Product Info

VTech proprietary and confidential
VTech Communications LTD.
R&D Department
The document is VTech’s proprietary information, Please do not disclose to third party without VTech’s consent
Ref. No.: 20191009 Version: 01 Date: 09 Oct, 2019 Page 15 of 33
Table 7-1 lists how the ADC digital gain selection values map to digital gain settings.
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
7.2.2.5 ADC digital IIR filte
The ADC contains 2 integrated anti-aliasing filters:
• A long IIR filter suitable for music (> 44.1 kHz).
• G.722 filter . This is a digital IIR filter that improves the stop-band attenuation required for G.722
compliance. This filter is the best selection for 8 kHz/16 kHz/voice.
7.2.3 DAC
The DAC consists of two high-quality DACs
• Each DAC has a fourth-order Sigma-Delta converter.
• Each DAC is a separate channel with identical functionality.
• Each channel has an analog and a digital gain stage.
7.2.3.1 DAC sample rate selectio
Each DAC supports the following sample rates:
• 8 kHz
• 11.025 kHz
• 16 kHz
• 22.050 kHz