Fine-Grained DDR PHY Clocking With Hierarchical FIFO Gating
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Solution Overview
Problem
Current clock gating mechanisms in double data rate physical layer interfaces offer limited power savings due to coarse granularity, failing to effectively manage power consumption while maintaining performance across multiple clock domains in system-on-chip environments.
Innovation Solution
Implementing fine-grained clocking and clock distribution through hierarchical clock gating, using active and on-demand first-in-first-out buffers, and programmable/trainable windows to manage clock signals dynamically across different clock domains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If coarse-grained clock gating is used in DDR physical layer interface, then device complexity is reduced, but power consumption cannot be effectively optimized across multiple clock domains
Solution Approach 1:
The patent segments the clock gating control into multiple hierarchical levels: a first clock gate control circuit for coarse-grained control and a second clock gate control circuit for fine-grained control. This segmentation allows the system to achieve effective power optimization across different granularities without overwhelming complexity, as each level handles specific aspects of clock management independently.
Solution Approach 2:
The patent implements dynamic clock gating control where the second clock gate control circuit can adjust clock signals in real-time based on operational conditions. The system dynamically enables or disables clock signals to specific components (such as write levelers or data paths) based on whether write operations are active, allowing adaptive power management that responds to changing system states.
2Loss of energy
If fine-grained clock gating is implemented, then power consumption is optimized, but device complexity increases
Solution Approach 1:
The patent employs a nested hierarchical structure where the second clock gate control circuit operates within the framework established by the first clock gate control circuit. The fine-grained control is nested within the coarse-grained control, allowing the system to achieve detailed power optimization while relying on the higher-level control structure to manage overall complexity. This nested approach enables progressive refinement of clock management without linearly increasing system complexity.
3Productivity
If multiple clock domains are used to meet different performance requirements, then system performance is improved, but clock domain crossing synchronization becomes more difficult
Solution Approach 1:
The patent applies local quality by providing different clock gating control mechanisms to different components based on their specific requirements. Fast write operations receive appropriate clock signals through the fine-grained control circuit, while other components operate at different frequencies through the hierarchical control structure. This localized approach to clock management allows each component to operate at its optimal frequency without requiring complex global synchronization across all clock domains.
Data Source
AI summary
A system includes a memory device and a memory controller operatively connected to the memory device via a physical layer interface (PHY). The PHY includes an active first-in-first-out (FIFO) buffer configured to receive commands from the memory controller. The PHY also includes one or more on-demand FIFO buffers configured to be selectively enabled by the active first-in-first-out buffer to handle a data payload. The system ensures efficient power usage by gating clocks and clock distribution to the one or more on-demand FIFO buffers.