The MAX9810 microphone preamplifier is intended for use inside electret condenser microphone (ECM) cartridges. Current solutions use a FET as an impedance converter. FETs have limited gain, are susceptible to noise and require additional components external to the ECM cartridge for biasing and amplification. The MAX9810 replaces the FET with a high-gain, high-noise rejection, low-output-impedance amplifier. Designed to be integrated inside the ECM cartridge, the MAX9810 offers a flat frequency response, tightly controlled gain, increased sensitivity, and high-noise rejection greatly simplifying system design. Target applications include ECM cartridges in cell phones, PDAs, notebooks, and other portable audio devices.