Memory system and data transmission method
AssigneeElpida Memory, Inc.
InventorYoshinori Matsui
Life of this patent
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AssigneeElpida Memory, Inc.
InventorYoshinori Matsui
Estimating the term…
A memory system of a high-speed operation can be realized by reducing an influence of reflection signals etc. caused by branching and impedance mismatching in various wirings between a memory controller and a memory module, and an influence due to transmission delays of data, command/address, and clocks in the memory module. To this end, a memory system comprises a memory controller and a memory module mounted with DRAMs. A buffer is mounted on the memory module. The buffer and the memory controller are connected to each other via data wiring, command/address wiring, and clock wiring. The DRAMs and the buffer on the memory module are connected to each other via internal data wiring, internal command/address wiring, and internal cock wiring. The data wiring, the command/address wiring, and the clock wiring may be connected to buffers of other memory modules in cascade. Between the DRAMs and the buffer on the memory module, high-speed data transmission is implemented using data phase signals synchronous with clocks.
A memory system having a plurality of memory circuits and a control circuit for controlling said plurality of memory circuits according to main clocks, wherein said plurality of memory circuits and said control circuit are connected via first wiring for transmitting/receiving data signals, and second wiring having a length different from that of said first wiring, characterized in that said control circuit attains a clock signal obtained by n-dividing (n is a positive integer equal to or greater than 2) said main clocks in frequency, outputs a command/address signal to said plurality of memory circuits via said second wiring while matching said command/address signal with said n-divided clock signal, and outputs via said first wiring a data phase signal (DPS) having a predetermined frequency relationship with said n-divided clock signal and representing a phase of said data signal, and said plurality of memory circuits each absorb a timing skew caused by a difference in wiring length between said first and second wirings, using said data phase signal.
Dependencies are inferred from the claim text.