Datasheet

Data Sheet ADN2817/ADN2818
Rev. E | Page 19 of 40
JITTER SPECIFICATIONS
The ADN2817/ADN2818 CDR is designed to achieve the best
bit error rate (BER) performance and exceeds the jitter transfer,
generation, and tolerance specifications proposed for SONET/SDH
equipment defined in the Telcordia® Technologies specification.
Jitter is the dynamic displacement of digital signal edges from
their long-term average positions, measured in unit intervals
(UI), where 1 UI = 1 bit period. Jitter on the input data can cause
dynamic phase errors on the recovered clock sampling edge. Jitter
on the recovered clock causes jitter on the retimed data.
The following sections briefly summarize the specifications
of jitter generation, transfer, and tolerance in accordance with
the Telcordia document (GR-253-CORE, Issue 3, September
2000) for the optical interface at the equipment level and the
ADN2817/ADN2818 performance with respect to those
specifications.
JITTER GENERATION
The jitter generation specification limits the amount of jitter
that can be generated by the device with no jitter and wander
applied at the input. For OC-48 devices, the band-pass filter
has a 12 kHz high-pass cutoff frequency with a roll-off of
20 dB/decade and a low-pass cutoff frequency of at least
20 MHz. The jitter generated must be less than 0.01 UI rms
and must be less than 0.1 UI p-p.
JITTER TRANSFER
The jitter transfer function is the ratio of the jitter on the output
signal to the jitter applied on the input signal vs. the frequency.
This parameter measures the limited amount of the jitter on
an input signal that can be transferred to the output signal
(see Figure 26).
0.1
ACCEPTABLE
RANGE
f
C
JITTER FREQUENCY (kHz)
SLOPE = –20dB/DECADE
JITTER GAIN (dB)
0
6001-015
Figure 26. Jitter Transfer Curve
JITTER TOLERANCE
The jitter tolerance is defined as the peak-to-peak amplitude of
the sinusoidal jitter applied on the input signal, which causes a
1 dB power penalty. This is a stress test intended to ensure that
no additional penalty is incurred under the operating conditions
(see Figure 27).
15.00
1.50
0.15
f
0
f
1
f
2
f
3
f
4
JITTER FREQUENCY (kHz)
SLOPE = –20dB/DECADE
INPUT JITTE
R
AMPLITUDE (UI p-p)
06001-016
Figure 27. SONET Jitter Tolerance Mask