OP97EJ AD [Analog Devices], OP97EJ Datasheet - Page 14

• Manufacturer Part Number: OP97EJ
• Description: LOW POWER, HIGH PRECISION OPERATIONAL AMPLIFIER
• Manufacturer: AD [Analog Devices]

OP97
The digitally programmable gain amplifier shown in Figure 38
has 12-bit gain resolution with 10-bit gain linearity over the
range of −1 to −1024. The low bias current of the OP97 main-
tains this linearity, while C1 limits the noise voltage bandwidth,
allowing accurate measurement down to microvolt levels.
Table 5.
DIGITAL IN
4095
2048
1024
512
256
128
64
32
16
8
4
2
1
0
Many high speed amplifiers suffer from less-than-perfect low
frequency performance. A combination amplifier consisting of
a high precision, slow device like the OP97 and a faster device such
as the AD8610 results in uniformly accurate performance from
dc to the high frequency limit of the AD8610, which has a gain-
bandwidth product of 25 MHz. The circuit shown in Figure 39
accomplishes this, with the AD8610 providing high frequency
amplification and the OP97 operating on low frequency signals
and providing offset correction. Offset voltage and drift of the
circuit are controlled by the OP97.
GAIN (A
−1.00024
−2
−4
−8
−16
−32
−64
−128
−256
−512
−1024
−2048
−4096
Open Loop
v
)
Rev. F | Page 14 of 16
V
IN
±2.5mV TO ±10V
RANGE DEPENDING
ON GAIN SETTING
100
90
10
0%
Figure 39. Combination High Speed, Precision Amplifier
2kΩ
0.1µF
V
R1
Figure 40. Combination Amplifier Transient Response
IN
Figure 38. Precision Programmable Gain Amplifier
5V
1V
10kΩ
1
2
2
3
1µF
I
3
OUT1
OP97
I
OUT2
20kΩ
R2
10kΩ
18
5
2
3
AD7541A
0.1µF
R
OP97
6
FB
+15V
–15V
2
3
+15V
AD8610
V
REF
6
16
5pF
A
V
= –
17
220pF
0.1µF
0.1µF
C1
R2
R1
6
2µs
0.1µF
V
OUT
V
OUT