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:
Nov. 05, 1991
Filed:
Aug. 31, 1989
John B Hughes, Hove, GB;
Kenneth W Moulding, Horley, GB;
U.S. Philips Corporation, New York, NY (US);
Abstract
An integrated temperature threshold sensing circuit comprises first and second bipolar transistors (Q1, Q2) biased so that the current density in the first transistor is larger than that in the second transistor by a first known factor. The first and second transistors have their collectors and bases connected to a first bias voltage source and to a second bias voltage source, respectively, and their emitters connected respectively to first and second current sources (12,14) for passing first and second bias currents (I.sub.1, I.sub.2) of known relative proportions (K:1) through the respective first and second transistors. A voltage comparator (26) is arranged to compare a first predetermined fraction (R(R+r)) of the base-emitter voltage of the first transistor (Q1) with a second, larger predetermined fraction (1) of the base-emitter voltage of the second transistor (Q2) so that an output (28) of the comparator assumes a first state when the temperature of the two devices is above a known threshold temperature and assumes a second state when the temperature of the two devices is below the known threshold temperature. The circuit is accurate and is compatible with MOS technology.