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:
Sep. 14, 1993
Filed:
Oct. 30, 1991
Carlos A Greaves, Austin, TX (US);
Mauricio A Zavaleta, Austin, TX (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A bandgap voltage reference circuit (50, 100) which operates at low power supply voltages provides a reference current as either a one- or a two-.DELTA.V.sub.BE voltage across a first resistor (82, 133). A current proportional to the reference current is mirrored into one terminal of a second resistor (94, 133) to provide the bandgap voltage. Compensation for base currents injected into the circuit (50, 100) by two transistors forming the .DELTA.V.sub.BE reference is provided. In one embodiment (50), base currents of first (66) and second (87) transistors which have equal emitter areas and collector current density as the two transistors (68, 85) forming the .DELTA.V.sub.BE reference compensate for the injected base currents. In another embodiment (100), a single transistor (127) injects current substantially equal to the sum of the base currents of the two transistors (116, 121) forming the .DELTA.V.sub.BE reference. The single transistor (127) has twice the emitter area of one of the transistors (116) forming the .DELTA.V.sub.BE reference.