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AWR2243: Samples decay

Yuval Peleg
Prodigy 10 points
Part Number: AWR2243

Hi,

We utilize the AWR2243 in cascade mode and have observed a tendency for our sample signals to decay towards the end of the chirp, as illustrated in the image below.



The chirp configuration was as follows:
- Center frequency: 78.78 GHz
- Chirp slope: 75.027 MHz/µs
- Total Chirp Cycle time: 27.5 µs
- Modulation bandwidth and ADC sampling: 1.50054 GHz
- Chirp Time (RF On): 24 µs

This issue was consistent across all samples tested with the AWR2243 chip. To investigate the issue further, we conducted a laboratory test where we injected two CW signals and used a horn antenna to receive the input. We then compared the IF received signal amplitude versus the CW signal. (see image below)


The results indicated a significant decrease (about 14dB) in gain versus frequency within our chirp bandwidth. However, in the same bandwidth at a different band, we observed much better gain flatness with only about 1dB decrease. see the below image.

Could you suggest any reasons for the significant RX gain drift observed and propose solutions to address this issue?

Thanks



  • 0
    TI__Mastermind 26915 points

    Hello,

    Is this a custom antenna? Your antenna gain will not be flat across frequency so there is probably a drop in gain as the frequency increases. 

    Regards,

    Adrian

  • 0 in reply to aozer
    Prodigy 10 points

    Hi Adrian,
    The antenna is custom-designed. We've verified its flatness at our target frequency both through simulations and actual measurements.
    The antennas used for TX and RX are identical. Measurements carried out on the TX antenna demonstrate satisfactory uniformity, leading us to expect similar performance from the RX antenna.

    Regards,
    Yuval

  • 0 in reply to Yuval Peleg
    TI__Mastermind 26915 points

    Hello,

    Is this phenomenon occurring on both master and slave devices? Have you checked the TX power, RX gain, and PMCLKLO monitors and if not, can you check these monitors?

    Lastly, I am assuming this is all done at room temperature. How are you setting up the RF INIT and run time calibrations?

    Regards,

    Adrian