Datasheet AD8337 (Analog Devices)

General-Purpose, Low Cost, DC-Coupled VGA Data Sheet AD8337 FEATURES GENERAL DESCRIPTION Low noise
The AD8337 is a low noise, single-ended, linear-in-dB, general-
Voltage noise = 2.2 nV/√Hz
purpose, variable gain amplifier (VGA) usable at frequencies
Current noise = 4.8 pA/√Hz (positive input)
from dc to 100 MHz; the −3 dB bandwidth is 280 MHz.
Wide bandwidth (−3 dB) = 280 MHz
Excellent bandwidth uniformity across the entire gain range
Nominal gain range: 0 dB to 24 dB (preamp gain = 6 dB)
and low output referred noise make the AD8337 ideal for
Gain scaling: 19.7 dB/V
gain trim applications and for driving high speed analog-to-
DC-coupled
digital converters (ADCs).
Single-ended input and output
Excellent dc characteristics combined with high speed make the
High speed uncommitted op amp input
AD8337 particularly suited for industrial ultrasound, PET
Supplies: +5 V, ±2.5 V, or ±5 V
scanners, and video applications. Dual-supply operation enables
Low power: 78 mW with ±2.5 V supplies
gain control of negative going pulses, such as those generated
APPLICATIONS
by photodiodes or photomultiplier tubes.
Gain trim
The AD8337 uses the Analog Devices, Inc., exclusive X-AMP®
PET scanners
architecture with 24 dB gain range scaled to 19.7 dB/V,
High performance AGC systems
referenced to VCOM.
I/Q signal processing
The AD8337 preamplifier is configured in a current feedback
Video
architecture optimized for gains of 6 dB to 24 dB. The AD8337
Industrial and medical ultrasound
is characterized by a noninverting preamplifier gain of 2× using a
Radar receivers
pair of 100 Ω resistors. The attenuator has a range of 24 dB, and the output amplifier has a fixed gain of 8× (18.06 dB). The lowest nominal gain range is 0 dB to 24 dB and can be shifted up or down by adjusting the preamplifier gain. Series connected AD8337 devices provide larger gain ranges, interstage filtering to suppress noise and distortion, and nulling of offset voltages.
FUNCTIONAL BLOCK DIAGRAM GAIN GAIN CONTROL INTERFACE EIGHT SECTIONS PREAMP INPP 18dB VOUT INPN PRAO
01 0 5-
VCOM
557 0 Figure 1
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Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUITS THEORY OF OPERATION OVERVIEW PREAMPLIFIER VGA GAIN CONTROL OUTPUT STAGE ATTENUATOR SINGLE-SUPPLY OPERATION AND AC COUPLING NOISE APPLICATIONS INFORMATION PREAMPLIFIER CONNECTIONS Noninverting Gain Configuration Inverting Gain Configuration DRIVING CAPACITIVE LOADS GAIN CONTROL CONSIDERATIONS THERMAL CONSIDERATIONS PSI (Ψ) BOARD LAYOUT EVALUATION BOARDS CIRCUIT OPTIONS OUTPUT PROTECTION MEASUREMENT SETUP BOARD LAYOUT CONSIDERATIONS OUTLINE DIMENSIONS ORDERING GUIDE