Circuitry for improving performance of electret microphone
US5978491A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 12, 1997 |
| Grant date | Nov 2, 1999 |
| Priority date | — |
| Expiry date | Nov 12, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R19/016
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
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 prov…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.