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