Datasheet AD8331, AD8332, AD8334 (Analog Devices)

Ultralow Noise VGAs with Preamplifier and Programmable RIN Data Sheet AD8331/ AD8332/ AD8334 FEATURES FUNCTIONAL BLOCK DIAGRAM LON LOP VIP VIN VCM HILO Ultralow noise preamplifier (preamp) Voltage noise = 0.74 nV/√Hz VMID 3.5dB OR 15.5dB Current noise = 2.5 pA/√Hz LNA – VOH 3 dB bandwidth 48dB INH 19dB ATTENUATOR 21dB PA AD8331: 1 20 MHz + VOL AD8332, AD8334: 10 0 MHz LMD CLAMP Low power VCM GAIN BIAS VGA BIAS AND CONTROL RCLMP INTERPOLATOR AD8331: 1 25 mW/channel INTERFACE AD8332, AD8334: 14 5 mW/channel AD8331/AD8332/AD8334 Wide gain range with programmable postamp
01 0 9-
ENB GAIN −4.5 dB to +43.5 dB in LO gain mode
319 0 Figure 1. Signal Path Block Diagram
7.5 dB to 55.5 dB in HI gain mode Low output-referred noise: 48 nV/√Hz typical 60 VGAIN = 1V HI GAIN Active input impedance matching MODE 50 Optimized for 10-bit/12-bit ADCs VGAIN = 0.8V Selectable output clamping level 40 V Single 5 V supply operation GAIN = 0.6V ) AD8332 and AD8334 a vailable in lead frame chip scale package B 30 d V ( GAIN = 0.4V IN APPLICATIONS 20 GA VGAIN = 0.2V Ultrasound and sonar time-gain controls 10 VGAIN = 0V High performance automatic gain control (AGC) systems I/Q signal processing 0
02
High speed, dual ADC drivers
0 9- 19
–10
03
GENERAL DESCRIPTION 100k 1M 10M 100M 1G FREQUENCY (Hz)
The AD8331/AD8332/AD8334 are single-, dual-, and quad- Figure 2. Frequency Response vs. Gain channel, ultralow noise linear-in-dB, variable gain amplifiers (VGAs). Optimized for ultrasound systems, they are usable as a Differential signal paths result in superb second- and third- low noise variable gain element at frequencies up to 120 MHz. order distortion performance and low crosstalk. Included in each channel are an ultralow noise preamp (LNA), The low output-referred noise of the VGA is advantageous in an X-AMP® VGA with 48 dB of gain range, and a selectable gain driving high speed differential ADCs. The gain of the postamp postamp with adjustable output limiting. The LNA gain is 19 dB can be pin selected to 3.5 dB or 15.5 dB to optimize gain range with a single-ended input and differential outputs. Using a single and output noise for 12-bit or 10-bit converter applications. The resistor, the LNA input impedance can be adjusted to match a output can be limited to a user-selected clamping level, preventing signal source without compromising noise performance. input overload to a subsequent ADC. An external resistor adjusts the clamping level. The 48 dB gain range of the VGA makes these devices suitable for a variety of applications. Excellent bandwidth uniformity is The operating temperature range is −40°C to +85°C. The maintained across the entire range. The gain control interface AD8331 is available in a 20-lead QSOP package, the AD8332 is provides precise linear-in-dB scaling of 50 dB/V for control available in 28-lead TSSOP and 32-lead LFCSP packages, and voltages between 40 mV and 1 V. Factory trim ensures excellent the AD8334 is available in a 64-lead LFCSP package. part-to-part and channel-to-channel gain matching.
Rev. I Document Feedback 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 One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Tel: 781.329.4700 ©2003–2016 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. Technical Support www.analog.com
Document Outline FEATURES APPLICATIONS GENERAL DESCRIPTION FUNCTIONAL BLOCK DIAGRAM TABLE OF CONTENTS REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS TEST CIRCUITS MEASUREMENT CONSIDERATIONS THEORY OF OPERATION OVERVIEW LOW NOISE AMPLIFIER (LNA) Active Impedance Matching LNA Noise VARIABLE GAIN AMPLIFIER X-AMP VGA Gain Control VGA Noise Common-Mode Biasing POSTAMPLIFIER Noise Output Clamping APPLICATIONS INFORMATION LNA—EXTERNAL COMPONENTS Gain Input VCM Input Logic Inputs—ENB, MODE, and HILO Optional Output Voltage Limiting Output Decoupling DRIVING ADCs OVERLOAD OPTIONAL INPUT OVERLOAD PROTECTION LAYOUT, GROUNDING, AND BYPASSING MULTIPLE INPUT MATCHING DISABLING THE LNA ULTRASOUND TGC APPLICATION HIGH DENSITY QUAD LAYOUT AD8331 EVALUATION BOARD GENERAL DESCRIPTION USER-SUPPLIED OPTIONAL COMPONENTS MEASUREMENT SETUP BOARD LAYOUT AD8331 EVALUATION BOARD SCHEMATICS AD8331 EVALUATION BOARD PCB LAYERS AD8332 EVALUATION BOARD GENERAL DESCRIPTION USER-SUPPLIED OPTIONAL COMPONENTS MEASUREMENT SETUP BOARD LAYOUT EVALUATION BOARD SCHEMATICS AD8332 EVALUATION BOARD PCB LAYERS AD8334 EVALUATION BOARD GENERAL DESCRIPTION CONFIGURING THE INPUT IMPEDANCE Driving the VGA from an External Source or Using the LNA to Drive an External Load Using the Clamp Circuit Viewing Signals MEASUREMENT SETUP BOARD LAYOUT EVALUATION BOARD SCHEMATICS AD8334 EVALUATION BOARD PCB LAYERS OUTLINE DIMENSIONS ORDERING GUIDE