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User manual for MERUS™ audio amplifier configurator
MA2304DNS/MA2304PNS
DSP audio blocks
5.2.2
Limiter details
A limiter functions based on a static input-to-output relationship and time domain parameters.
The input-to-output relationship is typically represented by an input/output curve, in decibels. Any static gain
setting applied to the input signal will shift the entire curve horizontally. Any gain applied to the output signal
would shift the entire curve vertically (sometimes referred to as makeup gain). In case of a digital input speaker
amplifier, like the MA2304xNS, the output limit is a fraction of the full-scale level (0 dB
voltage. Remember that any adjustment to the full-scale voltage (e.g., pvdd_scale setting) will change the
voltage limit at the output. This is especially important when limiting the output based on loudspeaker power
handling specifications and/or IC temperature.
Figure 50
shows an input/output plot showing the effects of the pre-gain and threshold parameters.
Let's assume that pre-gain = 10 dB and the threshold = -20 dB as shown in the plot. With these parameter
values, an input level of -20 dB will now, effectively, result in a -10 dB input level from the limiter's perspective,
which makes the limiter kick in sooner (more aggressive).
Figure 50
Limiter input/output curve with threshold = -20 dB and a pre-gain = 10 dB
User Manual
0
-20
pre-gain
-40
-60
-60
-40
pre-gain
-20
Input level (dB)
40
) and the full-scale
FS
0
V 1.1
2022-09-12
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