Amplifier circuit for electret microphone with enhanced performance
US6504937B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 15, 1998 |
| Grant date | Jan 7, 2003 |
| Priority date | — |
| Expiry date | Jul 15, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R19/016
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electret microphone circuit including an electret microphone having a field effect transistor (FET) with a gate coupled to an electret diaphragm, a drain coupled to provide audio frequency output to an audio output node, a source terminal coupled to ground, and an amplifier stage with an RLC circuit coupled to the drain for configuring the audio frequency output to desired characteristics and for obtaining microphone bias from the output node. The amplifier stage can comprise discrete transistors or integrated operational amplifiers. In another embodiment of the invention there is provided a transistor with a drain coupled to provide audio frequency output to an audio output node and for obtaining microphone bias am from said output node, a source terminal coupled to the microphone housing, and an NPN transistor current mirror stage with an RC or RLC circuit coupled to the source for configuring the audio frequency output to desired characteristics. In yet another embodiment of the invention there is provided a transistor with a source terminal coupled to ground, and an PNP transistor current mirror stage with an RC or RLC circuit coupled to the drain for configuring the audio f…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.