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AD8331:  Single VGA with Ultralow Noise Preamplifier and Programmable RIN

Product Details

The AD8331 is a single channel, ultralow noise, linear-in-dB, variable gain amplifier (VGA). Optimized for ultrasound systems, it is usable as a low noise variable gain element at frequencies up to 120 MHz.

Included is an ultralow noise preamplifier (LNA), an X-AMP® VGA with 48 dB of gain range, and a selectable gain postamplifier with adjustable output limiting. The LNA gain is 19 dB with a single-ended input and differential outputs. Using a single resistor, the LNA input impedance can be adjusted to match a signal source without compromising noise performance.

The 48 dB gain range of the VGA makes these devices suitable for a variety of applications. Excellent bandwidth uniformity is maintained across the entire range. The gain control interface provides precise linear-in-dB scaling of 50 dB/V for control voltages between 40 mV and 1 V. Factory trim ensures excellent part-to-part and channel-to-channel gain matching. Differential signal paths result in superb second- and third-order distortion performance and low crosstalk.

The operating temperature range is -40°C to +85°C. The AD8331 is available in a 20-lead QSOP package.

The AD8331 is a single version of the dual AD8332 and quad AD8334.

For information on specs, please see the AD8331/AD8332 datasheet.


  • Ultrasound and Sonar time-gain controls
  • High Performance AGC Systems
  • I/Q Signal Processing
  • High Speed ADC Drivers


  • Ultralow noise preamplifier:
    Voltage noise = 0.74 nV/√Hz
    Current noise = 2.5 pA/√Hz
  • 3 dB bandwidth: 120 MHz
  • Low power: 125 mW/channel
  • Wide gain range with programmable postamp
    -4.5 dB to +43.5 dB
    +7.5 dB to +55.5 dB
  • Low output-referred noise:
    48 nV/√Hz typical
  • Active input impedance matching
  • Optimized for 10-bit/12-bit ADCs
  • Selectable output clamping level
  • Single 5 V supply operation
  • Available in a 20-lead QSOP package

Functional Block Diagram for AD8331


Title Content Type File Type
AD8331/AD8332/AD8334: Ultralow Noise VGAs with Preamplifier and Programmable RIN Data Sheet (Rev G, 10/2010) (pdf, 861 kB) Data Sheets PDF
CN-0096: High Frequency Variable Gain Amplifier Extends the Dynamic Range of a 10-Bit, 65 MSPS ADC to Greater Than 100 dB  (pdf, 183 kB) Circuit Note PDF
Design and Operation of Automatic Gain Control Loops for Receivers in Modern Communication Systems  (pdf, 129 kB) Tutorials PDF
How Ultrasound System Considerations Influence Front-End Component Choice
by Eberhard Brunner, Analog Devices, Inc.
(Analog Dialogue Vol. 36, May-July 2002)
Technical Articles HTML
Variable Gain Amplifier Selection Table  (pdf, 68 kB) Product Selection Guide PDF
ADT7301: Accurate, SPI-Compatible Temperature Sensor in SOT Package  (htm)
(analogZone September 1, 2003)
Product Reviews HTM
RF Source Booklet  (PDF, 4353 kB)
RF IC Product Overview - Version P (02/2014)
Overview PDF
Leading Inside Advertorials: Solving Dynamic Range Problems in Analog Systems  (pdf, 75 kB) Overview PDF
What are Variable Gain Amplifiers (VGA's) and how are they used? FAQs/RAQs HTML
RAQs index Rarely Asked Questions HTML
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD8331 SPICE Macro-Model SPICE Models HTML

Evaluation Kits & Symbols & Footprints

Evaluation Boards & KitsView the Evaluation Boards and Kits page for documentation and purchasing

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Price, packaging, availability

AD8331 Model Options
Model Package Pins Temp.
Price*(100-499) Price*1000 pcs RoHS View PCN/ PDN Check Inventory/
AD8331ARQZ Status: Production 20 ld QSOP 20 Ind Tube, 56 $6.05 $5.45 Y  Material Info PCN Purchase
AD8331ARQZ-R7 Status: Production 20 ld QSOP 20 Ind Reel, 1000 $6.05 $5.45 Y  Material Info PCN Purchase
AD8331ARQZ-RL Status: Production 20 ld QSOP 20 Ind Reel, 2500 $6.05 $5.45 Y  Material Info PCN Purchase
Price Table Help

The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.

AD8331 Evaluation Board
Model Description Price RoHS View PCN/ PDN Check Inventory/
AD8331-EVALZ Status: Contact ADI Evaluation Board $82.38 Yes -

Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.

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