Circuit and method for a transimpedance audio amplifier providing variable gain while maintaining load impedance
US6816009B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 19, 2002 |
| Grant date | Nov 9, 2004 |
| Priority date | — |
| Expiry date | Jul 19, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03G3/3005
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A transimpedance amplifier (18) receives an audio signal from a power audio amplifier (14) and provides a variable power level to a loudspeaker (16). A first variable gain amplifier (28) receives the audio signal and provides a variable gain to a power amplifier (40). The output signal of the power amplifier drives the loudspeaker. A sense amplifier (52) subtracts a voltage representative of current flowing through the loudspeaker from a voltage applied to the loudspeaker and provides a difference signal. A second variable gain amplifier (70) receives the difference signal and provides a variable gain to a load amplifier (80). The gains of the first and second variable gain amplifiers are inversely proportional. A resistive element (84) having a real impedance is coupled between an output of the load amplifier and the input of the transimpedance amplifier to maintain the complex impedance of the loudspeaker at the output of the power audio amplifier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.