Digital Gain Selection
Value
ADC Digital Gain Setting
(dB)
Digital Gain Selection
Value
ADC Digital Gain Setting
(dB)
0
0
8
-24
1
3.5
9
-20.5
2
6
10
-18
3
9.5
11
-14.5
4
12
12
-12
5
15.5
13
-8.5
6
18
14
-6
7
21.5
15
-2.5
Table 9.2: ADC Audio Input Gain Rate
9.2.7
ADC Digital IIR Filter
The ADC contains 2 integrated anti-aliasing filters:
■
A
long
IIR filter suitable for music (>44.1kHz)
■
G.722 filter is a digital IIR filter that improves the stop-band attenuation required for G.722 compliance
(which is the best selection for 8kHz / 16kHz / voice)
For more information contact CSR.
9.2.8
DAC
The DAC consists of:
■
2 fourth-order Sigma-Delta converters enabling 2 separate channels that are identical in functionality, as
Figure 9.2 shows.
■
2 gain stages for each channel, 1 of which is an analogue gain stage and the other is a digital gain stage.
9.2.9
DAC Sample Rate Selection
Each DAC supports the following sample rates:
■
8kHz
■
11.025kHz
■
16kHz
■
22.050kHz
■
32kHz
■
40kHz
■
44.1kHz
■
48kHz
■
96kHz
9.2.10 DAC Digital Gain
A digital gain stage inside the DAC varies from -24dB to 21.5dB, see Table 9.3. There is also a
fine gain interface
with a 9-bit gain setting enabling gain changes in 1/32 steps, for more information contact CSR.
Advance Information
This material is subject to CSR's non-disclosure agreement
© Cambridge Silicon Radio Limited 2011
Page 40 of 110
CS-209182-DSP1
CSR8640 BGA
Data Sheet
