General-Purpose, Low Cost, DC-Coupled VGA
The AD8337 is a low noise, single-ended, linear-in-dB, general-purpose variable gain amplifier (VGA) usable at frequencies from dc to 100 MHz; the −3 dB bandwidth is 280 MHz. Excellent bandwidth uniformity across the entire gain range and low output-referred noise makes the AD8337 ideal for gain trim applications and for driving high speed analog-to-digital converters (ADCs).
Excellent dc characteristics combined with high speed make the AD8337 particularly suited for industrial ultrasound, PET scanners, and video applications. Dual-supply operation enables gain control of negative-going pulses such as generated by photodiodes or photomultiplier tubes.
The AD8337 uses the popular and versatile X-AMP® architecture, exclusively from Analog Devices, Inc., with a gain range of 24 dB. The gain control interface provides precise linear-in-dB scaling of 19.7 dB/V, referenced to VCOM.
The AD8337 includes an uncommitted operational current-feedback preamplifier (PrA) that operates in inverting or noninverting configurations. Using external resistors, the device can be configured for gains of 6 dB or greater. The AD8337 is characterized by a noninverting PrA gain of 2× using two external 100 Ω resistors. The attenuator has a range of 24 dB, and the output amplifier has a fixed gain of 8× (18.06 dB). The lowest nominal gain range is 0 dB to 24 dB and can be shifted up or down by adjusting the preamp gain. Multiple AD8337s can be connected in series for larger gain ranges, and for interstage filtering to suppress noise and distortion, and for nulling offset voltages.
The operating temperature range is –40°C to +85°C, and it is available in an 8-lead, 3 mm × 3 mm LFCSP.
- Gain trim
- PET scanners
- High performance AGC systems
- I/Q signal processing
- Industrial and medical ultrasound
- Radar receivers
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.
Three circuit configurations are available.
- AD8337-EVALZ, dc-coupled, with noninverting gain and dual power supplies.
- AD8337-EVALZ-INV, dc-coupled, with inverting gain and dual power supplies.
- AD8337-EVALZ-SS, ac-coupled, with noninverting gain configuration and a single supply.
These fully assembled and tested boards are ready to use. Only the appropriate power supply and signal source connections need to be made. SMA connectors are provided for the pream- plifier (PrA) and VGA outputs.
See AD8337 data sheet for 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.
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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.