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AFE7070EVM: RF Output Spectrum not as expected

Janardan M
Expert 1115 points

Part Number: AFE7070EVM

Hi,

We are working on TSW1400EVM interface with AFE7070EVM, we followed the set up as given in the AFE7070EVM user guide. On J4 connector of AFE7070EVM we are feeding 130MHz clock from external clock generator. To LO_In we are feeding 2.1GHz clock from external generator. Attached is the images of the configurations done for TSW1400EVM and AFE7070EVM. 

We generated the tones from GUI and followed the instructions given in user guide towards configuring AFE7070, TSW1400EVM and CDCM Clock generator. We are not able to see the expected spectrum.

The spectrum what we are seeing is attached with this thread, please find the same and suggest us to solve the issue.

Thanks,

Janardan M TSW1400-AFE7070.zip,

  • 0
    TI__Guru 70619 points

    Hi Janardan,

    I recall the AFE7070 EVM USB chip is not enumerate. It is possible that during the connection of both the TSW1400 and AFE7070 EVM that the AFE7070EVM GUI mistakenly grabbed on to the TSW1400 USB Chip or other USB peripherals. 

    Based on your screen shot, it is possible that the AFE7070EVM is not properly programmed.

    Please try the following:

    1. connect only the AFE7070EVM, do not connect the TSW1400 EVM

    2. launch the AFE7070EVM GUI, do not launch HSDC PRO GUI

    3. connect AFE7070EVM GUI to the AFE7070EVM by pressing "reset USB port " button. By now, the AFE7070 EVM should be connected to the GUI

    4. launch TSW1400EVM and HSDC PRO, connect to them and configure accordingly.

    Please also disconnect any other USB peripherals as the same USB chip is being shared among other common debugger tools such as Intel's byteblaster, etc.

    Please give it a try and report back.

    -Kang

  • 0 in reply to Kang Hsia
    Expert 1115 points

    Hi Kang,

    Thanks for the response. I am using 2 different laptops wherein on one laptop AFE7070EVM GUI is used and on other HSDC PRO is being used. Followed the procedure given in the document. The attached spectrum from the  previous post is from this setup. 

    On datasheet it is given  that qmc_gaina, qmc_gainb, qmc_gainc are the registers which are to be configured to compensate for I and Q imbalance present in an analog quadrature modulator. Also, it is given that LO feed through can be minimized by adjusting the DAC offset. Registers qmc_offseta(12:0) and qmc_offsetb(12:0) control the I and Q path offsets and are 13-bit values with a range of –4096 to 4095. I am not clear about on what basis can i set the values, is there some equations or some reference to decide on the value to be set.

    Thanks and Regards,

    Janardan M

  • 0 in reply to Janardan M
    Expert 1115 points

    HI,

    Can I expect the update?

    Thanks,

    JanardanM

  • 0 in reply to Janardan M
    TI__Guru 70619 points

    Hi,

    Regarding your question:

    Janardan M said:
    On datasheet it is given  that qmc_gaina, qmc_gainb, qmc_gainc are the registers which are to be configured to compensate for I and Q imbalance present in an analog quadrature modulator. Also, it is given that LO feed through can be minimized by adjusting the DAC offset. Registers qmc_offseta(12:0) and qmc_offsetb(12:0) control the I and Q path offsets and are 13-bit values with a range of –4096 to 4095. I am not clear about on what basis can i set the values, is there some equations or some reference to decide on the value to be set.

    The IQ imbalance can be corrected on an iterative approach. 

    please refer to section 8.6 and 8.7 of the sideband and LO correction procedure. it is applicable to AFE7070 as well.

    http://www.ti.com/lit/ug/slwu029d/slwu029d.pdf