Datasheet

AD9943/AD9944
Rev. B | Page 16 of 20
A/D CONVERTER
The ADC uses a 2 V input range. Better noise performance
results from using a larger ADC full-scale range. The ADC uses
a pipelined architecture with a 2 V full-scale input for low noise
performance.
VARIABLE GAIN AMPLIFIER
The VGA stage provides a gain range of 6 dB to 40 dB,
programmable with 10-bit resolution through the serial digital
interface. The minimum gain of 6 dB is needed to match a 1 V
input signal with the ADC full-scale range of 2 V. A plot of the
VGA gain curve is shown in Figure 13.
()
(
)
dB3.5dB035.0dB +×= CodeVGAGainVGA
VGA GAIN REGISTER MODE
42
12
383127
VGA GAIN (dB)
0
30
255
36
34
18
6
511 639 767 895 1023
02905-B-014
Figure 13. VGA Gain Curve