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SE Input and SE Output (TPA3122D2 Stereo Configuration)
V
GEN
C
IN
C
L
R
IN
R
GEN
Twisted-Pair Wire
Generator
Evaluation Module
Audio Power
Amplifier
Twisted-Pair Wire
R
L
R
ANA
C
ANA
Analyzer
R
ANA
C
ANA
L
filt
C
filt
TPA3122D2
SLOS527A – DECEMBER 2007 – REVISED DECEMBER 2007
The SE input and output configuration is used with class-AB amplifiers. A block diagram of a fully SE
measurement circuit is shown in
Figure 31
. SE inputs normally have one input pin per channel. In some cases,
two pins are present; one is the signal and the other is ground. SE outputs have one pin driving a load through
an output ac coupling capacitor and the other end of the load is tied to ground. SE inputs and outputs are
considered to be unbalanced, meaning one end is tied to ground and the other to an amplifier input/output.
The generator should have unbalanced outputs, and the signal should be referenced to the generator ground for
best results. Unbalanced or balanced outputs can be used when floating, but they may create a ground loop that
will effect the measurement accuracy. The analyzer should have balanced inputs to cancel out any
common-mode noise in the measurement.
Figure 31. SE Input—SE Output Measurement Circuit
The following general rules should be followed when connecting to APAs with SE inputs and outputs:
•
Use an unbalanced source to supply the input signal.
•
Use an analyzer with balanced inputs.
•
Use twisted pair wire for all connections.
•
Use shielding when the system environment is noisy.
•
Ensure the cables from the power supply to the APA, and from the APA to the load, can handle the large
currents (see
Table 4
)
Copyright © 2007, Texas Instruments Incorporated
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