Datasheet

ADAU1761

Rev. C | Page 34 of 92

Noise Gate Mode 2 (see Figure 42) is selected by setting the

NGTYP[1:0] bits to 10. In this mode, the ADAU1761 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 ADAU1761 does not do a hard mute after the fade is

complete, so some small background noise will still exist.

Noise Gate Mode 3 (see Figure 43) 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.

THRESHOLD

INPUT

ANALOG

GAIN

DIGITAL

MUTE

OUTPUT

INTERNAL

NOISE GATE

ENABLE SIGNAL

250ms

MIN GAIN

100ms

07680-029