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:
Oct. 18, 1994
Filed:
Jul. 07, 1993
Petar N Miljanic, Belgrade, YU;
Eddy So, Gloucester, CA;
National Research Council of Canada, Ottawa, CA;
Abstract
A transconductance amplifier circuit employs the known combination of a transconductance amplifier and a current comparator (with or without a ratio extender, preferably in the form of a two-stage current transformer) to compare the output current from the transconductance amplifier with that flowing through a reference resistor, both these currents having been derived from the same alternating input voltage. A current corresponding to the unbalanced ampere-turns in the current comparator is used to produce a feed-forward error signal that is used to modify the output of the transconductance amplifier. The invention is characterized by an output transformer that has coaxial inner and outer toroidal magnetic cores, and primary and correction windings outside the outer core. This primary winding receives the output current from the transconductance amplifier and the correction winding receives the error signal. A winding located between the cores detects the error current in the output transformer (its magnetizing current), and injects this error current into the current comparator. The secondary of the output transformer can be a single turn conductor extending through the hole formed by its toroidal cores. The result of this circuit arrangement is that the output current in the secondary of the output transformer follows the amplitude and phase of the input voltage with a very high level of accuracy.