AD8335

四通道，低噪声，低成本可变增益放大器 Quad Low Noise, Low Cost Variable Gain Amplifier

Product Details

The 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.

**Applications**

* Medical imaging ultrasound, gamma cameras

* Sonar

* Test and measurement

* Precise, stable wideband gain control

Data Sheet, Rev A, 08/2008

### Features and Benefits

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Low noise preamplifier PrA

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Voltage noise = 1.3 nV/√Hz typical

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Current noise = 2.4 pA/√Hz typical

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NF = 7 dB RS = RIN = 50 Ω

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Single-ended input; VIN maximum = 625 mV p-p

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Active input match

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Input SNR noise bandwidth = 20 MHz = 92 dB

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VGA

Differential output

VOUT maximum = 5 V p-p, RL = 500 Ω differential

Gain range 8 dB output gain step

−10 dB to +38 dB—low gain mode

−2 dB to +46 dB—high gain mode

Accurate linear-in-dB gain control

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For additional features please see data sheet