Datasheet AD8138 (Analog Devices)

Low Distortion, Differential ADC Driver Data Sheet AD8138 FEATURES PIN CONFIGURATION Easy to use, single-ended-to-differential conversion –IN 1 8 +IN Adjustable output common-mode voltage VOCM 2 7 NC Externally adjustable gain V+ 3 6 V– Low harmonic distortion +OUT 4 5 –OUT AD8138
001
−94 dBc SFDR at 5 MHz NC = NO CONNECT
01073-
−85 dBc SFDR at 20 MHz
Figure 1.
−3 dB bandwidth of 320 MHz, G = +1 Fast settling to 0.01% of 16 ns TYPICAL APPLICATION CIRCUIT Slew rate 1150 V/µs 5V 5V Fast overdrive recovery of 4 ns 499Ω Low input voltage noise of 5 nV/√Hz 499Ω V AVDD DVDD 1 mV typical offset voltage IN + AIN VOCM DIGITAL Wide supply range +3 V to ±5 V AD8138 ADC OUTPUTS 499Ω AIN – Low power 90 mW on 5 V AVSS VREF 0.1 dB gain flatness to 40 MHz 499Ω
002
Available in 8-Lead SOIC and MSOP packages
01073- Figure 2.
APPLICATIONS ADC drivers Single-ended-to-differential converters IF and baseband gain blocks Differential buffers Line drivers GENERAL DESCRIPTION
The AD8138 is a major advancement over op amps for The AD8138 eliminates the need for a transformer with high differential signal processing. The AD8138 can be used as a performance ADCs, preserving the low frequency and dc infor- single-ended-to-differential amplifier or as a differential-to- mation. The common-mode level of the differential output is differential amplifier. The AD8138 is as easy to use as an op adjustable by a voltage on the VOCM pin, easily level-shifting the amp and greatly simplifies differential signal amplification and input signals for driving single-supply ADCs. Fast overload driving. Manufactured on the proprietary ADI XFCB bipolar recovery preserves sampling accuracy. process, the AD8138 has a −3 dB bandwidth of 320 MHz and delivers a differential signal with the lowest harmonic distortion The AD8138 distortion performance makes it an ideal ADC available in a differential amplifier. The AD8138 has a unique driver for communication systems, with distortion performance internal feedback feature that provides balanced output gain good enough to drive state-of-the-art 10-bit to 16-bit converters and phase matching, suppressing even order harmonics. The at high frequencies. The high bandwidth and IP3 of the internal feedback circuit also minimizes any gain error that AD8138 also make it appropriate for use as a gain block in IF would be associated with the mismatches in the external gain and baseband signal chains. The AD8138 offset and dynamic setting resistors. performance makes it well suited for a wide variety of signal processing and data acquisition applications. The differential output of the AD8138 helps balance the input to differential ADCs, maximizing the performance of the ADC. The AD8138 is available in both SOIC and MSOP packages for operation over −40°C to +85°C temperatures.
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Document Outline FEATURES APPLICATIONS PIN CONFIGURATION TYPICAL APPLICATION CIRCUIT GENERAL DESCRIPTION TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ±DIN TO ±OUT SPECIFICATIONS VOCM TO ±OUT SPECIFICATIONS ±DIN TO ±OUT SPECIFICATIONS VOCM TO ±OUT SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Maximum Power Dissipation ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUITS OPERATIONAL DESCRIPTION DEFINITION OF TERMS THEORY OF OPERATION ANALYZING AN APPLICATION CIRCUIT SETTING THE CLOSED-LOOP GAIN ESTIMATING THE OUTPUT NOISE VOLTAGE THE IMPACT OF MISMATCHES IN THE FEEDBACK NETWORKS CALCULATING THE INPUT IMPEDANCE OF AN APPLICATION INPUT COMMON-MODE VOLTAGE RANGE IN SINGLE-SUPPLY APPLICATIONS SETTING THE OUTPUT COMMON-MODE VOLTAGE DRIVING A CAPACITIVE LOAD LAYOUT, GROUNDING, AND BYPASSING BALANCED TRANSFORMER DRIVER HIGH PERFORMANCE ADC DRIVING 3 V OPERATION OUTLINE DIMENSIONS ORDERING GUIDE