Digital Delay Locked Loop and Design Technique for High-Speed Synchronous Interface

Yoshinori OKAJIMA  Masao TAGUCHI  Miki YANAGAWA  Koichi NISHIMURA  Osamu HAMADA  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E79-C   No.6   pp.798-807
Publication Date: 1996/06/25
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on ULSI Memory Technology)
Category: Dynamic RAMs
Keyword: 
DLL,  synchronous interface,  DRAM,  bus timing skew,  

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Summary: 
We report two new timing control methods for high-speed synchronous interfaces in view of their application to high-speed synchronous DRAMs. These two new circuits are the measure-controlled DLL and the register-controlled DLL.We quantitatively analyzed the minimum operational cycle time for a synchronous interface, and related the minimum bus cycle time to two factors; the bus-to-clock timing skew, and the unit delay time of the DLL. Based on this analysis, we concluded that the I/O performance can be beyond 400 MHz by suppressing both factors to less than 200 ps.