ad797bn Analog Devices, Inc., ad797bn Datasheet - Page 16

• Manufacturer Part Number: ad797bn
• Description: Ultralow Distortion, Ultralow Noise Op Amp
• Manufacturer: Analog Devices, Inc.

AD797
The benefits of this begin at closed-loop gains of 100 and up.
A maximum value of ≈33 pF at gains of 1000 and up is
recommended. At a gain of 1000, the bandwidth is 450 kHz.
Table 6 and Figure 45 summarize the performance of the
AD797 with distortion cancellation and decompensation.
Table 6. Recommended External Compensation
Gain
10
100
1000
Figure 44. Recommended Connections for Distortion Cancellation
R1
Ω
909
1 k
10 k
A/B
R2
Ω
100
10
10
R2
R2
and Bandwidth Enhancement
C1
pF
0
0
0
2
3
2
3
C2
pF
50
50
50
R1
R1
AD797
AD797
A
3 dB
BW
6 MHz
1 MHz
110 kHz
8
8
C1, SEE TABLE
C2 = 50pF – C1
50pF
C2
C1
6
6
C1
pF
0
15
33
C2
pF
50
33
15
B
3 dB
450 kHz
BW
6 MHz
1.5 MHz
Rev. E | Page 16 of 20
Differential Line Receiver
The differential receiver circuit of Figure 46 is useful for many
applications from audio to MRI imaging. It allows extraction of
a low level signal in the presence of common-mode noise. As
shown in Figure 47, the AD797 provides this function with only
9 nV/√Hz noise at the output. Figure 45 shows the AD797’s
20-bit THD performance over the audio band and 16-bit
accuracy to 250 kHz.
–100
–110
–120
Figure 45. Total Harmonic Distortion (THD) vs. Frequency @ 3 V rms
–80
–90
100
DIFFERENTIAL
NOISE LIMIT, G = +1000
NOISE LIMIT, G = +100
**Use Power Supply Bypassing Shown in Figure 35
INPUT
300
1kΩ
1kΩ
Figure 46. Differential Line Receiver
1k
+V
FREQUENCY (Hz)
2
3
G = +1000
R
for Figure 44b.
S
1kΩ
20pF
L
3k
7
= 600Ω
AD797
G = +1000
R
**
L
20pF
1kΩ
= 10kΩ
**
10k
8
4
–V
G = +100
R
50pF*
S
6
L
= 600Ω
30k
G = +10
R
L
OUTPUT
*OPTIONAL
= 600Ω
100k
300k
0.01
0.003
0.001
0.0003
0.0001