Datasheet

AD8432 Data Sheet
Rev. C | Page 24 of 32
DIFFERENTIAL-TO-SINGLE-ENDED CONVERSION
Some applications require the low noise and high dynamic
range of the AD8432; however, they may also require a single-
ended output, rather than a differential output. The AD8129
or AD8130 differential receiver amplifier can be used for the
differential-to-single-ended conversion of the AD8432 output,
as shown in Figure 72.
The AD8129 is a low noise, high gain (10 or greater) amplifier
intended for applications over very long cables, where signal
attenuation is significant. The AD8130 is stable at a gain of 1
and can be used for applications where lower gains are required.
The AD8129 and AD8130 have user-adjustable gain, set by the
ratio of two resistors, to help compensate for losses in the
transmission line.
A transformer or balun can also be used to convert the differential
output of the AD8432 to a single-ended output. Transformers
have lower distortion; however, care must be taken to properly
match the impedance of the transformer. The test circuit for
distortion measurements in Figure 58 uses an ADTT1-1
transformer to perform differential-to-single-ended conversion.
08341-044
–
–
+
+
1
8
4
5
6
7
2
–V
S
+V
S
V
OUT1
BIAS
INL1
IND1
INH1
ENB VPS1 VPS2 COMM
OPH1
OPL1
LNA1
IN1
20Ω
499Ω 499Ω
20Ω
R
SH1
15Ω
C
SH1
47
pF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
GMH1
GOH1
GOL1
GML1
SERIES 20Ω
RESISTORS IF DRIVING
HIGH CAP LOAD
AC-COUPLING CAPS
(AD8432 HAS 2.5V
OUTPUT BIAS)
AD8130
499Ω RESISTORS PROVIDE
BIAS CURRENT PATH AND
TERMINATION IF NECESSARY
G = 12 dB
Figure 72. AD8432 Differential-to-Single-Ended Conversion Using the AD8129/AD8130 with Unity Gain