Reduced-Clock Command Latency Pipeline With 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, where a slower clock signal allows each flip-flop to store commands for a longer period, reducing the number of flip-flops needed to achieve the desired latency, and a FIFO or series of flip-flops stores phase information to align the delayed command with the correct clock cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a pipeline with many flip-flop stages is used to achieve desired command latency, then the latency requirement is met, but the device complexity and power consumption increase
Solution Approach 1:
The patent changes the clock frequency parameter of the flip-flops from a high local clock frequency to a lower divided clock frequency. This parameter change allows each flip-flop to hold data for a longer duration (multiple local clock cycles), thereby reducing the total number of flip-flop stages needed to achieve the required command latency. The divided clock signal is generated by dividing the local clock signal by a factor (e.g., 2 or 4), creating a slower clock that extends the hold time of each flip-flop stage.
2Loss of time
If a pipeline with many flip-flop stages is used to achieve desired command latency, then the latency requirement is met, but the power consumption increases
Solution Approach 1:
The patent reduces power consumption by changing the clock frequency parameter. Since power consumption in flip-flop pipelines is proportional to the number of active stages and their switching frequency, using a divided (lower frequency) clock signal reduces the switching activity per stage. Additionally, fewer stages are required to achieve the same latency, further reducing total power consumption. The relationship is: Power ∝ (Number of stages) × (Clock frequency), and both factors are reduced by using the divided clock approach.
3Productivity
If the clock frequency is increased to improve command processing speed, then the productivity increases, but the number of flip-flops needed for latency control increases
Solution Approach 1:
The patent segments the clock signal function into two distinct signals: a high-frequency local clock for rapid data processing and a lower-frequency divided clock for timing control and latency management. This segmentation allows the system to simultaneously achieve high processing speed (using the fast local clock) and precise latency control with fewer flip-flops (using the slower divided clock). The two clock signals operate independently to fulfill different functional requirements.
Solution Approach 2:
The patent introduces a divided clock signal with a frequency parameter that is a fraction (e.g., 1/2 or 1/4) of the local clock frequency. This parameter change enables the flip-flop pipeline to process data at the high local clock speed while using the slower divided clock to control the timing and number of stages needed for latency, thereby decoupling the processing speed from the latency control complexity.
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.