Switched microphone buffer

Details Switched microphone buffer Switched microphone buffer

2006-08-15

2006-08-15

Lee, Ping (Department: 2644)

Electrical audio signal processing systems and devices

Circuitry combined with specific type microphone or loudspeaker

With electrostatic microphone

C381S317000, C330S009000, C327S124000

Reexamination Certificate

active

07092538

ABSTRACT:
A method and apparatus for substantially reducing and virtually eliminating direct current flow through the input transistor(s) of an input buffer circuit for an electret microphone is disclosed. An input transistor is provided and operably connected to an input and an output of the input buffer circuit. The input transistor has a first operating state wherein current flow occurs in a first direction and a second operating state wherein the a current flow occurs in a second direction—opposite that of the first direction. The input transistor is biased to alternately control operation between the first operating state and the second operating state. The alternating, opposing flows of current of the respective operating states cooperate to substantially reduce and virtually eliminate the flow of direct current through the input transistor(s) of the buffer circuit. A reduction in excess noise associated with the input transistor results from the substantially decreased direct current flow through the input transistor(s) of the buffer circuit.

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