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. 29, 2003
Filed:
Apr. 17, 2001
Analog Devices, Inc., Norwood, MA (US);
Abstract
A four current transistor temperature sensor comprises a p-n junction, preferably the base-emitter junction of a bipolar transistor, which is driven with four different currents in a predetermined sequence. Each of the four currents induces a respective base-emitter voltage, which is measured. The temperature of the transistor is calculated based on the values of the four driving currents and the four measured base-emitter voltages. The four driving currents (I , I , I and I ) are preferably arranged such that I *I , I *I , I /I =A and I /I =A, where A is a predetermined current ratio. I and I produce respective base-emitter voltages which are subtracted from each other to produce &Dgr;V , and I and I produce respective base-emitter voltages which are subtracted from each other to produce &Dgr;V . When so arranged, the difference between &Dgr;V and &Dgr;V is entirely due to the effect of series base and emitter resistances r and r . Therefore, the &Dgr;V −&Dgr;V value provides a correction factor which enables temperature measurement errors due to r and r to be eliminated.