Datasheet

AD8610/AD8620
Rev. F | Page 21 of 24
High Speed, Low Noise Differential Driver
The AD8620 is a perfect candidate as a low noise differential
driver for many popular ADCs. There are also other applica-
tions (such as balanced lines) that require differential drivers.
The circuit of Figure 70 is a unique line driver widely used in
industrial applications. With ±13 V supplies, the line driver can
deliver a differential signal of 23 V p-p into a 1 k load. The
high slew rate and wide bandwidth of the AD8620 combine to
yield a full power bandwidth of 145 kHz while the low noise
front end produces a referred-to-input noise voltage spectral
density of 6 nV/√Hz. The design is a balanced transmission system
without transformers, where output common-mode rejection of
noise is of paramount importance. Like the transformer-based
design, either output can be shorted to ground for unbalanced
line driver applications without changing the circuit gain of 1.
This allows the design to be easily set to noninverting, inverting,
or differential operation.
3
2
V–
3
2
V–
V+
5
6
V+
1/2 AD8620
U2
AD8610
1/2 AD8620
U3
6
7
0
1
0
02730-070
R3
1kΩ
R4
1kΩ
R13
1kΩ
R5
1kΩ
R6
10kΩ
R7
1kΩ
R1
1kΩ
R12
1kΩ
R2
1kΩ
R10
50Ω
R11
50Ω
R8
1kΩ
R9
1kΩ
V
O
2
V
O
1
V
O
2 – V
O
1 = V
IN
V–
V+
Figure 70. Differential Driver