MAX9814 Microphone AGC Amplifier Board Electret Module Auto Gain Control for Programmable Attack and Release Ratio Low THD

The MAX9814 is a high-quality microphone amplifier with automatic gain control (AGC) and low-noise microphone bias. The MAX981lectret MIC microphone smplifier module features a low-noise preamplifier, variable gain amplifier (VGA), output amplifier, microphone-bias-voltage generator and AGC control circuitry. The low-noise preamp has a fixed 12 dB gain, while the VGA gain automatically adjusts from 20 dB to 0 dB, depending on the output voltage and AGC threshold. The output amplifier offers selectable gains of 8dB, 18dB and 28dB. Without compression, cascading the amplifiers results in an overall gain of 40dB, 50dB or 60dB. A trilevel digital input programs the gain of the output amplifier. An external resistive divider controls the AGC threshold and a single capacitor programs attack / release times.A tri-level digital input programs the relationship between attack and release time. The AGC wait time is fixed at 30 ms. The low-voltage microphone-bias-voltage generator can affect most electret microphones. The MAX9814 is specified over the -40°C to +85°C extended temperature range.