Datasheet

Data Sheet AD9278
Rev. A | Page 21 of 44
Each LNA output is dc-coupled to a VGA input. The VGA
consists of an attenuator with a range of −42 dB, followed by an
amplifier with 21 dB/24 dB/27 dB/30 dB of gain. The X-AMP
gain interpolation technique results in low gain error and
uniform bandwidth, and differential signal paths minimize
distortion.
LNA FULL SCALE
(0.450V p-p SINGLE-ENDED)
LNA INPUT-REFERRED
NOISE FLOOR
(5.8µV rms) AT AAF BW = 15MHz
LNA + VGA NOISE = 1.5nV/ Hz
ADC FULL SCALE (2V p-p)
~10dB MARGIN
>11dB MARGIN
ADC NOISE FLOOR
(224µV rms)
MINIMUM GAIN
MAXIMUM GAIN
LNA
ADC
70dB
VGA GAIN RANGE > 45dB
MAX CHANNEL GAIN > 48dB
88dB
09424-047
Figure 39. Gain Requirements of TGC Operation for a 12-Bit, 40 MSPS ADC