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US 2025/0280245 A1Published application
Electret capsule circuit
AssigneeFreedman Electronics Pty Ltd
InventorsPeter Freedman, Pieter Schillebeeckx
Life of this patent
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Abstract
The present invention relates generally to the field of electret capsule circuit, and more particularly to a circuit configuration of an impedance converter integrated in an electret capsule such as for use in condenser microphones. The electret capsule of a microphone may include a gate biasing field effect transistor (FET) to facilitate biasing of a low noise FET. Advantageously, the use of low noise FET in the electret capsule of a microphone provides for a reduced cost, while achieving lower self-noise.
Claims10
An electret capsule circuit comprising:
- a first and a second field effect transistor (FET), each FET including a source, a drain, and a gate;
- a biasing arrangement of said first and second FET, wherein said first FET is an impedance converter low noise FET and said second FET is a gate biasing FET, a source electrode of the first FET being electrically connected to a source electrode of the second of FET;
- a current setting element coupled to the source of said first FET;
- and
- a bypass capacitor in parallel with said current setting element.
2 more elements
Dependencies are inferred from the claim text.