Analog Devices ADAU1961 Manual page 32

ADAU1961
Noise Gate Mode 2 (see Figure 41) is selected by setting the
NGTYP[1:0] bits to 10. In this mode, the ADAU1961 improves
the sound of the noise gate operation by first fading the PGA
gain over a period of about 100 ms to the minimum PGA gain
value. The ADAU1961 does not do a hard mute after the fade is
complete, so some small background noise will still exist.
INPUT
ANALOG
GAIN
INTERNAL
NOISE GATE
ENABLE SIGNAL
DIGITAL
MUTE
OUTPUT
Figure 41. Noise Gate Mode 2 (Analog Fade)
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THRESHOLD
250ms
MIN GAIN
100ms
Noise Gate Mode 3 (see Figure 42) is selected by setting the
NGTYP[1:0] bits to 11. This mode is the same as Mode 2 except
that at the end of the PGA fade gain interval, a digital mute is
performed. In general, this mode is the best-sounding mode,
because the audible effect of the digital hard mute is reduced by
the fact that the gain has already faded to a low level before the
mute occurs.
INPUT
ANALOG
GAIN
INTERNAL
NOISE GATE
ENABLE SIGNAL
DIGITAL
MUTE
OUTPUT
Figure 42. Noise Gate Mode 3 (Analog Fade/Digital Mute)
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THRESHOLD
250ms
MIN GAIN
100ms