Record Signal Path; Input Signal Paths - Analog Devices ADAU1961 Manual

RECORD SIGNAL PATH

JACKDET/MICIN
LINN
LINP
LAUX
RAUX
RINP
RINN
RDVOL[5:0]

INPUT SIGNAL PATHS

The ADAU1961 can accept both line level and microphone
inputs. The analog inputs can be configured in a single-ended
or differential configuration. There is also an input for a digital
microphone. The analog inputs are biased at AVDD/2. Unused
input pins should be connected to CM.
Each of the six analog inputs has individual gain controls (boost
or cut). The input signals are mixed and routed to an ADC. The
mixed input signals can also bypass the ADCs and be routed
directly to the playback mixers. Left channel inputs are mixed
before the left ADC; however, it is possible to route the mixed
analog signal around the ADC and output it into a left or right
output channel. The same capabilities apply to the right channel
and the right ADC.
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LINNG[2:0]
–12dB TO +6dB
PGA
LDBOOST[1:0]
MUTE/0dB/20dB
–12dB TO
+35.25dB
LINPG[2:0]
–12dB TO +6dB
ALCSEL[2:0]
LDVOL[5:0] ALC
CONTROL
MX1AUXG[2:0]
–12dB TO +6dB
MX2AUXG[2:0]
–12dB TO +6dB
RINPG[2:0]
–12dB TO +6dB
PGA
RDBOOST[1:0]
MUTE/0dB/20dB
–12dB TO
+35.25dB
RINNG[2:0]
–12dB TO +6dB
ALCSEL[2:0]
ALC
CONTROL
DIGITAL
MICROPHONE
INTERFACE
MIXER 1
(LEFT RECORD
MIXER)
LEFT
MIXER 1
OUTPUT
(TO PLAYBACK
MIXER)
AUXILIARY
BYPASS
MIXER 2
OUTPUT
(TO PLAYBACK
MIXER)
RIGHT
MIXER 2
(RIGHT RECORD
MIXER)
Figure 31. Record Signal Path
Signals are inverted through the PGAs and the mixers. The
result of this inversion is that differential signals input through
the PGA are output from the ADCs at the same polarity as they
are input. Single-ended inputs that pass through the mixer but
not through the PGA are inverted. The ADCs are noninverting.
The input impedance of the analog inputs varies with the gain
of the PGA. This impedance ranges from 1.7 kΩ at the 35.25 dB
gain setting to 80.4 kΩ at the −12 dB setting. This range is shown
in Figure 22.
Rev. 0 | Page 27 of 76
MICIN LEFT
MICIN RIGHT
ADC
INSEL
ADC
INSEL
ADAU1961
DECIMATOR/
ALC/
DIGITAL
VOLUME