REV. D

–16–

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 k

Ω 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.

3

2

V–

3

2

V–

V+

5

6

1k

R8

V+

R10

50

1/2 OF AD8620

R1

1k

1k

R9

1k

R4

1k

R3

AD8610

1/2 OF AD8620

6

R2

1k

7

U3

U2

R13

1k

R5

1k

R6

10k

R7

1k

R12

1k

R11

50

V–

V+

0

1

0

Figure 30. Differential Driver