LOW SKEW, 1-TO-16

DIFFERENTIAL-TO-LVDS CLOCK DISTRIBUTION CHIP

8516 DATA SHEET

6

REVISION B 6/11/15

(12kHz to 20MHz)

= 148fs typical

-50

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-100

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1k

10k

100k

1M

10M

100M

The spectral purity in a band at a specific offset from the

fundamental compared to the power of the fundamental is

called the dBc Phase Noise. This value is normally expressed

using a Phase noise plot and is most often the specified plot

in many applications. Phase noise is defined as the ratio of the

noise power present in a 1Hz band at a specified offset from the

fundamental frequency to the power value of the fundamental.

This ratio is expressed in decibels (dBm) or a ratio of the power in

As with most timing specifications, phase noise measurements

have issues. The primary issue relates to the limitations of the

equipment. Often the noise floor of the equipment is higher

than the noise floor of the device. This is illustrated above. The

the 1Hz band to the power in the fundamental.When the required

offset is specified, the phase noise is called a dBc value, which

simply means dBm at a specified offset from the fundamental.

By investigating jitter in the frequency domain, we get a better

understanding of its effects on the desired application over the

entire time record of the signal. It is mathematically possible to

calculate an expected bit error rate given a phase noise plot.

device meets the noise floor of what is shown, but can actually

be lower. The phase noise is dependant on the input source and

measurement equipment.