Datasheet

Data Sheet ADN2812
Rev. E | Page 13 of 28
JITTER SPECIFICATIONS
The ADN2812 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 equip-
ment defined in the Telcordia Technologies GR-253-CORE
document.
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, jitter transfer, and jitter tolerance in
accordance with the GR-253-CORE from Telcordia for the
optical interface at the equipment level and the ADN2812
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 15).
04228-015
0.1
ACCEPTABLE
RANGE
f
C
JITTER FREQUENCY (kHz)
SLOPE = –20dB/DECADE
JITTER GAIN (dB)
Figure 15. 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 to ensure that no addi-
tional penalty is incurred under the operating conditions (see
Figure 16).
04228-016
15.00
1.50
0.15
f
0
f
1
f
2
f
3
f
4
JITTER FREQUENCY (kHz)
SLOPE = –20dB/DECADE
INPUT JITTERAMPLITUDE (UI p-p)
Figure 16. SONET Jitter Tolerance Mask