Patent ID: 6541983
Filing Date: 2003-04-01
Classification: G01R,G11C

Abstract:
A method for measuring an impedance of a fuse located in a fuse array comprising the steps of:(a) providing a fuse array including at least a conducting path and at least a switching circuit electrically connected thereto, the fuse array arranged in rows columns having each fuse located at an intersection of a row and a column with the fuse array; (b) positioning the fuse array in a tester having an internal write current source, a control for controlling the internal write current source, a test current source and an output port; (c) disabling the internal write current source; (d) supplying a reduced current having a magnitude from said test current source; (e) starting a write procedure; (f) stopping said write procedure to address a selected row and a selected column to select a fuse; (g) applying said reduced current to said selected fuse; (h) measuring a fuse voltage drop of the reduced current source after having propagated through said selected fuse; (i) providing a value indicative of a reference voltage drop based on a current having a similar magnitude to the reduced current propagating through the at least a conducting path and the at least a switching circuit similar to those within the fuse array; (j) determining the impedance of the fuse in dependence upon a difference between the value indicative of the reference voltage drop and the measured fuse voltage drop, as well as the magnitude of the reduced current; and, (k) providing the impedance of the fuse at the output port of the tester.