Datasheet

AD9734/AD9735/AD9736
Rev. A | Page 52 of 72
DC-COUPLED DAC OUTPUT
In some cases, it may be desirable to dc-couple the AD973x
output. The best method for doing this is shown in
Figure 94.
This circuit can be used with voltage or current feedback
amplifiers. Because the DAC output current is driving a virtual
ground, this circuit may offer enhanced settling times. The
settling time is limited by the op amp rather than by the DAC.
This circuit is intended for use where the amplifiers can be
powered by a bipolar supply.
04862-092
IOUTA
DAC
OUTPUT
20mA
FULL SCALE
IOUTB
100Ω
100Ω
100Ω
500Ω
500Ω
100Ω
500Ω
500Ω
AVSS
AVSS
OUTPUT
2V p-p
+1V TO –1V
2V p-p
0V TO –2V
Figure 94. Op Amp I to V Conversion Output Circuit
An alternate circuit is shown in Figure 95. It suffers from dc
offset at the output unless the DAC load resistors are small,
relative to the amplifier gain and feedback resistors.
04862-093
IOUTA
OUTPUT
AVSS
IOUTB
25Ω
25Ω
2kΩ
AVSS
2kΩ1kΩ
1kΩ
DAC OUTPUT
20mA
FULL SCALE
2V p-p
0V TO –2V
0.5V p-p
0V TO –0.5V
Figure 95. Differential Op Amp Output Circuit