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LMK00105: noise floor of output

Shubiao Wang
Intellectual 1490 points
Part Number: LMK00105


Hi there,

test condition:

1. the input is OSCin pin, 

2. frequency is 52Mhz, 

when the input changes from 1.8V to 1V, the noise floor of OUTPUT increases more than 10dB. 

my understanding is when the input voltage decreases, the SNR will drops about 6dB. however the noise increasing is far more than 6dB (more than 10dB), please help me figure out why the noise floor increases so much?

BRs

Shubiao

  • 0
    TI__Genius 13680 points

    Hi Shubiao, 

    One possibility is the input slew rate decreases when the input swing is reduced, which can make performance worse. Also, for frequencies above 40 MHz it is recommended to use the ClkIn pin instead of OSCIn as it has better performance overall. I would recommend trying the configuration shown in Figure 6 if possible. 

    Regards, 

    Connor