ADN2819
Rev. B | Page 10 of 24
LOS RESPONSE TIME
The LOS response time is the delay between the removal of the
input signal and indication of loss of signal (LOS) at SDOUT.
The ADN2819’s response time is 300 ns typ when the inputs are
dc-coupled. In practice, the time constant of ac-coupling at the
quantizer input determines the LOS response time.
JITTER SPECIFICATIONS
The ADN2819 CDR is designed to achieve the best bit-error-
rate (BER) performance, and has exceeded 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 UI (unit
intervals), 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 summarize the specifications of the 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
ADN2819 performance with respect to those specifications.
Jitter Generation
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 should be less than 0.01 UI rms
and 0.1 UI p-p.
Jitter Transfer
Jitter transfer function is the ratio of the jitter on the output
signal to the jitter applied on the input signal versus the
frequency. This parameter measures the limited amount of jitter
on an input signal that can be transferred to the output signal
SLOPE = –20dB/DECADE
JITTER FREQUENCY (kHz)
0.1
J
ITTE
R
GAIN
(dB)
fC
ACCEPTABLE
RANGE
02999-B
-011
Figure 11. Jitter Transfer Curve
Jitter Tolerance
Jitter tolerance is defined as the peak-to-peak amplitude of the
sinusoidal jitter applied on the input signal that causes a 1 dB
power penalty. This is a stress test that is intended to ensure no
additional penalty is incurred under the operating conditions
tolerance performance of the ADN2819.
SLOPE = –20dB/DECADE
f0
f1
f2
f3
f4
JITTER FREQUENCY (Hz)
15
1.5
0.15
IN
P
U
T
J
ITTE
R
AMP
L
IT
UDE
(UI
)
02999-B
-012
Figure 12. SONET Jitter Tolerance Mask
MODULATION FREQUENCY (Hz)
10
1k
100k
10M
100
10
0.1
A
M
P
L
ITUDE
(UI
p
-p
)
1
100
10k
1M
1
ADN2819
OC-48 SONET MASK
02999-B
-013
Figure 13. OC-48 Jitter Tolerance Curve