Triple Differential Receiver with

Adjustable Line Equalization

AD8123

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibilityis assumedbyAnalogDevicesforitsuse,norforanyinfringements of patents or other

rightsofthirdpartiesthatmayresultfromitsuse.Specificationssubjecttochangewithoutnotice.No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

www.analog.com

Fax: 781.461.3113

©2007 Analog Devices, Inc. All rights reserved.

FEATURES

Compensates cables to 300 meters for wideband video

Fast rise and fall times

4.9 ns with 2 V step @ 150 meters of UTP cable

8.0 ns with 2 V step @ 300 meters of UTP cable

55 dB peak gain at 100 MHz

Two frequency response gain adjustment pins

Compensates for variations between cables

Can be optimized for either UTP or coaxial cable

Low output offset voltage: 24 mV

Two on-chip comparators with hysteresis

Can be used for common-mode sync extraction

Available in 40-lead, 6 mm × 6 mm LFCSP

APPLICATIONS

Keyboard-video-mouse (KVM)

Digital signage

RGB video over UTP cables

Professional video projection and distribution

HD video

Security video

FUNCTIONAL BLOCK DIAGRAM

AD8123

Figure 1.

GENERAL DESCRIPTION

The AD8123 is a triple, high speed, differential receiver and

equalizer that compensates for the transmission losses of UTP

and coaxial cables up to 300 meters in length. Various gain

stages are summed together to best approximate the inverse

frequency response of the cable. Logic circuitry inside the AD8123

controls the gain functions of the individual stages so that the

lowest noise can be achieved at short-to-medium cable lengths.

This technique optimizes its performance for low noise, short-

to-medium range applications, while at the same time provides

the high gain bandwidth required for long cable equalization

(up to 300 meters). Each channel features a high impedance

differential input that is ideal for interfacing directly with the cable.

The AD8123 has three control pins for optimal cable

compensation, as well as an output offset adjust pin. Two

voltage-controlled pins are used to compensate for different

which compensates for the low frequency flat cable loss.

allows movement of the pole locations, allowing for the

compensation of different gauges and types of cable as well

as variations between different cables and/or equalizers. The

adding flexibility for dc-coupled systems.

The AD8123 is available in a 6 mm × 6 mm, 40-lead LFCSP

and is rated to operate over the extended temperature range of

−40°C to +85°C.

UXGA RESOLUTION IMAGE

AFTER 300 METER CAT-5 CABLE

AFTER AD8123.

UXGA RESOLUTION IMAGE

AFTER 300 METER CAT-5 CABLE

BEFORE AD8123.

Figure 2.