AD8366 is a matched pair of fully differential, low noise and low distortion, digitally programmable variable gain amplifier (VGA). The gain of each amplifier can be programmed separately or simultaneously over a range of 4.5dB to 20.25dB in steps of 0.25dB. The amplifier offers flat frequency performance from dc to 70MHz, independent of gain code.

It offers excellent spurious-free dynamic range, suitable for driving high resolution analog-to-digital converters (ADCs). The NF at maximum gain is 11.4dB at 10MHz and increases 2dB for every 4dB decrease in gain. Over the entire gain range, the HD3/HD2 are better than -90 dBc for 2Vp-p at the output at 10MHz into 200ohms. The two-tone intermodulation distortion of -90dBc into 200ohms translates to an OIP3 of 45 dBm (38 dBVrms). The differential input impedance of 200ohms provides a well-defined termination. The differential output has a low impedance of 25ohms.

The output common-mode voltage defaults to VPOS/2 but can be programmed via the VCMA and VCMB pins over a range of voltages. The input common-mode voltage also defaults to VPOS/2 but can be driven down to 1.5V. A built-in, dc offset compensation loop can be used to eliminate dc offsets from prior stages in the signal chain. This loop can also be disabled if dc-coupled operation is desired.

The digital interface allows for parallel or serial mode gain programming. It operates from a 4.75V to 5.25V supply and consumes typically 180mA. When disabled, the part consumes roughly 3mA.