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:
Dec. 03, 1996
Filed:
Dec. 02, 1994
Robert J Fronen, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A reference current source for generating a reference current (Irf) includes a bipolar first transistor (2) and a bipolar second transistor (4), the base of the first transistor (2) being coupled to the base of the second transistor (4), a first resistor (6) connected between the emitter of the first transistor (2) and the emitter of the second transistor (4), and a second resistor (8) connected between the emitter of the second transistor (4) and a supply terminal (10). The current source also includes a measurement circuit (16) having inputs (12, 14) coupled to the collector of the first transistor (2) and the collector of the second transistor (4), and having a measurement output (18) for supplying a measurement signal in response to a difference in the collector current of the first transistor (2) and the second transistor (4), a bipolar third transistor (28) having its base coupled to the measurement output (18), having its emitter coupled to the bases of the first (2) and the second transistor, and having a collector supplying the reference current (Irf), and a bipolar fourth transistor (34) having its base coupled to the base of the third transistor (28), and having its emitter connected to the emitter of the third transistor (28) via a base pinch resistor (36). The base pinch resistor (36) provides compensation for variations in the reference current (Irf) caused by spread in the saturation current of the bipolar transistors.