• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 29 subscribers
  • Views 739 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AWR1243: What is minimum/threshold input power of 20 GHz signal is required for cascade to reliably work ?

Vladimir Kolinko1
Prodigy 240 points
Part Number: AWR1243

The cascade application note suggests that AWR1243 20GHz output power is +6dBm and illustrates 6dB loss as an example. But what minimum/threshold input power is required for the 20 GHz sync cascade crct in the chip to  reliably work? Is it 0dBm  ( 6dBm output- 6db loss) or less? Thank you.

  • 0
    TI__Guru*** 148154 points
    Hi,

    We have to check with out hw design team.

    Will get back to you as soon as possible

    thank you
    Cesar
  • 0 in reply to Cesar
    TI__Mastermind 18470 points
    Hi Vladimir,

    At the moment, TI is specifying the LO distribution specification implicitly through an acceptable, example LO distribution link budget. This is captured in Table 7 of the AWR1243 Cascade Application Report: www.ti.com/.../swra574a.pdf

    The minimum input power is the minimum power shown in that link budget at the FMCW_SYNCIN pins: 0.1dBm. This is just the 6dBm output power minus the transmission-line and power divider losses.

    Please let me know if that answers your questions on this topic.

    Thanks.
    Randy
  • 0 in reply to Randy Rosales
    Prodigy 240 points
    Hi Randy,

    I am pretty sure that TI RF team has measured the minimum 20GHz input power required for the chip to run properly. The question here is whether it is necessary or wasteful to put an RF amp and supporting circuitry around if input is a few dB less that shown in the TI example.
    Is it possible to ask someone knowledgeable of this data?

    Thank you,
    Vladimir.
  • 0 in reply to Vladimir Kolinko1
    TI__Mastermind 18470 points
    Hi Vladimir,

    Yes, the device has been characterized to look at performance vs. LO input power. I have also discussed this topic further with the design team here. The 0.1 dBm input power values shown in the implicit link budget specification at the FMCW_SYNCIN pins are the current recommended minimum input power. This minimum LO power ensures minimum PA input power, as well as phase noise performance of the TX chain.

    So the current recommendation would be to do whatever you can in your design to meet this minimum LO input power number. As you progress to LO input power below this link budget minimum your system may show increased phase noise and degraded TX output power.

    Again, from the link budget, the FMCW_SYNCOUT and FMCW_CLKOUT pins both provide +6dBm output power for LO distribution. Is there something in your system design which results in more than 6dB of losses on the LO path?

    Thank you,
    Randy
  • 0 in reply to Randy Rosales
    Prodigy 240 points

    Hi Randy,

    Thank you for doing more research on this topic. Our design will have longer transmission lines with a few dB higher than 3dB insertion loss not including dividers. We were hoping to save some real estate on the PCB by not using 20GHz amps.

    Vladimir.