3. TECHNICAL BRIEF
22
3.3.6 Microphone
The microphone is placed to the front cover and contacted to main PCB.
The audio signal is passed to AIN1P and AININ pins of AD6720.
The voltage supply VMIC is output from AD6720, and is a biased voltage for the AIN1P.
The AIN1P and AIN1N signals are then A/D converted by the voiceband ADC part of AD6720.
The digitized speech (PCM 8KHz ,16KHz) is then passed to the DSP section of AD6720 for
processing (coding, interleaving etc).
Figure 3-8: Keypad Switches and Scanning
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