AD8610/AD8620
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 applications,
such as balanced lines, that require differential drivers. The circuit
of Figure 30 is a unique line driver widely used in industrial applica-
tions. With ±13 V supplies, the line driver can deliver a differential
signal of 23 V p-p into a 1 kΩ 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
transformerless, balanced transmission system 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.
R4 1k⍀
3 V+
6
R8 1k⍀
2 V– AD8610
0
R9 1k⍀
R3 1k⍀
U2
3
V+
1
VO1
2
V–
1/2 OF AD8620
R10
50⍀
R1
1k⍀
5 V+
7
R12
1k⍀
R13
1k⍀
R5
1k⍀
R6
10k⍀
R7
1k⍀
1/2 OF AD8620
6
V–
U3
R2
1k⍀
R11
50⍀
VO2
VO2 – VO1 = V IN
0
Figure 30. Differential Driver
–16–
REV. D