The capacitive acoustic sensor inside a microphone capsule has a very high output impedance-often in the hundreds of megaohms. Such high impedance makes it difficult to directly match with external amplification circuits.
In addition, the signal generated by the capacitive sensor is extremely weak, making it unsuitable for direct coupling with external amplifiers.
To solve this, a Field-Effect Transistor (FET) is built into the microphone capsule. The FET offers high input impedance and low output impedance, making it ideal for bridging the high-impedance sensor with the lower-impedance external circuitry.
This internal FET acts as a buffer and preamplifier, allowing effective signal transfer and impedance matching between the sensor and the external amplifier circuit. It also boosts the weak signal from the sensor, improving usability.
Once an FET is added, it requires a power supply. The typical operating voltage for the FET inside an electret microphone capsule ranges from 1.5V to 4.5V.
Our high-sensitivity microphone capsules use premium Korean high-gain FET chips, delivering sensitivity several times higher than standard models. These capsules are ideal for surveillance cameras, long-distance voice pickup, and voice-activated control systems.
