AD8432

Data Sheet

Rev. D | 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.

–

–

+

+

1

8

4

5

6

7

2

BIAS

INL1

IND1

INH1

ENB

VPS1

VPS2

COMM

OPH1

OPL1

LNA1

IN1

20Ω

499Ω

499Ω

20Ω

15Ω

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