AD8131
INPUT COMMON-MODE VOLTAGE RANGE IN
SINGLE-SUPPLY APPLICATIONS
The AD8131 is optimized for level-shifting ground referenced
input signals. For a single-ended input this would imply, for
example, that the voltage at −D
IN
in Figure 39 would be zero
volts when the amplifier’s negative power supply voltage (at V−)
was also set to zero volts.
In cases where more accurate control of the output common-
mode level is required, it is recommended that an external
source, or resistor divider (made up of 10 kΩ resistors), be used.
DRIVING A CAPACITIVE LOAD
A purely capacitive load can react with the pin and bondwire
inductance of the AD8131 resulting in high frequency ringing
in the pulse response. One way to minimize this effect is to
place a small resistor in series with the amplifier’s outputs as
shown in Figure 26.
SETTING THE OUTPUT COMMON-MODE VOLTAGE
The AD8131’s V
OCM
pin is internally biased at a voltage
approximately equal to the midsupply point (average value of
the voltages on V+ and V−). Relying on this internal bias results
in an output common-mode voltage that is within about 25 mV
of the expected value.
Rev. B | Page 17 of 20
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