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:
Oct. 15, 2019
Filed:
Jun. 13, 2016
International Business Machines Corporation, Armonk, NY (US);
Diyanesh B. Chinnakkonda Vidyapoornachary, Bangalore, IN;
Edgar R. Cordero, Round Rock, TX (US);
Stephen P. Glancy, Poughkeepsie, NY (US);
Jeremy R. Neaton, Fishkill, NY (US);
Saravanan Sethuraman, Bangalore, IN;
International Business Machines Corporation, Armonk, NY (US);
Abstract
Embodiments herein describe a memory system that includes a DRAM module with a plurality of individual DRAM chips. In one embodiment, the DRAM chips are per DRAM addressable (PDA) so that each DRAM chip can use a respective reference voltage (VREF) value to decode received data signals (e.g., DQ or CA signals). During runtime, the VREF value can drift away from its optimal value set when the memory system is initialized. To address possible drift in VREF value, the present embodiments perform VREF calibration dynamically. To do so, the memory system monitors a predefined criteria to determine when to perform VREF calibration. To calibrate VREF value, the memory system may write transmit data and then read out the test data to determine the width of a signal eye using different VREF values. The memory system selects the VREF value that results in the widest signal eye.