Title :
A 256-Mb SDRAM using a register-controlled digital DLL
Author :
Hatakeyama, Atsushi ; Mochizuki, Hirohiko ; Aikawa, Tadao ; Takita, Masato ; Ishii, Yuki ; Tsuboi, Hironobu ; Fujioka, Shin-Ya ; Yamaguchi, Shusaku ; Koga, Makoto ; Serizawa, Yuji ; Nishimura, Koichi ; Kawabata, Kuninori ; Okajima, Yoshinori ; Kawano, Mic
Author_Institution :
Dept. of Memory Design, Fujitsu Ltd., Kawasaki, Japan
fDate :
11/1/1997 12:00:00 AM
Abstract :
This paper describes the key technologies used in a 256-Mb synchronous DRAM with a clock access time of 1 ns. This DRAM is stable against temperature, voltage, and process variation through the use of a register-controlled digital delay-locked loop (RDLL). The total timing error of the RDLL is about 0.4 ns, sufficient for high frequency operation at 150 to 200 MHz. Unlike most conventional high-density DRAMs, the bit lines are placed above the storage capacitors in this DRAM to relax the design rules of the core area. The noise issues were analyzed and resolved to help implement the technology for mass production of 0.28- to 0.24-μm 200-MHz DRAMs
Keywords :
CMOS memory circuits; DRAM chips; circuit stability; delay circuits; integrated circuit design; integrated circuit noise; 0.24 to 0.28 micron; 1 ns; 150 to 200 MHz; 256 Mbit; digital delay-locked loop; high frequency operation; high-density DRAM; mass production; noise issues; register-controlled digital DLL; synchronous DRAM; Capacitors; Clocks; Delay; Frequency; Mass production; Random access memory; SDRAM; Temperature; Timing; Voltage;
Journal_Title :
Solid-State Circuits, IEEE Journal of
