NB3V110xC Series

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7

tr

Qn

80% V OH −VOL

CLKIN

tf

20% V OH −VOL

VOH

V OL

tPLH

V DD /2

Qn

V DD /2

CLKIN

tPHL

 

r

Output

F_carrier = 100 MHz

Output (DUT + Source)

Input Source

Integration Range: 12 kHz − 20 MHz

DUT + Source Phase Jitter = 66.92 fs

Input Source Phase Jitter = 36.72 fs

Input Source 100 MHz

The above phase noise data was captured using Agilent

E5052A/B. The data displays the input phase noise and

output phase noise used to calculate the additive phase jitter

at a specified integration range. The additive RMS phase

jitter contributed by the device (integrated between 12 kHz

and 20 MHz) is 55.94 fs. The additive RMS phase jitter

performance of the fan out buffer is highly dependent on the

phase noise of the input source.

To obtain the most precise additive phase noise

measurement, it is vital that the source phase noise be

notably lower than that of the DUT. If the phase noise of the

source is greater than the noise floor of the device under test,

the source noise will dominate the additive phase jitter

calculation and lead to an incorrect negative result for the

additive phase noise within the integration range. The

Figure above is a good example of the NB3V110xC source

generator phase noise having a significantly lower floor than

the DUT and results in an additive phase jitter of 55.94 fs.

Additive RMS phase jitter

+ RMS phase jitter of output2 * RMS phase jitter of input2

55.94 fs