AD8123ACPZ-R2

Triple Differential Receiver with Adjustable Line Equalization AD8123 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 High frequency peaking adjustment (VPEAK) Broadband flat gain adjustment (VGAIN) Pole location adjustment pin (VPOLE) Compensates for variations between cables Can be optimized for either UTP or coaxial cable DC output offset adjust (VOFFSET) 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 FUNCTIONAL BLOCK DIAGRAM VPEAK VPOLE VOFFSET VGAIN AD8123 –INR +INR –ING +ING OUTR OUTG –INB +INB –INCMP1 +INCMP1 –INCMP2 +INCMP2 OUTB OUTCMP1 OUTCMP2 APPLICATIONS Keyboard-video-mouse (KVM) Digital signage RGB video over UTP cables Professional video projection and distribution HD video Security video 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, shortto-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 cable lengths; the VPEAK pin controls the amount of high frequency peaking and the VGAIN pin adjusts the broadband flat gain, which compensates for the low frequency flat cable loss. Rev. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. For added flexibility, an optional pole adjustment pin, VPOLE, 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 VOFFSET pin allows the dc voltage at the output to be adjusted, 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 BEFORE AD8123. UXGA RESOLUTION IMAGE AFTER 300 METER CAT-5 CABLE AFTER AD8123. 06814-001 06814-019 Figure 2. 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. AD8123 TABLE OF CONTENTS Features .............................................................................................. 1 Applications....................................................................................... 1 Functional Block Diagram .............................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Absolute Maximum Ratings............................................................ 5 Thermal Resistance ...................................................................... 5 ESD Caution.................................................................................. 5 Pin Configuration and Function Description .............................. 6 Typical Performance Characteristics ............................................. 7 Theory of Operation ...................................................................... 10 Input Common-Mode Voltage Range Considerations ......... 10 Applications Information .............................................................. 11 Basic Operation .......................................................................... 11 Comparators ............................................................................... 11 Sync Pulse Extraction Using Comparators ............................. 12 Using the VPEAK, VPOLE, VGAIN, and VOFFSET Inputs ................... 12 Using the AD8123 with Coaxial Cable.................................... 13 Driving 75 Ω Video Cable With the AD8123 ........................ 13 Driving a Capacitive Load......................................................... 13 Filtering the RGB Outputs ........................................................ 13 Power Supply Filtering............................................................... 14 Layout and Power Supply Decoupling Considerations......... 14 Input Common-Mode Range ................................................... 14 Small Signal Frequency Response............................................ 15 Power-Down ............................................................................... 15 Outline Dimensions ....................................................................... 16 Ordering Guide............................................................................... 16 REVISION HISTORY 8/07—Revision 0: Initial Version Rev. 0 | Page 2 of 16 AD8123 SPECIFICATIONS TA = 25°C, VS = ±5 V, RL = 150 Ω, Belden Cable (BL-7987R), VOFFSET = 0 V, VPEAK, VGAIN, and VPOLE are set to recommended settings shown in Figure 17, unless otherwise noted. Table 1. Parameter PEAKING PERFORMANCE (NO CABLE) Peak Frequency Peak Gain DYNAMIC PERFORMANCE 10% to 90% Rise/Fall Time Settling Time to 2% –3 dB Large Signal Bandwidth Conditions VPEAK = 2 V, VGAIN = 0.6 V, VPOLE = 1 V VPEAK = 2 V, VGAIN = 0.6 V, VPOLE = 2 V VPEAK = 2 V, VGAIN = 0.6 V, VPOLE = 1 V VPEAK = 2 V, VGAIN = 0.6 V, VPOLE = 2 V VOUT = 2 V step, 150 meters Cat-5 VOUT = 2 V step, 300 meters Cat-5 VOUT = 2 V step, 150 meters Cat-5 VOUT = 2 V step, 300 meters Cat-5 VOUT = 1 V p-p,