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LMX2615-SP: Assessing the tolerance of the output power within 10 seconds and over 1 year

Prodigy 120 points

Replies: 3

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Part Number: LMX2615-SP

Dear all,

I am asked to do the WCA and assess the tolerance of the output put power LMX2615-SP  under two situations, and verify the usage and then purchase of the LMX.

1. RF system output signal power at the output interface shall be stable better than 0,01% within 10 seconds over the full specified frequency range?

2. When RF output power falls outside Pgoal_min_limt and Pgoal_max_limit the RF system output power shall be stable within +/- 0.01W over 1 year in orbit.

I do not exactly how to assess them.

I believe the first item should be assessed by checking the phase noise. But I do not know how to relate it to 10 seconds? Checking phase noise 0.1 Hz offset of the phase noise diagram is the expected variation of the power level within 10 seconds?

For the second one, I have no clue.

Please let me know, if you are aware of assessing these things in simulation or theoretically.

Best regards

  • Hi Mohammad,

    I am unclear if the first requirement refers to the output power stability in dBm, or the output frequency stability.

    • If the requirement refers to frequency stability, you could use the frequency over time transient analyzer mode of an E5052 (or similar equipment), which tracks frequency changes over time.
    • If the requirement actually suggests output power stability, you will likely want to use an RF power meter or other equipment with the capability to measure signal power. I am unclear how to interpret "better than 0,01%" for output power, when output power is typically reported as a logarithmic value - does this requirement give units for the measured variable?

    For the second requirement, I'm unsure what environmental factors the requirement is trying to control for. You could test a single device at the specified frequencies where RF output power is outside the limits, across supply voltage and temperature, to get an idea of the variation in output power at each frequency that could occur for typical testable environmental reasons. But if the requirement is trying to suggest there may be some change in output power due to radiation-related events, I'm not sure how we can test or simulate this. I will ask if we have any simulation or test data that could help answer this question, but it will take some time to get a reply due to the upcoming US Holiday.

    Derek Payne

    Texas Instruments

  • In reply to Derek Payne:

    Hi Derek,

    The requirements refer to power level in watt.

    As far as I understood from the requirement is that 10 second to second the power level should not vary more than 0.01% of the P_out in watt.

    In measurements, it is almost straight forward what to do. However, my main problem is that I do not know how to assess this requirement by checking the datasheet or simulation.

  • In reply to Mohammad Rajabi1:

    Hi Mohammad,

    I think your requirement is not well defined and does not apply to a component, your requirement is more or less the overall system requirement "at the output interface". (I guess this requirement is used for high power transmitter)

    In addition, no component will specify "output power stability within xxx second".

    Furthermore, 0.01% is an extremely small power variation, I don't think we are able to measure it for a low power device.