GS2985 datasheet(22/45 Pages) SEMTECH

22 / 45 page

GS2985 Multi-Rate SDI Reclocker with Equalization &

De-emphasis

Data Sheet

36663 - 5

July 2012

22 of 45

Proprietary & Confidential

The new LOS detector uses a measure of both signal amplitude and duration to minimize false

detection of the impulse like signals that are characteristic of cross-talk. In this mode, the signal

is tapped off at the output of the equalizer stage, prior to the high gain buffers.

The threshold setting within the detector can be adjusted to increase or decrease its sensitivity.

Gennum recommends using the least sensitive threshold level. This provides the most margin

against false de-assertion of LOS.

The LOS mode can be selected by using the host interface, in register TOP_1 (address 0x02).

4.7 Serial Digital Reclocker

The output of the Equalizer is fed to the reclocker. The function of the reclocker is to re-time the

input signal and to generate system clocks.

The reclocker operates at three frequencies; 2.97Gb/s, 1.485Gb/s and 270Mb/s, and provides a

minimum input jitter tolerance of 0.8UI to square-wave-modulated jitter at these rates.

When there is no serial input signal, the internal clock maintains a frequency close to the

expected incoming data rate, by locking to the external reference crystal.

4.8 Lock Detection

The lock detect block indicates, via the active-high LOCKED signal, when the device has

achieved lock to the incoming data stream.

The lock logic within the GS2985 includes a system that monitors the frequency and the phase

of the incoming data, as well as a monitor to detect harmonic lock.

The LOCKED output signal is also available via the host interface.

Table 4-5: Suggested LOS Threshold Settings

LOS Detection

Method Select

LOS Threshold

Adjust

Input Signal

Amplitude

>250mV

0x1

0x0

200mV to 250mV

0x1

150mV to 200mV

0x1

0x2

<150mV

0x1 or 0x0

0x3

Table 4-6: Lock Operation

Lock Signal

Status

HIGH

Locked

LOW

Not locked

GS2985 датащи(PDF) 22 Page - Semtech Corporation

GS2985 датащи(HTML) 22 Page - Semtech Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

датащи скачать

ссылки URL