AD8338:  Low Frequency to 18 MHz VGA With 80 dB Gain Range

Product Details

Product Status:Recommended for New Designs

The AD8338 is a variable gain amplifier (VGA) for applications that require a fully differential signal path, low power, low noise, and a well-defined gain over frequency. While the inputs are differential, the device can also be driven with a single-ended source if required.

The basic gain function is linear-in-dB and is controlled by the voltage applied to Pin GAIN. The nominal gain range spans from 0 dB to 80 dB for control voltages between 0.1 V to 1.1 V with a slope of 12.5 mV/dB. The nominal gain range can be shifted up or down via direct access to Pin INPD and Pin INMD, the current inputs of the VGA. For example, driving the INPD and INMD pins with 50 Ω resistors shifts the gain range up by 20 dB, that is, 20 dB to 100 dB, and lowers the input referred noise of the device to 1.5 nV/√Hz. Additionally, the gain slope can be inverted via logic Pin MODE.

The AD8338 includes additional circuit blocks to enable input offset correction and automatic gain control (AGC). DC offset voltages are removed by the offset correction circuit, which behaves like a high-pass filter whose corner is set with an external capacitor. The AGC function varies the gain of the AD8338 to maintain a constant RMS output voltage. An externally applied voltage to Pin VAGC with respect to the voltage at Pin VREF sets the output RMS amplitude. A capacitor from Pin DETO to ground sets the response time of the AGC circuit.

The AD8338 offers additional versatility by providing access to the internal summing nodes of the VGA core and the output amplifiers. With the addition of a few external passive components, users can customize the gain, bandwidth, input impedance, and noise profile of the part to fit their application.

The AD8338 uses a single supply voltage of 3.0 V to 5.0 V and is very power efficient, consuming as little as 3 mA quiescent current at mid gain. The AD8338 is available in a 3 mm × 3 mm, RoHS compliant, 16-lead LFCSP and is specified over the industrial temperature range of −40°C to +85°C.

  • Front end for inductive telemetry systems
  • Ultrasonic signal receivers
  • Signal compression for driving an ADC
  • AGC amplifiers


  • Voltage controlled gain range
    of 0 dB to 80 dB
  • 3 mA supply current at gain of
    40 dB
  • Low frequency (LF) to 18 MHz operation
  • Supply range: 3.0 V to 5.0 V
  • Low noise: 4.5nV/√Hz at 80 dB gain
  • Fully differential signal path
  • Offset correction (offset null) feature
  • Internal 1.5 V reference
  • 16-lead LFCSP
  • Automatic gain control feature
  • Wide gain range for high dynamic range signals

Functional Block Diagram for AD8338


Title Content Type File Type
AD8338: Low Power, 18 MHz Variable Gain Amplifier Data Sheet (Rev A, 11/2013) (pdf, 399 kB) Data Sheets PDF
AN-1192: Designing with the AD8338  (pdf, 350 kB) Application Notes PDF
UG-559: Evaluating the AD8338 Low Power VGA  (pdf, 264 kB) User Guides PDF
Glossary of EE Terms Glossary HTML

Design Tools,Models,Drivers & Software

Title Content Type File Type
AD8338 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

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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.

AD8338 Evaluation Board
Model Description Price RoHS View PCN/ PDN Check Inventory/
AD8338-EVALZ Status: Contact ADI Evaluation Board for 16 Lead LFSCP $100.00 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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