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Audio to MCU interface (programmable amplifier) | PCB Design

Audio to MCU interface (programmable amplifier)
Version 2 - Last update: Jun 1, 2016

This module contains 2 audio amplifiers with anti-aliasing filter, wich makes the output channels ready to be sampled by a simple microcontroller. There are 2 inputs: a standard stereo audio jack as well as an electret microphone. You can program the amplification of each channel seperatly as well as the selection of the audio input (electret, left or right) by SPI interface.


  • Programmable gain between 25 dB and 46 dB in 256 steps (simple SPI interface)

  • 2 separate channels

  • 2 audio inputs: electret microphone, stereo audio jack

  • 3th order anti-aliasing filter with cut-off frequency 8 kHz (simple adjustment by the change of feedback capacitors)

  • supply voltage: 2.7 V to 5.5 V

  • PCB area: 3 cm x 3 cm

This makes the module ideal for devices who needs to react on surrounding music or directly plugged in mp3-player. You can switch in realtime between the different audio inputs and you can implement your own automatic gain control algorithm.

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