OP471 Datasheet, PDF (11/16 Pages) Analog Devices – High Speed, Low Noise Quad Operational Amplifier

High-Speed Differential Line Driver
The circuit of Figure 15 is a unique line driver widely used in
professional audio applications. With ± 18 V supplies, the line
driver can deliver a differential signal of 30 V p-p into a 1.5 kW
load. The output of the differential line driver looks exactly like
a transformer. Either output can be shorted to ground without
changing the circuit gain of 5, so the amplifier can easily be set
for inverting, noninverting, or differential operation. The line
driver can drive unbalanced loads, like a true transformer.
+15V
V_IN
R3
1/4
200⍀
R1
OP471E
50⍀
R2
–15V 5k⍀
R4
50⍀
1/4
OP471E
R5
5k⍀
R6
200⍀
V_OUT = 100V_IN
1/4
R7
OP471E
50⍀
R9
200⍀
R8
5k⍀
1/4
R10
OP471E
50⍀
R12
200⍀
R11
5k⍀
Figure 13. Low-Noise Amplifier
High-Output Amplifier
The amplifier shown in Figure 16 is capable of driving 20 V p-p
into a floating 400 W load. Design of the amplifier is based on a
bridge configuration. A1 amplifies the input signal and drives
the load with the help of A2. Amplifier A3 is a unity-gain inverter
which drives the load with help from A4. Gain of the high output
amplifier with the component values shown is 10, but can
easily be changed by varying R1 or R2.
OP471
100
90
10
0%
Figure 14. Noise Density of Low-Noise Amplifier, G = 100
R4
10k⍀
R11
1/4
50⍀
OP471
R2
2k⍀
R8
10k⍀
IN
R1
1/4
10k⍀ _OP471
R7
2k⍀
R6
2k⍀
R9
10k⍀
R10
R3
2k⍀
1/4
50⍀
OP471
R5
10k⍀
–OUT
R14
1k⍀
R13
10k⍀
R12
1k⍀
+OUT
Figure 15. High-Speed Differential Line Driver
C1
10␮F
+
+15V
C2
0.1␮F
R1
1k⍀
1/4
OP471E
A1
V_IN
C3
0.1␮F
C4
10␮F
+
–15V
REV. A
R2
9k⍀
R3
50⍀
R5
5k⍀
R6
5k⍀
R7
50⍀
1/4
OP471E
A2
R4
50⍀
R8
R_L 50⍀
1/4
OP471E
A4
Figure 16. High-Output Amplifier
–11–
1/4
OP471E
A3