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Original question:

AWR1243: Output Power in Cascaded Mode

AWR1243: Output Power in Cascaded Mode

Kim Byungkwan
Prodigy 140 points
Part Number: AWR1243

Dear AWR1243 Experts,

I developed AWR1243 cascaded device with ES2.0 and I had simple tests with devices.
Recently, I read a post about power degradation issue at cascaded device. (the related question)

It seems that this problem is very critical for my system because I'm planning to gather precise radar data.

I had to post this question because I don't have enough facility to evaluate current system as TI has.

Referring to Vivek's answer to previous post, I have some questions as below.

1. Just to clarify once again, is this problem happening for "master device" or "all master & slave devices"?

I wonder if the 20GHz SYNCIN pin is problem, maybe all other devices can be affected in cascaded configuration.
Or it may be limited to master device because it is only device that generates and feeded back LO signal.

1-a. Can we workaround this by not using transmiters of master device? (Using master device as receiver with giving up 3 Tx...)

1-b. Is it possible to share your test results in this forum? or do I need NDA to see results?

1-c. Is this power degradation happening when

              a. 20GHz Sync is distributed via both FM_CW_SYNCOUT and FM_CW_CLKOUT
              b. when using one of FM_CW_SYNCOUT or FM_CW_CLKOUT

also, when 20GHz signal is looped back to master and fed to

              c. any pin between FM_CW_SYNCIN1 or FM_CW_SYNCIN2
              d. or specific one pin FM_CW_SYNCIN1 or 2

1-d. Is it possible to compensate the power degradation of 20GHz signal to master device, by using some amplifiers in LO distribution circuit?

1-e. Regardless of Tx power backoff that I set, it seems that it is not able to transmit constant power with AWR1243 ES2.0 cascaded device in 77-81 GHz?

2. To update cascaded device with ES3.0, Could you let me know how I can update the system? I can't find out any detail resources.

2-a. Is ES3.0 only available to NDA users for now?

  • 0
    TI__Mastermind 18500 points

    Hi Kim,

    Can you please link to the exact E2E post you are referencing to help me answer your questions?

    1. Just to clarify once again, is this problem happening for "master device" or "all master & slave devices"?

    I wonder if the 20GHz SYNCIN pin is problem, maybe all other devices can be affected in cascaded configuration.
    Or it may be limited to master device because it is only device that generates and feeded back LO signal.

    [TI] TX power in Cascaded operation becomes a function of the FMCW_SYNCIN1 or FMCW_SYNIN2 at lower input power levels. As explained the AWR1243 Cascade applicatio note, designs should target FMCW_SYNCIN power to be 0dB or better at the BGA. www.ti.com/.../swra574a.pdf. The same requirement exists on the Master and Slave devices.

    1-a. Can we workaround this by not using transmiters of master device? (Using master device as receiver with giving up 3 Tx...)

    [TI] not applicable question -- see question 1.

    1-b. Is it possible to share your test results in this forum? or do I need NDA to see results?
    [TI] Please contact your local TI sales representative to discuss this issue.

    1-c. Is this power degradation happening when

    a. 20GHz Sync is distributed via both FM_CW_SYNCOUT and FM_CW_CLKOUT
    b. when using one of FM_CW_SYNCOUT or FM_CW_CLKOUT

    [TI] There is no difference between FMCW_SYNCOUT/CLKOUT performance. No difference in performance when one or both 20 GHz output are used.

    also, when 20GHz signal is looped back to master and fed to

    c. any pin between FM_CW_SYNCIN1 or FM_CW_SYNCIN2
    d. or specific one pin FM_CW_SYNCIN1 or 2

    [TI] Currently the released firmware (DFP v1.2.0) only supports FMCW_SYNCIN1 input in Cascade mode.

    1-d. Is it possible to compensate the power degradation of 20GHz signal to master device, by using some amplifiers in LO distribution circuit?
    [TI] Additional, external 20GHz PA could be integrated into the path to increase available link budget, but all phase matching and minimum/maximim LO input power requirements must still be met for Cascade operation.

    1-e. Regardless of Tx power backoff that I set, it seems that it is not able to transmit constant power with AWR1243 ES2.0 cascaded device in 77-81 GHz?
    [TI] Please explain this question further. A particular backoff setting should produce a relatively constant output power across operating frequency. What do you see power being a function of other than backoff?

    2. To update cascaded device with ES3.0, Could you let me know how I can update the system? I can't find out any detail resources.
    [TI] Please contact your local TI sales representative to discuss this issue.

    2-a. Is ES3.0 only available to NDA users for now?
    [TI] Please contact your local TI sales representative to discuss this issue.

    Thank you,
    -Randy

  • 0 in reply to Randy Rosales
    Prodigy 140 points

    Dear Randy,

    Thanks for quick response to my question.

    The original E2E post I referred is :

    In this post, the question and answer from Vivek both tells us a ES2.0 cascaded device has power degradation from 77GHz-81GHz (and getting worse at higher frequency).

    I want to clear out some ambiguity from Vivek's answer.

    Could you please update your feedback based on this problem?

    I understood that I have to transfer some part of these questions via e-mail, not by e2e post.

    Best regards,

  • 0 in reply to Kim Byungkwan
    TI__Mastermind 18500 points
    Hi Kim,

    The problem Vivek referenced has to do specifically with ES2.0 devices operating in Cascade Master mode. In this Cascade master mode there has been an observed, unexpected, -10dBm output power degradation from 77-81GHz.

    This is not the case in ES3.0 devices, and this is not the case with single device mode or Cascade slave mode operation.

    Is there anything else you need cleared up specifically?

    Thank you,
    -Randy