Circuit for eliminating noise
US8073158B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 10, 2007 |
| Grant date | Dec 6, 2011 |
| Priority date | — |
| Expiry date | Oct 5, 2030 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R3/007
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A circuit for eliminating noise includes a sound card (30) with an audio signal output, a power supply (10) for providing working voltage to the sound card, a first transistor (Q1), a second transistor (Q2), and a third transistor (Q3). The power supply has a power good pin, a PSON# pin, and a standby voltage pin. During powering on time of the sound card, the power good pin is at low level and the second transistor is therefore turned on to ground the audio signal output so as to eliminate turn-on noise. During powering down time of the sound card, the PSON# pin turns from low to high level to turn on the third transistor before the audio power for providing working voltage to the sound card is powered down, thus the first transistor turns off, and the second transistor turns on to ground the audio signal output of the sound card so as to eliminate turn-off noise.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.