I am doing a project using a PIC18F25K80 to stream live audio through ZigBee. I used the PIC audio development board (Microchip) as my reference circuit. In this circuit the in-built ADC of the PIC is used for Analog-to-Digital conversion and in-built PWM is used for Digital-to-Analog conversion.
In this circuit, sampling rate is 8kHz, ADC resolution is 10-bit and PWM frequency is 25kHz. The circuit is affected by severe noise while in playback and the signal strength is very low. How can I solve this issue?