Datasheet
10k
1M
1G
FREQUENCY (Hz)
0.0
8.0
16
24
GAIN (dB)
100
M
10M
100k
20
12
4.0
2.0
6.0
10
14
18
22
V
S
= ±5.0V
A
V
= +10
R
G
= 110:
R
F
= 500:
R
L
= 1k:
100
10k
10M
FREQUENCY (Hz)
30n
38n
46n
54n
1M
100k
1k
50n
42n
34n
32n
36n
40n
44n
48n
52n
V
S
= ±5.0V
A
V
= +10
R
G
= 110:
R
F
= 500:
R
L
= 1k:
OUTPUT REFERED NOISE (V/
Hz)
A
V
=
2
R
F
R
C
R
IN
1
=
N
2
R
S
-
+
-
+
R
S
V
S
1 : N
R
IN
R
C
110
:
R
F 500
:
R
F
500
:
+V
OUT
/2
-V
OUT
/2
LMH6622
LMH6622
TO ADC
x
LMH6622
www.ti.com
SNOS986D –DECEMBER 2001–REVISED MARCH 2013
The factor '2 ' appears here because of differential output.
DIFFERENTIAL ANALOG-TO-DIGITAL DRIVER
Figure 38. Circuit for Differential A/D Driver
The LMH6622 is a low noise, low distortion high speed operational amplifier. The LMH6622 comes in either
SOIC-8 or VSSOP-8 packages. Because two channels are available in each package the LMH6622 can be used
as a high dynamic range differential amplifier for the purpose of driving a high speed analog-to-digital converter.
Driving a 1kΩ load, the differential amplifier of Figure 38 provides 20dB gain, a flat frequency response up to
6MHz, and harmonic distortion that is lower than 80dBc. This circuit makes use of a transformer to convert a
single-ended signal to a differential signal. The input resistor R
IN
is chosen by the following equation,
(15)
The gain of this differential amplifier can be adjusted by R
C
and R
F
,
(16)
Figure 39. Frequency Response Figure 40. Total Output Referred Noise Density
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