Command Latency Pipeline Using Slower Clock and Phase Alignment
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Solution Overview
Problem
Existing memory systems face challenges in efficiently managing command latency, requiring a large number of flip-flops to delay commands, which increases complexity and power consumption as clock speeds increase.
Innovation Solution
A reduced clock flip-flop pipeline is used, with a slower clock signal to delay commands, and a FIFO or series of flip-flops to store phase information, allowing fewer flip-flops to achieve the desired latency by aligning the delayed command with the appropriate clock cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a pipeline with many flip-flops is used to delay commands, then the required latency is achieved, but the device complexity and power consumption increase
Solution Approach 1:
The command delay pipeline is segmented into multiple stages, each stage using a small number of flip-flops (e.g., 2-3 flip-flops per stage). Multiple stages are cascaded to achieve the total required latency. This segmentation reduces the complexity of individual stages while maintaining the overall delay requirement through hierarchical organization of the pipeline stages.
Solution Approach 2:
The patent employs periodic clocking schemes where flip-flops are clocked at different phases or frequencies to create the required delay. By using periodic action and timing relationships between clock cycles, the system achieves command latency without requiring a linear sequence of flip-flops for every clock cycle of delay, thereby reducing the total flip-flop count.
2Productivity
If the clock frequency is increased to improve processing speed, then productivity increases, but the number of flip-flops required to achieve the same latency increases
Solution Approach 1:
The patent implements dynamic pipeline staging where the number and configuration of flip-flop stages can be adjusted based on operating conditions. When clock frequency increases, the system can dynamically reconfigure the pipeline to use fewer stages or different staging patterns, maintaining the required latency product (frequency × delay) while adapting to the higher productivity requirement.
Solution Approach 2:
The system changes operational parameters including flip-flop clocking frequencies, phase relationships, and pipeline stage configurations based on the required productivity and latency specifications. By parameterizing the pipeline design, the same hardware structure can achieve different latency values at different clock frequencies without linearly increasing the flip-flop count.
Data Source
AI summary
Examples of command latency systems and methods are described. In some examples, phase information associated with a received command signal is stored, a received command signal is propagated through a reduced clock flip-flop pipeline and the delayed command signal is combined with the stored phase information. The reduced clock flip-flop pipeline may use a clock having a lower frequency than that used to issue the command signal. Accordingly, fewer flip-flops may be required.