Low Cost, High Speed Differential Driver AD8131 FEATURES FUNCTIONAL BLOCK DIAGRAM High speed D 1 8 +D IN IN 400 MHz, 3 dB full power bandwidth 750 750 2000 V/s slew rate V 2 7 NC OCM Fixed gain of 2 with no external components V+ 3 6 V 1.5k 1.5k Internal common-mode feedback to improve gain and phase balance: 60 dB 10 MHz +OUT45 OUT AD8131 Separate input to set the common-mode output voltage Low distortion: 68 dB SFDR 5 MHz 200 load NC = NO CONNECT Power supply range +2.7 V to 5 V Figure 1. APPLICATIONS Video line driver Digital line driver Low power differential ADC driver Differential in/out level shifting Single-ended input to differential output driver GENERAL DESCRIPTION The AD8131 is a differential or single-ended input to 20 V = 2V p-p OUT, dm differential output driver requiring no external components for V / V OUT, cm OUT, dm 30 a fixed gain of 2. The AD8131 is a major advancement over op amps for driving signals over long lines or for driving 40 differential input ADCs. The AD8131 has a unique internal feedback feature that provides output gain and phase matching 50 that are balanced to 60 dB at 10 MHz, reducing radiated EMI and suppressing harmonics. Manufactured on the Analog V = +5V S 60 Devices, Inc. next generation XFCB bipolar process, the AD8131 has a 3 dB bandwidth of 400 MHz and delivers a 70 differential signal with very low harmonic distortion. V = 5V S The AD8131 is a differential driver for the transmission of 80 1 10 100 1000 high-speed signals over low-cost twisted pair or coax cables. FREQUENCY (MHz) The AD8131 can be used for either analog or digital video Figure 2. Output Balance Error vs. Frequency signals or for other high-speed data transmission. The AD8131 driver is capable of driving either Cat3 or Cat5 twisted pair or The AD8131s differential output also helps balance the input coax with minimal line attenuation. The AD8131 has for differential ADCs, optimizing the distortion performance of considerable cost and performance improvements over discrete the ADCs. The common-mode level of the differential output is line driver solutions. adjustable by a voltage on the VOCM pin, easily level-shifting the input signals for driving single-supply ADCs with dual supply The AD8131 can replace transformers in a variety of applications, signals. Fast overload recovery preserves sampling accuracy. preserving low frequency and dc information. The AD8131 does not have the susceptibility to magnetic interference and hysteresis The AD8131 is available in both SOIC and MSOP packages for of transformers. It is smaller, easier to work with, and has the high operation over 40C to +125C. reliability associated with ICs. Rev. B 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. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Specifications subject to change without notice. No license is granted by implication Tel: 781.329.4700 www.analog.com or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. Fax: 781.461.3113 2005 Analog Devices, Inc. All rights reserved. BALANCE ERROR (dB) 01072-001 01072-002AD8131 TABLE OF CONTENTS Specifications..................................................................................... 3 Estimating the Output Noise Voltage ...................................... 16 DIN to OUT Specifications...................................................... 3 Calculating the Input Impedance of an Application Circuit..................................................................... 16 VOCM to OUT Specifications ..................................................... 4 Input Common-Mode Voltage Range in DIN to OUT Specifications...................................................... 5 Single-Supply Applications ....................................................... 17 V to OUT Specifications ..................................................... 6 OCM Setting the Output Common-Mode Voltage .......................... 17 Absolute Maximum Ratings............................................................ 7 Driving a Capacitive Load......................................................... 17 ESD Caution.................................................................................. 7 Applications..................................................................................... 18 Pin Configuration and Function Descriptions............................. 8 Twisted-Pair Line Driver........................................................... 18 Typical Performance Characteristics ............................................. 9 3 V Supply Differential A-to-D Driver.................................... 18 Operational Description................................................................ 15 Unity-Gain, Single-Ended-to-Differential Driver ................. 19 Theory of Operation ...................................................................... 16 Outline Dimensions ....................................................................... 20 Analyzing an Application Circuit............................................. 16 Ordering Guide .......................................................................... 20 Closed-Loop Gain ...................................................................... 16 REVISION HISTORY 6/05Rev. A to Rev. B Updated Format..................................................................Universal Changed Upper Operating Limit .....................................Universal Changes to Ordering Guide .......................................................... 20 Rev. B Page 2 of 20