AD9577BCPZ-R7 datasheet(26/44 Pages) AD

26 / 44 page

AD9577

Data Sheet

Rev. A | Page 26 of 44

Therefore, to accurately estimate the TJ p-p, separate

measurements of the rms value of the random jitter (RJ rms)

and the peak-to-peak value of the deterministic jitter (DJ p-p)

must be taken. To measure the RJ rms of the clock signal,

integrate the clock phase noise over the desired bandwidth, with

spurs disabled (that is, removed) from the measurement. If the

DJ spurs were included in the measurement, the DJ

contribution would also be multiplied by 14.06 in Equation 2,

leading to a grossly pessimistic estimate of the total jitter. This is

why it is important to measure the integrated jitter with spurs

disabled. Due to the 14.06 factor in Equation 2, the spurious DJ

components on the clock output only have a small impact on

the TJ p-p measurement and, consequently, the system BER

performance. Therefore, it is clear that the DJ component (that

is, the spur) should not be added to the rms value of the random

jitter directly. However, if the phase noise jitter measurement

was preformed with spurs enabled, this is exactly what the

measurement would be reporting. For more background

information, see Fibre Channel, Methodologies for Jitter and

Signal Quality Specification-MJSQ, Rev. 14, June 9, 2004.

AD9577BCPZ-R7 Datasheet(PDF) 26 Page - Analog Devices