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User manual for MERUS™ evaluation boards
EVAL_AUDIO_MA12070_B and EVAL_AUDIO_MA12070P_B
Measurement methods
4
Measurement methods
Setting up a reliable measurement configuration for MA12070 or MA12070P takes a little bit more effort than
linear amplifiers and even "regular" switching amplifiers. This is mainly because MA12070 and MA12070P are
filterless amplifiers, which means they do not require an external (usually expensive and bulky) LC filter to
remove switching residuals. The filterless application is enabled by the MERUS™ audio multilevel technique,
which makes sure that the switching residual is orders lower compared to "regular" switching amplifiers. For
more information on the multilevel switching technique, please refer to the datasheet.
To obtain reliable measurement results when measuring MA12070 or MA12070P devices requires a separate
external LPF in front of the input stage of the audio analyzer. Most audio analyzers are bandwidth limited at
their input stage, which means that they cannot follow the rapid changes of the amplifier's output stage. This
can result in inaccurate and high THD + N measurements.
Figure 4 shows the recommended measurement setup. The setup shows an LPF stage (AUX-2500) in front of the
audio analyzer (APX-515). In this case the measurement setup has been built around Audio Precision hardware,
but this can also be some other audio analyzer hardware. Please note that it is recommended to use both
balanced input and output measurement configurations. Note that
(MA12070). To use the setup for digital input (MA12070P), simply replace the balanced analog input path with
the I
S input path.
2
User Manual
Figure 4
13 of 23
shows the setup for analog input
V 1.0
2023-03-02
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