The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 05, 1984
Filed:
Apr. 28, 1982
Gilbert M Ferrieu, Bievres, FR;
Abstract
Circuitry for avoiding sustained oscillations in a closed-loop system, particularly a loud-speaking telephone set. The object is to avoid sustained annoying oscillations in a looped system, such as a looped electro-acoustic system or a control system. The circuitry comprises a variable-gain amplifier (11) incorporated in a first path (C.sub.1) which forms part of the loop. Connected between the input terminal (A) and the output terminal (B) of the said first path is a second path (C.sub.2) having at least one part which is separate from the first path. A device is provided to ensure that the gain in the second path remains higher than the gain in the first path in the overall frequency band where the oscillations are liable to be produced. A signal (W) formed in the part of the second path which is separate from the first path is applied to the input of a linear regulator 13, which controls the variable-gain amplifier (11) of the first path and a variable-gain amplifier (12) of the second path so as to keep the signal at the input of the regulator (13) constant for a certain value of the signal (W) formed in the second path.