Memory Controller Signal Timing for DDR Latching Stability
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Solution Overview
Problem
As memory modules evolve to higher speeds, signal quality deteriorates due to variations in printed circuit boards and pin specifications, making it challenging for memory controllers to adjust clock signals to ensure proper latching intervals, especially for address signals, leading to errors and reduced system stability.
Innovation Solution
A memory controller and signal generating method that generates clock signals, command signals, and address signals with specific edge timing to expand latching intervals, allowing multiple command groups with consecutive commands to ensure correct data latching across DDR memory modules, even when rising edges fall outside conventional latching intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If memory access clock speed is increased to improve productivity, then memory access speed is improved, but signal quality deteriorates and latching intervals become smaller causing errors
Solution Approach 1:
The address signal is divided into two separate parts: a first part transmitted during the first clock cycle and a second part transmitted during the second clock cycle. This segmentation allows each part to be transmitted with sufficient time margin, maintaining signal quality while supporting higher overall memory access speeds.
Solution Approach 2:
The memory controller operates in periodic cycles where each command group is followed by a NOP command, creating regular intervals for signal transmission. This periodic structure ensures that address signals are transmitted at manageable intervals, maintaining latching reliability even at higher clock speeds.
2Productivity
If memory access clock speed is increased to improve productivity, then memory access speed is improved, but latching intervals become smaller leading to data latching errors
Solution Approach 1:
The address signal is divided into two separate parts: a first part transmitted during the first clock cycle and a second part transmitted during the second clock cycle. This segmentation allows each part to be transmitted with sufficient time margin, maintaining signal quality while supporting higher overall memory access speeds.
Solution Approach 2:
The memory controller transmits the first part of the address signal in advance during the first clock cycle before the actual data operation occurs. This preliminary transmission ensures that the address is ready and latched properly before the high-speed data transfer begins, preventing latching errors.
3Productivity
If conventional signal transmission is used at high clock speeds, then productivity is improved, but system stability decreases due to latching errors
Solution Approach 1:
The memory controller operates in periodic cycles where each command group is followed by a NOP command, creating regular intervals for signal transmission. This periodic structure ensures that address signals are transmitted at manageable intervals, maintaining latching reliability even at higher clock speeds.
Solution Approach 2:
The memory controller inserts NOP (No Operation) commands between command groups to create time cushions or margins. These NOP commands provide buffer periods that allow signals to stabilize and be properly latched, preventing errors and maintaining system stability during high-speed operations.
Data Source
AI summary
The invention is directed to a memory controller and an associated signal generating method. By appropriately arranging a sequence according to which command signals are generated and expanding a latching interval of a part of address signals, not only the memory controller is enabled to control the DDR memory modules in a functional manner to further overcome issues of conventionally small latching intervals, but also system stability and access performance are reinforced as the memory access clock speed continue to increase.