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AFE7700EVM: How to provide the input through RX1 SMA pin to ADC

Part Number: AFE7700EVM
Other Parts Discussed in Thread: AFE7700

Hi,

Our understanding of the repeater mode case from the TI ticket "AFE7700EVM: How to read the register space - RF & microwave forum - RF & microwave - TI E2E support forums" is that we are using the internal data as input to the ADC. Now we want to feed an analog signal at RX1 input(Please refer to the screenshot below) and observe this at the TX1 SMA pin.

When I provide a 1Mhz, 1Vp-p sine wave at RX1 SMA pin, I am not seeing any signal at the TX1 SMA. I checked in the register MAP of ADC and DAC to find if there is any register that enables the ADC to take input from SMA (Simillarly for DAC to feed the output at SMA), I couldn't find any. 

Can you please help me here?

Thanks.

Jaswanth

  • Providing the screenshot of the path tested

  • Jaswanth,

    In repeater mode RX input signal gets converted to digital data by RX chain and sent as digital input to TX chain. It's not possible to use internal data as input to RX or ADC chain.

    RF input/output frequency range supported by AFE7700 is 600MHz to 6GHz. The EVM you are using is optimized for 3.5GHz frequency band. 1MHz input signal will not work.

    You can set the LO in config script to 3.5GHz and use input tone at 3.51GHz to test this mode. 

    Regards,

    Vijay

  • "RF input/output frequency range supported by AFE7700 is 600MHz to 6GHz. The EVM you are using is optimized for 3.5GHz frequency band. 1MHz input signal will not work."  --> Just for clarity do you mean RF input/output frequency range or clock input frequency range? Can you give me an example of an input that we can provide at RX1 Input (Please provide frequency as well as amplitude)

  • Just for clarity do you mean RF input/output frequency range or clock input frequency range?

    RF input/output frequency range

    Can you give me an example of an input that we can provide at RX1 Input (Please provide frequency as well as amplitude)

    3.51GHz and -16dBm.

    You can refer to AFE7700 datasheet for RF input/output frequency range and input/output full scale power levels. Datasheet can be accessed at www.ti.com/mysecuresoftware 

    Regards,

    Vijay

  • Thanks for the reply Vijayendra!

    Currently, we do not have the equipment to provide a 3.51G sine wave. In section 8.13 of the AFE7700 datasheet, we observed Flo and Fin combination of 815MHz and 825MHz respectively. Can you please confirm if we can use that combination?

  • We provided following input tone at RX1, none of them worked as I saw only noise at TX1 output

    Fin – 825MHz

    Flo – 810MHz

    data rate = 245.76 MSPS

    fADC = 2949.12 MSPS

    12x decimation

    Vp-p – Tried 0.8, 1, 2.1

    We are seeing some noise at TX1 output, but this is coming only when we are providing a signal at RX1 input. When we remove the input we are seeing the flat line at TX1. Any modifications in DAC parameters you suggest for this issue?

    The signal we are seeing at TX1 out:

    Thanks