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SN65HVD62EVM　about　Spurious characteristic

Tomohiko Sugiyama
Intellectual 815 points

Hi

Please advice about the validity of the measurement results.

My customer was measured spurious characteristics.

But the Result is worse than standard of AISG.

(Only when conditions over 700MHz)

The measurement results are correct?

Please refer to the Appendix.

Best regards

Sugiyama

2022.Spurious characteristic.pdf

  • 0
    TI__Mastermind 21952 points

    Hi Sugiyama-san,

    Can you share the positions that you have the jumpers in on the EVM? JU4 sets the output voltage of the TXOUT pin.

    I will check with the team to see if the EVM set-up is the same as the AISG test that we are claiming compliance to in the datasheet. From experience I know that board layout has a very large impact on the emissions performance at high frequencies. In addition the requirement of around -100dBm for the high frequency emissions is very hard to meet even from a testing stand point. Is the customer making these measurements in an anechoic chamber? What does the test set-up look like?

    I will follow up when I know more.

    Thanks,

    John

  • 0 in reply to John Griffith
    Intellectual 815 points

    Ｈｉ　John-san

    I'm sorry for the late reply.

    JU4 position is 2-3(RESpin voltage is 1.5V(max))

    >>these measurements in an anechoic chamber?

    YES,They were put  evaluation board, DC power, HPF (high bandwidth measurement)in a shielded box.

    I'm looking forward to reply.

    Best regards

    Sugiyama


  • 0 in reply to Tomohiko Sugiyama
    TI__Mastermind 21952 points

    Hi Sugiyama-san,

    I just heard back from the team that developed the device (sorry I was not part of it), and they said that the EVM was not tuned for high frequency performance. They reiterated that the results will be very dependent on the board layout.

    The team had originally planned to create another board that was specifically designed for RF performance, but that has not been completed yet. We have however had two customers successfully integrate the device into their systems without any mask violations.

    If I am able to get any plots on high frequency performance I will share them with you, but as of now the team does not have any to share. I am sorry that I do not have better news.

    Thanks,

    John

  • 0 in reply to John Griffith
    TI__Mastermind 21952 points

    Hi Sugiyama-san,

    Sorry for the second message, I just heard back one more thing from the design team.

    “The most important part of the spec for AISG modem vendor is from 9kHz up to 30MHz. 30MHz-12.75GHz section is more like a system level requirements including the bias-T in antenna line up. Bias-T provides isolation / attenuation on frequencies higher than 30MHz, so the AISG modem as a standalone component does not need to meet 30MHz-12.75GHz section.“

    Thanks,

    John

  • 0 in reply to John Griffith
    Intellectual 815 points

    Hi John-san

    I'm so grateful that you were able to help us with this.

    Best regards

    Sugiyama