The AD8369ARUZ is a 45dB Digitally Controlled VGA for use from low frequencies to a -3dB frequency of 600MHz at all gain codes. The AD8369 delivers excellent distortion performance, the two-tone, third-order intermodulation distortion is -69dBc at 70MHz for a 1V p-p composite output into a 1kW load. It has a nominal noise figure of 7dB when at maximum gain, then increases with decreasing gain. Output IP3 is +19.5dBm at 70MHz into a 1kW load and remains fairly constant over the gain range. The signal input is applied to pins INHI and INLO. Variable gain is achieved via two methods. The 6dB gain steps are implemented using a discrete X-AMP? structure, in which the input signal is progressively attenuated by a 200W R-2R ladder network that also sets the input impedance, the 3dB steps are implemented at the output of the amplifier. This combination provides very accurate 3dB gain steps over a span of 45dB. The output impedance is set by on-chip resistors across differential output pins.
Digitally controlled variable gain in 3dB steps
Less than 0.2dB flatness over a +20MHz bandwidth up to 380MHz
(EN)
