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8.2.4 AFC Control
The 13HMz system clock frequency is controlled by a 13bit sigma-delta D/A in the VEGA chip.
Figure 5:
AFC block diagram
450-0805
8.2.5 Audio
VEGA provides the analogue interface for the digital audio samples processed by the DSP in Gemini.
Voice Uplink path
Figure 6:
Voice ADC block diagram
450-0806
MCUK971001G8
Section 8
Issue 1
Technical Guide
8 - 3
Revision 0
VEGA
13 BIT DIGITAL
MODULATOR
1 BIT DAC
& LOW - PASS
FILTER
PROGRAMATION REGISTER
RINT1
RINT2
Output swing
control
VTCXO
CEXT
AFC
3/5 V
MICBIAS
MICIP
MICIN
AUXI
Bias
Generator
Microphone
Amplifier
Auxiliary
Amplifier
PGA
Sigma_Delta
Modulator
SINC
Filter
IIR
Bandpass
Filter
To voice
serial
interface
fs2=40 KHz
fs3=8.0 KHz
fs1=1 MHz