Electrical audio signal processing systems and devices – Circuitry combined with specific type microphone or loudspeaker – With electrostatic microphone
Patent
1997-11-12
1999-11-02
Harvey, Minsun Oh
Electrical audio signal processing systems and devices
Circuitry combined with specific type microphone or loudspeaker
With electrostatic microphone
381111, 381 92, H04R 300
Patent
active
059784911
ABSTRACT:
In one embodiment of the invention there is provided an electret microphone circuit including an electret microphone including a field effect transistor (FET) having a gate coupled to an electret element, a drain coupled to provide audio frequency output to an audio output node, and a source coupled to ground via a first resistor so as to reduce drain current swings; and an RLC circuit coupled to the drain for configuring the audio frequency output from the drain to desired characteristics. In an alternative embodiment there is provided a circuit coupled to said FET for operating said FET in a source follower mode so as to create low output impedance. In another embodiment of the invention there is provided a method of improving performance of an electret microphone, the microphone including a field effect transistor (FET) having a gate coupled to an electret element, a drain coupled to provide audio frequency output to an audio output node, and a source. The method includes coupling the source to ground via a first resistor so as to reduce drain current swings; and operating the FET in a source follower mode so as to create low output impedance. In another embodiment there is provided a step of configuring the audio frequency output from the drain to desired characteristics.
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Product specificaiton sheet for Professional Boom Microphones, Model 736 from Lectret S.A., 25 Pr. Champs-Frechets, CH-1217, Meyrin-Geneve.
Harvey Minsun Oh
VXI Corporation
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