b8 is always seen as 0x20. Does it indicate that the input signal is very low power?

During the test, the input signal was kept constant and in the ILA we could see the data waveform.

Please help in understanding this better.

Thank you,

~Jinoj

RxGain: | -4 |

rssi: | 50.75 |

RxGain: | -3 |

rssi: | 50.75 |

RxGain: | -2 |

rssi: | 51.75 |

RxGain: | -1 |

rssi: | 52.75 |

RxGain: | 0 |

rssi: | 53.75 |

RxGain: | 1 |

rssi: | 54.75 |

RxGain: | 2 |

rssi: | 55.75 |

RxGain: | 3 |

rssi: | 59.75 |

RxGain: | 4 |

rssi: | 60.75 |

RxGain: | 5 |

rssi: | 61.75 |

RxGain: | 6 |

rssi: | 62.75 |

RxGain: | 7 |

rssi: | 63.75 |

RxGain: | 8 |

rssi: | 64.75 |

RxGain: | 9 |

rssi: | 65.75 |

RxGain: | 10 |

rssi: | 66.75 |

RxGain: | 11 |

rssi: | 67.75 |

RxGain: | 12 |

rssi: | 68.75 |

RxGain: | 13 |

rssi: | 69.75 |

RxGain: | 14 |

rssi: | 70.75 |

RxGain: | 15 |

rssi: | 71.75 |

RxGain: | 16 |

rssi: | 72.75 |

RxGain: | 17 |

rssi: | 73.75 |

RxGain: | 18 |

rssi: | 74.75 |

RxGain: | 19 |

rssi: | 75.75 |

RxGain: | 20 |

rssi: | 76.75 |

RxGain: | 21 |

rssi: | 77.75 |

RxGain: | 22 |

rssi: | 78.75 |

RxGain: | 23 |

rssi: | 79.75 |

RxGain: | 24 |

rssi: | 80.75 |

RxGain: | 25 |

rssi: | 82.75 |

RxGain: | 26 |

rssi: | 83.75 |

RxGain: | 27 |

rssi: | 84.75 |

RxGain: | 28 |

rssi: | 85.75 |

RxGain: | 29 |

rssi: | 86.75 |

RxGain: | 30 |

rssi: | 86.75 |

RxGain: | 31 |

rssi: | 87.75 |

RxGain: | 32 |

rssi: | 88.75 |

RxGain: | 33 |

rssi: | 89.75 |

RxGain: | 34 |

rssi: | 90.75 |

RxGain: | 35 |

rssi: | 91.75 |

RxGain: | 36 |

rssi: | 92.75 |

RxGain: | 37 |

rssi: | 93.75 |

RxGain: | 38 |

rssi: | 94.75 |

RxGain: | 39 |

rssi: | 95.75 |

RxGain: | 40 |

rssi: | 96.75 |

RxGain: | 41 |

rssi: | 97.75 |

RxGain: | 42 |

rssi: | 98.75 |

RxGain: | 43 |

rssi: | 99.75 |

RxGain: | 44 |

rssi: | 100.75 |

RxGain: | 45 |

rssi: | 101.75 |

RxGain: | 46 |

rssi: | 102.75 |

RxGain: | 47 |

rssi: | 103.75 |

RxGain: | 48 |

rssi: | 104.75 |

RxGain: | 49 |

rssi: | 105.75 |

RxGain: | 50 |

rssi: | 105.75 |

RxGain: | 51 |

rssi: | 106.75 |

RxGain: | 52 |

rssi: | 107.75 |

RxGain: | 53 |

rssi: | 108.25 |

RxGain: | 54 |

rssi: | 109 |

RxGain: | 55 |

rssi: | 110 |

RxGain: | 56 |

rssi: | 111 |

RxGain: | 57 |

rssi: | 112 |

RxGain: | 58 |

rssi: | 113 |

RxGain: | 59 |

rssi: | 113 |

RxGain: | 60 |

rssi: | 114.25 |

RxGain: | 61 |

rssi: | 112.25 |

RxGain: | 62 |

rssi: | 115.5 |

RxGain: | 63 |

rssi: | 116.5 |

RxGain: | 64 |

rssi: | 116.5 |

RxGain: | 65 |

rssi: | 117.75 |

RxGain: | 66 |

rssi: | 118.25 |

RxGain: | 67 |

rssi: | 118 |

RxGain: | 68 |

rssi: | 118.75 |

RxGain: | 69 |

rssi: | 118.5 |

RxGain: | 70 |

rssi: | 119.25 |

RxGain: | 71 |

rssi: | 118.5 |

How much signal was applied at the input? It is possible that with too much signal the part is compressing.

UG-570 describes how the gain is controlled in the part. You can read section Custom Gain Tables which will provide you a lot of insight on gain control. Gain Tables can be found here: Gain Tables in .csv format

Gain tables show how much gain each stage in the signal chain has vs gain index.

You can download AD9361 documentation at this link:

AD9361 and AD9364 Integrated RF Agile Transceiver Design Resources | Analog Devices