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:
Jan. 27, 2004
Filed:
Apr. 27, 2001
Yosuke Kawamata, Tokyo, JP;
Other;
Abstract
There is provided a memory testing apparatus and a memory testing method, for testing a semiconductor memory having redundant cells. In addition to a plurality of main cell fail information memories for a main cell array in the semiconductor memory under test, one redundant cell fail information memory is provided for redundant cells in the semiconductor memory under test. An address synthesizing circuit receives respective comparison results outputted in parallel from a plurality of comparators, each of which compares an output signal outputted from a semiconductor memory under test with an expected value, and an address supplied to the semiconductor memory under test, and for synthesizing a redundant cell fail information memory address for the redundant cell fail information memory. When at least one of the comparison results outputted in parallel from the plurality of comparators indicates a “fail”, a control circuit writes fail information into the redundant cell fail information memory at the redundant cell fail information memory address thus synthesized, with the result that fail information represented by a plurality of fail information bits outputted from the plurality of comparators is written into one cell within the fail information memory with one writing access.