LOW NOISE AMPLIFIER FOR MICROPHONE

摘要

A preamplifier for use with high impedance audio frequency transducers, having two capacitance coupled stages each including a field effect transistor connected in follower mode. The two stages provide an impedance converter. The first field effect transistor is of substantially smaller geometry than the second, providing a low noise, low input capacitance. The second stage further reduces output impedance while maintaining low power supply feedthrough. A capacitor connected in shunt between the stages is employed for frequency shaping.