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US 2009/0214057 A1Published application
Microphone bias circuits
AssigneeMediatek Inc.
InventorChih-Hong Lou
Life of this patent
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Abstract
A microphone bias circuit is disclosed. A current source provides a first current. A voltage buffer provides a first reference voltage. A microphone coupled between the current source and the first reference voltage receives acoustic waves and converts the received acoustic waves to a second current. A loading device coupled between the current source and a second reference voltage lower than the first reference voltage outputs an output voltage according to the first current and the second current.
Claims19
A microphone bias circuit, comprising:
- a current source providing a first current;
- a voltage buffer providing a first reference voltage;
- a microphone coupled between the current source and the first reference voltage, receiving acoustic waves and converting the received acoustic waves to a second current;
- and
- a loading device coupled between the current source and a second reference voltage lower than the first reference voltage, outputting an output voltage according to the first current and the second current.
2 more elements
A microphone bias circuit, comprising:
- a voltage buffer providing a first reference voltage;
- a driving circuit providing a bias voltage according to a first input voltage, a second input voltage and a second reference voltage, wherein the second reference is lower than the first reference voltage;
- a microphone coupled between the first reference voltage and the bias voltage, receiving acoustic waves, and converting the received acoustic waves to a sensing current;
- and
- a loading device coupled between the driving circuit and the microphone, and outputting a first output voltage according to the bias voltage and the sensing current.
2 more elements
Dependencies are inferred from the claim text.