WM1811A Datasheet, PDF (72/328 Pages) Wolfson Microelectronics plc – Multi-Channel Audio Hub CODEC for Smartphones

WM1811A
The DRC parameters are listed in Table 26.
REF
PARAMETER
DESCRIPTION
1
[DRC]_KNEE_IP
Input level at Knee1 (dB)
2
[DRC]_KNEE_OP
Output level at Knee2 (dB)
3
[DRC]_HI_COMP
Compression ratio above Knee1
4
[DRC]_LO_COMP
Compression ratio below Knee1
5
[DRC]_KNEE2_IP
Input level at Knee2 (dB)
6
[DRC]_NG_EXP
Expansion ratio below Knee2
7
[DRC]_KNEE2_OP
Output level at Knee2 (dB)
Table 26 DRC Response Parameters
Production Data
The noise gate is enabled when the [DRC]_NG_ENA register is set. When the noise gate is not
enabled, parameters 5, 6, 7 above are ignored, and the [DRC]_LO_COMP slope applies to all input
signal levels below Knee1.
The DRC_KNEE2_OP knee is enabled when the [DRC]_KNEE2_OP_ENA register is set. When this
bit is not set, then parameter 7 above is ignored, and the Knee2 position always coincides with the low
end of the [DRC]_LO_COMP region.
The “Knee1” point in Figure 21 is determined by register fields [DRC]_KNEE_IP and
[DRC]_KNEE_OP.
Parameter Y0, the output level for a 0dB input, is not specified directly, but can be calculated from the
other parameters, using the equation:
GAIN LIMITS
The minimum and maximum gain applied by the DRC is set by register fields [DRC]_MINGAIN,
[DRC]_MAXGAIN and [DRC]_NG_MINGAIN. These limits can be used to alter the DRC response
from that illustrated in Figure 21. If the range between maximum and minimum gain is reduced, then
the extent of the dynamic range control is reduced.
The minimum gain in the Compression regions of the DRC response is set by [DRC]_MINGAIN. The
mimimum gain in the Noise Gate region is set by [DRC]_NG_MINGAIN. The minimum gain limit
prevents excessive attenuation of the signal path.
The maximum gain limit set by [DRC]_MAXGAIN prevents quiet signals (or silence) from being
excessively amplified.
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PD, November 2013, Rev 4.1
72