ADN2819 データシートの表示（PDF） - Analog Devices

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ADN2819

Multirate to 2.7 Gb/s Clock and Data Recovery IC with Integrated Limiting Amp

Analog Devices 

ADN2819

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

(see Figure 11).

0.1

ACCEPTABLE

RANGE

SLOPE = –20dB/DECADE

fC

JITTER FREQUENCY (kHz)

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

(see Figure 12). Figure 13 shows the typical OC-48 jitter

tolerance performance of the ADN2819.

15

SLOPE = –20dB/DECADE

1.5

0.15

f0

f1

f2 f3

f4

JITTER FREQUENCY (Hz)

Figure 12. SONET Jitter Tolerance Mask

100

ADN2819

10

1

OC-48 SONET MASK

0.1

1

10

100

1k

10k 100k

1M

10M

MODULATION FREQUENCY (Hz)

Figure 13. OC-48 Jitter Tolerance Curve

Rev. B | Page 10 of 24

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