Ultralow Noise VGAs
Data Sheet
Ultralow Noise VGAs with Preamplifier and Programmable RIN
AD8331/AD8332/AD8334
FEATURES
Ultralow noise pre...
Description
Data Sheet
Ultralow Noise VGAs with Preamplifier and Programmable RIN
AD8331/AD8332/AD8334
FEATURES
Ultralow noise preamplifier (preamp) Voltage noise = 0.74 nV/√Hz Current noise = 2.5 pA/√Hz
3 dB bandwidth AD8331: 120 MHz AD8332, AD8334: 100 MHz
Low power AD8331: 125 mW/channel AD8332, AD8334: 145 mW/channel
Wide gain range with programmable postamp −4.5 dB to +43.5 dB in LO gain mode 7.5 dB to 55.5 dB in HI gain mode
Low output-referred noise: 48 nV/√Hz typical Active input impedance matching Optimized for 10-bit/12-bit ADCs Selectable output clamping level Single 5 V supply operation AD8332 and AD8334 available in lead frame chip scale package
APPLICATIONS
Ultrasound and sonar time-gain controls High performance automatic gain control (AGC) systems I/Q signal processing High speed, dual ADC drivers
GENERAL DESCRIPTION
The AD8331/AD8332/AD8334 are single-, dual-, and quadchannel, ultralow noise linear-in-dB, variable gain amplifiers (VGAs). Optimized for ultrasound systems, they are usable as a low noise variable gain element at frequencies up to 120 MHz.
Included in each channel are an ultralow noise preamp (LNA), an X-AMP® VGA with 48 dB of gain range, and a selectable gain postamp 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 suit...
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