Quad Low Noise, Low Cost Variable Gain Amplifier
The AD8335 is a quad variable gain amplifier (VGA) with low noise preamplifier intended for cost and power sensitive applications. Each channel features a gain range of 48 dB, fully differential signal paths, active input preamplifier matching, and user-selectable maximum gains of 46 dB and 38 dB. Individual gain controls are provided for each channel.
The preamplifier (PrA) has a single-ended to differential gain of ×8 (18.06 dB) and accepts input signals <625 mV p-p. PrA noise is 1.2 nV/√Hz and the combined input referred voltage noise of the PrA and VGA is 1.3 nV/√Hz at maximum gain.
Assuming a 20 MHz noise bandwidth (NBW), the Nyquist frequency for a 40 MHz ADC, the input SNR is 92 dB. The HLxx pin optimizes the output SNR for 10-bit and 12-bit ADCs with 1 V p-p or 2 V p-p full-scale (FS) inputs.
Channel 1 and Channel 2 are enabled through the EN12 pin and Channel 3 and Channel 4 are enabled through the EN34 pin. For VGA only applications, the PrAs can be powered down, significantly reducing power consumption.
The AD8335 is available in a 64-lead lead frame chip scale package (9 mm × 9 mm) for the industrial temperature range of −40°C to +85°C.
Data Sheet, Rev A, 08/2008
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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.
Jumpers provide for exercising the user-selectable features of the AD8335, such as the preamp and VGAs and the optional high and low gain ranges. Test pins are provided for power and gain voltage connections and for probes used to observe waveforms at the input and outputs. Provisions are also made for driving the gain controls dynamically.
See the AD8335 data sheet for measurement setup, 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)
Temperature monitor measures three thermal zones
by Susan Pratt, Analog Devices, Inc. (EDN, 12/11/03)
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.