Memory module
AssigneeElpida Memory, Inc.
InventorsKayoko Shibata, Yoji Nishio
Life of this patent
Estimating the term…
Abstract
A memory module is provided with a resistor serving as an impedance adjuster which is connected directly or indirectly to an output terminal of an output transistor of a C/A register. The resistor adjusts the output impedance of the C/A register viewed from an input terminal of a C/A bus in such a manner that the output impedance becomes substantially constant within an operating voltage range of an internal signal output from the C/A register. The memory module is further provided with a capacitor serving as a rise time/fall time adjuster which adjusts rise time and fall time of the internal signal to specific values such that satisfactory waveforms are obtained.
Claims21
A memory module comprising:
- a command/address register device for generating an internal signal according to an external command/address signal, said command/address register device having an output transistor;
- a plurality of memory devices divided into first and second groups;
- wiring interconnecting said command/address register device and said memory devices;
- and
- a substrate on which said command/address register device and said multiple memory devices are mounted;
- wherein said wiring includes:
- a first wiring section extending from said command/address register device to a first branch point;
- a second wiring section extending from the first branch point to a second branch point;
- a third wiring section extending from the first branch point to a third branch point;
- a fourth wiring section which branches out from the second branch point and extends up to the memory devices of said first group;
- and
- a fifth wiring section which branches out from the third branch point and extends up to the memory devices of said second group;
- and
- said command/address register device includes:
- an impedance adjuster for adjusting the output impedance of said command/address register device viewed from a junction point between said command/address register device and the first wiring section in such a manner that said output impedance becomes substantially constant within an operating voltage range of the internal signal;
- and
- a rise time/fall time adjuster for adjusting rise time and fall time of the internal signal to specific values.
Dependencies are inferred from the claim text.