发明公开

ELECTRET MICROPHONE
摘要:
An electret microphone is provided, comprising a microphone capsule with an output connection, a first input connection as an earth connection and a second input connection for providing a supply voltage for the microphone capsule and for leading out a microphone output signal of the microphone capsule, and a cascode consisting of a first and second transistor. An output connection of the microphone capsule is provided as input of the cascode. The second transistor is configured as a field effect transistor FET and the gate connection thereof is coupled to the output connection of the microphone capsule. A drain connection of the second transistor is coupled to an emitter connection of the first transistor as bipolar transistor or to a source connection of the first transistor as an FET transistor. Furthermore, a third transistor is provided as bipolar transistor, whose emitter connection is coupled to the second input connection. A collector connection of the third transistor is coupled via a capacitor to earth. A base connection of the third transistor is coupled via a resistance to the second input connection. The base connection of the third transistor is coupled to a collector connection of the first transistor as bipolar transistor or to a drain connection of the first transistor as FET transistor. A resistance is coupled between the drain connection of the second transistor and the collector connection of the third transistor.
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