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:
Jun. 24, 2003
Filed:
Jun. 22, 2001
William J. Bright, Dallas, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A current correction circuit eliminates beta mismatches between a thermometer encoded segment and a R-2R ladder segment of a current steering digital-to-analog converter The circuit consists of three replica MSB unit current sources, I , I and I . The replica current I acts as a replica to a cascode device of the MSB unit of the current steering DAC The replica current I replicates an effective base current equal to the total base current in the R-2R ladder circuit portion of the current steering DAC The replica current I replicates the total base current of the L output switches in the LSB segment of the current steering DAC A high impedance summing node produces a correction current I =I −(I +I ). This current is equal to the current difference between an MSB unit and the LSB segment This correction current is then subtracted from the MSB unit current source that supplies current into the R-2R ladder such that the current supplied to the R-2R ladder will be equal to the MSB replica current source minus the correction current.