Memory Command Queue Overlap for Read Time Reduction

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Solution Overview

Problem

Current memory sub-systems face significant read-time overhead and power consumption due to the sequential processing of read commands, which cumulatively increase as multiple commands are handled, especially when dealing with consecutive read operations on the same word line.

Innovation Solution

Implementing a command queue within the memory device allows for combined read operations, where subsequent read commands are processed concurrently with the current command, overlapping phases such as word line voltage ramping and recovery, thereby reducing the overall overhead time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If sequential processing of read commands is used, then command processing order is maintained, but cumulative overhead time increases significantly

Engineering Contradiction:

Improvecumulative overhead timeVSAvoidcommand processing throughput

Core Design Contradiction:

Loss of timeVSProductivity

Solution Approach 1:

The patent stores subsequent read commands in a command queue before they are executed, allowing the memory device to prepare for future operations in advance. This preliminary action enables overlapping of voltage ramping and recovery phases across multiple commands, reducing cumulative overhead time while maintaining proper command execution order.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements combined read operations where voltage ramping for one command overlaps with recovery phases of previous commands, and recovery phases overlap with voltage ramping of subsequent commands. This continuous overlapping of useful actions eliminates idle time between sequential operations, significantly reducing total overhead time.

Inventive Principle:

Principle #20Continuity of useful action

2Loss of time

If combined read operations with overlapping phases are implemented, then overhead time is reduced, but device complexity increases

Engineering Contradiction:

Improveread operation overhead timeVSAvoidcommand queue management complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent segments the read command processing into distinct phases (voltage ramping, recovery, data reading) that can be overlapped across multiple commands. By dividing the processing into manageable segments stored in the command queue, the system can coordinate overlapping operations without requiring complex global control logic.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The command queue acts as an intermediary structure that decouples command submission from command execution. This intermediary allows the memory device to manage overlapping operations by retrieving commands in sequence while performing operations out of strict sequential order, simplifying the control logic needed for combined read operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11922993B2Read-time overhead and power optimizations with command queues in memory device

Publication Date: 2024.03.05 MICRON TECHNOLOGY INC

AI summary

A device includes an array of memory cells with a first word line coupled to at least a subset of the array of memory cells and control logic coupled to the first word line. The control logic to detect, within a queue, a first read command to read first data from a first page of the subset and a second read command to read second data from a second page of the subset. The control logic is further to cause a voltage applied to the first word line to move to a target value. The control logic is further to cause a page buffer to sense the first data from a first bit line coupled to the first page and to sense the second data from a second bit line coupled to the second page. The control logic is further to cause the first word line to be discharged.