Hybrid Memory Module Controller for DRAM Cache and Nonvolatile Storage
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Solution Overview
Problem
Volatile memory devices like DRAM face challenges in maintaining data integrity when power is shut off, and their large unit cell size restricts capacity expansion, especially in space-constrained systems.
Innovation Solution
A nonvolatile memory module is designed with a nonvolatile memory device, a volatile memory device as cache, and a module controller that manages data through separate buses, forming a set associative memory structure to enhance performance and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If DRAM is used as main memory to achieve fast response and operation speed, then speed is improved, but data reliability deteriorates because data is lost when power is shut off
Solution Approach 1:
The memory system is segmented into two distinct parts: volatile DRAM for fast data access and nonvolatile memory for data retention. The memory controller manages these segments separately, allowing each to fulfill its specialized function without compromising the other's performance characteristics.
Solution Approach 2:
A memory controller acts as an intermediary between the volatile DRAM and nonvolatile memory, coordinating data transfers and managing the hybrid memory architecture. This mediator enables seamless operation by handling data movement between the fast but volatile DRAM and the reliable but slower nonvolatile storage.
2Quantity of substance
If DRAM unit cell size is increased to expand capacity, then capacity is improved, but area occupied deteriorates making it difficult to increase capacity when space is restricted
Solution Approach 1:
The patent merges DRAM and nonvolatile memory into a unified hybrid memory system, leveraging the high-density packaging capabilities of nonvolatile memory technology to achieve greater capacity without proportionally increasing the unit cell area, thus improving capacity density.
Solution Approach 2:
The hybrid memory architecture transitions from a single-dimension capacity expansion approach to utilizing vertical stacking and three-dimensional memory structures, allowing capacity increase without linearly increasing the planar area occupied by each memory cell.
3Reliability
If separate devices are used to retain DRAM data, then data reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines DRAM and nonvolatile memory into a single integrated memory module, reducing the number of separate devices and interconnections required. This integration maintains data retention reliability while simplifying the overall system structure and reducing complexity.
Solution Approach 2:
The hybrid memory module serves multiple functions within a single device: it provides fast data access like traditional DRAM, maintains data retention without power, and offers expanded capacity. This multi-functionality reduces the need for separate specialized devices and simplifies system architecture.
Data Source
AI summary
A nonvolatile memory module may include a nonvolatile memory device, a nonvolatile memory controller configured to control the nonvolatile memory device, a volatile memory device configured as a cache memory of the nonvolatile memory device, and a module controller configured to receive a command and an address from an external device, external to the nonvolatile memory module, and to send a volatile memory command and a volatile memory address to the volatile memory device through a first bus and a nonvolatile memory command and a nonvolatile memory address to the controller through a second bus in response to the received command and address. The volatile memory device is configured to load two or more cache data on each of two or more memory data line groups and two or more tags on each of two or more tag data line groups in response to the volatile memory address.