AD8264

四， 235兆赫，直流耦合VGA和差分输出放大器 Quad, 235 MHz, DC-Coupled VGA and Differential Output Amplifier

Product Details

The is a quad, linear-in-dB, general-purpose variable gain amplifier VGA with a preamplifier preamp, and a flexible differential output buffer. DC coupling, combined with wide bandwidth, makes this amplifier a very good pulse processor. Each channel includes a single-ended input preamp/VGA section to preserve the wide bandwidth and fast slew rate for low distortion pulse applications. A 6 dB differential output buffer with common-mode and offset adjustments enable direct coupling to most modern high speed analog-to-digital converters ADCs, using the converter reference output for perfect dc matching levels.

The −3 dB bandwidth of the preamp/VGA is dc to 235 MHz, and the bandwidth of the differential driver is 80 MHz. The floating gain control interface provides a precise linear-in-dB scale of 20 dB/V and is easy to interface to a variety of external circuits. The gain of each channel is adjusted independently, and all channels are referenced to a single pin, GNLO. Combined with a multioutput, digital-to-analog converter DAC, each section of the AD8264 can be used for active calibration or as a trim amplifier.

Operation from a bipolar power supply enables amplification of negative voltage pulses generated by current-sinking pulses into a grounded load, such as is typical of photodiodes or photomultiplier tubes PMT. Delay-free processing of wideband video signals is also possible.

Applications

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Multichannel data acquisition

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Positron emission tomography

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Gain trim

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Industrial and medical ultrasound

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Radar receivers

### Features and Benefits

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Low noise

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Voltage noise: 2.3 nV/√Hz

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Current noise: 2 pA/√Hz

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Wide bandwidth

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Small signal: 235 MHz VGAx; 80 MHz output amplifier

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Large signal: 80 MHz

1 V p-p

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Gain range

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0 to 24 dB input to VGA output

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6 to 30 dB input to differential output

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Gain scaling: 20 dB/V

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DC-coupled

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Single-ended input and differential output

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Supplies: ±2.5 V to ±5 V

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Low power: 140 mW per channel at ±3.3 V