Back to results
US 5,317,640 AGranted
Switched amplifier
AssigneeAscom Audiosys AG
InventorFrancois Callias
Life of this patent
Estimating the term…
Abstract
In a hearing aid having a switched amplifier, an amplifier circuit is provided so that the pulse amplitude of the switched output signal is adjusted as a function of the envelope of the audio signal to be amplified. A controllable amplifier is switched in series ahead of the switched amplifier, whereby its control by the audio signal to be amplified proceeds in such a manner that the product of the amplifications of the two amplifiers remains constant for all audio signal levels.
Claims1
A hearing aid comprising:
- an amplifier circuit including a switched amplifier providing a switched output signal, and circuit means for adjusting the pulse amplitude of the switched output signal as a function of the envelope curve of the audio signal to be amplified, in which the circuit means includes a controllable amplifier in series with and ahead of the switched amplifier and is controlled by the audio signal to be amplified so that the product of the amplifier gain of the switched amplifier and of the controllable amplifier remains substantially constant for all levels of the audio signal to be amplified.
Dependencies are inferred from the claim text.