Pre-Amplifier for MEMS Microphone

  • Rajkumar Sharma
  • 78 Views
  • easy
  • Tested

This is a low-cost, small-size audio pre-amplifier for MEMS microphone, OPAMP-based circuit amplifies the low-level analog signal coming from MEMS microphone to the desired level required for the next stage which is an audio amplifier, basically microphone level to line level.

Resistor R4 and R7 are used to generate a voltage reference to bias the input common-mode voltage of the op-amp at VCC/2, C7, C8, and R7 help to reduce power supply noise. R5 and C5 allow AC coupling of the microphone signal.  R2 and C2 create a low-pass gain so as not to amplify noise beyond the audio bandwidth. R3 and C6 create a high-pass gain so as not to amplify the DC biasing of the op-amp (including input offset voltage). The cut-off frequency is 59 Hz. D1 is a power LED, this board has a dual option for MEMS microphones. Users may solder onboard microphones or connect external microphones. This board is tested with external Analog MEMS microphone modules from PUI Audio which comes with 3 connections VCC, GND, and output.

Features

  • Supply 3.3V
  • Very Low Noise Output
  • On-Board Power LED
  • Dual Microphone Option (Onboard or External Microphone)
  • PCB Dimensions 27.78 x 14.29 mm

Schematic

Parts List

NO.QNTY.REF.DESC.MANUFACTURERSUPPLIERPART NO
11CN14 PIN MALE HEADER CONNECTOR PITCH 2.54MMWURTHDIGIKEY732-5317-ND
21CN2AMM-3742-T-EB-RPUI AUDIODIGIKEY668-AMM-3742-T-EB-R-ND
32C1,C51uF/25V SMD SIZE 1206MURATA/YAGEODIGIKEY
41C2560PF/50V SMD SIZE 0805MURATA/YAGEODIGIKEY
51C30.1uF/50V SMD SIZE 0805MURATA/YAGEODIGIKEY
62C4,C810uF/6.3V SMD SIZE 1206MURATA/YAGEODIGIKEY
71C63.3uF/10V SMD SIZE 1206MURATA/YAGEODIGIKEY
81C722uF/10V SMD SIZE 1206MURATA/YAGEODIGIKEY
91D1LED SMD SIZE 0805LITE ON INCDIGIKEY160-1427-1-ND
101R11K 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
111R227K 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
121R3820E 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
134R4,R5,R6,R710K 5% SMD SIZE 0805MURATA/YAGEODIGIKEY
141U1TS971STDIGIKEY497-8150-1-ND
151U2ICS-40180( Optional) DO NOT POPULATETDK

Connections

MEMS Microphone Specifications



Gerber View

Photos

Video

ICS-40180 Datasheet

ds-000021-v1.22

PCB

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