AD8338

Low Frequency to 18 MHz VGA with 80 dB Gain Range

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Product Details

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.

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

Product Lifecycle

checked Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits

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Product Details

The user guide UG-559 describes the AD8338 evaluation board and discusses common configurations. The design of this board (AD8338-EVALZ) emphasizes simplicity and ease of use, which is evident in the minimalist approach to connector implementation.

The AD8338 data sheet covers the details of the device’s operation. Using this data sheet for reference will help the designer in their end application. The data sheet is helpful for understanding the operation of the AD8338 evaluation board, especially during the initial configuration and when powering up for the first time.

Tools & Simulations

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SPICE Models

Design Resources

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ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well.  "Zero defects" for shipped products is always our goal.

AD8338 Material Declaration
PCN-PDN Information Quality And Reliability Symbols and Footprints

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Overview

9 Reviews
8 out of 8 (100%) customers recommend this product.
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Most Helpful Review

by maojoujou
this chip is perfect for IF amplifer. But the pspice model offered is uncomplete.

Most Recent Review

by Design Engineer
The AD8338 allowed us to simplify our design which previously consisted of a fixed gain low noise amplifier followed by a voltage controlled gain amplifier. Filtering at the input was also simplified.

All Reviews

by Design Engineer, 11 Feb 15
This product simplified our design
The AD8338 allowed us to simplify our design which previously consisted of a fixed gain low noise amplifier followed by a voltage controlled gain amplifier. Filtering at the input was also simplified.
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by Anonymous, 14 Jan 15
Easy to use VGA
The AD8338 is a VGA easy to use with a powerful response in the time as well as in the frequency domain. Moreover, it is suitable for a lot of applications which include a micro-controller or not.
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by Dennis D, 12 Nov 14
Review of AD8338 evaluation module
This module should have standoffs like offerings from other manufacturers. The choice of signal in and out connectors was hard to work with for an evaluation unit. The op amps for single ended input and output should have been loaded. This is an important point and ADI could have done much better! Seriously...what kind of evaluation is expected when you don't load parts and you don't provide reference layouts and notes. Not a good evaluation module.
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by Halcyonrichard, 15 Apr 14
AD8338
Excellent product it provides a lot of functionality in a very small package. very pleased with simplicity of use.
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by DrGraphene, 26 Mar 14
PHENOMENAL GAIN BANDWIDTH
This VGA has constant bandwidth as its gain is varied. That is very useful. The gain-bandwidth product at the full gain of 80 dB is 180 GHz. That's phenomenal!
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by maojoujou, 15 Jan 14
pspice
this chip is perfect for IF amplifer. But the pspice model offered is uncomplete.
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by CW, 8 Jan 14
AD8338-EVALZ
The board worked fine and allowed me to evaluate the performance of the AD8338 in my design. I added the single-ended to differential and differential to single-ended buffer chips since this was a requirement for my design proposal. This was a useful feature of the board.
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by Anonymous, 14 Dec 13
This IC in HF receiver has great features
In radio receiver, an IF amplifier with a wide dynamic AGC is an important task.
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by fantech, 3 Nov 13
Great design.... as usual !
The easy way to build the first stage of data processing. Sure need a sample soon !
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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.


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Evaluation Boards Pricing displayed is based on 1-piece.
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.