Single VGA with Ultralow Noise Preamplifier and Programmable RIN
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, see the AD8331/AD8332/AD8334 datasheet.
- Ultrasound and sonar time-gain controls
- High performance automatic gain control (AGC) systems
- I/Q signal processing
- High speed, dual ADC drivers
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
The board is provided completely assembled and tested; the user simply connects an input signal, VGAIN sources, and a 5 V power supply. The AD8331-EVALZ is lead free and RoHS compliant.
See the AD8331 data sheet available on line for user-supplied optional components, board layout and further details.
Product Selection Guide
Variable Gain Amplifier Selection Table
How Ultrasound System Considerations Influence Front-End Component Choice
by Eberhard Brunner, Analog Devices, Inc.
(Analog Dialogue Vol. 36, May-July 2002)
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.
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.