30V N-channel JFET matched-pair transistor with self-biased gates for electret condenser microphones

The JFE2325 is a monolithic, matched-pair discrete

JFET intended for use with very high-impedance sensors such as electret condenser

microphones (ECMs). The device consists of two N-channel JFETs, laid out for

excellent matching on a single die. The gate of each JFET is biased by an integrated

diode which allows for direct coupling of a signal source to the gate without the

need for a biasing resistor. The JFE2325 achieves much higher input impedance

(>400GOhm) than possible if discrete resistors were used to bias the gate.

Furthermore, the JFE2325 features an extremely low input capacitance of 0.85pF per

JFET which maximizes signal levels from transducers with extremely low output

capacitance.

Each JFET is capable of 0.7mS of

transconductance when configured to run at the full drain current of 385µA. The

JFETs can be used individually, or in parallel for higher transconductance and lower

noise.

The JFE2325 can withstand a high gate-to-drain

voltage of 30V. The temperature range is specified from –40°C to +125°C.