The AD8331 is a single, ultralow 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 120 MHz. Included is an ultralow noise preamplifier (LNA), an X-AMP® VGA with 48 dB of gain range, and a selectable gain postamplifier 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 operating temperature range is -40°C to +85°C. The AD8331 is available in a 20-lead QSOP package. The AD8331 is a single version of the dual AD8332 and quad AD8334. For information on specs, please see the AD8331/AD8332 datasheet.