Stacked-Die Memory Vault Prefetching for Bandwidth Efficiency

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Solution Overview

Problem

Current semiconductor memory systems face a mismatch in performance between host processors and memory subsystems, leading to inefficiencies in bandwidth and density, with existing interfaces failing to optimize memory power and adapt to evolving technologies.

Innovation Solution

The proposed memory system employs a stacked-die 3D memory array architecture with shared control logic, known as 'memory vaults,' which enables increased energy efficiency, standardized interfaces, and concurrent data transfer, along with a prefetch controller to optimize memory operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If memory bandwidth is increased to match processor performance, then processor utilization improves, but memory subsystem complexity and power consumption increase

Engineering Contradiction:
Improveprocessor utilizationVSAvoidmemory subsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The memory subsystem is segmented into multiple independent memory channels, each capable of autonomous operation. This allows the system to scale bandwidth by adding channels rather than increasing the complexity of a single channel, resolving the contradiction between productivity and device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The memory system implements prefetching mechanisms that proactively load data into buffers before it is actually needed by the processor. This preliminary action reduces wait states and improves processor utilization without requiring proportional increases in memory subsystem complexity.

Inventive Principle:
Principle #10Preliminary action

2Quantity of substance

If memory density is increased to satisfy application demands, then storage capacity improves, but interface bandwidth requirements increase

Engineering Contradiction:
Improvememory densityVSAvoidinterface bandwidth requirements
Core Design Contradiction:
Quantity of substanceVSPower

Solution Approach 1:

The patent transitions from two-dimensional planar memory architectures to three-dimensional stacked memory configurations. This dimensional change increases storage density without proportionally increasing interface bandwidth requirements, as multiple memory layers can be accessed through shared interfaces.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Multiple memory devices are combined into memory modules with shared control logic and interfaces. This merging approach increases effective density while reducing the total interface bandwidth required compared to having separate interfaces for each memory device.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If custom memory interfaces are designed to optimize performance, then bandwidth efficiency improves, but adaptability to future technologies decreases

Engineering Contradiction:
Improvebandwidth efficiencyVSAvoidinterface adaptability
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The memory interface is designed with universal components that can accommodate different memory technologies and configurations. The phased array driver and signal routing structures are configured to work with various memory device types, maintaining bandwidth efficiency while providing adaptability to future technological changes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Loss of energy

If memory power consumption is reduced to improve energy efficiency, then system power savings increase, but operational performance may deteriorate

Engineering Contradiction:
Improvememory power consumptionVSAvoidoperational performance
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The memory system implements periodic refresh operations and power gating strategies that reduce average power consumption while maintaining operational performance. Memory banks are refreshed periodically rather than continuously, and unused banks are powered down, achieving energy efficiency without sacrificing performance when memory is actively accessed.

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP2396790B1Memory prefetch systems and methods
Publication Date: 2017.08.23 MICRON TECHNOLOGY INC
  • EP2396790B1 patent drawingFigure 1
  • EP2396790B1 patent drawingFigure 2
  • EP2396790B1 patent drawingFigure 3~4

AI summary

Systems and methods are disclosed herein, including those that operate to prefetch a programmable number of data words from a selected memory vault in a stacked-die memory system when a pipeline associated with the selected memory vault is empty.