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LMX2592: Tantalum Bypass Capacitor

Randy4TIics
Prodigy 165 points
Part Number: LMX2592

What would be the problem of using tantalum capacitors on VREGIN, VREFVCO, VREGVCO, VREFVCO2, VBIASVCO, VBIASVCO2, VBIASVARAC instead of ceramics? If environment has strong and inherent vibration ceramic capacitors (>1uF) might affect phase noise due to their piezo-electric noise.

  • 0
    TI__Mastermind 28001 points

    Randy,

    We always use ceramic capacitors for this characterization and these capacitors are important to roll off noise.

    For these pins, the DC bias levels might be different as well.

    So in summary, theoretically what you say makes sense.  However, since we have never tried it, it makes me apprehensive.  So the only drawback I see is that it hasn't been tried and we dont' test under these conditions.  If you do try this, I would be curious as to what you find.

    Regards,
    Dean

  • 0
    TI__Genius 11900 points

    Hello Randy,

    The vibration will probably hurt your reference clock the most. However for the LMX2592, I would still recommend the ceramic capacitors. Ceramic capacitors are more stable with respect to the ESR.

    Thanks,

    Vibhu