ADC Channel Response for Decimation Filter C
(Red line corresponds to –60 dB)
0
–20
–40
–60
–100
–80
–120
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
Frequency Normalized to f
S
Magnitude
–
dB
G015
Digital Microphone Input/Decimation Filter
2.3.3.1.3.3 Decimation Filter C
Filter type C along with AOSR of 32 is specially designed for 192ksps operation for the ADC. The pass
band which extends up to 0.11*Fs ( corresponds to 21kHz), is suited for audio applications.
Table 2-11. Decimation Filter C, Specifications
Parameter
Condition
Value (Typical)
Units
Filter Gain from 0 to 0.11Fs
0…0.11Fs
±0.033
dB
Filter Gain from 0.28Fs to 16Fs
0.28Fs…16Fs
–60
dB
Filter Group Delay
11/Fs
Sec.
Pass Band Ripple, 8 ksps
0…0.11Fs
0.033
dB
Pass Band Ripple, 44.1 ksps
0…0.11Fs
0.033
dB
Pass Band Ripple, 48 ksps
0…0.11Fs
0.032
dB
Pass Band Ripple, 96 ksps
0…0.11Fs
0.032
dB
Pass Band Ripple, 192 ksps
0…20kHz
0.086
dB
Figure 2-19. Decimation Filter C, Frequency Response
2.3.3.1.4 ADC Data Interface
The decimation filter and signal processing block in the ADC channel passes 32-bit data words to the
audio serial interface once every cycle of Fs,ADC. During each cycle of Fs,ADC, a pair of data words ( for
left and right channel ) are passed. The audio serial interface rounds the data to the required word length
of the interface before converting to serial data as per the different modes for audio serial interface.
32
TLV320DAC3203 Application
SLAU434 – May 2012
Copyright © 2012, Texas Instruments Incorporated