Datasheet

2–4
2.1.4 MIC Input
The auxiliary inputs (AURXFP, AURXCP, and AURXM) can be programmed to interface with a microphone such as
an electret microphone, as illustrated in Figure 2.5, by writing a 1 to bit D6 and D4 of control register 1. Enabling MIC
input with DG automatically selects AURx channel for ADC input.
Sigma-
Delta
ADC
PGA
TLV320AIC10
Anti-
Aliasing
Filter
AURXFP
Electret
Microphone
MIC_BIAS VMID
10 kΩ
AURXM
AURXCP
S2D
+
–
1 kΩ
10 kΩ
0.1 µF
V
ref
Figure 2–5. Typical Microphone Interface
2.1.5 Antialiasing Filter
The built-in antialiasing filter has a 3-dB cutoff frequency of 70 kHz.
2.1.6 Sigma-Delta ADC
The sigma-delta analog-to-digital converter is a sigma-delta modulator with 128× oversampling. The ADC provides
high-resolution, low-noise performance using oversampling techniques. Due to the oversampling employed, only
single-pole RC filters are required on the analog inputs.
2.1.7 Decimation Filter
The decimation filters reduce the digital data rate to the sampling rate. This is accomplished by decimating with a ratio
of 1:64. The output of the decimation filter is a 16-bit 2s-complement data word clocking at the sample rate selected
for that particular data channel. The BW of the filter is 0.45 × FS and scales linearly with the sample rate.
2.1.8 Sigma-Delta DAC
The sigma-delta digital-to-analog converter is a sigma-delta modulator with 128× oversampling. The DAC provides
high-resolution, low-noise performance using oversampling techniques.
2.1.9 Interpolation Filter
The interpolation filter resamples the digital data at a rate of 64 times the incoming sample rate. The high-speed data
output from the interpolation filter is then used in the sigma-delta DAC. The BW of the filter is 0.45 x FS and scales
linearly with the sample rate.