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:
Apr. 26, 1994
Filed:
Dec. 19, 1991
Applicant:
Inventors:
Rolf H Wendt, Beaverton, OR (US);
Steven E Hossner, Hillsboro, OR (US);
Assignee:
Nec America, Inc., Melville, NY (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
379418 ; 379253 ; 379413 ;
Abstract
A low frequency high voltage AC power for a telephone system is provided by a ring signal generator, which produces a ring signal from a DC power supply using a pair of switches controlled by pulse width modulation (PWM) circuit. The ring signal generator includes a PWM circuit driving a pair of MOSFET transistors via a respective pair of opto-isolators. The output of the MOSFET transistor switches is commonly connected to a low pass filter network. The ring signal generator of the present invention advantageously produces a 65 VRMS ring signal at very high efficiency.