AD708 Analog Devices, AD708 Datasheet - Page 10

• Manufacturer Part Number: AD708
• Description: Ultralow Offset Voltage Dual Op Amp
• Manufacturer: Analog Devices

Specifications of AD708

• -3db Bandwidth: 900kHz
• Slew Rate: 300mV/µs
• Vos: 30µV
• Ib: 1nA
• # Opamps Per Pkg: 2
• Input Noise (nv/rthz): 9.6nV/rtHz
• Vcc-vee: 6V to 36V
• Isy Per Amplifier: 2.75mA
• Packages: DIP

AD708
THEORY OF OPERATION
CROSSTALK PERFORMANCE
The AD708 exhibits very low crosstalk as shown in Figure 25,
Figure 26, and Figure 27. Figure 25 shows the offset voltage
induced on Side B of the AD708 when Side A output is moving
slowly (0.2 Hz) from −10 V to +10 V under no load. This is the
least stressful situation to the part because the overall power in
the chip does not change. Only the location of the power in the
output device changes. Figure 26 shows the input offset voltage
change to Side B when Side A is driving a 2 kΩ load. Here the
power changes in the chip with the maximum power change
occurring at 7.5 V. Figure 27 shows crosstalk under the most
severe conditions. Side A is connected as a follower with
0 V input, and is forced to sink and source ±5 mA of output
current.
Even this large change in power causes only an 8 μV (linear)
change in the input offset voltage of Side B.
Power = (30 V)(5 mA) = 150 mW
V
10Ω
Figure 25. Crosstalk with No Load
IN
= ±10V
10Ω
V
OUTA
= 2V/DIV
A
10kΩ
B
V
V
OUTA
OUTB
2V
Rev. C | Page 10 of 16
Figure 27. Crosstalk Under Forced Source and Sink Conditions
Figure 26. Crosstalk with 2 kΩ Load
V
10Ω
10Ω
IN
= ±10V
10Ω
10Ω
V
IN
OUTA
A
= 1mA/DIV
= 2V/DIV
A
B
A
B
10kΩ
10kΩ
I
IN
2kΩ
2kΩ
= ±5mA
V
V
OUTA
OUTB
V
V
2V
2V
OUTB
IN
= ±10V