Main Content

MEMS Microphones is setting a new performance benchmark across a growing number of industries. These innovative silicon microphones were designed to extend the benefits of the lowest possible self-noise (high SNR) and lowest distortion to an ever-expanding number of applications. The project presented here is a low noise analog MEMS microphone Preamplifier with compression and noise gating. The project provides a studio-quality audio experience. The project is built using SSM2167 chip and InvenSense ICS-40180 Low-Noise Microphone with bottom port and analog output.

This is a complete microphone signal conditioning project. Designed primarily for voice-band applications, this project provides amplification, limiting, variable compression, and noise gate. User-adjustable compression ratio, noise gate threshold, and two different fixed gains optimize circuit operation for a variety of applications.

This is a complete and flexible solution for conditioning MEMS microphones for personal electronics and computer audio systems. It is also excellent for improving vocal clarity in communications and the public address systems. A low noise voltage-controlled amplifier (VCA) provides a gain that is dynamically adjusted by a control loop to maintain a set compressions characteristic. The compression ratio is set by a jumper and can be varied from 1:1 to over 10:1 relative to the fixed rotation point. Signals above the rotation point are limited to prevent overload and eliminate popping.

A downward expander (noise gate) prevents the amplification of background noise or hum. This results in an optimized signal level prior to digitization, thereby eliminating the need for additional gain or attenuation in the digital domain. The flexibility of setting the compression ratio and the time constant of the level detector, coupled with two values of rotation point, make the SSM2167 easy to integrate into a wide variety of microphone conditioning applications.”

Link to article