Self-biasing, low noise amplifier of extended dynamic range
US5097224A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 11, 1991 |
| Grant date | Mar 17, 1992 |
| Priority date | — |
| Expiry date | Apr 11, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R25/00
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An audio frequency amplification circuit for use with low level, high impedance signal sources, such as a miniature electret microphone, particularly useful where the power supply range is variable or may be limited to a single cell. The preferred embodiments of the circuit include a field effect transistor preamplifier stage operating as a voltage follower which is biased by a first and second impedance network coupled to the gate electrode of the FET transistor. A first impedance network is coupled between the power source terminals to provide a floating bias point. A second, high impedance network comprising (in one embodiment) a pair of parallel, reverse oriented diodes and a high impedance resistor is coupled between the bias point and the gate terminal of the transistor. In a further embodiment, the first impedance network comprises series connected high impedance resistors, and the second impedance network includes only the parallel, reverse oriented diodes. In either embodiment, extremely low capacitance elements may be coupled across the high impedance resistors, the elements preferably comprising stray capacitance from circuit conductor layout. Such source-follower biasin…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.