Memory Controller Implicit Precharge Command Management
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Solution Overview
Problem
DRAM memory devices face delays due to refresh, precharge, and activate operations, which limit data access rates and require extensive circuitry for timing constraints, leading to inefficiencies in resource usage and production costs.
Innovation Solution
Implementing a memory controller that limits the number of co-pending consolidated ACT/iPRE commands to a threshold below the theoretical maximum, allowing the memory device to internally manage precharge operations and reduce the need for explicit commands, thereby optimizing resource usage and reducing circuitry requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the memory device supports more co-pending ACT/iPRE commands up to the theoretical maximum, then the data access rate and command flexibility improve, but the circuitry complexity and resource requirements increase
Solution Approach 1:
The memory device autonomously manages precharge operations by internally generating precharge commands based on received ACT commands and tracking circuit state. This self-service mechanism eliminates the need for explicit precharge commands from the controller, reducing command overhead and simplifying the interface while maintaining support for multiple co-pending operations.
Solution Approach 2:
The memory device performs precharge operations in advance or concurrently with activate operations by internally scheduling precharge commands. The tracking circuit monitors the state of memory banks and proactively initiates precharge sequences before they are explicitly requested, enabling smoother command pipelining and improving data access rates without increasing external circuitry complexity.
2Reliability
If explicit precharge commands are used for each row deactivation, then timing precision and reliability improve, but the command overhead and access delays increase
Solution Approach 1:
The patent combines the activate command with implicit precharge functionality into a single ACT/iPRE command. Instead of requiring separate PRE and ACT commands, the memory device interprets the ACT command as also requesting precharge of other banks, merging two operations into one. This reduces command overhead and access delays while the tracking circuit ensures timing constraints are met through internal scheduling.
Solution Approach 2:
The tracking circuit acts as an intermediary between the controller and memory banks, monitoring bank states and internally generating precharge commands as needed. This intermediary mechanism allows the system to maintain precise timing control without requiring explicit precharge commands from the controller, thereby reducing command overhead while ensuring reliability.
3Ease of manufacture
If the memory device autonomously manages precharge operations internally, then resource efficiency and space utilization improve, but the complexity of internal control logic increases
Solution Approach 1:
The memory device includes a tracking circuit that autonomously monitors bank states and generates precharge commands without external intervention. This self-service capability reduces the need for complex external control logic and minimizes command overhead, improving resource efficiency. The tracking circuit uses simple state tracking and comparison logic to determine when precharge is needed, keeping internal complexity manageable.
Solution Approach 2:
The tracking circuit continuously monitors the state of memory banks and uses this feedback to internally generate appropriate precharge commands. This feedback mechanism enables the memory device to autonomously manage precharge operations based on actual bank states, improving resource efficiency while using straightforward feedback logic rather than complex control algorithms.
Data Source
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AI summary
Techniques and mechanisms for exchanging information between a memory controller and a memory device. In an embodiment, a memory controller receives information indicating for a memory device a threshold number of pending consolidated activation commands to access that memory device. The threshold number indicated by the information is less than a theoretical maximum number of pending consolidated activation commands, the theoretical maximum number defined based on timing parameters of the memory device. In another embodiment, the memory controller limits communication of consolidated activation commands to the memory device based on the information indicating the threshold number.