Fred S Floru

US Patent:

57368465, Apr 7, 1998

Filed:

Oct 6, 1995

Appl. No.:

8/540045

Inventors:

Fred Floru - Newton MA
Gary K. Hebert - Shrewsbury MA

Assignee:

THAT Corporation - Marlborough MA

International Classification:

G01R 1148
G01R 1900

US Classification:

324127

Abstract:

A current sensor for detecting AC current through a load impedance of an electrical circuit. Sensor components are fabricated within a multilayer board so that a board can be made to comprise a plurality of independent sensors. The sensor includes a transformer circuit including a primary coil which is electrically coupled in series with the current path of the electrical circuit. This primary coil includes at least one current path element, in the form of a conductive strip constructed so as to add minimal resistance and inductance to the electrical circuit. The transformer secondary comprises at least a first electrically conductive coil inductively coupled to at least a part of the current path, and preferably a second electrically conductive coil inductively coupled to a second part of current path of the electrical circuit. The secondary coils are electrically connected in series with one another, so that voltages generated across the coils in response to current in the current path are additive, while interference voltages which are induced in the coils by the presence of uniform external magnetic fields or cross talk between adjacent sensors on the same board (where multiple sensors are provided) are cancelled.

US Patent:

61604518, Dec 12, 2000

Filed:

Apr 16, 1999

Appl. No.:

9/293033

Inventors:

Fred Floru - Needham MA

Assignee:

THAT Corporation - Milford MA

International Classification:

H03F 318

US Classification:

330263

Abstract:

The present invention is directed to a buffer stage for buffering and isolating a signal source from an external load. The stage has a signal input terminal for receiving an input signal from said signal source and a signal output terminal for providing an output signal, corresponding to said input signal, to the external load. The stage comprises an input section including at least two driver transistors each arranged so as to operate with a predetermined bias current. The stage further comprises an output section including at least two output transistors each arranged so as to operate with a predetermined quiescent current, and a voltage source, coupled to the input and output sections and constructed and arranged so as to set the quiescent currents flowing through the output transistors substantially independent of the size of the bias current flowing through the driver transistors.