The AD8331 is a single channel ultra low noise linear-in-dB variable gain amplifier (VGA). Optimized for ultrasound systems, it is usable as a low noise variable gain element at frequencies up to 120MHz.

Included is an ultra low noise preamplifier (LNA), an X-AMP VGA with 48dB of gain range, and a selectable gain post amplifier with adjustable output limiting. The LNA gain is 19dB 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 48dB 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 50dB/V for control voltages between 40mV and 1V. 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 operating temperature range is -40°C to +85°C. The AD8331 is available in a 20-lead QSOP package.