The AD8334 is an ultralow noise, quad channel linear-in-dB variable gain amplifier (VGA). Although optimized for ultrasound systems, it may be used as a low noise variable gain control in any application whose operating frequency is less than 100 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 suitable for a variety of applications. Excellent bandwidth uniformity is maintained across the entire range. The gain control interface provides precise linear-in-dB scaling of 50 dB/V for control voltages between 40 mV and 1 V. Factory trim ensures excellent part-to-part and channel-to-channel gain matching. Differential signal paths result in superb second- and third-order distortion performance and low crosstalk.

The AD8334 is a quad version of the single AD8331 and dual AD8332.

For information on specs, see the AD8331/AD8332/AD8334 datasheet.

Applications

• Ultrasound and sonar time-gain controls
• High performance automatic gain control (AGC) systems
• I/Q signal processing
• High speed, dual ADC drivers

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.