DRAM Refresh with Concurrent Interface Calibration to Cut Command Overhead
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Solution Overview
Problem
Existing DRAM maintenance operations, including refresh and calibration, are inefficient and require significant command overhead, especially in systems without internal clock feedback loops, leading to performance bottlenecks.
Innovation Solution
Concurrent execution of auto-refresh operations and interface maintenance in DRAM devices, utilizing an auto-refresh command to perform burst refresh and calibration of the command interface, including loopback mode for phase and termination calibration, optimizing bank order to minimize delays and resource conflicts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate refresh and calibration operations are performed, then maintenance functionality is complete, but command overhead increases and performance decreases
Solution Approach 1:
The patent combines refresh operations and calibration operations into a single integrated maintenance operation. The memory controller issues a unified maintenance command that simultaneously triggers both refresh of memory cells and calibration of the command interface, eliminating the need for separate command sequences and reducing overall command overhead.
Solution Approach 2:
The maintenance operation is designed to serve multiple functions concurrently. A single maintenance command structure supports both refresh functionality and calibration functionality, allowing the system to perform diverse maintenance tasks through a universal command interface rather than requiring separate specialized commands for each function.
2Reliability
If multiple maintenance operations are executed sequentially, then each operation is performed thoroughly, but command overhead increases
Solution Approach 1:
The patent enables continuous useful action by overlapping the execution of refresh and calibration operations. While refresh operations are being performed on memory banks, calibration operations simultaneously proceed on the command interface. This parallel continuity ensures both operations complete thoroughly without sequential waiting, minimizing total maintenance time.
Solution Approach 2:
The integrated maintenance command structure is prepared in advance to accommodate both refresh and calibration operations. The command format includes pre-defined fields for specifying refresh parameters and calibration parameters, allowing the system to initiate both operations immediately upon command issuance without requiring additional setup or intermediate commands.
3Reliability
If refresh operations are performed without concurrent calibration, then memory cells are refreshed, but interface signaling optimization is delayed
Solution Approach 1:
The patent merges refresh operations and calibration operations into a single concurrent execution framework. The memory controller issues an integrated maintenance command that simultaneously initiates refresh of memory cells and calibration of the command interface signaling, ensuring both data retention maintenance and signaling optimization occur together rather than sequentially.
Data Source
AI summary
A system includes a memory controller and a memory device having a command interface, refresh circuitry, control logic, and a plurality of memory banks, each with a plurality of rows of memory cells. The command interface is operable to receive a refresh command from a memory controller and the refresh circuitry is configured to perform one or more refresh operations to refresh data stored in at least one bank of the plurality of memory banks during a refresh time interval in response to the refresh command from the memory controller. The control logic is to configure the command interface to enter a calibration mode during the refresh time interval, and the command interface is configured to perform a calibration operation in the calibration mode during the refresh time interval.