GENERAL DESCRIPTION

The SSM2165 is a complete and flexible solution for condition ing microphone inputs in computer audio systems. It is also excellent for improving vocal clarity in communications and 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 compression characteristic. The compression ratio is set by a single resistor and can be varied from 1:1 to over 15:1 relative to the fixed rotation point. Signals above the rotation point are limited to prevent overload and to eliminate “popping.” A downward expander (noise gate) prevents amplification of noise or hum. This results in optimized signal levels prior to digitization, thereby eliminating the need for additional gain or attenuation in the digital domain that could add noise or impair accuracy of speech recognition algorithms. The flexibility of setting the compression ratio and the time constant of the level detector, coupled with two values of rotation point, make the SSM2165 easy to integrate in a wide variety of microphone conditioning applications.

FEATURES

Complete Microphone Conditioner in an 8-Lead Package

Single 5 V Operation

Preset Noise Gate Threshold

Compression Ratio Set by External Resistor

Automatic Limiting Feature Prevents ADC Overload

Adjustable Release Time

Low Noise and Distortion

20 kHz Bandwidth (±1 dB)

Low Cost

APPLICATIONS

Microphone Preamplifier/Processor

Computer Sound Cards

Public Address/Paging Systems

Communication Headsets

Telephone Conferencing

Guitar Sustain Effects Generator

Computerized Voice Recognition

Surveillance Systems

Karaoke and DJ Mixers