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:
Nov. 11, 2003
Filed:
Apr. 30, 1999
Shi-Yu Huang, Tainan, TW;
Ding-Ming Kwai, Taipei, TW;
Worldwide Semiconductor Manufacturing Corporation, Hsinchu, TW;
Abstract
A built-in-self-test (BIST) circuit for RAMBUS DRAM is disclosed. Unlike other conventional memory devices, a RAMBUS DRAM operates at a much higher speed (e.g., 400 MHz) with a complicated protocol imposed on its input stimuli. In order to provide at-speed testing, a new BIST architecture is needed. The new architecture consists of three major components—two interacting finite state machines (FSMs) and a high-speed time-division multiplexer. The two finite state machines, defining the underlying test algorithms jointly, are used to generate a sequence of generic memory commands. Through the time-division multiplexer, each memory command is then further mapped into a multi-cycle packet compliant to the specification of a target RAMBUS DRAM. Among these components, the finite state machines often form the performance bottleneck. A simple master-slave synchronization mechanism is used to convert these two finite state machines into a multi-cycle path component, thereby eliminating the timing criticality.