REV. A

–8–

ADN2811

JITTER SPECIFICATIONS

The ADN2811 CDR is designed to achieve the best bit-error-rate

(BER) performance and has exceeded the jitter generation, trans-

fer, 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 section briefly summarizes 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

ADN2811 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 should be less than 0.01 UI rms and 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 versus the fre-

quency. This parameter measures the limited amount of jitter

on an input signal that can be transferred to the output signal

(see Figure 7).

SLOPE = –20dB/DECADE

JITTER FREQUENCY – kHz

0.1

ACCEPTABLE

RANGE

Figure 7. 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 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 (see Figure 8). Figure 9 shows the typical OC-48

jitter tolerance performance of the ADN2811.

SLOPE = –20dB/DECADE

JITTER FREQUENCY – Hz

15

1.5

0.15

Figure 8. SONET Jitter Tolerance Mask

MODULATION FREQUENCY – Hz

1.00E+01

1.00E+03

1.00E+05

1.00E+07

1.00E+02

1.00E+01

1.00E–01

1.00E+00

1.00E+02

1.00E+04

1.00E+06

1.00E+00

ADN2811

OC-48 SONET MASK

Figure 9. OC-48 Jitter Tolerance Curve