Patent Number: 6,167,495

Title: Method and apparatus for detecting an initialization signal and a command packet error in packetized dynamic random access memories

Abstract: A system for detecting an initialization flag signal and distinguishing it from a normal flag signal having half the duration of the initialization flag signal. The initialization flag detection system may be included in the command buffer of a packetized DRAM that is used in a computer system. In one embodiment, the initialization flag detection system includes a pair of shift registers receiving the flag signal at their respective data inputs. One of the shift registers is clocked by a signal corresponding to an externally applied to command clock signal, while the other shift register is clocked by a quadrature clock signal. Together, the shift registers store a number of samples taken over a duration that is longer than the duration of the normal flag signal. The outputs of the shift registers are applied to a logic circuit, such as a NAND gate, that generates an initialization signal when all of the samples stored in the shift registers correspond to the logic levels of the flag signal. In another embodiment, the initialization flag detection system includes a plurality of latches receiving the flag signals at their data inputs. The latches are clocked by respective strobe signals corresponding to the command clock signal, but having phases that differ from each other. The outputs of the latches are applied to a logic circuit, such as a NAND) gate. Finally, in another embodiment of the invention, the bits of the command packet are sampled along with the flag signal and compared to the samples of the flag signal to detect when a command packet having a predetermined pattern does not correspond to a flag signal having a predetermined pattern.

Inventors: Keeth; Brent (Boise, ID), Manning; Troy A. (Meridian, ID)

Assignee: Micron Technology, Inc.

International Classification: G11C 7/10 (20060101); G11C 7/20 (20060101); G11C 7/00 (20060101); G06F 012/16 ()

Expiration Date: 12/26/2017