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:
May. 06, 1997
Filed:
Apr. 10, 1995
Michael J Gay, Vaud, CH;
Motorola, Inc., Schaumburg, IL (US);
Abstract
In a telephone line interface circuit, a first transistor (Q1) is arranged in series in the signal line (3) and a second transistor (Q2) is arranged in parallel across the telephone line (3, 4), both transistors being controlled from a control circuit (5), so that, when the voltage across the telephone line falls below that required to keep the first transistor (Q1) in normal conduction, the second transistor (Q2) maintains the signal path. In order to reduce cross-over distortion, a negative feedback loop (Q5, R1, Q3, Q1) and supply voltage sensing means (6) controls the first transistor (Q1) so that it conducts only sufficient quiescent current to power the circuit, any remaining current being conducted by the second transistor (Q2), thereby maintaining both transistors in conduction down to low quiescent line current levels.