Switched microphone buffer
US7092538B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 2003 |
| Grant date | Aug 15, 2006 |
| Priority date | — |
| Expiry date | Jan 31, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/185
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.