AEC+

Equalizer

Filter

AEC-

MUTE

DC

Restoration/

Level Control

Automatic

Equalization

Control

SDI

SDI

SDO

SDO

BYPASS

Output

Driver

$

Carrier

Detect/

Mute

Energy

Detect

Energy

Detect

CD

LMH0344

www.ti.com

SNLS233O – APRIL 2007 – REVISED JULY 2015

7 Detailed Description

7.1 Overview

The LMH0344 3-Gbps HD–SD SDI Adaptive Cable Equalizer is designed to equalize data transmitted over cable

or any other media with similar dispersive loss characteristics. The equalizer operates over a wide range of data

rates from 125 Mbps to 2.97 Gbps and supports ST 424, ST 292, ST 344, and ST 259.

7.2 Functional Block Diagram

7.3 Feature Description

7.3.1 Block Description

The Equalizer Filter block is a multistage adaptive filter. If BYPASS is high, the equalizer filter is disabled.

The DC Restoration / Level Control block receives the differential signals from the equalizer filter block. This

block incorporates a self-biasing DC restoration circuit to fully DC restore the signals. If BYPASS is high, this

function is disabled.

The signals before and after the DC Restoration / Level Control block are used to generate the Automatic

Equalization Control (AEC) signal. This control signal sets the gain and bandwidth of the equalizer filter. The

loop response in the AEC block is controlled by an external 1-µF capacitor placed across the AEC+ and AEC–

pins.

The Carrier Detect / Mute block generates the carrier detect signal and controls the mute function of the output.

The Output Driver produces SDO and SDO.

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