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LMX2592: Output Frequency issue

Tommy Tzeng
Genius 5770 points
Part Number: LMX2592

Hi Sir,

could help confirm and provide suggestion as below question,thanks.

customer currently using LMX2592 output is LO: 18.84375 GHz.

OSC in is a 10Mhz external signal, and the OSC 10Mhz input range is -15~+10 dbm.

at present, when the OSC 10Mhz input= 0dbm & -15dbm is tested, but the phase noise difference is 8dB, is this the correct range?

  • 0
    TI__Genius 11900 points

    Hello Tommy,

    -15 dBm does not follow the specification for reference input voltage specified on the datasheet. You require at least 200 mVppd, with -15 dBm you only get ~112 mVppd (assuming you are using a differential input). If single ended then you are only providing half of that.

    -10 dBm for a differential signal is right under the datasheet specification. So power level above -10 dBm must be used.

    In general as the swing is increased the phase noise increases. This effect will be seen more at lower input frequencies.

    Thanks,

    Vibhu