Reset Clock Multiplexing for Synchronized Flip-Flop Timing
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Solution Overview
Problem
In semiconductor systems, setting a reset timing for flip-flops in the power domain within the same clock cycle is challenging, especially with high-frequency clocks, leading to potential errors and increased circuit area due to the need for numerous buffers in the reset tree.
Innovation Solution
A semiconductor system and method that uses a clock multiplexer to input a slower reset reference clock during reset operations, allowing flip-flops in the power domain to be reset within the same clock cycle, reducing the need for buffers and circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-frequency function clock is used for reset operations, then the reset operation speed is improved, but it becomes difficult to set reset timing for all flip-flops within the same clock cycle and requires numerous buffers increasing circuit area
Solution Approach 1:
The patent dynamically switches the clock frequency based on the operation mode. During reset operations, a lower-frequency reference clock is used to enable synchronized reset timing across all flip-flops without requiring excessive buffers. During normal operations, the higher-frequency function clock is used to maintain high-speed performance. This dynamic clock frequency adjustment resolves the contradiction between reset operation speed and circuit area complexity.
Solution Approach 2:
The patent changes the clock frequency parameter depending on the operational phase. By using a lower frequency reference clock during reset operations and switching to a higher frequency function clock during normal operations, the system achieves both synchronized reset timing and high-speed performance without increasing circuit area.
2Manufacturing precision
If multiple buffers are added to the reset tree to synchronize reset timing, then reset timing accuracy is improved, but the circuit area increases
Solution Approach 1:
Instead of adding multiple buffers to achieve timing synchronization, the patent changes the clock frequency parameter during reset operations. By using a lower-frequency reference clock, the system naturally achieves synchronized reset timing across all flip-flops without requiring additional buffer infrastructure, thereby maintaining timing accuracy while avoiding circuit area expansion.
3Manufacturing precision
If a slower reference clock is used during reset operations, then reset timing synchronization across flip-flops is improved, but the normal operation speed may be affected
Solution Approach 1:
The system dynamically switches between clock sources based on operational requirements. During reset operations, the lower-frequency reference clock is used to achieve precise timing synchronization. During normal operations, the system switches to the higher-frequency function clock to maintain high productivity. This dynamic switching resolves the contradiction between reset timing synchronization and normal operation speed.
Solution Approach 2:
The patent segments the operational phases into reset operations and normal operations, using different clock frequencies for each phase. This segmentation allows the system to optimize for timing synchronization during resets and for speed during normal operations, eliminating the need to compromise either requirement.
Data Source
AI summary
Disclosed are a semiconductor system and a method of controlling a reset operation clock of the semiconductor system for easily determining a reset timing by inputting a reference clock slower than a function clock to a clock operation unit by a clock multiplexer during a reset operation or reset release operation. The semiconductor system includes a clock management unit configured to operate according to a function clock to generate and output an output function clock for an operation of the semiconductor system, and a power management unit configured to perform power management of the semiconductor system including a reset operation or a reset release operation. The clock management unit includes a clock operation unit configured to operate according to the function clock in an operation mode to generate and output the output function clock, and a clock multiplexer configured to select different input clocks to be input to the clock operation unit in the operation mode and a reset mode and output the input clocks to the clock operation unit.